Network Working Group´╗┐

Internet Engineering Task Force (IETF)                     S. Nandakumar
Internet-Draft
Request for Comments: 8859                                         Cisco
Intended status:
Category: Standards Track                       February 28, 2018
Expires: September 1, 2018                                       May 2020
ISSN: 2070-1721

   A Framework for SDP Session Description Protocol (SDP) Attributes when When
                              Multiplexing
                draft-ietf-mmusic-sdp-mux-attributes-17

Abstract

   The purpose of this specification is to provide a framework for
   analyzing the multiplexing characteristics of Session Description
   Protocol (SDP) attributes when SDP is used to negotiate the usage of
   a single 5-tuple for sending and receiving media associated with
   multiple media descriptions.

   This specification also categorizes the existing SDP attributes based
   on the framework described herein.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on September 1, 2018.
   https://www.rfc-editor.org/info/rfc8859.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  SDP Attribute Analysis Framework  . . . . . . . . . . . . . .   6
     4.1.  Category: NORMAL  . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Category: CAUTION . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Category: IDENTICAL . . . . . . . . . . . . . . . . . . .   8
     4.4.  Category: SUM . . . . . . . . . . . . . . . . . . . . . .   9
     4.5.  Category: TRANSPORT . . . . . . . . . . . . . . . . . . .   9
     4.6.  Category: INHERIT . . . . . . . . . . . . . . . . . . . .  10
     4.7.  Category: IDENTICAL-PER-PT  . . . . . . . . . . . . . . .  11
     4.8.  Category: SPECIAL . . . . . . . . . . . . . . . . . . . .  12
     4.9.  Category: TBD . . . . . . . . . . . . . . . . . . . . . .  12
   5.  Analysis of Existing Attributes . . . . . . . . . . . . . . .  12
     5.1.  RFC4566:  RFC 4566: SDP  . . . . . . . . . . . . . . . . . . . . . .  13
     5.2.  RFC4585:  RFC 4585: RTP/AVPF . . . . . . . . . . . . . . . . . . . .  14
     5.3.  RFC5761:  RFC 5761: Multiplexing RTP and RTCP  . . . . . . . . . . .  15
     5.4.  RFC3312:  RFC 3312: Integration of Resource Management and SIP . . .  15
     5.5.  RFC4574:  RFC 4574: SDP Label "label" Attribute  . . . . . . . . . . . . . .  16
     5.6.  RFC5432: QOS  RFC 5432: QoS Mechanism Selection in SDP . . . . . . . . .  16
     5.7.  RFC4568:  RFC 4568: SDP Security Descriptions  . . . . . . . . . . .  17
     5.8.  RFC5762:  RFC 5762: RTP over DCCP  . . . . . . . . . . . . . . . . .  17
     5.9.  RFC6773:  RFC 6773: DCCP-UDP Encapsulation . . . . . . . . . . . . .  18
     5.10. RFC5506: RFC 5506: Reduced-Size RTCP in RTP Profile . . . . . . . .  19
     5.11. RFC6787: RFC 6787: Media Resource Control Protocol Version 2  . . .  19
     5.12. RFC5245: RFC 8445: ICE  . . . . . . . . . . . . . . . . . . . . . .  20
     5.13. RFC5285: RFC 5285: RTP Header Extensions  . . . . . . . . . . . . .  21
     5.14. RFC3605: RFC 3605: RTCP attribute Attribute in SDP  . . . . . . . . . . . . .  22
     5.15. RFC5576: RFC 5576: Source-Specific SDP Attributes . . . . . . . . .  22
     5.16. RFC7273: RFC 7273: RTP Clock Source Signalling  . . . . . . . . . .  23 Signaling
     5.17. RFC6236: RFC 6236: Image Attributes in SDP  . . . . . . . . . . . .  24
     5.18. RFC7197: RFC 7197: Duplication Delay Attribute in SDP . . . . . . .  25
     5.19. RFC7266: RFC 7266: RTCP XR Blocks for MOS Metric Reporting  . . . .  25
     5.20. RFC6285: RFC 6285: Rapid Acquisition of Multicast RTP Sessions  . .  25
     5.21. RFC6230: RFC 6230: Media Control Channel Framework  . . . . . . . .  26
     5.22. RFC6364: RFC 6364: SDP Elements for FEC Framework . . . . . . . . .  26
     5.23. RFC4796: Content RFC 4796: "content" Attribute  . . . . . . . . . . . . . . .  27
     5.24. RFC3407: RFC 3407: SDP Simple Capability Declaration  . . . . . . .  27
     5.25. RFC6284: RFC 6284: Port Mapping between Unicast and Multicast RTP
            Sessions  . . . . . . . . . . . . . . . . . . . . . . . .  28
     5.26. RFC6714: RFC 6714: MSRP-CEMA  . . . . . . . . . . . . . . . . . . .  29
     5.27. RFC4583: RFC 4583: SDP Format for BFCP Streams  . . . . . . . . . .  29
     5.28. RFC5547: RFC 5547: SDP Offer/Answer for File Transfer . . . . . . .  30
     5.29. RFC6849: RFC 6849: SDP and RTP Media Loopback Extension . . . . . .  30
     5.30. RFC5760: RFC 5760: RTCP with Unicast Feedback . . . . . . . . . . .  31
     5.31. RFC3611: RFC 3611: RTCP XR  . . . . . . . . . . . . . . . . . . . .  31
     5.32. RFC5939: RFC 5939: SDP Capability Negotiation . . . . . . . . . . .  32
     5.33. RFC6871: RFC 6871: SDP Media Capabilities Negotiation . . . . . . .  32
     5.34. RFC7006: RFC 7006: Miscellaneous Capabilities Negotiation in SDP . . .  33
     5.35. RFC4567: RFC 4567: Key Management Extensions for SDP and RTSP . . .  34
     5.36. RFC4572: RFC 4572: Comedia over TLS in SDP  . . . . . . . . . . . .  35
     5.37. RFC4570: RFC 4570: SDP Source Filters . . . . . . . . . . . . . . .  35
     5.38. RFC6128: RFC 6128: RTCP Port for Multicast Sessions . . . . . . . .  36
     5.39. RFC6189: RFC 6189: ZRTP . . . . . . . . . . . . . . . . . . . . . .  36
     5.40. RFC4145: RFC 4145: Connection-Oriented Media  . . . . . . . . . . .  37
     5.41. RFC6947: RFC 6947: The SDP altc "altc" Attribute . . . . . . . . . . . . .  37
     5.42. RFC7195: RFC 7195: SDP Extension for Circuit Switched Circuit-Switched Bearers in
            PSTN . . . . . . . . . . . . . . . . . . . . . . . . .  38
     5.43. RFC7272: RFC 7272: IDMS Using the RTP Control Protocol (RTCP) . . .  38
     5.44. RFC5159: RFC 5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP
            Attributes  . . . . . . . . . . . . . . . . . . . . . . .  39
     5.45. RFC6193: RFC 6193: Media Description for IKE in SDP . . . . . . . .  39
     5.46. RFC2326: RFC 2326: Real Time Streaming Protocol . . . . . . . . . .  40
     5.47. RFC6064: RFC 6064: SDP and RTSP Extensions for 3GPP . . . . . . . .  41
     5.48. RFC3108: RFC 3108: ATM SDP  . . . . . . . . . . . . . . . . . . . .  43
     5.49. 3GPP TS 26.114  . . . . . . . . . . . . . . . . . . . . .  45
     5.50. 3GPP TS 183.063 . . . . . . . . . . . . . . . . . . . . .  46
     5.51.
     5.50. 3GPP TS 24.182  . . . . . . . . . . . . . . . . . . . . .  46
     5.52.
     5.51. 3GPP TS 24.183  . . . . . . . . . . . . . . . . . . . . .  47
     5.53.
     5.52. 3GPP TS 24.229  . . . . . . . . . . . . . . . . . . . . .  47
     5.54.
     5.53. ITU T.38  . . . . . . . . . . . . . . . . . . . . . . . .  48
     5.55.
     5.54. ITU-T Q.1970  . . . . . . . . . . . . . . . . . . . . . .  50
     5.56.
     5.55. ITU-T H.248.15  . . . . . . . . . . . . . . . . . . . . .  50
     5.57. RFC4975:
     5.56. RFC 4975: The Message Session Relay Protocol . . . . . . .  51
     5.58.
     5.57. Historical Attributes . . . . . . . . . . . . . . . . . .  52
   6.  bwtype Attribute Analysis . . . . . . . . . . . . . . . . . .  52
     6.1.  RFC4566:  RFC 4566: SDP  . . . . . . . . . . . . . . . . . . . . . .  53
     6.2.  RFC3556:  RFC 3556: SDP Bandwidth Modifiers for RTCP Bandwidth . . .  53
     6.3.  RFC3890:  RFC 3890: Bandwidth Modifier for SDP . . . . . . . . . . .  54
   7.  rtcp-fb Attribute Analysis  . . . . . . . . . . . . . . . . .  54
     7.1.  RFC4585:  RFC 4585: RTP/AVPF . . . . . . . . . . . . . . . . . . . .  54
     7.2.  RFC5104:  RFC 5104: Codec Control Messages in AVPF . . . . . . . . .  55
     7.3.  RFC6285:  RFC 6285: Unicast-Based Rapid Acquisition of Multicast RTP
           Sessions (RAMS) . . . . . . . . . . . . . . . . . . . . .  56
     7.4.  RFC6679:  RFC 6679: ECN for RTP over UDP/IP  . . . . . . . . . . . .  56
     7.5.  RFC6642:  RFC 6642: Third-Party Loss Report  . . . . . . . . . . . .  57
     7.6.  RFC5104:  RFC 5104: Codec Control Messages in AVPF . . . . . . . . .  58
   8.  group Attribute Analysis  . . . . . . . . . . . . . . . . . .  58
     8.1.  RFC5888:  RFC 5888: SDP Grouping Framework . . . . . . . . . . . . .  58
     8.2.  RFC3524:  RFC 3524: Mapping Media Streams to Resource Reservation
           Flows . . . . . . . . . . . . . . . . . . . .  59
     8.3.  RFC4091:  RFC 4091: ANAT Semantics . . . . . . . . . . . . . . . . .  59
     8.4.  RFC5956:  RFC 5956: FEC Grouping Semantics in SDP  . . . . . . . . .  59
     8.5.  RFC5583:  RFC 5583: Signaling Media Decoding Dependency in SDP . . .  60
     8.6.  RFC7104:  RFC 7104: Duplication Grouping Semantics in the SDP . . .  60
   9.  ssrc-group Attribute Analysis . . . . . . . . . . . . . . . .  61
     9.1.  RFC5576:  RFC 5576: Source-Specific SDP Attributes . . . . . . . . .  61
     9.2.  RFC7104:  RFC 7104: Duplication Grouping Semantics in the SDP  . . .  61
   10. QoS Mechanism Token Analysis  . . . . . . . . . . . . . . . .  62
     10.1.  RFC5432:  RFC 5432: QoS Mechanism Selection in SDP  . . . . . . . .  62
   11. k= Attribute Analysis . . . . . . . . . . . . . . . . . . . .  62
     11.1.  RFC4566:  RFC 4566: SDP . . . . . . . . . . . . . . . . . . . . . .  63
   12. content Attribute Analysis  . . . . . . . . . . . . . . . . .  63
     12.1.  RFC4796  . . . . . . . . . . . . . . . . . . . . . . . .  63  RFC 4796
   13. Payload Formats . . . . . . . . . . . . . . . . . . . . . . .  64
     13.1.  RFC5109:  RFC 5109: RTP Payload Format for Generic FEC  . . . . . .  64
   14. Multiplexing Considerations for Encapsulating Attributes  . .  64
     14.1.  RFC3407:  RFC 3407: cpar Attribute Analysis . . . . . . . . . . . .  65
     14.2.  RFC5939  RFC 5939 Analysis . . . . . . . . . . . . . . . . . . . .  65
       14.2.1.  Recommendation: Procedures for Potential Configuration
               Pairing  . . . . . . . . . . . . . . .  66
         14.2.1.1.  Example: Transport Capability Multiplexing . . .  67
         14.2.1.2.  Example: Attribute Capability Multiplexing . . .  68
     14.3.  RFC6871  RFC 6871 Analysis . . . . . . . . . . . . . . . . . . . .  69
       14.3.1.  Recommendation: Dealing with Payload Type Numbers  .  69
         14.3.1.1.  Example: Attribute Capability Under Shared
                    Payload Type . . . . . . . . . . . . . . . . . .  69
       14.3.2.  Recommendation: Dealing with Latent Configurations .  70
   15. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  71
     15.1.  New 'Multiplexing Categories' subregistry  . . . . . . .  71 "Multiplexing Categories" Subregistry
     15.2.  'Mux Category' column  "Mux Category" Column for subregistries  . . . . . . . .  72 Subregistries
       15.2.1.  Table: SDP bwtype  . . . . . . . . . . . . . . . . .  72
       15.2.2.  Table: att-field (session level) . . . . . . . . . .  72
       15.2.3.  Table: att-field (both session and media level)  . .  73
       15.2.4.  Table: att-field (media level only)  . . . . . . . .  75
       15.2.5.  Table: att-field (source level)  . . . . . . . . . .  78
       15.2.6.  Table: content SDP Parameters  . . . . . . . . . . .  79
       15.2.7.
       15.2.4.  Table: Semantics for the 'group' "group" SDP Attribute . . .  79
       15.2.8.
       15.2.5.  Table: 'rtcp-fb' "rtcp-fb" Attribute Values  . . . . . . . . .  80
       15.2.9.
       15.2.6.  Table: 'ack' "ack" and 'nack' "nack" Attribute Values . . . . . .  80
       15.2.10.
       15.2.7.  Table: 'depend' "depend" SDP Attribute Values . . . . . . . .  80
       15.2.11.
       15.2.8.  Table: 'cs-correlation' "cs-correlation" Attribute Values . . . . . .  81
       15.2.12.
       15.2.9.  Table: Semantics for the 'ssrc-group' "ssrc-group" SDP Attribute   81
       15.2.13.
       15.2.10. Table: SDP/RTSP key management protocol identifiers   81
       15.2.14. Key Management Protocol Identifiers
       15.2.11. Table: Codec Control Messages  . . . . . . . . . . .  82
       15.2.15.
       15.2.12. Table: QoS Mechanism Tokens  . . . . . . . . . . . .  82
       15.2.16.
       15.2.13. Table: SDP Capability Negotiation Option Tags  . . .  82
       15.2.17.
       15.2.14. Table: Timestamp Reference Clock Source Parameters .  83
       15.2.18.
       15.2.15. Table: Media Clock Source Parameters . . . . . . . .  83
   16. Security Considerations . . . . . . . . . . . . . . . . . . .  84
   17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  84
   18. Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .  84
   19. References  . . . . . . . . . . . . . . . . . . . . . . . . .  88
     19.1.
     17.1.  Normative References . . . . . . . . . . . . . . . . . .  88
     19.2.
     17.2.  Informative References . . . . . . . . . . . . . . . . .  88
   Acknowledgements
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  97

1.  Introduction

   SDP defines several attributes for capturing characteristics that
   apply to the individual media descriptions (described by "m=" lines") lines)
   and the overall multimedia session.  Typically  Typically, different media types
   (audio, video, etc.) described using different media descriptions
   represent separate RTP sessions that are carried over individual
   transport layer
   transport-layer flows.  However
   [I-D.ietf-mmusic-sdp-bundle-negotiation]  However, [RFC8843] defines a way to use a
   single address:port combination (BUNDLE address) for receiving media
   associated with multiple SDP media descriptions.  This would, for
   example
   example, allow the usage of a single set of Interactive Connectivity
   Establishment (ICE) [RFC5245] [RFC8445] candidates for multiple media
   descriptions.  This  This, in turn turn, has made it necessary to understand the
   interpretation and usage of the SDP attributes defined for the
   multiplexed media descriptions.

   Given the number of SDP attributes registered with the [IANA] and the
   possibility of new attributes being defined in the future, there is
   need for a framework to analyze these attributes for their
   applicability in the transport multiplexing use-cases. use cases.

   The document starts with providing the motivation for requiring such
   a framework.  This is followed by introduction to the SDP attribute
   analysis framework/procedures, framework and procedures, following which several sections
   apply the framework to the SDP attributes registered with the [IANA].

2.  Terminology

   5-tuple:  A collection of the following values: source address,
      source port, destination address, destination port, and transport-layer transport-
      layer protocol.

   3GPP:  Third Generation Partnership Project; see http://www.3gpp.org
      <https://www.3gpp.org> for more information about this
      organization.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Motivation

   The

   An effort to reduce the number of necessary transport-level flows is
   required because of the time and complications of involved in setting up ICE [RFC5245] and Datagram
   Transport Layer Security (DTLS) based
   Secure Real-time Transport Protocol (SRTP) [RFC5763] transports for
   use by RTP, reasons to
   conserve RTP based on ICE [RFC8445] and Datagram Transport Layer
   Security (DTLS).  These procedures motivate conservation of ports
   bindings on the Network Address Translators (NAT),
   forms a requirement to try and reduce the number of transport level
   flows needed. (NATs).  This necessity
   has resulted in the definition of ways, such as
   [I-D.ietf-mmusic-sdp-bundle-negotiation] that described in
   [RFC8843], to multiplex RTP over a single transport flow in order to
   preserve network resources such as port numbers.  This imposes
   further restrictions on applicability of the SDP attributes as they
   are defined today.

   The specific problem is that there are attribute combinations which that
   make sense when specified on independent "m=" lines -- as with
   classical SDP -- that do not make sense when those "m=" lines are
   then multiplexed over the same transport.  To give an obvious
   example, ICE permits each "m=" line to have an independently
   specified ice-ufrag "ice-ufrag" attribute.  However, if the media from multiple
   "m=" lines is multiplexed over the same ICE component, then the
   meaning of media-level ice-ufrag "ice-ufrag" attributes becomes muddled.

   At the time of writing this document document, there are close to 250 SDP
   attributes registered with the [IANA] [IANA], and more will be added in the
   future.  There is no clearly defined procedure to establish the
   validity/applicability of these attributes when used with transport
   multiplexing.

4.  SDP Attribute Analysis Framework

   Attributes in an SDP session description can be defined at the
   session-level or media-level
   session level, media level, or source-level. source level.  Informally, there are
   various semantic groupings for these attributes.  One such grouping
   could be notes as below:

   o follows:

   *  Attributes related to media content such as media type, encoding
      schemes
      schemes, and payload types.

   o

   *  Attributes specifying media transport characteristics like RTP/RTP such as RTP/
      RTP Control Protocol (RTCP) port numbers, network addresses addresses, and QOS.

   o
      QoS.

   *  Metadata description attributes capturing session timing and
      origin information.

   o

   *  Attributes establishing relationships between media descriptions descriptions,
      such as grouping framework [RFC5888] [RFC5888].

   The proposed framework analyzes the SDP attributes usage under
   multiplexing and assigns each SDP attribute to an appropriate
   multiplexing category.  Since the multiplexing categories defined in
   this specification are independent of any informal semantic groupings
   of the SDP attributes, the categorizations assigned are normative.

4.1.  Category: NORMAL

   The attributes in the NORMAL category can be independently specified
   when multiplexed multiplexed, and they retain their original semantics.

   In the example given below, the direction and label attributes are
   independently specified for audio and video "m=" lines.  These
   attributes are not impacted by multiplexing these media streams over
   a single transport layer transport-layer flow.

        v=0
        o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
        s=
        c=IN IP4 host.atlanta.example.com
        t=0 0
        m=audio 49172 RTP/AVP 99
        a=sendonly
        a=label:1
        a=rtpmap:99 iLBC/8000
        m=video 49172 RTP/AVP 31
        a=recvonly
        a=label:2
        a=rtpmap:31 H261/90000

4.2.  Category: CAUTION

   The

   It is not advisable to multiplex with the attributes in the CAUTION category are advised against
   multiplexing
   category, since their usage under multiplexing might lead to
   incorrect behavior.

   Example: Multiplexing media descriptions over a single Datagram
   Congestion Control Protocol (DCCP) transport [RFC5762] is not
   recommended
   recommended, since DCCP being is a connection oriented connection-oriented protocol and
   therefore doesn't allow multiple connections on the same 5-tuple.

        v=0
        o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
        s=
        c=IN IP4 client.biloxi.example.com
        t=0 0
        m=video 5004 DCCP/RTP/AVP 99
        a=rtpmap:99 h261/9000
        a=dccp-service-code:SC=x52545056
        a=setup:passive
        a=connection:new
        m=video 5004 DCCP/RTP/AVP 100
        a=rtpmap:100 h261/9000
        a=dccp-service-code:SC=x5254504f
        a=setup:passive
        a=connection:new

4.3.  Category: IDENTICAL

   The attributes and their associated values (if any) in the IDENTICAL
   category MUST be repeated across all the media descriptions under
   multiplexing.

   Attributes such as rtcp-mux fall into this category.  Since RTCP
   reporting is done per RTP session, RTCP Multiplexing multiplexing MUST be enabled
   for both the audio and video "m=" lines if they are transported over
   a single 5-tuple.

        v=0
        o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
        s=
        c=IN IP4 client.biloxi.example.com
        t=0 0
        m=audio 34567 RTP/AVP 97
        a=rtcp-mux
        m=video 34567 RTP/AVP 31
        a=rtpmap:31 H261/90000
        a=rtcp-mux

   Note: Eventhough Even though IDENTICAL attributes must be repeated across all
   media descriptions under multiplexing, they might not always be
   explicitly encoded across all media descriptions.
   [I-D.ietf-mmusic-sdp-bundle-negotiation]  [RFC8843] defines
   rules for when attributes and their values are implicitly applied to
   media description.

4.4.  Category: SUM

   The attributes in the SUM category can be set as they are normally
   used
   used, but software using them in the multiplexing scenario MUST apply
   the sum of all the attributes being multiplexed instead of trying to
   use them independently.  This is typically used for bandwidth or
   other rate limiting rate-limiting attributes to the underlying transport.

   The software parsing the SDP sample below, below should use the aggregate
   Application Specific (AS) bandwidth value from the individual media
   descriptions to determine the AS value for the multiplexed session.
   Thus the calculated AS value would be 256+64 kilobits per second for
   the given example.

         v=0
         o=test 2890844526 2890842807 IN IP4 client.biloxi.example.com
         c=IN IP4 client.biloxi.example.com
         t=0 0
         m=audio 49170 RTP/AVP 0
         b=AS:64
         m=video 51372 RTP/AVP 31
         b=AS:256

4.5.  Category: TRANSPORT

   The attributes in the TRANSPORT category can be set normally for
   multiple items in a multiplexed group group, but the software MUST pick the
   one that's associated with the "m=" line whose information is used
   for setting up the underlying transport.

   In the example below, the "a=crypto" attribute is defined for both
   the audio and the video "m=" lines.  The video media line's a=crypto
   attribute is chosen since its mid value (bar) appears first in the
   a=group:BUNDLE line.  This is due to the BUNDLE grouping semantic
   [I-D.ietf-mmusic-sdp-bundle-negotiation]
   [RFC8843], which mandates that the values from the "m=" line
   corresponding to the mid appearing first on the a=group:BUNDLE line to
   be considered for setting up the RTP
   Transport. transport.

        v=0
        o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
        s=
        c=IN IP4 host.atlanta.example.com
        t=0 0
        a=group:BUNDLE bar foo
        m=audio 49172 RTP/AVP 99
        a=mid:foo
        a=crypto:1 AES_CM_128_HMAC_SHA1_80
          inline:d0RmdmcmVCspeEc3QGZiNWpVLFJhQX1cfHAwJSoj|2^20|1:32
        a=rtpmap:99 iLBC/8000
        m=video 51374 RTP/AVP 31
        a=mid:bar
        a=crypto:1 AES_CM_128_HMAC_SHA1_80
          inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32
        a=rtpmap:96 H261/90000

4.6.  Category: INHERIT

   The attributes in the INHERIT category encapsulate other SDP
   attributes or parameters.  These attributes inherit their
   multiplexing characteristics from the attributes or parameters they
   encapsulate.  Such attributes are defined in [RFC3407], [RFC5939] [RFC5939],
   and [RFC6871] as part of a generic framework for indicating and
   negotiating capabilities in the SDP related to transport, media, and
   media format related capabilities
   in the SDP. format.

   The inheritance manifests itself when the encapsulated attribute or
   parameter is being leveraged.  In the case of SDP Capability
   Negotiation [RFC5939] [RFC5939], for example, this occurs when a capability
   (encapsulating attribute) is used as part of a configuration; the
   configuration inherits the multiplexing category of each of its
   constituent (encapsulated) attributes and parameters.  The inherited
   attributes MUST be coherent in order to form a valid configuration
   from a multiplexing point of view (see Section 14 for further
   details).

          v=0
          o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
          s=
          c=IN IP4 host.atlanta.example.com
          t=0 0
          m=video 3456 RTP/AVP 100
          a=rtpmap:100 VP8/90000
          a=fmtp:100 max-fr=30;max-fs=8040
          a=sqn: 0
          a=cdsc: 1 video RTP/AVP 100
          a=cpar: a=rtcp-mux
          m=video 3456 RTP/AVP 101
          a=rtpmap:101 VP8/90000
          a=fmtp:100 max-fr=15;max-fs=1200
          a=cdsc: 2 video RTP/AVP 101
          a=cpar: a=rtcp-mux

   In the above this example, the category IDENTICAL is inherited by the cpar cpar-
   encapsulated rtcp-mux "rtcp-mux" attribute.

4.7.  Category: IDENTICAL-PER-PT

   The attributes in the IDENTICAL-PER-PT category define the RTP
   payload configuration on per Payload Type the basis of the payload type, and they MUST
   have identical values across all the media descriptions for a given
   RTP
   Payload Type payload type when repeated.  These Payload Types payload types identify the
   same codec configuration as defined in the Section 10.1.2 9.1 of
   [I-D.ietf-mmusic-sdp-bundle-negotiation] [RFC8843] under
   this context.

   In the SDP example below, Payload Types 96 and 97 are repeated across
   all the video "m=" lines lines, and all the payload specific payload-specific parameters (ex:
   rtpmap,
   (for example, rtpmap and fmtp) are identical identical.  (Note: some line
   breaks included are due to formatting only). only.)

        v=0
        o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
        s=
        c=IN IP4 host.atlanta.example.com
        t=0 0
        a=group:BUNDLE cam1 cam2
        m=video 96 97
        a=mid:cam1
        a=rtpmap:96 H264/90000
        a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000;
        max-mbps=108000; max-br=1000
        a=rtpmap:97 H264/90000
        a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000;
        max-mbps=7200; max-br=200
        m=video  96 97
        a=mid:cam2
        a=rtpmap:96 H264/90000
        a=fmtp:96 profile-level-id=42400d; max-fs=3600; max-fps=3000;
        max-mbps=108000; max-br=1000
        a=rtpmap:97 H264/90000
        a=fmtp:97 profile-level-id=42400a; max-fs=240; max-fps=3000;
        max-mbps=7200; max-br=200

4.8.  Category: SPECIAL

   For the attributes in the SPECIAL category, the text in the
   specification defining the attribute MUST be consulted for further
   handling when multiplexed.

   As an exampe, example, for the attribute extmap "extmap" [RFC5285], the
   specification defining the extension needs to be referred consulted to
   understand the multiplexing implications.

4.9.  Category: TBD

   The attributes in the TBD category have not been analyzed under the
   proposed multiplexing framework and SHOULD NOT be multiplexed.

5.  Analysis of Existing Attributes

   This section analyzes attributes listed in [IANA], grouped under the
   IETF document that defines them.

   The "Level" column indicates whether the attribute is currently
   specified as:

   o

   *  S -- Session level
   o

   *  M -- Media level

   o

   *  B -- Both (Implies either a session level or a media level
      attribute)

   o

   *  SR -- Source-level (for a single SSRC) [RFC5576]

   The "Mux Category" column identifies the multiplexing category
   assigned
   per attribute to each attribute, and the "Notes" column captures
   additional informative details regarding the assigned category,
   wherever necessary.

5.1.  RFC4566:  RFC 4566: SDP

   [RFC4566] defines SDP that is intended for describing multimedia
   sessions for the purposes of session announcement, session
   invitation, and other forms of multimedia session initiation.

   +----------------+-----------------------+-------+------------------+

    +----------------+---------------------+-------+------------------+
    | Name           | Notes               | Level | Mux Category     |
   +----------------+-----------------------+-------+------------------+
    +================+=====================+=======+==================+
    | sendrecv       | Not impacted        | B     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | sendonly       | Not impacted        | B     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | recvonly       | Not impacted        | B     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | inactive       | Not impacted        | B     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | cat            | Not impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | ptime          | The attribute value | M     | IDENTICAL-PER-PT |
    |                | MUST be the same for a    |       |                  |
    |                | for a given codec   |       |                  |
    |                | configuration         |       |                  |
   |                | configuration.      |       |                  |
    +----------------+---------------------+-------+------------------+
    | maxptime       | The attribute value | M     | IDENTICAL-PER-PT |
    |                | MUST be the same for a    |       |                  |
    |                | for a given codec   |       |                  |
    |                | configuration         |       |                  |
   |                | configuration.      |       |                  |
    +----------------+---------------------+-------+------------------+
    | orient         | Not Impacted impacted        | M     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | framerate      | The attribute value | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
    |                | MUST be the same for a    |       | PT                  |
    |                | for a given codec   |       |                  |
    |                | configuration         |       |                  |
   |                | configuration.      |       |                  |
    +----------------+---------------------+-------+------------------+
    | quality        | Not Impacted impacted        | M     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | rtpmap         | The attribute value | M     | IDENTICAL-PER-PT |
    |                | MUST be the same for a    |       |                  |
    |                | for a given codec   |       |                  |
    |                | configuration         |       |                  |
   |                | configuration.      |       |                  |
    +----------------+---------------------+-------+------------------+
    | fmtp           | The attribute value | M     | IDENTICAL-PER-PT |
    |                | MUST be the same for a    |       |                  |
    |                | for a given codec   |       |                  |
    |                | configuration         |       |                  |
   |                | configuration.      |       |                  |
    +----------------+---------------------+-------+------------------+
    | keywds         | Not impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | type           | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | type:broadcast | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | type:H332      | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | type:meeting   | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | type:moderated | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | type:test      | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | tool           | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | charset        | Not Impacted impacted        | S     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | sdplang        | Not Impacted impacted        | B     | NORMAL           |
   |                |                       |       |                  |
    +----------------+---------------------+-------+------------------+
    | lang           | Not Impacted impacted        | B     | NORMAL           |
   |                |                       |       |                  |
   +----------------+-----------------------+-------+------------------+

                      5.1 RFC4566
    +----------------+---------------------+-------+------------------+

                    Table 1: RFC 4566 Attribute Analysis

5.2.  RFC4585:  RFC 4585: RTP/AVPF

   [RFC4585] defines an extension to the Audio-visual Profile (AVP) that
   enables receivers to provide, statistically, more immediate feedback
   to the senders and thus allows for short-term adaptation and
   efficient feedback-based repair mechanisms to be implemented.

   +---------+------------------------------+-------+------------------+

    +---------+---------------------------+-------+------------------+
    | Name    | Notes                     | Level | Mux Category     |
   +---------+------------------------------+-------+------------------+
    +=========+===========================+=======+==================+
    | rtcp- rtcp-fb | Since RTCP feedback       | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
    | fb         | attributes are Payload Type scoped by  |       | PT                  |
    |         | (PT) scoped, payload type (PT), their values  |       |                  |
    |         | values MUST be identical for a  |       |                  |
    |         | for a given PT across the |       |                  |
    |         | multiplexed "m=" lines.   |       |                  |
   |         |                              |       |                  |
   +---------+------------------------------+-------+------------------+

                      5.2 RFC4585
    +---------+---------------------------+-------+------------------+

                   Table 2: RFC 4585 Attribute Analysis

5.3.  RFC5761:  RFC 5761: Multiplexing RTP and RTCP

   [RFC5761] discusses issues that arise when multiplexing RTP data
   packets and RTP Control Protocol (RTCP) packets on a single UDP port.
   It describes when such multiplexing is and is not appropriate, and it
   explains how the SDP can be used to signal multiplexed sessions.

   +----------+------------------------------------+-------+-----------+

   +----------+---------------------------------+-------+--------------+
   | Name     | Notes                           | Level | Mux          |
   |          |                                 |       | Category     |
   +----------+------------------------------------+-------+-----------+
   +==========+=================================+=======+==============+
   | rtcp- rtcp-mux | RTP and RTCP Multiplexing affects multiplexing       | M     | IDENTICAL    |
   | mux          | affects the entire RTP session             |       |           |
   |          | session. |       |              |
   +----------+------------------------------------+-------+-----------+

                      5.3 RFC5761
   +----------+---------------------------------+-------+--------------+

                    Table 3: RFC 5761 Attribute Analysis

5.4.  RFC3312:  RFC 3312: Integration of Resource Management and SIP

   [RFC3312] defines a generic framework for preconditions, which are
   extensible through IANA registration.  This document also discusses
   how network quality of service can be made a precondition for
   establishment of sessions initiated by the Session Initiation
   Protocol (SIP).  These preconditions require that the participant
   reserve network resources before continuing with the session.

         +-------+-----------------------+-------+--------------+

          +------+----------------------+-------+--------------+
          | Name | Notes                | Level | Mux Category |
         +-------+-----------------------+-------+--------------+
          +======+======================+=======+==============+
          | des  | Refer to notes below | M     | CAUTION      |
         |       |                       |       |              |
          +------+----------------------+-------+--------------+
          | conf | Refer to notes below | M     | CAUTION      |
         |       |                       |       |              |
          +------+----------------------+-------+--------------+
          | curr | Refer to notes below | M     | CAUTION      |
         |       |                       |       |              |
         +-------+-----------------------+-------+--------------+

                      5.4 RFC3312
          +------+----------------------+-------+--------------+

                   Table 4: RFC 3312 Attribute Analysis

   NOTE: A mismatched set of preconditions across media descriptions
   results in Session session establishment failures due to inability to meet
   right
   the requested resource reservations requested. reservations.

5.5.  RFC4574:  RFC 4574: SDP Label "label" Attribute

   [RFC4574] defines a new SDP media-level attribute: "label".  The
   "label" attribute carries a pointer to a media stream in the context
   of an arbitrary network application that uses SDP.  The sender of the
   SDP document can attach the "label" attribute to a particular media
   stream or streams.  The application can then use the provided pointer
   to refer to each particular media stream in its context.

             +--------+---------------+-------+--------------+

              +-------+--------------+-------+--------------+
              | Name  | Notes        | Level | Mux Category |
             +--------+---------------+-------+--------------+
              +=======+==============+=======+==============+
              | label | Not Impacted impacted | M     | NORMAL       |
             |        |               |       |              |
             +--------+---------------+-------+--------------+

                      5.5 RFC4574
              +-------+--------------+-------+--------------+

                    Table 5: RFC 4574 Attribute Analysis

5.6.  RFC5432: QOS  RFC 5432: QoS Mechanism Selection in SDP

   [RFC5432] defines procedures to negotiate QOS for negotiating QoS mechanisms using the
   SDP offer/answer model.

     +----------------+-----------------------+-------+--------------+

      +---------------+----------------------+-------+--------------+
      | Name          | Notes                | Level | Mux Category |
     +----------------+-----------------------+-------+--------------+
      +===============+======================+=======+==============+
      | qos-mech-send | Refer to Section 10 10. | B     | TRANSPORT    |
     |                |                       |       |              |
      +---------------+----------------------+-------+--------------+
      | qos-mech-recv | Refer to Section 10 10. | B     | TRANSPORT    |
     |                |                       |       |              |
     +----------------+-----------------------+-------+--------------+

                      5.6 RFC5432
      +---------------+----------------------+-------+--------------+

                    Table 6: RFC 5432 Attribute Analysis

5.7.  RFC4568:  RFC 4568: SDP Security Descriptions

   [RFC4568] defines a an SDP cryptographic attribute for unicast media
   streams.  The attribute describes a cryptographic key and other
   parameters that serve to configure security for a unicast media
   stream in either a single message or a roundtrip exchange.

   +--------+--------------------------------------+-------+-----------+

     +--------+---------------------------------+-------+-----------+
     | Name   | Notes                           | Level | Mux       |
     |        |                                 |       | Category  |
   +--------+--------------------------------------+-------+-----------+
     +========+=================================+=======+===========+
     | crypto | crypto attribute MUST be the one    | M     | TRANSPORT |
     |        | one that corresponds to the "m=" line     |       |           |
     |        | "m=" line chosen for setting up the underlying |       |           |
     |        | the underlying transport flow                       |       |           |
   |        | flow.  |       |           |
   +--------+--------------------------------------+-------+-----------+

                      5.7 RFC4568
     +--------+---------------------------------+-------+-----------+

                   Table 7: RFC 4568 Attribute Analysis

5.8.  RFC5762:  RFC 5762: RTP over DCCP

   RTP is a widely used transport for real-time multimedia on IP
   networks.  DCCP is a transport protocol that provides desirable
   services for real-time applications.  [RFC5762] specifies a mapping
   of RTP onto DCCP, along with associated signaling, such that real-
   time applications can make use of the services provided by DCCP.

   +-------------------+--------------------------+---------+----------+

     +-------------------+----------------------+---------+----------+
     | Name              | Notes                | Current | Mux      |
     |                   |                      |         | Category |
   +-------------------+--------------------------+---------+----------+
     +===================+======================+=========+==========+
     | dccp-service- dccp-service-code | If RFC6773 RFC 6773 is not being   | M       | CAUTION  |
     | code                   | being used in        |         |          |
     |                   | addition to RFC5762, |         |          |
     |                   | RFC5762, the port in the "m=" |         |          |
     |                   | "m=" line is a DCCP port. |         |          |
     |                   | port. DCCP being Being a connection-  |         |          |
     |                   | connection oriented protocol,   |         |          |
     |                   | protocol DCCP does not allow  |         |          |
     |                   | multiple connections on |         |          |
     |                   | on the same 5-tuple         |         |          |
   |                   | 5-tuple. |         |          |
   +-------------------+--------------------------+---------+----------+

                      5.8 RFC5762
     +-------------------+----------------------+---------+----------+

                    Table 8: RFC 5762 Attribute Analysis

   NOTE: If RFC6773 RFC 6773 is being used in addition to RFC5762 RFC 5762, and provided
   that the
   DCCP-in-UDP layer has additional demultiplexing, then it can may be
   possible to use different DCCP service codes for each DCCP flow,
   given each uses a different DCCP port.  Although  However, doing so might
   conflict with the media type of the "m=" line.  None of this is
   standardized yet yet, and it wouldn't work as explained.  Hence
   performing multiplexing is not recommended even in this alternate
   scenario.

5.9.  RFC6773:  RFC 6773: DCCP-UDP Encapsulation

   [RFC6773] specifies an alternative encapsulation of DCCP, referred to
   as DCCP-UDP.  This encapsulation allows DCCP to be carried through
   the current generation of Network Address Translation (NAT) middle
   boxes
   middleboxes without modification of those middle boxes.

   +-----------+------------------------------------+-------+----------+ middleboxes.

      +-----------+------------------------------+-------+----------+
      | Name      | Notes                        | Level | Mux      |
      |           |                              |       | Category |
   +-----------+------------------------------------+-------+----------+
      +===========+==============================+=======+==========+
      | dccp- dccp-port | Multiplexing is not recommended          | M     | CAUTION  |
      | port           | recommended due to potential conflict between |       |          |
      |           | conflict between the port used for DCCP    |       |          |
      |           | en/decapsulation and the RTP used for DCCP encapsulation/ |       |          |
      |           | decapsulation and the RTP.   |       |          |
   +-----------+------------------------------------+-------+----------+

                      5.9 RFC6773
      +-----------+------------------------------+-------+----------+

                    Table 9: RFC 6773 Attribute Analysis

   NOTE: RFC6773 is about tunneling DCCP in UDP, RFC 6773 allows DCCP-UDP encapsulation, with the UDP port being
   the port of the DCCP en-/de-capsulation encapsulation/decapsulation service.  This
   encapsulation allows arbitrary DCCP packets to be encapsulated encapsulated, and
   the DCCP port chosen can conflict with the port chosen for the RTP
   traffic.  For
   multiplexing  Multiplexing several DCCP-in-UDP encapsulations on the same
   UDP port with no RTP traffic on the same port implies collapsing
   several DCCP port spaces together.  This can  Whether or cannot work depending not this works depends
   on the nature of DCCP encapsulation and ports choices thus rendering choices; it to
   be is thus
   very application dependent.

5.10.  RFC5506:  RFC 5506: Reduced-Size RTCP in RTP Profile

   [RFC5506] discusses benefits and issues that arise when allowing RTCP
   packets to be transmitted with reduced size.

   +------------+----------------------------------+-------+-----------+

     +------------+---------------------------+-------+--------------+
     | Name       | Notes                     | Level | Mux       |
   |            |                                  |       | Category |
   +------------+----------------------------------+-------+-----------+
     +============+===========================+=======+==============+
     | rtcp- rtcp-rsize | Reduced size Reduced-size RTCP affects the | M     | IDENTICAL    |
     | rsize            | the entire RTP session               |       |           |
   |            | session.   |       |              |
   +------------+----------------------------------+-------+-----------+

                      5.10 RFC5506
     +------------+---------------------------+-------+--------------+

                   Table 10: RFC 5506 Attribute Analysis

5.11.  RFC6787:  RFC 6787: Media Resource Control Protocol Version 2

   The Media Resource Control Protocol Version 2 (MRCPv2) allows client
   hosts to control media service resources such as speech synthesizers,
   recognizers, verifiers, and identifiers residing in servers on the
   network.  MRCPv2 is not a "stand-alone" protocol -- protocol; it relies on other
   protocols, such as the SIP, to coordinate MRCPv2 clients and
   servers, servers
   and manage session between them, and SDP to describe, discover, and
   exchange capabilities.  It also depends on SIP and SDP to establish
   the media sessions and associated parameters between the media source
   or sink and the media server.  Once this is done, the MRCPv2 exchange
   operates over the control session established above, allowing the
   client to control the media processing media-processing resources on the speech
   resource server.  [RFC6787] defines attributes for this purpose.

           +-----------+---------------+-------+--------------+

            +----------+--------------+-------+--------------+
            | Name     | Notes        | Level | Mux Category |
           +-----------+---------------+-------+--------------+
            +==========+==============+=======+==============+
            | resource | Not Impacted impacted | M     | NORMAL       |
           |           |               |       |              |
            +----------+--------------+-------+--------------+
            | channel  | Not Impacted impacted | M     | NORMAL       |
           |           |               |       |              |
            +----------+--------------+-------+--------------+
            | cmid     | Not Impacted impacted | M     | NORMAL       |
           |           |               |       |              |
           +-----------+---------------+-------+--------------+

                      5.11 RFC6787
            +----------+--------------+-------+--------------+

                  Table 11: RFC 6787 Attribute Analysis

5.12.  RFC5245:  RFC 8445: ICE

   [RFC5245]

   [RFC8445] describes a protocol for NAT traversal for UDP-based
   multimedia sessions established with the offer/answer model.  ICE
   makes use of the Session Traversal Utilities for NAT (STUN) protocol
   and its extension, Traversal Using Relay NAT (TURN).  ICE can be used
   by any protocol utilizing the offer/answer model, such as the SIP.

   +-------------------+---------------------------+-------+-----------+
   | Name              | Notes                     | Level | Mux       |
   |                   |                           |       | Category  |
   +-------------------+---------------------------+-------+-----------+
   +===================+===========================+=======+===========+
   | ice-lite          | Not Impacted impacted              | S     | NORMAL    |
   |                   |                           |       |           |
   +-------------------+---------------------------+-------+-----------+
   | ice-options       | Not Impacted impacted              | S     | NORMAL    |
   |                   |                           |       |           |
   +-------------------+---------------------------+-------+-----------+
   | ice-mismatch      | Not Impacted impacted              | S     | NORMAL    |
   |                   |                           |       |           |
   +-------------------+---------------------------+-------+-----------+
   | ice-pwd           | ice-pwd MUST be the one   | B     | TRANSPORT |
   |                   | that corresponds to the   |       |           |
   |                   | "m=" line chosen for      |       |           |
   |                   | setting up the underlying            |       |           |
   |                   | underlying transport flow      |       |           |
   |                   | flow.                     |       |           |
   +-------------------+---------------------------+-------+-----------+
   | ice-ufrag         | ice-ufrag MUST be the one     | B     | TRANSPORT |
   |                   | one that corresponds to the   |       |           |
   |                   | the "m=" line chosen for      |       |           |
   |                   | for setting up the underlying        |       |           |
   |                   | underlying transport flow      |       |           |
   |                   | flow.                     |       |           |
   +-------------------+---------------------------+-------+-----------+
   | candidate         | ice candidate MUST be the     | M     | TRANSPORT |
   |                   | the one that corresponds to              |       |           |
   |                   | corresponds to the "m="   |       |           |
   |                   | line chosen for setting   |       |           |
   |                   | setting up the underlying         |       |           |
   |                   | transport flow            |       |           |
   |                   | flow.           |       |           |
   +-------------------+---------------------------+-------+-----------+
   | remote- remote-candidates | ice remote candidate MUST      | M     | TRANSPORT |
   | candidates                   | MUST be the one that      |       |           |
   |                   | corresponds to the "m="   |       |           |
   |                   | line chosen for setting   |       |           |
   |                   | up the underlying         |       |           |
   |                   | transport flow flow.           |       |           |
   +-------------------+---------------------------+-------+-----------+
   | ice2              | Not impacted              | S     | NORMAL    |
   +-------------------+---------------------------+-------+-----------+

                      5.12 RFC5245

                   Table 12: RFC 8445 Attribute Analysis

5.13.  RFC5285:  RFC 5285: RTP Header Extensions

   [RFC5285] provides a general mechanism to use for using the header extension header-extension
   feature of RTP.  (Note: [RFC5285] has been obsoleted by [RFC8285].)
   It provides the option to use a small number of small extensions in
   each RTP packet, where the universe of possible extensions is large
   and registration is de-centralized. decentralized.  The actual extensions in use in a
   session are signaled in the setup information for that session.

   +--------+---------------------------------------+-------+----------+

    +--------+--------------------------------+-------+--------------+
    | Name   | Notes                          | Level | Mux      |
   |        |                                       |       | Category |
   +--------+---------------------------------------+-------+----------+
    +========+================================+=======+==============+
    | extmap | Refer to the document defining the | B     | SPECIAL      |
    |        | the specific RTP Extension                |       |          |
   |        | extension.    |       |              |
   +--------+---------------------------------------+-------+----------+

                      5.13 RFC5285
    +--------+--------------------------------+-------+--------------+

                  Table 13: RFC 5285 Attribute Analysis

5.14.  RFC3605:  RFC 3605: RTCP attribute Attribute in SDP

   Originally, SDP assumed that RTP and RTCP were carried on consecutive
   ports.  However, this is not always true when NATs are involved.
   [RFC3605] specifies an early mechanism to indicate for indicating the RTCP port.

   +------+----------------------------------------+-------+-----------+

       +------+--------------------------------+-------+-----------+
       | Name | Notes                          | Level | Mux       |
       |      |                                |       | Category  |
   +------+----------------------------------------+-------+-----------+
       +======+================================+=======+===========+
       | rtcp | RTCP Port port MUST be the one that | M     | TRANSPORT |
       |      | corresponds to the "m=" line chosen   |       |           |
       |      | chosen for setting up the underlying      |       |           |
       |      | underlying transport flow.     |       |           |
   |      |                                        |       |           |
   +------+----------------------------------------+-------+-----------+

                      5.14 RFC3605
       +------+--------------------------------+-------+-----------+

                   Table 14: RFC 3605 Attribute Analysis

5.15.  RFC5576:  RFC 5576: Source-Specific SDP Attributes

   [RFC5576] defines a mechanism to describe for describing RTP media sources, sources --
   which are identified by their synchronization source (SSRC) identifiers,
   identifiers -- in SDP, to associate attributes with these sources, sources and to
   express relationships among sources.  It also defines several source-level source-
   level attributes that can be used to describe properties of media
   sources.

   +---------------+------------------------+-------+------------------+

    +---------------+---------------------+-------+------------------+
    | Name          | Notes               | Level | Mux Category     |
   +---------------+------------------------+-------+------------------+
    +===============+=====================+=======+==================+
    | ssrc          | Refer to Notes below notes      | M     | NORMAL           |
    |               | below.              |       |                  |
    +---------------+---------------------+-------+------------------+
    | ssrc-group    | Refer to Section 9 for  | M     | NORMAL           |
    |               | for specific analysis of        |       |                  |
    |               | analysis of the grouping           |       |                  |
   |               | semantics     |       |                  |
    |               | grouping semantics. |       |                  |
    +---------------+---------------------+-------+------------------+
    | cname         | Not Impacted impacted        | SR    | NORMAL           |
    +---------------+---------------------+-------+------------------+
    |               |                        |       |                  |
   | previous- previous-ssrc | Refer to notes below      | SR    | NORMAL           |
    | ssrc          |                        |       |                  |
   |               | below               |       |                  |
    +---------------+---------------------+-------+------------------+
    | fmtp          | The attribute value | SR    | IDENTICAL-PER- IDENTICAL-PER-PT |
    |               | MUST be the same for a    |       | PT                  |
    |               | for a given codec   |       |                  |
    |               | configuration          |       |                  |
   |               | configuration.      |       |                  |
   +---------------+------------------------+-------+------------------+

                      5.15 RFC5576
    +---------------+---------------------+-------+------------------+

                  Table 15: RFC 5576 Attribute Analysis

   NOTE: If SSRCs are repeated across "m=" lines being multiplexed, they
   MUST all represent the same underlying RTP Source.

5.16.  RFC7273:  RFC 7273: RTP Clock Source Signalling Signaling

   [RFC7273] specifies SDP signalling signaling that identifies timestamp reference
   clock sources and SDP signalling signaling that identifies the media clock
   sources in a multimedia session.

       +--------------------+---------------+-------+--------------+

        +-------------------+--------------+-------+--------------+
        | Name              | Notes        | Level | Mux Category |
       +--------------------+---------------+-------+--------------+
        +===================+==============+=======+==============+
        | ts-refclk         | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | mediaclk          | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ts-refclk:ntp     | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ts-refclk:ptp     | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ts-refclk:gps     | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ts-refclk:gal     | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ts-refclk:glonass | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ts-refclk:local   | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ts-refclk:private | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | mediaclk:sender   | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | mediaclk:direct   | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | mediaclk:IEEE1722 | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
       +--------------------+---------------+-------+--------------+

                      5.16 RFC7273
        +-------------------+--------------+-------+--------------+

                   Table 16: RFC 7273 Attribute Analysis

5.17.  RFC6236:  RFC 6236: Image Attributes in SDP

   [RFC6236] proposes a new generic session setup attribute to make it
   possible to negotiate different image attributes attributes, such as image size.
   A possible use case is to make it possible for a low-end hand-held handheld
   terminal to display video without the need to rescale the image,
   something that may consume large amounts of memory and processing
   power.  The document also helps to maintain an optimal bitrate for
   video as only the image size that is desired by the receiver is
   transmitted.

   +-----------+----------------------------+-------+------------------+

    +-----------+--------------------------+-------+------------------+
    | Name      | Notes                    | Level | Mux Category     |
   +-----------+----------------------------+-------+------------------+
    +===========+==========================+=======+==================+
    | imageattr | The attribute value MUST | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
    |           | be the same for a given codec  |       | PT               |
   |           | configuration  |       |                  |
    |           | codec configuration.     |       |                  |
   +-----------+----------------------------+-------+------------------+

                      5.17 RFC6236
    +-----------+--------------------------+-------+------------------+

                   Table 17: RFC 6236 Attribute Analysis

5.18.  RFC7197:  RFC 7197: Duplication Delay Attribute in SDP

   [RFC7197] defines an attribute to indicate the presence of temporally
   redundant media streams and the duplication delay in SDP.

       +--------------------+---------------+-------+--------------+

        +-------------------+--------------+-------+--------------+
        | Name              | Notes        | Level | Mux Category |
       +--------------------+---------------+-------+--------------+
        +===================+==============+=======+==============+
        | duplication-delay | Not Impacted impacted | B     | NORMAL       |
       |                    |               |       |              |
       +--------------------+---------------+-------+--------------+

                      5.18 RFC7197
        +-------------------+--------------+-------+--------------+

                   Table 18: RFC 7197 Attribute Analysis

5.19.  RFC7266:  RFC 7266: RTCP XR Blocks for MOS Metric Reporting

   [RFC7266] defines an RTCP Extended Report (XR) Block including that includes
   two new segment types and associated SDP parameters that allow the
   reporting of mean opinion score (MOS) Metrics metrics for use in a range of
   RTP applications.

          +-------------+---------------+-------+--------------+

           +------------+--------------+-------+--------------+
           | Name       | Notes        | Level | Mux Category |
          +-------------+---------------+-------+--------------+
           +============+==============+=======+==============+
           | calgextmap | Not Impacted impacted | B     | NORMAL       |
          |             |               |       |              |
          +-------------+---------------+-------+--------------+

                      5.19 RFC7266
           +------------+--------------+-------+--------------+

                  Table 19: RFC 7266 Attribute Analysis

5.20.  RFC6285:  RFC 6285: Rapid Acquisition of Multicast RTP Sessions

   [RFC6285] describes a method of using the existing RTP and RTCP
   machinery that reduces the acquisition delay.  In this method, an
   auxiliary unicast RTP session carrying the Reference Information reference information to
   the receiver precedes or accompanies the multicast stream.  This
   unicast RTP flow can be transmitted at a faster than natural faster-than-natural bitrate
   to further accelerate the acquisition.  The motivating use case for
   this capability is multicast applications that carry real-time
   compressed audio and video.

        +---------------+------------------+-------+--------------+

         +--------------+-----------------+-------+--------------+
         | Name         | Notes           | Level | Mux Category |
        +---------------+------------------+-------+--------------+
         +==============+=================+=======+==============+
         | rams-updates | Not recommended | M     | CAUTION      |
        |               |                  |       |              |
        +---------------+------------------+-------+--------------+

                      5.20 RFC6285
         +--------------+-----------------+-------+--------------+

                   Table 20: RFC 6285 Attribute Analysis

5.21.  RFC6230:  RFC 6230: Media Control Channel Framework

   [RFC6230] describes a framework and protocol for application
   deployment where the application programming logic and media
   processing are distributed.  This implies that application
   programming logic can seamlessly gain access to appropriate resources
   that are not co-located on the same physical network entity.  The
   framework uses SIP to establish an application-level control
   mechanism between application servers and associated external servers
   such as media servers.

            +---------+---------------+-------+--------------+

             +--------+--------------+-------+--------------+
             | Name   | Notes        | Level | Mux Category |
            +---------+---------------+-------+--------------+
             +========+==============+=======+==============+
             | cfw-id | Not Impacted impacted | M     | NORMAL       |
            |         |               |       |              |
            +---------+---------------+-------+--------------+

                      5.21 RFC6230
             +--------+--------------+-------+--------------+

                  Table 21: RFC 6230 Attribute Analysis

5.22.  RFC6364:  RFC 6364: SDP Elements for FEC Framework

   [RFC6364] specifies the use of SDP to describe the parameters
   required to signal the Forward Error Correction (FEC) Framework
   Configuration Information between the sender(s) and receiver(s).
   This document also provides examples that show the semantics for
   grouping multiple source and repair flows together for the
   applications that simultaneously use multiple instances of the FEC
   Framework.

   +-----------------+------------------------------+-------+----------+

       +-----------------+----------------------+-------+----------+
       | Name            | Notes                | Level | Mux      |
       |                 |                      |       | Category |
   +-----------------+------------------------------+-------+----------+
       +=================+======================+=======+==========+
       | fec-source- fec-source-flow | Refer to the document         | M     | SPECIAL  |
       | flow                 | document defining specific FEC        |       |          |
   |                 | Scheme    |       |          |
       |                 | specific FEC scheme. |       |          |
       +-----------------+----------------------+-------+----------+
       | fec-repair- fec-repair-flow | Refer to the document         | M     | SPECIAL  |
       | flow                 | document defining specific FEC        |       |          |
   |                 | Scheme    |       |          |
       |                 | specific FEC scheme. |       |          |
       +-----------------+----------------------+-------+----------+
       | repair-window   | Refer to the document         | M     | SPECIAL  |
       |                 | document defining specific FEC        |       |          |
   |                 | Scheme    |       |          |
       |                 | specific FEC scheme. |       |          |
   +-----------------+------------------------------+-------+----------+

                      5.22 RFC6364
       +-----------------+----------------------+-------+----------+

                   Table 22: RFC 6364 Attribute Analysis

5.23.  RFC4796: Content  RFC 4796: "content" Attribute

   [RFC4796] defines a new SDP media-level attribute, 'content'. "content".  The
   'content'
   "content" attribute defines the content of the media stream to a more
   detailed level than the media description line.  The sender of an SDP
   session description can attach the 'content' "content" attribute to one or more
   media streams.  The receiving application can then treat each media
   stream differently (e.g., show it on a big or small screen) based on
   its content.

            +----------+---------------+-------+--------------+

             +---------+--------------+-------+--------------+
             | Name    | Notes        | Level | Mux Category |
            +----------+---------------+-------+--------------+
             +=========+==============+=======+==============+
             | content | Not Impacted impacted | M     | NORMAL       |
            |          |               |       |              |
            +----------+---------------+-------+--------------+

                      5.23 RFC4796
             +---------+--------------+-------+--------------+

                   Table 23: RFC 4796 Attribute Analysis

5.24.  RFC3407:  RFC 3407: SDP Simple Capability Declaration

   [RFC3407] defines a set of SDP attributes that enables SDP to provide
   a minimal and backwards compatible backwards-compatible capability declaration mechanism.

       +----------+------------------------+-------+--------------+

         +---------+----------------------+-------+--------------+
         | Name    | Notes                | Level | Mux Category |
       +----------+------------------------+-------+--------------+
         +=========+======================+=======+==============+
         | sqn     | Not Impacted impacted         | B     | NORMAL       |
       |          |                        |       |              |
         +---------+----------------------+-------+--------------+
         | cdsc    | Not Impacted. impacted         | B     | NORMAL       |
       |          |                        |       |              |
         +---------+----------------------+-------+--------------+
         | cpar    | Refer to Section 14  | B     | INHERIT      |
       |          |                        |       |              |
         +---------+----------------------+-------+--------------+
         | cparmin | Refer to notes below | B     | SPECIAL      |
       |          |                        |       |              |
         +---------+----------------------+-------+--------------+
         | cparmax | Refer to notes below | B     | SPECIAL      |
       |          |                        |       |              |
       +----------+------------------------+-------+--------------+

                      5.24 RFC3407
         +---------+----------------------+-------+--------------+

                   Table 24: RFC 3407 Attribute Analysis

   NOTE: The attributes (a=cparmin "a=cparmin" and a=cparmax) "a=cparmax" define minimum and
   maximum numerical values associated with the attributes described in
   a=cpar.
   "a=cpar".

   Since the cpar attribute can either define a 'b=' "b=" attribute or any
   'a='
   "a=" attribute, the multiplexing category depends on the actual
   attribute being encapsulated and the implications of the numerical
   values assigned.  Hence it is recommended to consult the
   specification defining attributes (cparmin/cparmax) "cparmin" and "cparmax" to further
   analyze their behavior under multiplexing.

5.25.  RFC6284:  RFC 6284: Port Mapping between Unicast and Multicast RTP Sessions

   [RFC6284] presents a port mapping port-mapping solution that allows RTP receivers
   to choose their own ports for an auxiliary unicast session in RTP
   applications using both unicast and multicast services.  The solution
   provides protection against denial-of-service or packet amplification
   attacks that could be used to cause one or more RTP packets to be
   sent to a victim client.

   +-----------------+------------------------------+-------+----------+

     +-----------------+-------------------------+-------+----------+
     | Name            | Notes                   | Level | Mux      |
     |                 |                         |       | Category |
   +-----------------+------------------------------+-------+----------+
     +=================+=========================+=======+==========+
     | portmapping- portmapping-req | Not recommended, recommended if port | M     | CAUTION  |
     | req                 | mapping is required by the  |       |          |
     |                 | the application         |       |          |
   |                 |                              |       |          |
   +-----------------+------------------------------+-------+----------+

                      5.25 RFC6284
     +-----------------+-------------------------+-------+----------+

                  Table 25: RFC 6284 Attribute Analysis

5.26.  RFC6714:  RFC 6714: MSRP-CEMA

   [RFC6714] defines a Message Session Relay Protocol (MSRP) extension,
   Connection Establishment for Media Anchoring (CEMA).  Support of this
   extension is optional.  The extension allows middle boxes middleboxes to anchor
   the MSRP connection, connection without the need for middle boxes middleboxes to modify the
   MSRP messages; thus, it also enables secure end-to-end MSRP
   communication in networks where such middle boxes middleboxes are deployed.  This
   document also defines a an SDP attribute, 'msrp-cema', "msrp-cema", that MSRP
   endpoints use to indicate support of the CEMA extension.

       +------------+-----------------------+-------+--------------+

        +-----------+----------------------+-------+--------------+
        | Name      | Notes                | Level | Mux Category |
       +------------+-----------------------+-------+--------------+
        +===========+======================+=======+==============+
        | msrp-cema | Refer to notes below | M     | TBD          |
       |            |                       |       |              |
       +------------+-----------------------+-------+--------------+

                      5.26 RFC6714
        +-----------+----------------------+-------+--------------+

                   Table 26: RFC 6714 Attribute Analysis

   NOTE: As per section Section 9 of [I-D.ietf-mmusic-sdp-bundle-negotiation], [RFC8843], there exists no publicly
   available specification that defines procedures for multiplexing/demultiplexing MRSP multiplexing/
   demultiplexing MSRP flows over a single 5-tuple.  Once such a
   specification is available, the assignments of multiplexing
   categories assignments for the attributes in this section could be revisited.

5.27.  RFC4583:  RFC 4583: SDP Format for BFCP Streams

   [RFC4583] document specifies how to describe Binary Floor Control Protocol
   (BFCP) streams in SDP descriptions.  User agents using the
   offer/answer offer/
   answer model to establish BFCP streams use this format in their
   offers and answers.

       +------------+-----------------------+-------+--------------+

        +-----------+----------------------+-------+--------------+
        | Name      | Notes                | Level | Mux Category |
       +------------+-----------------------+-------+--------------+
        +===========+======================+=======+==============+
        | floorctrl | Refer to notes below | M     | TBD          |
       |            |                       |       |              |
        +-----------+----------------------+-------+--------------+
        | confid    | Not Impacted Refer to notes below | M     | NORMAL       |
       |            |                       |       | TBD          |
        +-----------+----------------------+-------+--------------+
        | userid    | Not Impacted Refer to notes below | M     | NORMAL       |
       |            |                       |       | TBD          |
        +-----------+----------------------+-------+--------------+
        | floorid   | Not Impacted Refer to notes below | M     | NORMAL       |
       |            |                       |       | TBD          |
       +------------+-----------------------+-------+--------------+

                      5.27 RFC4583
        +-----------+----------------------+-------+--------------+

                   Table 27: RFC 4583 Attribute Analysis

   NOTE: [RFC4583] has been obsoleted by [RFC8856], which redefines the
   SDP attributes listed in this section, including the "Mux Category"
   values.  However, [RFC8856] does not change the "Mux Category" values
   of the attributes.

   NOTE: As per section Section 9 of [I-D.ietf-mmusic-sdp-bundle-negotiation], [RFC8843], there exists no publicly
   available specification that defines procedures for multiplexing/demultiplexing multiplexing/
   demultiplexing BFCP streams over a single 5-tuple.  Once such a
   specification is available, the assignments of multiplexing
   categories assignments for the attributes in this section could be revisited.

5.28.  RFC5547:  RFC 5547: SDP Offer/Answer for File Transfer

   [RFC5547] provides a mechanism to negotiate the transfer of one or
   more files between two endpoints by using the SDP offer/answer model
   specified in [RFC3264].

   +-------------------+-----------------------+-------+--------------+

    +------------------+----------------------+-------+--------------+
    | Name             | Notes                | Level | Mux Category |
   +-------------------+-----------------------+-------+--------------+
    +==================+======================+=======+==============+
    | file-selector    | Refer to notes below | M     | TBD          |
   |                   |                       |       |              |
    +------------------+----------------------+-------+--------------+
    | file-transfer-id | Refer to notes below | M     | TBD          |
   |                   |                       |       |              |
    +------------------+----------------------+-------+--------------+
    | file-disposition | Refer to notes below | M     | TBD          |
   |                   |                       |       |              |
    +------------------+----------------------+-------+--------------+
    | file-date        | Refer to notes below | M     | TBD          |
   |                   |                       |       |              |
    +------------------+----------------------+-------+--------------+
    | file-icon        | Refer to notes below | M     | TBD          |
   |                   |                       |       |              |
    +------------------+----------------------+-------+--------------+
    | file-range       | Refer to notes below | M     | TBD          |
   |                   |                       |       |              |
   +-------------------+-----------------------+-------+--------------+

                      5.28 RFC5547
    +------------------+----------------------+-------+--------------+

                  Table 28: RFC 5547 Attribute Analysis

   NOTE: As per section Section 9 of [I-D.ietf-mmusic-sdp-bundle-negotiation], [RFC8843], there exists no publicly
   available specification that defines procedures for multiplexing/demultiplexing MRSP multiplexing/
   demultiplexing MSRP flows over a single 5-tuple.  Once such a
   specification is available, the assignments of multiplexing
   categories assignments for attributes in this section could be revisited.

5.29.  RFC6849:  RFC 6849: SDP and RTP Media Loopback Extension

   [RFC6849] adds new SDP media types and attributes, which attributes that enable
   establishment of media sessions where the media is looped back to the
   transmitter.  Such media sessions will serve as monitoring and
   troubleshooting tools by providing the means for measurement of more
   advanced Voice over IP (VoIP), Real-time Text, real-time text, and Video over IP
   performance metrics.

   +--------------------+-------------------+-------+------------------+

    +--------------------+----------------+-------+------------------+
    | Name               | Notes          | Level | Mux Category     |
   +--------------------+-------------------+-------+------------------+
    +====================+================+=======+==================+
    | loopback rtp-pkt-  | The attribute  | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
    | loopback           | value MUST be  |       | PT                  |
    |                    | same for a given     |       |                  |
    |                    | given codec    |       |                  |
    |                    | configuration     |       |                  |
   |                    | configuration. |       |                  |
    +--------------------+----------------+-------+------------------+
    | loopback rtp-      | The attribute  | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
    | media-loopback     | value MUST be  |       | PT                  |
    |                    | same for a given     |       |                  |
    |                    | given codec    |       |                  |
    |                    | configuration     |       |                  |
   |                    | configuration. |       |                  |
    +--------------------+----------------+-------+------------------+
    | loopback-source    | Not Impacted impacted   | M     | NORMAL           |
   |                    |                   |       |                  |
    +--------------------+----------------+-------+------------------+
    | loopback-mirror    | Not Impacted impacted   | M     | NORMAL           |
   |                    |                   |       |                  |
   +--------------------+-------------------+-------+------------------+

                           5.29 RFC6849
    +--------------------+----------------+-------+------------------+

                       Table 29: RFC 6849 Analysis

5.30.  RFC5760:  RFC 5760: RTCP with Unicast Feedback

   [RFC5760] specifies an extension to RTCP to use unicast feedback to a
   multicast sender.  The proposed extension is useful for single-source
   multicast sessions such as Source-Specific Multicast (SSM) source-specific multicast (SSM)
   communication where the traditional model of many-to-many group
   communication is either not available or not desired.

   +--------------+--------------------------------+-------+-----------+

      +--------------+-------------------------+-------+-----------+
      | Name         | Notes                   | Level | Mux       |
      |              |                         |       | Category  |
   +--------------+--------------------------------+-------+-----------+
      +==============+=========================+=======+===========+
      | rtcp- rtcp-unicast | The attribute MUST be reported   | M     | IDENTICAL |
      | unicast              | reported across all "m=" lines     |       |           |
      |              | multiplexed "m=" lines. |       |           |
   |              |                                |       |           |
   +--------------+--------------------------------+-------+-----------+

                      5.30 RFC5760
      +--------------+-------------------------+-------+-----------+

                  Table 30: RFC 5760 Attribute Analysis

5.31.  RFC3611:  RFC 3611: RTCP XR

   [RFC3611] defines the Extended Report (XR) packet type for RTCP, RTCP and
   defines how the use of XR packets can be signaled by an application
   if it employs the Session Description Protocol (SDP).

            +----------+---------------+-------+--------------+

             +---------+--------------+-------+--------------+
             | Name    | Notes        | Level | Mux Category |
            +----------+---------------+-------+--------------+
             +=========+==============+=======+==============+
             | rtcp-xr | Not Impacted impacted | B     | NORMAL       |
            |          |               |       |              |
            +----------+---------------+-------+--------------+

                      5.31 RFC3611
             +---------+--------------+-------+--------------+

                   Table 31: RFC 3611 Attribute Analysis

5.32.  RFC5939:  RFC 5939: SDP Capability Negotiation

   [RFC5939] defines a general SDP Capability Negotiation framework.  It
   also specifies how to provide attributes and transport protocols as
   capabilities and negotiate them using the framework.  Extensions for
   other types of capabilities (e.g., media types and media formats) may
   be provided in other documents.

        +---------+-----------------------+-------+--------------+

          +--------+---------------------+-------+--------------+
          | Name   | Notes               | Level | Mux Category |
        +---------+-----------------------+-------+--------------+
          +========+=====================+=======+==============+
          | pcfg   | Refer to Section 14 | M     | SPECIAL      |
        |         |                       |       |              |
          +--------+---------------------+-------+--------------+
          | acfg   | Refer to Section 14 | M     | SPECIAL      |
        |         |                       |       |              |
          +--------+---------------------+-------+--------------+
          | csup   | Not Impacted impacted        | B     | NORMAL       |
        |         |                       |       |              |
          +--------+---------------------+-------+--------------+
          | creq   | Not Impacted impacted        | B     | NORMAL       |
        |         |                       |       |              |
          +--------+---------------------+-------+--------------+
          | acap   | Refer to Section 14 | B     | INHERIT      |
        |         |                       |       |              |
          +--------+---------------------+-------+--------------+
          | tcap   | Refer to Section 14 | B     | INHERIT      |
        |         |                       |       |              |
          +--------+---------------------+-------+--------------+
          | cap-v0 | Not Impacted impacted        | B     | NORMAL       |
        |         |                       |       |              |
        +---------+-----------------------+-------+--------------+

                      5.32 RFC5939
          +--------+---------------------+-------+--------------+

                   Table 32: RFC 5939 Attribute Analysis

5.33.  RFC6871:  RFC 6871: SDP Media Capabilities Negotiation

   SDP capability negotiation provides a general framework for
   indicating and negotiating capabilities in SDP.  The base framework
   defines
   only defines capabilities for negotiating transport protocols and
   attributes.  [RFC6871] extends the framework by defining media
   capabilities that can be used to negotiate media types and their
   associated parameters.

      +---------+-----------------------+-------+-------------------+

       +--------+----------------------+-------+------------------+
       | Name   | Notes                | Level | Mux Category     |
      +---------+-----------------------+-------+-------------------+
       +========+======================+=======+==================+
       | rmcap  | Refer to Section 14  | B     | IDENTICAL-PER-PT |
      |         |                       |       |                   |
       +--------+----------------------+-------+------------------+
       | omcap  | Not Impacted impacted         | B     | NORMAL           |
      |         |                       |       |                   |
       +--------+----------------------+-------+------------------+
       | mfcap  | Refer to Section 14  | B     | IDENTICAL-PER-PT |
      |         |                       |       |                   |
       +--------+----------------------+-------+------------------+
       | mscap  | Refer to Section 14  | B     | INHERIT          |
      |         |                       |       |                   |
       +--------+----------------------+-------+------------------+
       | lcfg   | Refer to Section 14  | B     | SPECIAL          |
      |         |                       |       |                   |
       +--------+----------------------+-------+------------------+
       | sescap | Refer to notes below | S     | CAUTION          |
      |         |                       |       |                   |
       +--------+----------------------+-------+------------------+
       | med-v0 | Not Impacted impacted         | S     | NORMAL           |
      |         |                       |       |                   |
      +---------+-----------------------+-------+-------------------+

                     5.33 RFC6871 -
       +--------+----------------------+-------+------------------+

                  Table 33: RFC 6871 Attribute Analysis

   NOTE: The "sescap" attribute is not recommended for use with
   multiplexing.  The reason is that it requires the use of unique
   configuration numbers across the entire SDP (per [RFC6871]) as
   opposed to within a media description only (per [RFC5939]).  As
   described in Section 14, the use of identical configuration numbers
   between multiplexed (bundled) media descriptions is the default way
   of indicating compatible configurations in a bundle.

5.34.  RFC7006:  RFC 7006: Miscellaneous Capabilities Negotiation in SDP

   [RFC7006] extends the SDP capability negotiation Capability Negotiation framework to allow
   endpoints to negotiate three additional SDP capabilities.  In
   particular, this memo provides a mechanism to negotiate bandwidth
   ("b=" line), connection data ("c=" line), and session or media titles
   ("i=" line for each session or media).

   +---------+-------------------------------------+-------+-----------+

    +---------+----------------------------------+-------+-----------+
    | Name    | Notes                            | Level | Mux       |
    |         |                                  |       | Category  |
   +---------+-------------------------------------+-------+-----------+
    +=========+==================================+=======+===========+
    | bcap    | Inherit the category SUM as      | B     | INHERIT   |
    |         | applicable to b= the "b=" attribute |       |           |
   |         |                                     |       |           |
    +---------+----------------------------------+-------+-----------+
    | bcap-v0 | Not Impacted impacted                     | B     | NORMAL    |
   |         |                                     |       |           |
    +---------+----------------------------------+-------+-----------+
    | ccap    | The connection address type MUST be | B     | IDENTICAL |
    |         | be identical across all the      |       |           |
    |         | multiplexed "m=" lines              |       |           |
   |         | lines.          |       |           |
    +---------+----------------------------------+-------+-----------+
    | ccap-v0 | Not Impacted impacted                     | B     | NORMAL    |
   |         |                                     |       |           |
    +---------+----------------------------------+-------+-----------+
    | icap    | Not Impacted impacted                     | B     | NORMAL    |
   |         |                                     |       |           |
    +---------+----------------------------------+-------+-----------+
    | icap-v0 | Not Impacted impacted                     | B     | NORMAL    |
   |         |                                     |       |           |
   +---------+-------------------------------------+-------+-----------+

                     5.34 RFC7006 -
    +---------+----------------------------------+-------+-----------+

                  Table 34: RFC 7006 Attribute Analysis

5.35.  RFC4567:  RFC 4567: Key Management Extensions for SDP and RTSP

   [RFC4567] defines general extensions for SDP and Real Time Streaming
   Protocol (RTSP) to carry messages, as specified by a key management
   protocol, in order to secure the media.  These extensions are
   presented as a framework, framework to be used by one or more key management
   protocols.  As such, their use is meaningful only when complemented
   by an appropriate key management protocol.

   +----------+------------------------------------+-------+-----------+

        +----------+--------------------------+-------+-----------+
        | Name     | Notes                    | Level | Mux       |
        |          |                          |       | Category  |
   +----------+------------------------------------+-------+-----------+
        +==========+==========================+=======+===========+
        | key- key-mgmt | Key management protocol MUST be  | B     | IDENTICAL |
        | mgmt          | MUST be identical across all the "m="      |       |           |
   |          | lines |       |           |
        |          | all the "m=" lines.      |       |           |
        +----------+--------------------------+-------+-----------+
        | mikey    | Key management protocol MUST be  | B     | IDENTICAL |
        |          | MUST be identical across all the "m="      |       |           |
   |          | lines |       |           |
        |          | all the "m=" lines.      |       |           |
   +----------+------------------------------------+-------+-----------+

                      5.35 RFC4567
        +----------+--------------------------+-------+-----------+

                   Table 35: RFC 4567 Attribute Analysis

5.36.  RFC4572:  RFC 4572: Comedia over TLS in SDP

   [RFC4572] specifies how to establish secure connection-oriented media
   transport sessions over the Transport Layer Security (TLS) protocol
   using SDP.  (Note: [RFC4572] has been obsoleted by [RFC8122].)  It
   defines a new SDP protocol identifier, 'TCP/TLS'. "TCP/TLS".  It also defines
   the syntax and semantics for an SDP 'fingerprint' "fingerprint" attribute that
   identifies the certificate that will be presented for the TLS
   session.  This mechanism allows media transport over TLS connections
   to be established securely, so long as the integrity of session
   descriptions is assured.

   +-------------+---------------------------------+-------+-----------+
   | Name        | Notes                           | Level | Mux       |
   |             |                                 |       | Category  |
   +-------------+---------------------------------+-------+-----------+
   +=============+=================================+=======+===========+
   | fingerprint | fingerprint value MUST be the       | B     | TRANSPORT |
   |             | the one that corresponds to the        |       |           |
   |             | to the "m=" line chosen for setting up         |       |           |
   |             | for setting up the underlying transport flow              |       |           |
   |             | underlying transport flow.      |       |           |
   +-------------+---------------------------------+-------+-----------+

                      5.36 RFC4572

                   Table 36: RFC 4572 Attribute Analysis

5.37.  RFC4570:  RFC 4570: SDP Source Filters

   [RFC4570] describes how to adapt SDP to express one or more source
   addresses as a source filter for one or more destination "connection"
   addresses.  It defines the syntax and semantics for an SDP "source-
   filter" attribute that may reference either IPv4 or IPv6 address(es)
   as either an inclusive or exclusive source list for either multicast
   or unicast destinations.  In particular, an inclusive source-filter source filter
   can be used to specify a Source-Specific Multicast source-specific multicast (SSM) session.

   +---------------+-------------------------------+-------+-----------+

      +---------------+-------------------------+-------+-----------+
      | Name          | Notes                   | Level | Mux       |
      |               |                         |       | Category  |
   +---------------+-------------------------------+-------+-----------+
      +===============+=========================+=======+===========+
      | source- source-filter | The attribute MUST be   | B     | IDENTICAL |
      | filter               | repeated across all "m="     |       |           |
      |               | lines multiplexed "m=" lines. |       |           |
   |               |                               |       |           |
   +---------------+-------------------------------+-------+-----------+

                      5.37 RFC4570
      +---------------+-------------------------+-------+-----------+

                   Table 37: RFC 4570 Attribute Analysis

5.38.  RFC6128:  RFC 6128: RTCP Port for Multicast Sessions

   SDP has an attribute that allows RTP applications to specify an
   address and a port associated with the RTCP traffic.  In RTP-based
   source-specific multicast (SSM) sessions, the same attribute is used
   to designate the address and the RTCP port of the Feedback Target in
   the SDP description.  However, the RTCP port associated with the SSM
   session itself cannot be specified by the same attribute to avoid
   ambiguity,
   ambiguity and thus, thus is required to be derived from the "m=" line of
   the media description.  Deriving the RTCP port from the "m=" line
   imposes an unnecessary restriction.  [RFC6128] removes this
   restriction by introducing a new SDP attribute.

   +----------------+------------------------------+-------+-----------+

     +----------------+--------------------------+-------+-----------+
     | Name           | Notes                    | Level | Mux       |
     |                |                          |       | Category  |
   +----------------+------------------------------+-------+-----------+
     +================+==========================+=======+===========+
     | multicast- multicast-rtcp | Multicast RTCP port MUST be | B     | IDENTICAL |
     | rtcp                | be identical across all the  |       |           |
     |                | the "m=" lines                   |       |           |
   |                | lines.          |       |           |
   +----------------+------------------------------+-------+-----------+

                      5.38 RFC6128
     +----------------+--------------------------+-------+-----------+

                   Table 38: RFC 6128 Attribute Analysis

5.39.  RFC6189:  RFC 6189: ZRTP

   [RFC6189] defines ZRTP, a protocol for media path Diffie-Hellman
   exchange to agree on a session key and parameters for establishing
   unicast SRTP sessions for (VoIP VoIP applications.

   +-----------+-----------------------------------+-------+-----------+

    +-----------+---------------------------------+-------+-----------+
    | Name      | Notes                           | Level | Mux       |
    |           |                                 |       | Category  |
   +-----------+-----------------------------------+-------+-----------+
    +===========+=================================+=======+===========+
    | zrtp- zrtp-hash | The zrtp-hash attribute MUST be the | M     | TRANSPORT |
    | hash           | the one that corresponds to the "m=" |       |           |
    |           | "m=" line chosen for setting up the |       |           |
    |           | the underlying transport flow         |       |           |
   |           | flow.  |       |           |
   +-----------+-----------------------------------+-------+-----------+

                      5.39 RFC6189
    +-----------+---------------------------------+-------+-----------+

                   Table 39: RFC 6189 Attribute Analysis

5.40.  RFC4145:  RFC 4145: Connection-Oriented Media

   [RFC4145] describes how to express media transport over TCP using
   SDP.  It defines the SDP 'TCP' "TCP" protocol identifier, the SDP 'setup' "setup"
   attribute, which describes the connection setup procedure, and the
   SDP 'connection' "connection" attribute, which handles connection reestablishment. re-
   establishment.

   +------------+----------------------------------+-------+-----------+
   | Name       | Notes                            | Level | Mux       |
   |            |                                  |       | Category  |
   +------------+----------------------------------+-------+-----------+
   +============+==================================+=======+===========+
   | setup      | The setup attribute MUST be the  | B     | TRANSPORT |
   |            | one that corresponds to the "m="      |       |           |
   |            | "m=" line chosen for setting up the  |       |           |
   |            | the underlying transport flow.   |       |           |
   |            |                                  |       |           |
   +------------+----------------------------------+-------+-----------+
   | connection | The connection attribute MUST be    | B     | TRANSPORT |
   |            | be the one that corresponds to the   |       |           |
   |            | the "m=" line chosen for setting up         |       |           |
   |            | setting up the underlying transport flow.        |       |           |
   |            | transport flow.                  |       |           |
   +------------+----------------------------------+-------+-----------+

                      5.40 RFC4145

                   Table 40: RFC 4145 Attribute Analysis

5.41.  RFC6947:  RFC 6947: The SDP altc "altc" Attribute

   [RFC6947] proposes a mechanism that allows the same SDP offer to
   carry multiple IP addresses of different address families (e.g., IPv4
   and IPv6).  The proposed attribute, the "altc" attribute, attribute solves the
   backward-compatibility backward-
   compatibility problem that plagued Alternative Network Address Types
   (ANAT) due to their syntax.

   +------+----------------------------------------+-------+-----------+

      +------+---------------------------------+-------+-----------+
      | Name | Notes                           | Level | Mux       |
      |      |                                 |       | Category  |
   +------+----------------------------------------+-------+-----------+
      +======+=================================+=======+===========+
      | altc | The IP Address address and port MUST be the | M     | TRANSPORT |
      |      | one the ones that corresponds correspond to the "m=" line |       |           |
      |      | "m=" line chosen for setting up the underlying |       |           |
      |      | the underlying transport flow                         |       |           |
   |      | flow.  |       |           |
   +------+----------------------------------------+-------+-----------+

                      5.41 RFC6947
      +------+---------------------------------+-------+-----------+

                  Table 41: RFC 6947 Attribute Analysis

5.42.  RFC7195:  RFC 7195: SDP Extension for Circuit Switched Circuit-Switched Bearers in PSTN

   [RFC7195] describes use cases, requirements, and protocol extensions
   for using the SDP offer/answer model for establishing audio and video
   media streams over circuit-switched bearers in the Public Switched
   Telephone Network (PSTN).

   +-------------------------+-------------------+-------+-------------+

     +-------------------------+-------------+-------+--------------+
     | Name                    | Notes       | Level | Mux         |
   |                         |                   |       | Category |
   +-------------------------+-------------------+-------+-------------+
     +=========================+=============+=======+==============+
     | cs- cs-correlation:callerid | Refer to notes    | M     | TBD          |
     | correlation:callerid                         | notes below |       |              |
   |                         |                   |       |             |
     +-------------------------+-------------+-------+--------------+
     | cs-correlation:uuie     | Refer to notes    | M     | TBD          |
     |                         | notes below |       |              |
   |                         |                   |       |             |
     +-------------------------+-------------+-------+--------------+
     | cs-correlation:dtmf     | Refer to notes    | M     | TBD          |
     |                         | notes below |       |              |
     +-------------------------+-------------+-------+--------------+
     |                         |                   |       |             |
   | cs- cs-correlation:external | Refer to notes    | M     | TBD          |
     | correlation:external                         | notes below |       |              |
   |                         |                   |       |             |
   +-------------------------+-------------------+-------+-------------+

                      5.42 RFC7195
     +-------------------------+-------------+-------+--------------+

                  Table 42: RFC 7195 Attribute Analysis

   NOTE: [RFC7195] defines SDP attributes for establishing audio and
   video media streams over circuit-switched bearers by defining a new
   nettype value value, "PSTN".  However, section Section 7.2 of
   [I-D.ietf-mmusic-sdp-bundle-negotiation] [RFC8843] requires
   the "c=" line nettype value of to be "IN".  If in future there exists in future a
   specification that defines procedures to multiplex media streams over
   nettype "PSTN", the multiplexing categories for attributes in this
   section could be revisited.

5.43.  RFC7272:  RFC 7272: IDMS Using the RTP Control Protocol (RTCP)

   [RFC7272] defines a new RTCP Packet Type packet type and an RTCP Extended Report
   (XR) Block Type to be used for achieving Inter-Destination Media
   Synchronization (IDMS).

           +------------+---------------+-------+--------------+

            +-----------+--------------+-------+--------------+
            | Name      | Notes        | Level | Mux Category |
           +------------+---------------+-------+--------------+
            +===========+==============+=======+==============+
            | rtcp-idms | Not Impacted impacted | M     | NORMAL       |
           |            |               |       |              |
           +------------+---------------+-------+--------------+

                      5.43 RFC7272
            +-----------+--------------+-------+--------------+

                   Table 43: RFC 7272 Attribute Analysis

5.44.  RFC5159:  RFC 5159: Open Mobile Alliance (OMA) Broadcast (BCAST) SDP
       Attributes

   [RFC5159] provides descriptions of SDP attributes used by the Open
   Mobile Alliance's Broadcast Service "Service and Content Protection for Mobile
   Broadcast Services" specification.

   +--------------------+-----------------------+-------+--------------+

       +--------------------+---------------+-------+--------------+
       | Name               | Notes         | Level | Mux Category |
   +--------------------+-----------------------+-------+--------------+
       +====================+===============+=======+==============+
       | bcastversion       | Not Impacted impacted  | S     | NORMAL       |
   |                    |                       |       |              |
       +--------------------+---------------+-------+--------------+
       | stkmstream         | Not Impacted impacted  | B     | NORMAL       |
   |                    |                       |       |              |
       +--------------------+---------------+-------+--------------+
       | SRTPAuthentication | Needs further | M     | TBD          |
       |                    | analysis      |       |              |
   |                    |                       |       |              |
       +--------------------+---------------+-------+--------------+
       | SRTPROCTxRate      | Needs further | M     | TBD          |
       |                    | analysis      |       |              |
   |                    |                       |       |              |
   +--------------------+-----------------------+-------+--------------+

                      5.44 RFC5159
       +--------------------+---------------+-------+--------------+

                   Table 44: RFC 5159 Attribute Analysis

5.45.  RFC6193:  RFC 6193: Media Description for IKE in SDP

   [RFC6193] specifies how to establish a media session that represents
   a virtual private network using the Session Initiation Protocol for
   the purpose of on-demand media/application sharing between peers.  It
   extends the protocol identifier of SDP so that it can negotiate use
   of the Internet Key Exchange Protocol (IKE) for media sessions in the
   SDP offer/answer model.

   +------------------+-----------------------------+-------+----------+

   +------------------+----------------------------+-------+----------+
   | Name             | Notes                      | Level | Mux      |
   |                  |                            |       | Category |
   +------------------+-----------------------------+-------+----------+
   +==================+============================+=======+==========+
   | ike-setup        | Unlikely to use IKE in the | B     | CAUTION  |
   |                  | context of multiplexing    |       |          |
   |                  |                             |       |          |
   +------------------+----------------------------+-------+----------+
   | psk-fingerprint  | Unlikely to use IKE in the | B     | CAUTION  |
   |                  | context of multiplexing    |       |          |
   |                  |                             |       |          |
   +------------------+----------------------------+-------+----------+
   | ike-esp          | Unlikely to use IKE in the | B     | CAUTION  |
   |                  | context of multiplexing    |       |          |
   +------------------+----------------------------+-------+----------+
   |                  |                             |       |          |
   | ike-esp- ike-esp-udpencap | Unlikely to use IKE in the | B     | CAUTION  |
   | udpencap                  | context of multiplexing    |       |          |
   |                  |                             |       |          |
   +------------------+-----------------------------+-------+----------+

                      5.45 RFC6193
   +------------------+----------------------------+-------+----------+

                  Table 45: RFC 6193 Attribute Analysis

5.46.  RFC2326:  RFC 2326: Real Time Streaming Protocol

   The Real Time Streaming Protocol, or RTSP, is an application-level
   protocol for control over the delivery of data with real-time
   properties.  RTSP provides an extensible framework to enable
   controlled, on-demand delivery of real-time data, such as audio and
   video.

   +---------+-------------------------------------+-------+-----------+

      +---------+---------------------------+-------+--------------+
      | Name    | Notes                     | Level | Mux       |
   |         |                                     |       | Category |
   +---------+-------------------------------------+-------+-----------+
      +=========+===========================+=======+==============+
      | etag    | RTSP is not supported for RTP | B     | CAUTION      |
      |         | Stream multiplexing                 |       |           |
   |         | RTP stream multiplexing.  |       |              |
      +---------+---------------------------+-------+--------------+
      | range   | RTSP is not supported for RTP | B     | CAUTION      |
      |         | Stream multiplexing                 |       |           |
   |         | RTP stream multiplexing.  |       |              |
      +---------+---------------------------+-------+--------------+
      | control | RTSP is not supported for RTP | B     | CAUTION      |
      |         | Stream multiplexing                 |       |           |
   |         | RTP stream multiplexing.  |       |              |
      +---------+---------------------------+-------+--------------+
      | mtag    | RTSP is not supported for RTP | B     | CAUTION      |
      |         | Stream multiplexing                 |       |           |
   |         | RTP stream multiplexing.  |       |              |
   +---------+-------------------------------------+-------+-----------+

                      5.46 RFC2326
      +---------+---------------------------+-------+--------------+

                  Table 46: RFC 2326 Attribute Analysis

   NOTE: [RFC2326] defines SDP attributes that are applicable in the
   declarative usage of SDP alone.  For the purposes of this document,
   only the Offer/Answer offer/answer usage of SDP is considered as to be mandated by
   [I-D.ietf-mmusic-sdp-bundle-negotiation].
   [RFC8843].

5.47.  RFC6064:  RFC 6064: SDP and RTSP Extensions for 3GPP

   The Packet-switched Streaming Service (PSS) and the Multimedia
   Broadcast/Multicast Service (MBMS) defined by 3GPP use SDP and RTSP
   with some extensions.  [RFC6064] provides information about these
   extensions and registers the RTSP and SDP extensions with IANA.

   +--------------------------------+---------------+-------+----------+

   +------------------------------+-------------+-------+--------------+
   | Name                         | Notes       | Level | Mux          |
   |                              |             |       | Category     |
   +--------------------------------+---------------+-------+----------+
   +==============================+=============+=======+==============+
   | X-predecbufsize              | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | X-initpredecbufperiod        | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | X-initpostdecbufperiod       | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | X-decbyterate                | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3gpp-videopostdecbufsize     | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | framesize                    | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-Integrity-Key           | Refer to    | S     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-SDP-Auth                | Refer to    | S     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-SRTP-Config             | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | alt                          | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | alt-default-id               | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | alt-group                    | Refer to    | S     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-Adaptation-Support      | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-Asset-Information       | Refer to    | B     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | mbms-mode                    | Refer to    | B     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | mbms-flowid                  | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | mbms-repair                  | Refer to    | B     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics             | Refer to    | M     | CAUTION      |
   |                              | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Corruption  | Refer to    | M     | CAUTION      |
   | duration                     | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Rebuffering | Refer to    | M     | CAUTION      |
   | duration                     | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Initial     | Refer to    | M     | CAUTION      |
   | buffering duration           | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Successive  | Refer to    | M     | CAUTION      |
   | loss of RTP packets          | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Frame rate  | Refer to    | M     | CAUTION      |
   | deviation                    | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Jitter      | Refer to    | M     | CAUTION      |
   | duration                     | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Content     | Refer to    | B     | CAUTION      |
   | Switch Time                  | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Average Codec     | Refer to    | M     | CAUTION      |
   | Codec Bitrate                | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Codec       | Refer to    | M     | CAUTION      |
   | Information                  | notes below |       |              |
   |                                |               |       |          |
   +------------------------------+-------------+-------+--------------+
   | 3GPP-QoE-Metrics:Buffer      | Refer to    | M     | CAUTION      |
   | Status                       | notes below |       |              |
   |                                |               |       |          |
   +--------------------------------+---------------+-------+----------+

                      5.47 RFC6064
   +------------------------------+-------------+-------+--------------+

                   Table 47: RFC 6064 Attribute Analysis

   NOTE: [RFC6064] defines SDP attributes that are applicable in the
   declarative usage of SDP alone.  For the purposes of this document,
   only the Offer/Answer offer/answer usage of SDP is considered as to be mandated by
   [I-D.ietf-mmusic-sdp-bundle-negotiation].
   [RFC8843].

5.48.  RFC3108:  RFC 3108: ATM SDP

   [RFC3108] describes conventions for using SDP described for
   controlling ATM Bearer Connections, bearer connections and any associated ATM Adaptation
   Layer (AAL).

   +-----------------------+--------------------+-------+--------------+

      +-----------------------+-------------+-------+--------------+
      | Name                  | Notes       | Level | Mux Category |
   +-----------------------+--------------------+-------+--------------+
      +=======================+=============+=======+==============+
      | aalType               | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | eecid                 | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | capability            | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | qosClass              | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | bcob                  | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | stc                   | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | upcc                  | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | atmQOSparms           | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | atmTrfcDesc           | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | abrParms              | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | abrSetup              | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | bearerType            | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | lij                   | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | anycast               | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | cache                 | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | bearerSigIE           | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | aalApp                | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | cbrRate               | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | sbc                   | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | clkrec                | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | fec                   | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | prtfl                 | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | structure             | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | cpsSDUsize            | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | aal2CPS               | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | aal2CPSSDUrate        | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | aal2sscs3661unassured | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | aal2sscs3661assured   | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | aal2sscs3662          | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | aal5sscop             | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | atmmap                | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | silenceSupp           | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | ecan                  | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | gc                    | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | profileDesc           | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | vsel                  | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | dsel                  | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | fsel                  | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | onewaySel             | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | codecconfig           | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | isup_usi              | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | uiLayer1_Prot         | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      | chain                 | Refer to notes    | B     | CAUTION      |
      |                       | notes below |       |              |
   |                       |                    |       |              |
   +-----------------------+--------------------+-------+--------------+

                      5.48 RFC3108
      +-----------------------+-------------+-------+--------------+

                  Table 48: RFC 3108 Attribute Analysis

   NOTE: RFC3108 RFC 3108 describes conventions for using SDP for characterizing
   ATM bearer connections using an AAL1, AAL2 AAL2, or AAL5 adaptation layers. layer.
   For AAL1, AAL2 AAL2, and AAL5, bearer connections can be used to transport
   single media streams.  In addition, for AAL1 and AAL2, multiple media
   streams can be multiplexed into a bearer connection.  For all
   adaptation types (AAL1, AAL2 AAL2, and AAL5), bearer connections can be
   bundled into a single media group.  In all cases addressed by
   RFC3108, a RFC
   3108, a real-time media stream (voice, video, voiceband data,
   pseudo-wire,
   pseudowire, and others) or a multiplex of media streams is mapped
   directly into an ATM connection.  RFC3108  RFC 3108 does not address cases
   where ATM serves as a low-level transport pipe for IP packets which that
   can, in turn can turn, carry one or more real-time (e.g. (e.g., VoIP) media sessions
   with a life-cycle life cycle different from that of the underlying ATM
   transport.

5.49.  3GPP TS 26.114

   [R3GPPTS26.114] specifies IP multimedia subsystem: Media handling and
   interaction
   +---------------------+--------------------------+-------+----------+
   | Name                | Notes                    | Level | Mux      |
   |                     |                          |       | Category |
   +---------------------+--------------------------+-------+----------+
   | 3gpp_sync_info      | Usage defined for the IP | M     | NORMAL   |
   |                     | Multimedia Subsystem     |       |          |
   |                     |                          |       |          |
   | 3gpp_MaxRecvSDUSize | Usage defined for the IP | M     | NORMAL   |
   |                     | Multimedia Subsystem     |       |          |
   |                     |                          |       |          |
   +---------------------+--------------------------+-------+----------+

                  5.49 3GPP TS 26.114 Attribute Analysis

5.50.  3GPP TS 183.063

   [R3GPPTS183.063]

   [TISPAN] describes Telecommunications and Internet converged Services
   and Protocols for Advanced Networking (TISPAN);

      +---------------------+---------------+-------+--------------+

       +--------------------+--------------+-------+--------------+
       | Name               | Notes        | Level | Mux Category |
      +---------------------+---------------+-------+--------------+
       +====================+==============+=======+==============+
       | PSCid              | Not Impacted impacted | S     | NORMAL       |
      |                     |               |       |              |
       +--------------------+--------------+-------+--------------+
       | bc_service         | Not Impacted impacted | S     | NORMAL       |
      |                     |               |       |              |
       +--------------------+--------------+-------+--------------+
       | bc_program         | Not Impacted impacted | S     | NORMAL       |
      |                     |               |       |              |
       +--------------------+--------------+-------+--------------+
       | bc_service_package | Not Impacted impacted | S     | NORMAL       |
      |                     |               |       |              |
      +---------------------+---------------+-------+--------------+

                  5.50
       +--------------------+--------------+-------+--------------+

               Table 49: 3GPP TS 183.063 Attribute Analysis

5.51.

5.50.  3GPP TS 24.182

   [R3GPPTS24.182]

   [IMS-CAT] specifies an IP multimedia subsystem Custom Alerting
   tones
   +------------+----------------------------------+-------+-----------+ for customized
   alerting tones.

      +------------+-------------------------+-------+--------------+
      | Name       | Notes                   | Level | Mux       |
   |            |                                  |       | Category |
   +------------+----------------------------------+-------+-----------+
      +============+=========================+=======+==============+
      | g.3gpp.cat | Usage defined for the IP   | M     | NORMAL       |
      |            | Multimedia Subsystem             |       |           |
   |            | IP multimedia subsystem |       |              |
   +------------+----------------------------------+-------+-----------+

                  5.51
      +------------+-------------------------+-------+--------------+

                Table 50: 3GPP TS 24.182 Attribute Analysis

5.52.

5.51.  3GPP TS 24.183

   [R3GPPTS24.183]

   [IMS-CRS] specifies an IP multimedia subsystem Custom Ringing
   Signal

   +------------+----------------------------------+-------+-----------+ for customized ringing
   signal.

      +------------+-------------------------+-------+--------------+
      | Name       | Notes                   | Level | Mux       |
   |            |                                  |       | Category |
   +------------+----------------------------------+-------+-----------+
      +============+=========================+=======+==============+
      | g.3gpp.crs | Usage defined for the IP   | M     | NORMAL       |
      |            | Multimedia Subsystem             |       |           |
   |            | IP multimedia subsystem |       |              |
   +------------+----------------------------------+-------+-----------+

                  5.52
      +------------+-------------------------+-------+--------------+

                Table 51: 3GPP TS 24.183 Attribute Analysis

5.53.

5.52.  3GPP TS 24.229

   [R3GPPTS24.229]

   [IP-CALL] specifies an IP multimedia call control protocol based on
   Session Initial protocol and Session Description Protocol.

   +-----------------+-----------------------------+-------+-----------+

   +-----------------+----------------------------+-------+-----------+
   | Name            | Notes                      | Level | Mux       |
   |                 |                            |       | Category  |
   +-----------------+-----------------------------+-------+-----------+
   +=================+============================+=======+===========+
   | secondary- secondary-realm | secondary-realm MUST be    | M     | TRANSPORT |
   | realm                 | the one that corresponds to   |       |           |
   |                 | to the "m=" line chosen for    |       |           |
   |                 | for setting up the underlying         |       |           |
   |                 | underlying transport flow              |       |           |
   |                 | flow. |       |           |
   +-----------------+----------------------------+-------+-----------+
   | visited-realm   | visited-realm MUST be the  | M     | TRANSPORT |
   |                 | one that corresponds to the    |       |           |
   |                 | the "m=" line chosen for   |       |           |
   |                 | setting up the underlying  |       |           |
   |                 | transport flow              |       |           |
   |                 | flow.            |       |           |
   +-----------------+----------------------------+-------+-----------+
   | omr-m-cksum     | Not Impacted impacted               | M     | NORMAL    |
   |                 |                             |       |           |
   +-----------------+----------------------------+-------+-----------+
   | omr-s-cksum     | Not Impacted impacted               | M     | NORMAL    |
   |                 |                             |       |           |
   +-----------------+----------------------------+-------+-----------+
   | omr-m-att       | Not Impacted impacted               | M     | NORMAL    |
   |                 |                             |       |           |
   +-----------------+----------------------------+-------+-----------+
   | omr-s-att       | Not Impacted impacted               | M     | NORMAL    |
   |                 |                             |       |           |
   +-----------------+----------------------------+-------+-----------+
   | omr-m-bw        | Not Impacted impacted               | M     | NORMAL    |
   |                 |                             |       |           |
   +-----------------+----------------------------+-------+-----------+
   | omr-s-bw        | Not Impacted impacted               | M     | NORMAL    |
   |                 |                             |       |           |
   +-----------------+----------------------------+-------+-----------+
   | omr-codecs      | Not Impacted impacted               | M     | NORMAL    |
   |                 |                             |       |           |
   +-----------------+-----------------------------+-------+-----------+

                  5.53
   +-----------------+----------------------------+-------+-----------+

               Table 52: 3GPP TS 24.229 Attribute Analysis

5.54.

5.53.  ITU T.38

   [T.38] defines procedures for real-time Group 3 facsimile
   communications over IP networks.

   +-----------------------+--------------------+-------+--------------+

      +-----------------------+-------------+-------+--------------+
      | Name                  | Notes       | Level | Mux Category |
   +-----------------------+--------------------+-------+--------------+
      +=======================+=============+=======+==============+
      | T38FaxVersion         | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38MaxBitRate         | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxFillBitRemoval  | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxTranscodingMMR  | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
      +-----------------------+-------------+-------+--------------+
      |                       |                    |       |              |
   | T38FaxTranscodingJBIG T38FaxTranscodingJBIG | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxRateManagement  | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxMaxBuffer       | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxMaxDatagram     | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxUdpEC           | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxMaxIFP          | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxUdpECDepth      | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38FaxUdpFECMaxSpan   | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38ModemType          | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
      +-----------------------+-------------+-------+--------------+
      | T38VendorInfo         | Refer to notes    | M     | TBD          |
      |                       | notes below |       |              |
   |                       |                    |       |              |
   +-----------------------+--------------------+-------+--------------+

                     5.54
      +-----------------------+-------------+-------+--------------+

                  Table 53: ITU T.38 Attribute Analysis

   NOTE: As per section Section 9 of [I-D.ietf-mmusic-sdp-bundle-negotiation], [RFC8843], there exists no publicly
   available specification that defines procedures for multiplexing/demultiplexing multiplexing/
   demultiplexing fax protocols protocol flows over a single 5-tuple.  Once such a
   specification is available, the multiplexing category assignments for
   the attributes in this section could be revisited.

5.55.

5.54.  ITU-T Q.1970

   [Q.1970] defines Bearer Independent Call Control (BICC) IP bearer
   control protocol.

   +-------+----------------------------------------+-------+----------+

    +-------+-------------------------------------+-------+----------+
    | Name  | Notes                               | Level | Mux      |
    |       |                                     |       | Category |
   +-------+----------------------------------------+-------+----------+
    +=======+=====================================+=======+==========+
    | ipbcp | ipbcp version identifies type of IP the types  | S     | SPECIAL  |
    |       | of IP bearer control protocol (IPBCP)       |       |          |
    |       | (IPBCP) message used in BICC (ITU-T Q.1901) |       |          |
    |       | Q.1901) environment which that are limited to        |       |          |
    |       | single media payload. Refer limited to the single-media payload.    |       |          |
    |       | Refer to the pertinent ITU-T specifications while   |       |          |
   |       | multiplexing        |       |          |
    |       | specifications while multiplexing.  |       |          |
   +-------+----------------------------------------+-------+----------+

                   5.55
    +-------+-------------------------------------+-------+----------+

                Table 54: ITU-T Q.1970 Attribute Analysis

5.56.

5.55.  ITU-T H.248.15

   ITU-T H.248.15 [H.248.15] defines the Gateway Control Protocol SDP
   H.248 package attribute attribute.

   +----------+-------------------------------------+-------+----------+
   | Name     | Notes                               | Level | Mux      |
   |          |                                     |       | Category |
   +----------+-------------------------------------+-------+----------+
   +==========+=====================================+=======+==========+
   | h248item | It is only applicable for signaling           | B     | SPECIAL  |
   |          | signaling the inclusion of H.248 extension    |       |          |
   |          | extension packages to a gateway     |       |          |
   |          | via the local and remote            |       |          |
   |          | and remote descriptors.  The attribute         |       |          |
   |          | attribute itself is unaffected by             |       |          |
   |          | multiplexing, but the packaged package       |       |          |
   |          | referenced in a specific use of the     |       |          |
   |          | the attribute can be impacted. Further      |       |          |
   |          | Further analysis of each package is needed    |       |          |
   |          | is needed to determine if there is an issue.     |       |          |
   |          | is an issue.  This is only a concern in        |       |          |
   |          | concern in environments using a decomposed     |       |          |
   |          | decomposed server/gateway with H.248 signaled      |       |          |
   |          | H.248 signaled between them.  The ITU-T will need   |       |          |
   |          | ITU-T will need to do further       |       |          |
   |          | analysis of various packages when   |       |          |
   |          | packages when they specify how to signal the      |       |          |
   |          | signal the use of multiplexing to a |       |          |
   |          | gateway                             |       |          |
   |          | gateway.   |       |          |
   +----------+-------------------------------------+-------+----------+

                  5.56

                Table 55: ITU-T H.248.15 Attribute Analysis

5.57.  RFC4975:

5.56.  RFC 4975: The Message Session Relay Protocol

   [RFC4975] describes the Message Session Relay Protocol, a protocol
   for transmitting a series of related instant messages in the context
   of a session.  Message sessions are treated like any other media
   stream when set up via a rendezvous or session creation session-creation protocol such
   as the Session Initiation Protocol.

   +----------------------+---------------------+-------+--------------+

       +----------------------+-------------+-------+--------------+
       | Name                 | Notes       | Level | Mux Category |
   +----------------------+---------------------+-------+--------------+
       +======================+=============+=======+==============+
       | accept-types         | Refer to notes    | M     | TBD          |
       |                      | notes below |       |              |
       +----------------------+-------------+-------+--------------+
       |                      |                     |       |              |
   | accept-wrapped- accept-wrapped-types | Refer to notes    | M     | TBD          |
       | types                      | notes below |       |              |
   |                      |                     |       |              |
       +----------------------+-------------+-------+--------------+
       | max-size             | Refer to notes    | M     | TBD          |
       |                      | notes below |       |              |
   |                      |                     |       |              |
       +----------------------+-------------+-------+--------------+
       | path                 | Refer to notes    | M     | TBD          |
       |                      | notes below |       |              |
   |                      |                     |       |              |
   +----------------------+---------------------+-------+--------------+

                      5.57 RFC4975
       +----------------------+-------------+-------+--------------+

                   Table 56: RFC 4975 Attribute Analysis

   NOTE: As per section Section 9 of [I-D.ietf-mmusic-sdp-bundle-negotiation], [RFC8843], there exists no publicly
   available specification that defines procedures for multiplexing/demultiplexing MRSP multiplexing/
   demultiplexing MSRP flows over a single 5-tuple.  Once such a
   specification is available, the multiplexing categories assignments
   for the attributes in this section could be revisited.

5.58.

5.57.  Historical Attributes

   This section specifies analysis for the attributes that are included
   for historic usage alone by the [IANA].

        +----------+----------------------+-------+--------------+

         +---------+---------------------+-------+--------------+
         | Name    | Notes               | Level | Mux Category |
        +----------+----------------------+-------+--------------+
         +=========+=====================+=======+==============+
         | rtpred1 | Historic attributes | M     | CAUTION      |
        |          |                      |       |              |
         +---------+---------------------+-------+--------------+
         | rtpred2 | Historic attributes | M     | CAUTION      |
        |          |                      |       |              |
        +----------+----------------------+-------+--------------+

                    5.58
         +---------+---------------------+-------+--------------+

                 Table 57: Historical Attribute Analysis

6.  bwtype Attribute Analysis

   This section specifies handling of specific bandwidth attributes when
   used in multiplexing scenarios.

6.1.  RFC4566:  RFC 4566: SDP

   [RFC4566] defines SDP that is intended for describing multimedia
   sessions for the purposes of session announcement, session
   invitation, and other forms of multimedia session initiation.

   +-----------+------------------------------------+-------+----------+

    +-----------+---------------------------------+-------+----------+
    | Name      | Notes                           | Level | Mux      |
    |           |                                 |       | Category |
   +-----------+------------------------------------+-------+----------+
    +===========+=================================+=======+==========+
    | bwtype:CT | Not Impacted impacted                    | S     | NORMAL   |
   |           |                                    |       |          |
    +-----------+---------------------------------+-------+----------+
    | bwtype:AS | For the media level media-level usage, the      | B     | SUM      |
    |           | aggregate of individual bandwidth         |       |          |
    |           | bandwidth values is considered               | considered. |       |          |           |                                    |       |          |
   +-----------+------------------------------------+-------+----------+

                        6.1 RFC4566
    +-----------+---------------------------------+-------+----------+

                    Table 58: RFC 4566 bwtype Analysis

6.2.  RFC3556:  RFC 3556: SDP Bandwidth Modifiers for RTCP Bandwidth

   [RFC3556] defines an extension to SDP to specify two additional
   modifiers for the bandwidth attribute.  These modifiers may be used
   to specify the bandwidth allowed for RTCP packets in a an RTP session.

   +-----------+------------------------------------+-------+----------+

     +-----------+--------------------------------+-------+----------+
     | Name      | Notes                          | Level | Mux      |
     |           |                                |       | Category |
   +-----------+------------------------------------+-------+----------+
     +===========+================================+=======+==========+
     | bwtype:RS | Session level Session-level usage represents | B     | SUM      |
     |           | session aggregate aggregate, and media level media-  |       |          |
     |           | level usage indicates SUM of the   |       |          |
     |           | the individual values while    |       |          |
     |           | multiplexing                       |       |          |
   |           | multiplexing.                  |       |          |
     +-----------+--------------------------------+-------+----------+
     | bwtype:RR | Session level Session-level usage represents | B     | SUM      |
     |           | session aggregate aggregate, and media level media-  |       |          |
     |           | level usage indicates SUM of the   |       |          |
     |           | the individual values while    |       |          |
     |           | multiplexing                       |       |          |
   |           | multiplexing.                  |       |          |
   +-----------+------------------------------------+-------+----------+

                        6.2 RFC3556
     +-----------+--------------------------------+-------+----------+

                     Table 59: RFC 3556 bwtype Analysis

6.3.  RFC3890:  RFC 3890: Bandwidth Modifier for SDP

   [RFC3890] defines SDP Transport Independent Application Specific
   Maximum (TIAS) bandwidth modifier that does not include transport
   overhead; instead instead, an additional packet rate packet-rate attribute is defined.
   The transport independent bit-rate transport-independent bitrate value together with the maximum
   packet rate can then be used to calculate the real bit-rate bitrate over the
   transport actually used.

   +-------------+----------------------------------+-------+----------+
   | Name        | Notes                            | Level | Mux      |
   |             |                                  |       | Category |
   +-------------+----------------------------------+-------+----------+
   +=============+==================================+=======+==========+
   | bwtype:TIAS | The usage of TIAS is not defined         | B     | SPECIAL  |
   |             | defined under Offer/Answer usage. offer/answer       |       |          |
   |             | usage.                           |       |          |
   +-------------+----------------------------------+-------+----------+
   | maxprate    | The usage of TIAS and maxprate            | B     | SPECIAL  |
   |             | maxprate is not well defined under        |       |          |
   |             | multiplexing             |       |          |
   |             | defined under multiplexing.      |       |          |
   +-------------+----------------------------------+-------+----------+

                        6.3 RFC3890

                     Table 60: RFC 3890 bwtype Analysis

   NOTE: The intention of TIAS is that the media level bit-rate media-level bitrate is
   multiplied with the known per-packet overhead for the selected
   transport and the maxprate value to determine the worst case bit-rate worst-case bitrate
   from the transport to more accurately capture the required usage.
   Summing TIAS values independently across "m=" lines and multiplying
   the computed sum with maxprate and the per-packet overhead would
   inflate the value significantly.  Instead  Instead, performing multiplication
   and adding the individual values is a more appropriate usage.

7.  rtcp-fb Attribute Analysis

   This section analyzes rtcp-fb SDP attributes.

7.1.  RFC4585:  RFC 4585: RTP/AVPF

   [RFC4585] defines an extension to the Audio-visual Audio-Visual Profile (AVP) that
   enables receivers to provide, statistically, more immediate feedback
   to the senders and senders; it thus allows for short-term adaptation and
   implementation of efficient feedback-based repair mechanisms to be implemented.

   +---------+------------------------------+-------+------------------+ mechanisms.

   +---------+-----------------------------+-------+------------------+
   | Name    | Notes                       | Level | Mux Category     |
   +---------+------------------------------+-------+------------------+
   +=========+=============================+=======+==================+
   | ack     | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
   | rpsi    | the same for a given codec  |       | PT               |
   |         | configuration                |       |                  |
   |         | configuration.              |       |                  |
   +---------+-----------------------------+-------+------------------+
   | ack app | Feedback parameters MUST be | M     | SPECIAL          |
   | app         | handled in the app specific app-specific |       |                  |
   |         | way when multiplexed         |       |                  |
   |         | multiplexed.       |       |                  |
   +---------+-----------------------------+-------+------------------+
   | nack    | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
   |         | the same for a given codec  |       | PT               |
   |         | configuration                |       |                  |
   |         | configuration.              |       |                  |
   +---------+-----------------------------+-------+------------------+
   | nack    | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
   | pli     | the same for a given codec  |       | PT               |
   |         | configuration                |       |                  |
   |         | configuration.              |       |                  |
   +---------+-----------------------------+-------+------------------+
   | nack    | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
   | sli     | the same for a given codec  |       | PT               |
   |         | configuration                |       |                  |
   |         | configuration.              |       |                  |
   +---------+-----------------------------+-------+------------------+
   | nack    | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
   | rpsi    | the same for a given codec  |       | PT               |
   |         | configuration                |       |                  |
   |         | configuration.              |       |                  |
   +---------+-----------------------------+-------+------------------+
   | nack    | Feedback parameters MUST be | M     | SPECIAL          |
   | app     | handled in the app specific |       |                  |
   |         | way when multiplexed         |       |                  |
   |         | multiplexed.       |       |                  |
   +---------+-----------------------------+-------+------------------+
   | trr- trr-int | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
   | int         | the same for a given codec  |       | PT               |
   |         | configuration                |                  |
   |         | configuration.              |       |                  |                  |
   +---------+------------------------------+-------+------------------+

                      7.1 RFC4585
   +---------+-----------------------------+-------+------------------+

                  Table 61: RFC 4585 Attribute Analysis

7.2.  RFC5104:  RFC 5104: Codec Control Messages in AVPF

   [RFC5104] specifies a few extensions to the messages defined in the
   Audio-Visual Profile with Feedback (AVPF).  They are helpful
   primarily in conversational multimedia scenarios where centralized
   multipoint functionalities are in use.  However, some are also usable
   in smaller multicast environments and point-to-point calls.

   +------+---------------------------------+-------+------------------+

      +------+--------------------------+-------+------------------+
      | Name | Notes                    | Level | Mux Category     |
   +------+---------------------------------+-------+------------------+
      +======+==========================+=======+==================+
      | ccm  | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      |      | be the same for a given codec          |       | PT               |
   |      | configuration  |       |                  |
      |      | codec configuration.     |       |                  |
   +------+---------------------------------+-------+------------------+

                      7.2 RFC5104
      +------+--------------------------+-------+------------------+

                  Table 62: RFC 5104 Attribute Analysis

7.3.  RFC6285:  RFC 6285: Unicast-Based Rapid Acquisition of Multicast RTP
      Sessions (RAMS)

   [RFC6285] describes a method of using the existing RTP and RTCP
   machinery that reduces the acquisition delay.  In this method, an
   auxiliary unicast RTP session carrying the Reference Information to
   the receiver precedes or accompanies the multicast stream.  This
   unicast RTP flow can be transmitted at a faster than natural faster-than-natural bitrate
   to further accelerate the acquisition.  The motivating use case for
   this capability is multicast applications that carry real-time
   compressed audio and video.

   +--------+-------------------------------+-------+------------------+

      +------+--------------------------+-------+------------------+
      | Name | Notes                    | Level | Mux Category     |
   +--------+-------------------------------+-------+------------------+
      +======+==========================+=======+==================+
      | nack | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      | rai  | be the same for a given codec        |       | PT               |
   |        | configuration  |       |                  |
      |      | codec configuration.     |       |                  |
   +--------+-------------------------------+-------+------------------+

                      7.3 RFC6285
      +------+--------------------------+-------+------------------+

                  Table 63: RFC 6285 Attribute Analysis

7.4.  RFC6679:  RFC 6679: ECN for RTP over UDP/IP

   [RFC6679] specifies how Explicit Congestion Notification (ECN) can be
   used with the RTP running over UDP, using the RTCP as a feedback
   mechanism.  It defines a new RTCP Extended Report (XR) block for
   periodic ECN feedback, a new RTCP transport feedback message for
   timely reporting of congestion events, and a STUN extension used in
   the optional initialization method using ICE.

   +-----------------+-----------------------------+-------+-----------+

   +-----------------+----------------------------+-------+-----------+
   | Name            | Notes                      | Level | Mux       |
   |                 |                            |       | Category  |
   +-----------------+-----------------------------+-------+-----------+
   +=================+============================+=======+===========+
   | ecn-capable- ecn-capable-rtp | ECN markup are is enabled at   | M     | IDENTICAL |
   | rtp                 | the RTP session level       |       |           |
   |                 | level.     |       |           |
   +-----------------+----------------------------+-------+-----------+
   | nack ecn        | This attribute enables ECN | M     | IDENTICAL |
   |                 | at the RTP session level    |       |           |
   |                 | level.  |       |           |
   +-----------------+-----------------------------+-------+-----------+

                      7.4 RFC6679
   +-----------------+----------------------------+-------+-----------+

                  Table 64: RFC 6679 Attribute Analysis

7.5.  RFC6642:  RFC 6642: Third-Party Loss Report

   In a large RTP session using the RTCP feedback mechanism defined in
   [RFC4585], a feedback target may experience transient overload if
   some event causes a large number of receivers to send feedback at
   once.  This overload is usually avoided by ensuring that feedback
   reports are forwarded to all receivers, allowing them to avoid
   sending duplicate feedback reports.  However, there are cases where
   it is not recommended to forward feedback reports, and this may allow
   feedback implosion.  [RFC6642] memo discusses these cases and defines a
   new RTCP Third-Party Loss Report that can be used to inform receivers
   that the feedback target is aware of some loss event, allowing them
   to suppress feedback.  Associated SDP signaling is also defined.

   +---------+------------------------------+-------+------------------+

      +-------+--------------------------+-------+------------------+
      | Name  | Notes                    | Level | Mux Category     |
   +---------+------------------------------+-------+------------------+
      +=======+==========================+=======+==================+
      | nack  | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      | tllei | be the same for a given codec       |       | PT               |
   |         | configuration  |       |                  |
      |       | codec configuration.     |       |                  |
      +-------+--------------------------+-------+------------------+
      | nack  | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      | pslei | be the same for a given codec       |       | PT               |
   |         | configuration  |       |                  |
      |       | codec configuration.     |       |                  |
   +---------+------------------------------+-------+------------------+

                      7.5 RFC6642
      +-------+--------------------------+-------+------------------+

                   Table 65: RFC 6642 Attribute Analysis

7.6.  RFC5104:  RFC 5104: Codec Control Messages in AVPF

   [RFC5104] specifies a few extensions to the messages defined in the
   Audio-Visual Profile with Feedback (AVPF).  They are helpful
   primarily in conversational multimedia scenarios where centralized
   multipoint functionalities are in use.  However, some are also usable
   in smaller multicast environments and point-to-point calls.

   +--------+-------------------------------+-------+------------------+

      +-------+--------------------------+-------+------------------+
      | Name  | Notes                    | Level | Mux Category     |
   +--------+-------------------------------+-------+------------------+
      +=======+==========================+=======+==================+
      | ccm   | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      | fir   | be the same for a given codec        |       | PT               |
   |        | configuration  |       |                  |
      |       | codec configuration.     |       |                  |
      +-------+--------------------------+-------+------------------+
      | ccm   | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      | tmmbr | be the same for a given codec        |       | PT               |
   |        | configuration  |       |                  |
      |       | codec configuration.     |       |                  |
      +-------+--------------------------+-------+------------------+
      | ccm   | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      | tstr  | be the same for a given codec        |       | PT               |
   |        | configuration  |       |                  |
      |       | codec configuration.     |       |                  |
      +-------+--------------------------+-------+------------------+
      | ccm   | The attribute value MUST be | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
      | vbcm  | be the same for a given codec        |       | PT               |
   |        | configuration  |       |                  |
      |       | codec configuration.     |       |                  |
   +--------+-------------------------------+-------+------------------+

                      7.6 RFC5104
      +-------+--------------------------+-------+------------------+

                   Table 66: RFC 5104 Attribute Analysis

8.  group Attribute Analysis

   This section analyzes SDP "group" attribute semantics [RFC5888].

8.1.  RFC5888:  RFC 5888: SDP Grouping Framework

   [RFC5888] defines a framework to group "m" "m=" lines in SDP for
   different purposes.

           +------------+---------------+-------+--------------+

            +-----------+--------------+-------+--------------+
            | Name      | Notes        | Level | Mux Category |
           +------------+---------------+-------+--------------+
            +===========+==============+=======+==============+
            | group:LS  | Not Impacted impacted | S     | NORMAL       |
           |            |               |       |              |
            +-----------+--------------+-------+--------------+
            | group:FID | Not Impacted impacted | S     | NORMAL       |
           |            |               |       |              |
           +------------+---------------+-------+--------------+

                      8.1 RFC5888
            +-----------+--------------+-------+--------------+

                   Table 67: RFC 5888 Attribute Analysis

8.2.  RFC3524:  RFC 3524: Mapping Media Streams to Resource Reservation Flows

   [RFC3524] defines an extension to the SDP grouping framework.  It
   allows requesting a group of media streams to be mapped into a single
   resource reservation flow.  The SDP syntax needed is defined, as well
   as a new "semantics" attribute called Single Reservation Flow (SRF).

           +------------+---------------+-------+--------------+

            +-----------+--------------+-------+--------------+
            | Name      | Notes        | Level | Mux Category |
           +------------+---------------+-------+--------------+
            +===========+==============+=======+==============+
            | group:SRF | Not Impacted impacted | S     | NORMAL       |
           |            |               |       |              |
           +------------+---------------+-------+--------------+

                      8.2 RFC3524
            +-----------+--------------+-------+--------------+

                   Table 68: RFC 3524 Attribute Analysis

8.3.  RFC4091:  RFC 4091: ANAT Semantics

   [RFC4091] defines ANAT semantics for the SDP grouping framework.
   (Note: [RFC4091] has been obsoleted by [RFC8445].)  The ANAT
   semantics allow alternative types of network addresses to establish a
   particular media stream.

   +-------------+------------------------------+-------+--------------+

   +------------+------------------------------+-------+--------------+
   | Name       | Notes                        | Level | Mux Category |
   +-------------+------------------------------+-------+--------------+
   +============+==============================+=======+==============+
   | group:ANAT | ANAT semantics is obsoleted obsoleted. | S     | CAUTION      |
   |             |                              |       |              |
   +-------------+------------------------------+-------+--------------+

                      8.3 RFC4091
   +------------+------------------------------+-------+--------------+

                  Table 69: RFC 4091 Attribute Analysis

8.4.  RFC5956:  RFC 5956: FEC Grouping Semantics in SDP

   [RFC5956] defines the semantics for grouping the associated source
   and FEC-based (Forward Error Correction) repair flows in SDP.  The semantics defined in the
   document are to be used with the SDP Grouping Framework [RFC5888].
   These semantics allow the description of grouping relationships
   between the source and repair flows when one or more source and/or
   repair flows are associated in the same
   group, and group; they also provide
   support for additive repair flows.  SSRC-
   level (Synchronization Source)  SSRC-level grouping semantics are
   also defined in this document for RTP streams using SSRC
   multiplexing.

         +---------------+---------------+-------+--------------+

          +--------------+--------------+-------+--------------+
          | Name         | Notes        | Level | Mux Category |
         +---------------+---------------+-------+--------------+
          +==============+==============+=======+==============+
          | group:FEC-FR | Not Impacted impacted | S     | NORMAL       |
         |               |               |       |              |
         +---------------+---------------+-------+--------------+

                      8.4 RFC5956
          +--------------+--------------+-------+--------------+

                  Table 70: RFC 5956 Attribute Analysis

8.5.  RFC5583:  RFC 5583: Signaling Media Decoding Dependency in SDP

   [RFC5583] defines semantics that allow for signaling the decoding
   dependency of different media descriptions with the same media type
   in SDP.  This is required, for example, if media data is separated
   and transported in different network streams as a result of the use
   of using a
   layered or multiple descriptive media coding process.

   +-----------+----------------------------+-------+------------------+

    +-----------+--------------------------+-------+------------------+
    | Name      | Notes                    | Level | Mux Category     |
   +-----------+----------------------------+-------+------------------+
    +===========+==========================+=======+==================+
    | group:DDP | Not Impacted impacted             | S     | NORMAL           |
   |           |                            |       |                  |
    +-----------+--------------------------+-------+------------------+
    | depend    | The attribute value MUST | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
    | lay       | be the same for a given codec  |       | PT               |
   |           | configuration  |       |                  |
    |           | codec configuration.     |       |                  |
    +-----------+--------------------------+-------+------------------+
    | depend    | The attribute value MUST | M     | IDENTICAL-PER- IDENTICAL-PER-PT |
    | mdc       | be the same for a given codec  |       | PT               |
   |           | configuration  |       |                  |
    |           | codec configuration.     |       |                  |
   +-----------+----------------------------+-------+------------------+

                      8.5 RFC5583
    +-----------+--------------------------+-------+------------------+

                   Table 71: RFC 5583 Attribute Analysis

8.6.  RFC7104:  RFC 7104: Duplication Grouping Semantics in the SDP

   [RFC7104] defines the semantics for grouping redundant streams in
   SDP,
   SDP.  The semantics defined in this document are to be used with the
   SDP Grouping Framework.  Grouping semantics at the SSRC)level synchronization
   source (SSRC) level are also defined in this document for RTP streams
   using SSRC multiplexing.

           +------------+---------------+-------+--------------+

            +-----------+--------------+-------+--------------+
            | Name      | Notes        | Level | Mux Category |
           +------------+---------------+-------+--------------+
            +===========+==============+=======+==============+
            | group:DUP | Not Impacted impacted | S     | NORMAL       |
           |            |               |       |              |
           +------------+---------------+-------+--------------+

                      8.6 RFC7104
            +-----------+--------------+-------+--------------+

                   Table 72: RFC 7104 Attribute Analysis

9.  ssrc-group Attribute Analysis

   This section analyzes "ssrc-group" semantics.

9.1.  RFC5576:  RFC 5576: Source-Specific SDP Attributes

   [RFC5576] defines a mechanism to describe for describing RTP media sources, sources --
   which are identified by their synchronization source (SSRC) identifiers,
   identifiers -- in SDP, to associate attributes with these sources, sources and to
   express relationships among sources.  It also defines several source-level source-
   level attributes that can be used to describe properties of media
   sources.

       +--------------------+---------------+-------+--------------+

        +-------------------+--------------+-------+--------------+
        | Name              | Notes        | Level | Mux Category |
       +--------------------+---------------+-------+--------------+
        +===================+==============+=======+==============+
        | ssrc-group:FID    | Not Impacted impacted | SR    | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ssrc-group:FEC    | Not Impacted impacted | SR    | NORMAL       |
       |                    |               |       |              |
        +-------------------+--------------+-------+--------------+
        | ssrc-group:FEC-FR | Not Impacted impacted | SR    | NORMAL       |
       |                    |               |       |              |
       +--------------------+---------------+-------+--------------+

                      9.1 RFC5576
        +-------------------+--------------+-------+--------------+

                   Table 73: RFC 5576 Attribute Analysis

9.2.  RFC7104:  RFC 7104: Duplication Grouping Semantics in the SDP

   [RFC7104] defines the semantics for grouping redundant streams in
   SDP.  The semantics defined in this document are to be used with the
   SDP Grouping Framework.  Grouping semantics at the Synchronization
   Source synchronization
   source (SSRC) level are also defined in this document for RTP streams
   using SSRC multiplexing.

        +-----------------+---------------+-------+--------------+

         +----------------+--------------+-------+--------------+
         | Name           | Notes        | Level | Mux Category |
        +-----------------+---------------+-------+--------------+
         +================+==============+=======+==============+
         | ssrc-group:DUP | Not Impacted impacted | SR    | NORMAL       |
        |                 |               |       |              |
        +-----------------+---------------+-------+--------------+

                      9.2 RFC7104
         +----------------+--------------+-------+--------------+

                  Table 74: RFC 7104 Attribute Analysis

10.  QoS Mechanism Token Analysis

   This section analyzes QoS tokes specified with SDP.

10.1.  RFC5432:  RFC 5432: QoS Mechanism Selection in SDP

   [RFC5432] defines procedures to negotiate QOS QoS mechanisms using the
   SDP offer/answer model.

   +------+----------------------------------------+-------+-----------+

       +------+--------------------------------+-------+-----------+
       | Name | Notes                          | Level | Mux       |
       |      |                                |       | Category  |
   +------+----------------------------------------+-------+-----------+
       +======+================================+=======+===========+
       | rsvp | rsvp attribute MUST be the one that | B     | TRANSPORT |
       |      | that corresponds to the "m=" line chosen   |       |           |
       |      | line chosen for setting up the underlying |       |           |
       |      | underlying transport flow                         |       |           |
   |      | flow.     |       |           |
       +------+--------------------------------+-------+-----------+
       | nsis | rsvp attribute MUST be the one that | B     | TRANSPORT |
       |      | that corresponds to the "m=" line chosen   |       |           |
       |      | line chosen for setting up the underlying          |       |           |
   |      | transport |       |           |
       |      | underlying transport.          |       |           |
   +------+----------------------------------------+-------+-----------+

                      10.1 RFC5432
       +------+--------------------------------+-------+-----------+

                   Table 75: RFC 5432 Attribute Analysis

   NOTE: A single Differentiated Services Code Point (DSCP) code point
   per for each
   flow being multiplexed doesn't impact multiplexing multiplexing, since QOS QoS
   mechanisms are signaled/scoped per flow.  For scenarios that involve
   having different DSCP code points for packets being transmitted over
   the same 5-tuple, issues as discussed in [RFC7657] need to be taken
   into consideration.

11.  k= Attribute Analysis

11.1.  RFC4566:  RFC 4566: SDP

   [RFC4566] defines SDP that is intended for describing multimedia
   sessions for the purposes of session announcement, session
   invitation, and other forms of multimedia session initiation.

   +------+-----------------------------------------+-------+----------+

    +------+-----------------------------------+-------+--------------+
    | Name | Notes                             | Level | Mux Category |
    +======+===================================+=======+==============+
    |      |                                         |       | Category |
   +------+-----------------------------------------+-------+----------+
   | k= k=   | It is not recommended to use this | S     | CAUTION      |
    |      | attribute under multiplexing            |       |          |
   |      | multiplexing.     |       |              |
   +------+-----------------------------------------+-------+----------+

                      11.1 RFC4566
    +------+-----------------------------------+-------+--------------+

                   Table 76: RFC 4566 Attribute Analysis

12.  content Attribute Analysis

12.1.  RFC4796  RFC 4796

   [RFC4796] defines a new SDP media-level attribute, 'content'. "content".  The
   'content'
   "content" attribute defines the content of the media stream to a more
   detailed level than the media description media-description line.  The sender of an SDP
   session description can attach the 'content' "content" attribute to one or more
   media streams.  The receiving application can then treat each media
   stream differently (e.g., show it on a big or small screen) based on
   its content.

        +------------------+---------------+-------+--------------+

         +-----------------+--------------+-------+--------------+
         | Name            | Notes        | Level | Mux Category |
        +------------------+---------------+-------+--------------+
         +=================+==============+=======+==============+
         | content:slides  | Not Impacted impacted | M     | NORMAL       |
        |                  |               |       |              |
         +-----------------+--------------+-------+--------------+
         | content:speaker | Not Impacted impacted | M     | NORMAL       |
        |                  |               |       |              |
         +-----------------+--------------+-------+--------------+
         | content:main    | Not Impacted impacted | M     | NORMAL       |
        |                  |               |       |              |
         +-----------------+--------------+-------+--------------+
         | content:sl      | Not Impacted impacted | M     | NORMAL       |
        |                  |               |       |              |
         +-----------------+--------------+-------+--------------+
         | content:alt     | Not Impacted impacted | M     | NORMAL       |
        |                  |               |       |              |
        +------------------+---------------+-------+--------------+

                      12.1 RFC4796
         +-----------------+--------------+-------+--------------+

                   Table 77: RFC 4796 Attribute Analysis

13.  Payload Formats

13.1.  RFC5109:  RFC 5109: RTP Payload Format for Generic FEC

   [RFC5109] describes a payload format for generic Forward Error
   Correction (FEC) for media data encapsulated in RTP.  It is based on
   the exclusive-or (parity) operation.  The payload format allows end
   systems to apply protection using various protection lengths and
   levels, in addition to using various protection group sizes to adapt
   to different media and channel characteristics.  It enables complete
   recovery of the protected packets or partial recovery of the critical
   parts of the payload payload, depending on the packet loss situation.

   +--------------------+---------------------------+-------+----------+

         +--------------+---------------------+-------+----------+
         | Name         | Notes               | Level | Mux      |
         |              |                     |       | Category |
   +--------------------+---------------------------+-------+----------+
         +==============+=====================+=======+==========+
         | audio/ulpfec | Not recommended for | M     | CAUTION  |
         |              | multiplexing due to reuse |       |          |
         |              | reuse of SSRCs                  |       |          |
   |                    | SSRCs.     |       |          |
         +--------------+---------------------+-------+----------+
         | video/ulpfec | Not recommended for | M     | CAUTION  |
         |              | multiplexing due to reuse |       |          |
         |              | reuse of SSRCs                  |       |          |
   |                    | SSRCs.     |       |          |
         +--------------+---------------------+-------+----------+
         | text/ulpfec  | Not recommended for | M     | CAUTION  |
         |              | multiplexing due to reuse |       |          |
         |              | reuse of SSRCs                  |       |          | SSRCs.     |       |          |
         +--------------+---------------------+-------+----------+
         |          |
   | application/ulpfec application/ | Not recommended for | M     | CAUTION  |
         | ulpfec       | multiplexing due to reuse |       |          |
         |              | reuse of SSRCs                  |       | SSRCs.     |       |          |                           |       |          |
   +--------------------+---------------------------+-------+----------+

                   13.1 RFC5109
         +--------------+---------------------+-------+----------+

                 Table 78: RFC 5109 Payload Format Analysis

14.  Multiplexing Considerations for Encapsulating Attributes

   This sections section deals with recommendations for defining the multiplexing
   characteristics of the SDP attributes that encapsulate other SDP
   attributes/parameters.  Such attributes as  As of today, such attributes, for example,
   are defined in [RFC3407], [RFC5939] and [RFC6871] as part of a
   generic framework for indicating and negotiating transport, media, transport-, media-,
   and media format related media-format-related capabilities in the SDP.

   The behavior of such attributes under multiplexing is is, in turn turn,
   defined by the multiplexing behavior of the attributes they encapsulate
   encapsulate, which are made known once the Offer/Answer offer/answer negotiation
   process is completed.

14.1.  RFC3407:  RFC 3407: cpar Attribute Analysis

   The [RFC3407] capability parameter attribute (a=cpar) "a=cpar" encapsulates b= a
   "b=" (bandwidth) or an a= "a=" attribute.  For bandwidth attribute
   encapsulation, the category SUM is inherited.  For the case of a= "a="
   attribute, the category corresponding to the SDP attribute being
   encapsulated is inherited.

    v=0
    o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
    s=
    c=IN IP4 host.atlanta.example.com
    t=0 0
    m=video 3456 RTP/AVP 100
    a=rtpmap:100 VP8/90000
    a=sqn: 0
    a=cdsc: 1 video RTP/AVP 100
    a=cpar: a=rtcp-mux
    m=video 3456 RTP/AVP 101
    a=rtpmap:101 VP8/90000
    a=fmtp:100 max-fr=15;max-fs=1200
    a=cdsc: 2 video RTP/AVP 101
    a=cpar: a=rtcp-mux

   In this example, the above example,the category IDENTICAL is inherited for the cpar cpar-
   encapsulated rtcp-mux "rtcp-mux" attribute.

14.2.  RFC5939  RFC 5939 Analysis

   [RFC5939] defines a general SDP capability negotiation framework.  It
   also specifies how to provide transport protocols and SDP attributes
   as capabilities and negotiate them using the framework.

   For this purpose, [RFC5939] defines the following

   o following:

   *  A set of capabilities for the session and its associated media media-
      stream components, supported by each side.  The attribute
      ("a=acap") "a=acap"
      defines how to list an attribute name and its associated value (if
      any) as a capability.  The attribute
      ("a=tcap") "a=tcap" defines how to list
      transport protocols (e.g., "RTP/
      AVP") "RTP/AVP") as capabilities.

   o

   *  A set of potential configurations ("a=pcfg") provided by the
      offerer to indicate which combinations of those capabilities can
      be used for the session and its associated media stream
      components.  Potential configurations are not ready for use until
      fully negotiated.  They provide an alternative that MAY be used,
      subject to SDP capability negotiation capability-negotiation procedures.  In particular particular,
      the answerer MAY choose one of the potential configurations for
      use as part of the current Offer/Answer offer/answer exchange.

   o

   *  An actual configuration ("a=acfg") for the session and its
      associated media stream components.  The actual configuration
      identifies the potential configuration that was negotiated for
      use.  Use of an actual configuration does not require any further
      negotiation.

   o

   *  A negotiation process that takes the current actual and the set of
      potential configurations (combinations of capabilities) as input
      and provides the negotiated actual configurations as output.  In
      [RFC5939]
      [RFC5939], the negotiation process is done independently for each
      media description.

14.2.1.  Recommendation: Procedures for Potential Configuration Pairing

   This section provides recommendations for entities generating and
   processing SDP under the generic capability negotiation capability-negotiation framework as
   defined in [RFC5939] under the context of media stream media-stream multiplexing.

   These recommendations are provided for the purposes of enabling the
   Offerer
   offerer to make sure that the generated potential configurations
   between the multiplexed streams can (easily) be negotiated to be
   consistent between those streams.  In particular, the procedures aim
   to simplify Answerer's the answerer's procedure to choose for choosing potential
   configurations that are consistent across all the multiplexed media
   descriptions.

   A potential configuration selects a set of attributes and parameters
   that become part of the media description when negotiated.  When
   multiplexing media descriptions with potential configurations
   specified, there MAY be a need for coordinating this selection
   between multiplexed media descriptions to ensure the right
   multiplexing behavior.

   Although it is possible to analyze the various potential
   configurations in multiplexed media descriptions to find combinations
   that satisfy such constraints, it can quickly become complicated to
   do so.

   The procedures defined in [RFC5939] state that each potential
   configuration in the SDP has a unique configuration number, however number; however,
   the scope of uniqueness is limited to each media description.  To
   make it simple for the answerer to chose valid combinations of
   potential configurations across media descriptions in a given bundle
   group, we provide a simple rule for constructing potential
   configurations

   o
   configurations:

   *  Let m-bundle be the set of media descriptions that form a given
      bundle .

   o
      bundle.

   *  Let m-bundle-pcfg be the set of media descriptions in m-bundle
      that include one or more potential configurations.

   o

   *  Each media description in m-bundle-pcfg MUST have at least one
      potential configuration with the same configuration number (e.g. (e.g.,
      "1").

   o

   *  For each potential configuration with configuration number x in m-
      bundle-pcfg, the offerer MUST ensure that if the answerer chooses
      configuration number x in each of the media descriptions in m-
      bundle-pcfg, then the resulting SDP will have all multiplexing
      constraints satisfied for those media descriptions.

   o

   *  Since it is nearly impossible to define a generic mechanism for
      various capability extensions, this document does't doesn't provide
      procedures for dealing with the capability extension capability-extension attributes.
      However, Section 14.3 provide provides analysis of media capability media-capability-
      extension attributes as defined in [RFC6871].

   The above allows the answerer to easily find multiplexing compatible multiplexing-compatible
   combinations of potential configurations: configurations.  The answerer simply choses
   chooses a potential configuration (number) that is present in all of
   the media descriptions with potential configurations in the bundle.

   Note that it is still possible for the offerer to provide additional
   potential configurations with independent configuration numbers.  The
   answerer will have to perform more complicated analysis to determine
   valid multiplexed combinations of those.

14.2.1.1.  Example: Transport Capability Transport-Capability Multiplexing

   v=0
   o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
   s=
   c=IN IP4 host.atlanta.example.com
   t=0 0
   a=tcap:1 RTP/SAVPF
   a=tcap:2 RTP/SAVP
   a=group:BUNDLE audio video
   m=audio
   a=mid:audio
   a=pcfg:1 t=1
   a=pcfg:2
   m=video
   a=mid:video
   a=pcfg:1 t=1
   a=pcfg:2 t=2

   In the example above, this example, the potential configurations that offer
   transport transport-
   protocol capability of RTP/SAVPF has have the same configuration number
   "1" in both the audio and video media descriptions.

14.2.1.2.  Example: Attribute Capability Attribute-Capability Multiplexing

   v=0
   o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com
   s=
   c=IN IP4 host.atlanta.example.com
   t=0 0
   a=acap:1 a=rtcp-mux
   a=acap:2 a=crypto:1 AES_CM_128_HMAC_SHA1_80
     inline:EcGZiNWpFJhQXdspcl1ekcmVCNWpVLcfHAwJSoj|2^20|1:32
   a=group:BUNDLE audio video
   m=audio 49172 RTP/AVP 99
   a=mid:audio
   a=pcfg:1 a=1
   a=pcfg:2
   m=video 560024 RTP/AVP 100
   a=mid:video
   a=pcfg:1 a=1
   a=pcfg:2 a=2

   In the example above, this example, the potential configuration number "1" is repeated
   while referring to attribute capability a=rtcp-mux, since the
   behavior is IDENTICAL for the attribute a=rtcp-mux under
   multiplexing.

14.3.  RFC6871  RFC 6871 Analysis

   [RFC6871] extends the capability negotiation framework described in
   [RFC5939] by defining media capabilities that can be used to indicate
   and negotiate media types and their associated format parameters.  It
   also allows indication of latent configurations and session
   capabilities.

14.3.1.  Recommendation: Dealing with Payload Type Numbers

   [RFC6871] defines a new payload type ("pt") parameter ("pt") to be used with
   the potential, actual, and latent configuration parameters.  The
   parameter associates RTP payload type numbers with the referenced
   RTP-based media format media-format capabilities ("a=rmcap") defined in [RFC6871]
   and is appropriate only when the transport protocol uses RTP.  This
   means that the same payload type number can be assigned as part of
   potential or actual configurations in different media descriptions in
   a bundle.  There are rules for the usage of identical Payload Type payload type
   values across multiplexed "m=" lines as lines, described in
   [I-D.ietf-mmusic-sdp-bundle-negotiation], [RFC8843], which
   must be followed here here, as well.  As described in Section 14.2.1, the
   use of identical configuration numbers for compatible configurations
   in different media descriptions that are part of the bundle provides
   a way to ensure that the answerer can easily pick compatible
   configurations
   here here, as well.

14.3.1.1.  Example: Attribute Capability Under under Shared Payload Type

   The attributes (a=rmcap, a=mfcap) "a=rmcap" and "a=mfcap" follow the above
   recommendations under multiplexing.

   v=0
   o=- 25678 753849 IN IP4 192.0.2.1
   s=
   c=IN IP4 192.0.2.1
   t=0 0
   a=creq:med-v0
   m=audio 54322 RTP/AVP 96
   a=rtpmap:96 AMR-WB/16000/1
   a=fmtp:96 mode-change-capability=1; max-red=220;
   mode-set=0,2,4,7
   a=rmcap:1,3 audio AMR-WB/16000/1
   a=rmcap:2 audio AMR/8000/1
   a=mfcap:1,2 mode-change-capability=1
   a=mfcap:3 mode-change-capability=2
   a=pcfg:1 m=1 pt=1:96
   a=pcfg:2 m=2 pt=2:97
   a=pcfg:3 m=3 pt=3:98
   m=audio 54322 RTP/AVP 96
   a=rtpmap:96 AMR-WB/16000/1
   a=fmtp:96 mode-change-capability=1; max-red=220;
   mode-set=0,2,4,7
   a=rmcap:4 audio AMR/8000/1
   a=rmcap:5 audio OPUS/48000/2
   a=mfcap:5 minptime=40
   a=mfcap:4 mode-change-capability=1
   a=pcfg:1 m=4 pt=4:97
   a=pcfg:4 m=5 pt=5:101

   In the example above, this example, the potential configuration number "1" is repeated
   when referring to media and media format media-format capability used for the
   Payload Type 96.  This implies that both the media capability capabilities 2 and 4 4,
   along with their media format capabilities media-format capabilities, MUST refer to the same
   codec configuration, as per the definition of IDENTICAL-PER-PT.

14.3.2.  Recommendation: Dealing with Latent Configurations

   [RFC6871] adds the notion of a latent configurations, which configuration that provides
   configuration information that may be used to guide a subsequent
   offer/exchange, e.g.
   offer/exchange -- e.g., by adding another media stream or use using
   alternative codec combinations not currently offered.  Latent
   configurations have configuration numbers which that cannot overlap with
   the potential configuration numbers [RFC6871].  Supported
   combinations of potential and latent configurations are indicated by
   use of the "a=sescap" attribute, however attribute; however, use of this attribute is
   not recommended with multiplexed media, since it requires the use of
   unique configuration numbers across the SDP.  Taken together, this
   means there is no well-defined way to indicate supported combinations
   of latent configurations, or combinations of latent and potential
   configurations with multiplexed media.  It is still allowed to use
   the latent configuration attribute, however attribute; however, the limitations above
   will apply.  To determine valid combinations, actual negotiation will
   have to be attempted subsequently instead.

15.  IANA Considerations

   [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this
   document.]

   Section 15.1 defines a new subregistry to be subregistry, which has been added by the IANA
   IANA, for identifying the initial registrations for various
   multiplexing categories applicable, as proposed described in this document.

   IANA is also requested to add has added a new column named "Mux Category" to several of the
   subregistries in the "Session Description Protocol (SDP) Parameters"
   registry.  The tables in Section 15.2 identify name the names of an entry entries
   in the existing subregistry and specify the value to be put in the
   new "Mux Category" column of the associated IANA registry. registry for each.

15.1.  New 'Multiplexing Categories' subregistry "Multiplexing Categories" Subregistry

   A new sub-registry needs to be defined subregistry has been created.  It is called the "Multiplexing
   Categories", with
   Categories" and has the following registrations created initially:
   "NORMAL", "CAUTION", "IDENTICAL", "TRANSPORT", "SUM", "INHERIT",
   "IDENTICAL-PER-PT", "SPECIAL" and "TBD" as defined in this document.

   Initial value registration for "Multiplexing Categories".

   +-------------------------+-----------+
   | Multiplexing Categories | Reference |
   +-------------------------+-----------+
   +=========================+===========+
   | NORMAL                  | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | CAUTION                 | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | IDENTICAL               | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | TRANSPORT               | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | SUM                     | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | INHERIT                 | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | IDENTICAL-PER-PT        | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | SPECIAL                 | RFCXXXX RFC 8859  |
   +-------------------------+-----------+
   | TBD                     | RFCXXXX RFC 8859  |
   +-------------------------+-----------+

                   Table 79

   Further entries can be registered using Standard Actions policies
   outlined in [RFC5226], [RFC8126], which requires IESG review and approval and
   standards-track
   Standards Track IETF RFC publication.

   Each registration needs to indicate the multiplexing category value
   to be added to the "Multiplexing Categories" subregistry subregistry, as defined
   in this section.

   Such a registration MUST also indicate the applicability of the newly
   defined multiplexing category value to various subregistries defined
   at
   in the "Session Description Protocol (SDP) Parameters" registry.

15.2.  'Mux Category' column  "Mux Category" Column for subregistries Subregistries

   Each sub-section subsection identifies a subregistry in of the "Session Description
   Protocol (SDP) Parameters" registry.  The tables list the column that
   identifies the SDP attribute name/Token/Value from the corresponding
   subregistries and the values to be used for the new "Mux Category"
   column to be added.

   For the entries

   Entries in the existing subregistries, under subregistries of the "Session Description
   Protocol (SDP) Parameters" registry, registry that lack a value for the "Mux
   Category" in this specification will get a value of "TBD".

   The registration policy for updates to the 'Mux Category' "Mux Category" column
   values for existing parameters, or when registering new parameters,
   are
   is beyond the scope of this document.  The registration policy for
   the affected table is defined in [I-D.ietf-mmusic-rfc4566bis]. [SDP].

15.2.1.  Table: SDP bwtype

   The following values are to be have been added to the 'SDP bwtype' "bwtype" subregistry
   in of
   the "Session Description Protocol (SDP) Parameters" registry.  The
   references should be have been updated to point at to this RFC as well as the
   previous references.

   +----------+--------------+
   | SDP Name | Mux Category |
   +----------+--------------+
   +==========+==============+
   | CT       | NORMAL       |
   +----------+--------------+
   | AS       | SUM          |
   +----------+--------------+
   | RS       | SUM          |
   +----------+--------------+
   | RR       | SUM          |
   +----------+--------------+
   | TIAS     | SPECIAL      |
   +----------+--------------+

             Table 80

15.2.2.  Table: att-field (session level)

   The following values are to be have been added to the "att-field (session
   level)" "att-field" subregistry in
   of the "Session Description Protocol (SDP) Parameters" registry.  The
   references should be have been updated to point at to this RFC as well as the
   previous references.

   +---------------------+--------------+

   NOTE: The attributes from [FLUTE] ("flute-tsi", "flute-ch", "FEC-
   declaration", "FEC-OTI-extension", "content-desc") were not analyzed
   for their multiplexing behavior, due to the expired status of the
   draft.  For the purposes of this specification, the multiplexing
   category of "TBD" is assigned.

   +--------------------------+------------------+
   | SDP Name                 | Mux Category     |
   +---------------------+--------------+
   +==========================+==================+
   | cat                      | NORMAL           |
   +--------------------------+------------------+
   | keywds                   | NORMAL           |
   +--------------------------+------------------+
   | type                     | NORMAL           |
   +--------------------------+------------------+
   | type:broadcast           | NORMAL           |
   +--------------------------+------------------+
   | type:H332                | NORMAL           |
   +--------------------------+------------------+
   | type:meeting             | NORMAL           |
   +--------------------------+------------------+
   | type:moderated           | NORMAL           |
   +--------------------------+------------------+
   | type:test                | NORMAL           |
   +--------------------------+------------------+
   | charset                  | NORMAL           |
   +--------------------------+------------------+
   | charset:iso8895-1        | NORMAL           |
   +--------------------------+------------------+
   | tool                     | NORMAL           |
   +--------------------------+------------------+
   | ipbcp                    | SPECIAL          |
   +--------------------------+------------------+
   | group                    | NORMAL           |
   +--------------------------+------------------+
   | ice-lite                 | NORMAL           |
   +--------------------------+------------------+
   | ice-options              | NORMAL           |
   +--------------------------+------------------+
   | bcastversion             | NORMAL           |
   +--------------------------+------------------+
   | 3GPP-Integrity-Key  | CAUTION      |
   | 3GPP-SDP-Auth       | CAUTION      |
   | alt-group           | CAUTION      |
   | PSCid               | NORMAL       |
   | bc_service          | NORMAL       |
   | bc_program          | NORMAL       |
   | bc_service_package  | NORMAL       |
   | sescap              | CAUTION      |
   | rtsp-ice-d-m        | TBD          |
   +---------------------+--------------+

15.2.3.  Table: att-field (both session and media level)

   The following values are to be added to the "att-field (both session
   and media level)" subregistry in the "Session Description Protocol
   (SDP) Parameters" registry.  The references should be updated to
   point at this RFC as well as the previous references.

   NOTE: The attributes from draft-ietf-rmt-flute-sdp ('flute-tsi',
   'flute-ch', 'FEC-declaration', 'FEC-OTI-extension', 'content-desc')
   were not analyzed for their multiplexing behavior due to the expired
   status of the draft.  For purposes of this specification, the
   multiplexing category of 'TBD' is assigned.

   +-------------------------+-------------------+ 3GPP-Integrity-Key       | SDP Name CAUTION          | Mux Category
   +--------------------------+------------------+
   | 3GPP-SDP-Auth            | CAUTION          |
   +--------------------------+------------------+
   | alt-group                | CAUTION          |
   +--------------------------+------------------+
   | PSCid                    | NORMAL           |
   +--------------------------+------------------+
   | bc_service               | NORMAL           |
   +--------------------------+------------------+
   | bc_program               | NORMAL           |
   +--------------------------+------------------+
   | bc_service_package       | NORMAL           |
   +--------------------------+------------------+
   | sescap                   | CAUTION          |
   +-------------------------+-------------------+
   +--------------------------+------------------+
   | rtsp-ice-d-m             | TBD              |
   +--------------------------+------------------+
   | recvonly                 | NORMAL           |
   +--------------------------+------------------+
   | sendrecv                 | NORMAL           |
   +--------------------------+------------------+
   | sendonly                 | NORMAL           |
   +--------------------------+------------------+
   | sdplang                  | NORMAL           |
   +--------------------------+------------------+
   | lang                     | NORMAL           |
   +--------------------------+------------------+
   | h248item                 | SPECIAL          |
   +--------------------------+------------------+
   | sqn                      | NORMAL           |
   +--------------------------+------------------+
   | cdsc                     | NORMAL           |
   +--------------------------+------------------+
   | cpar                     | INHERIT          |
   +--------------------------+------------------+
   | cparmin                  | SPECIAL          |
   +--------------------------+------------------+
   | cparmax                  | SPECIAL          |
   +--------------------------+------------------+
   | rtcp-xr                  | NORMAL           |
   +--------------------------+------------------+
   | maxprate                 | SPECIAL          |
   +--------------------------+------------------+
   | setup                    | TRANSPORT        |
   +--------------------------+------------------+
   | connection               | TRANSPORT        |
   +--------------------------+------------------+
   | key-mgmt                 | IDENTICAL        |
   +--------------------------+------------------+
   | source-filter            | IDENTICAL        |
   +--------------------------+------------------+
   | inactive                 | NORMAL           |
   +--------------------------+------------------+
   | fingerprint              | TRANSPORT        |
   +--------------------------+------------------+
   | flute-tsi                | TBD              |
   +--------------------------+------------------+
   | flute-ch                 | TBD              |
   +--------------------------+------------------+
   | FEC-declaration          | TBD              |
   +--------------------------+------------------+
   | FEC-OTI-extension        | TBD              |
   +--------------------------+------------------+
   | content-desc             | TBD              |
   +--------------------------+------------------+
   | ice-pwd                  | TRANSPORT        |
   +--------------------------+------------------+
   | ice-ufrag                | TRANSPORT        |
   +--------------------------+------------------+
   | stkmstream               | NORMAL           |
   +--------------------------+------------------+
   | extmap                   | SPECIAL          |
   +--------------------------+------------------+
   | qos-mech-send            | TRANSPORT        |
   +--------------------------+------------------+
   | qos-mech-recv            | TRANSPORT        |
   +--------------------------+------------------+
   | csup                     | NORMAL           |
   +--------------------------+------------------+
   | creq                     | NORMAL           |
   +--------------------------+------------------+
   | acap                     | INHERIT          |
   +--------------------------+------------------+
   | tcap                     | INHERIT          |
   +--------------------------+------------------+
   | 3GPP-QoE-Metrics         | CAUTION          |
   +--------------------------+------------------+
   | 3GPP-Asset-Information   | CAUTION          |
   +--------------------------+------------------+
   | mbms-mode                | CAUTION          |
   +--------------------------+------------------+
   | mbms-repair              | CAUTION          |
   +--------------------------+------------------+
   | ike-setup                | IDENTICAL        |
   +--------------------------+------------------+
   | psk-fingerprint          | IDENTICAL        |
   +--------------------------+------------------+
   | multicast-rtcp           | IDENTICAL        |
   +--------------------------+------------------+
   | rmcap                    | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | omcap                    | NORMAL           |
   +--------------------------+------------------+
   | mfcap                    | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | mscap                    | INHERIT          |
   +--------------------------+------------------+
   | 3gpp.iut.replication     | TBD              |
   +--------------------------+------------------+
   | bcap                     | INHERIT          |
   +--------------------------+------------------+
   | ccap                     | IDENTICAL        |
   +--------------------------+------------------+
   | icap                     | NORMAL           |
   | 3gpp_sync_info          | NORMAL            |
   | 3gpp_MaxRecvSDUSize     | NORMAL            |
   +--------------------------+------------------+
   | etag                     | CAUTION          |
   +--------------------------+------------------+
   | duplication-delay        | NORMAL           |
   +--------------------------+------------------+
   | range                    | CAUTION          |
   +--------------------------+------------------+
   | control                  | CAUTION          |
   +--------------------------+------------------+
   | mtag                     | CAUTION          |
   +--------------------------+------------------+
   | ts-refclk                | NORMAL           |
   +--------------------------+------------------+
   | mediaclk                 | NORMAL           |
   +--------------------------+------------------+
   | calgextmap               | NORMAL           |
   +-------------------------+-------------------+

15.2.4.  Table: att-field (media level only)

   The following values are to be added to the "att-field (media level
   only)" registry in the "Session Description Protocol (SDP)
   Parameters" registry.  The references should be updated to point at
   this RFC as well as the previous references.

   +---------------------------+-------------------+
   | SDP Name                  | Mux Category      |
   +---------------------------+-------------------+
   +--------------------------+------------------+
   | ptime                    | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | orient                   | NORMAL           |
   +--------------------------+------------------+
   | orient:portrait          | NORMAL           |
   +--------------------------+------------------+
   | orient:landscape         | NORMAL           |
   +--------------------------+------------------+
   | orient:seascape          | NORMAL           |
   +--------------------------+------------------+
   | framerate                | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | quality                  | NORMAL           |
   +--------------------------+------------------+
   | rtpmap                   | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | fmtp                     | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | rtpred1                  | CAUTION          |
   +--------------------------+------------------+
   | rtpred2                  | CAUTION          |
   +--------------------------+------------------+
   | T38FaxVersion            | TBD              |
   +--------------------------+------------------+
   | T38MaxBitRate            | TBD              |
   +--------------------------+------------------+
   | T38FaxFillBitRemoval     | TBD              |
   +--------------------------+------------------+
   | T38FaxTranscodingMMR     | TBD              |
   +--------------------------+------------------+
   | T38FaxTranscodingJBIG    | TBD              |
   +--------------------------+------------------+
   | T38FaxRateManagement     | TBD              |
   +--------------------------+------------------+
   | T38FaxMaxBuffer          | TBD              |
   +--------------------------+------------------+
   | T38FaxMaxDatagram        | TBD              |
   +--------------------------+------------------+
   | T38FaxUdpEC              | TBD              |
   +--------------------------+------------------+
   | maxptime                 | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | des                      | CAUTION          |
   +--------------------------+------------------+
   | curr                     | CAUTION          |
   +--------------------------+------------------+
   | conf                     | CAUTION          |
   +--------------------------+------------------+
   | mid                      | NORMAL           |
   +--------------------------+------------------+
   | rtcp                     | TRANSPORT        |
   +--------------------------+------------------+
   | rtcp-fb                  | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | label                    | NORMAL           |
   +--------------------------+------------------+
   | T38VendorInfo            | TBD              |
   +--------------------------+------------------+
   | crypto                   | TRANSPORT        |
   +--------------------------+------------------+
   | eecid                    | CAUTION          |
   +--------------------------+------------------+
   | aalType                  | CAUTION          |
   +--------------------------+------------------+
   | capability               | CAUTION          |
   +--------------------------+------------------+
   | qosClass                 | CAUTION          |
   +--------------------------+------------------+
   | bcob                     | CAUTION          |
   +--------------------------+------------------+
   | stc                      | CAUTION          |
   +--------------------------+------------------+
   | upcc                     | CAUTION          |
   +--------------------------+------------------+
   | atmQOSparms              | CAUTION          |
   +--------------------------+------------------+
   | atmTrfcDesc              | CAUTION          |
   +--------------------------+------------------+
   | abrParms                 | CAUTION          |
   +--------------------------+------------------+
   | abrSetup                 | CAUTION          |
   +--------------------------+------------------+
   | bearerType               | CAUTION          |
   +--------------------------+------------------+
   | lij                      | CAUTION          |
   +--------------------------+------------------+
   | anycast                  | CAUTION          |
   +--------------------------+------------------+
   | cache                    | CAUTION          |
   +--------------------------+------------------+
   | bearerSigIE              | CAUTION          |
   +--------------------------+------------------+
   | aalApp                   | CAUTION          |
   +--------------------------+------------------+
   | cbrRate                  | CAUTION          |
   +--------------------------+------------------+
   | sbc                      | CAUTION          |
   +--------------------------+------------------+
   | clkrec                   | CAUTION          |
   +--------------------------+------------------+
   | fec                      | CAUTION          |
   +--------------------------+------------------+
   | prtfl                    | CAUTION          |
   +--------------------------+------------------+
   | structure                | CAUTION          |
   +--------------------------+------------------+
   | cpsSDUsize               | CAUTION          |
   +--------------------------+------------------+
   | all2CPS aal2CPS                  | CAUTION          |
   +--------------------------+------------------+
   | all2CPSSDUrate aal2CPSSDUrate           | CAUTION          |
   +--------------------------+------------------+
   | aal2sscs3661unassured    | CAUTION          |
   +--------------------------+------------------+
   | aal2sscs3661assured      | CAUTION          |
   +--------------------------+------------------+
   | aal2sscs3662             | CAUTION          |
   +--------------------------+------------------+
   | aal5sscop                | CAUTION          |
   +--------------------------+------------------+
   | atmmap                   | CAUTION          |
   +--------------------------+------------------+
   | silenceSupp              | CAUTION          |
   +--------------------------+------------------+
   | ecan                     | CAUTION          |
   +--------------------------+------------------+
   | gc                       | CAUTION          |
   +--------------------------+------------------+
   | profileDesc              | CAUTION          |
   +--------------------------+------------------+
   | vsel                     | CAUTION          |
   +--------------------------+------------------+
   | dsel                     | CAUTION          |
   +--------------------------+------------------+
   | fsel                     | CAUTION          |
   +--------------------------+------------------+
   | onewaySel                | CAUTION          |
   +--------------------------+------------------+
   | codecconfig              | CAUTION          |
   +--------------------------+------------------+
   | isup_usi                 | CAUTION          |
   +--------------------------+------------------+
   | uiLayer1_Prot            | CAUTION          |
   +--------------------------+------------------+
   | chain                    | CAUTION          |
   +--------------------------+------------------+
   | floorctrl                | TBD              |
   +--------------------------+------------------+
   | confid                   | NORMAL TBD              |
   +--------------------------+------------------+
   | userid                   | NORMAL TBD              |
   +--------------------------+------------------+
   | floorid                  | NORMAL TBD              |
   +--------------------------+------------------+
   | FEC                      | NORMAL           |
   +--------------------------+------------------+
   | accept-types             | TBD              |
   +--------------------------+------------------+
   | accept-wrapped-types     | TBD              |
   +--------------------------+------------------+
   | max-size                 | TBD              |
   +--------------------------+------------------+
   | path                     | TBD              |
   +--------------------------+------------------+
   | dccp-service-code        | CAUTION          |
   +--------------------------+------------------+
   | rtcp-mux                 | IDENTICAL        |
   +--------------------------+------------------+
   | candidate                | TRANSPORT        |
   +--------------------------+------------------+
   | ice-mismatch             | NORMAL           |
   +--------------------------+------------------+
   | remote-candidates        | TRANSPORT        |
   +--------------------------+------------------+
   | SRTPAuthentication       | TBD              |
   +--------------------------+------------------+
   | SRTPROCTxRate            | TBD              |
   +--------------------------+------------------+
   | rtcp-rsize               | IDENTICAL        |
   +--------------------------+------------------+
   | file-selector            | TBD              |
   +--------------------------+------------------+
   | file-transfer-id         | TBD              |
   +--------------------------+------------------+
   | file-disposition         | TBD              |
   +--------------------------+------------------+
   | file-date                | TBD              |
   +--------------------------+------------------+
   | file-icon                | TBD              |
   +--------------------------+------------------+
   | file-range               | TBD              |
   +--------------------------+------------------+
   | depend                   | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | ssrc                     | NORMAL           |
   +--------------------------+------------------+
   | ssrc-group               | NORMAL           |
   +--------------------------+------------------+
   | rtcp-unicast             | IDENTICAL        |
   +--------------------------+------------------+
   | pcfg                     | SPECIAL          |
   +--------------------------+------------------+
   | acfg                     | SPECIAL          |
   +--------------------------+------------------+
   | zrtp-hash                | TRANSPORT        |
   +--------------------------+------------------+
   | X-predecbufsize          | CAUTION          |
   +--------------------------+------------------+
   | X-initpredecbufperiod    | CAUTION          |
   +--------------------------+------------------+
   | X-initpostdecbufperiod   | CAUTION          |
   +--------------------------+------------------+
   | X-decbyterate            | CAUTION          |
   +--------------------------+------------------+
   | 3gpp-videopostdecbufsize | CAUTION          |
   +--------------------------+------------------+
   | framesize                | CAUTION          |
   +--------------------------+------------------+
   | 3GPP-SRTP-Config         | CAUTION          |
   +--------------------------+------------------+
   | alt                      | CAUTION          |
   +--------------------------+------------------+
   | alt-default-id           | CAUTION          |
   +--------------------------+------------------+
   | 3GPP-Adaption-Support    | CAUTION          |
   +--------------------------+------------------+
   | mbms-flowid              | CAUTION          |
   +--------------------------+------------------+
   | fec-source-flow          | SPECIAL          |
   +--------------------------+------------------+
   | fec-repair-flow          | SPECIAL          |
   +--------------------------+------------------+
   | repair-window            | SPECIAL          |
   +--------------------------+------------------+
   | rams-updates             | CAUTION          |
   +--------------------------+------------------+
   | imageattr                | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | cfw-id                   | NORMAL           |
   +--------------------------+------------------+
   | portmapping-req          | CAUTION          |
   | g.3gpp.cat                | NORMAL            |
   +--------------------------+------------------+
   | g.3gpp.crs               | NORMAL           |
   +--------------------------+------------------+
   | ecn-capable-rtp          | IDENTICAL        |
   +--------------------------+------------------+
   | visited-realm            | TRANSPORT        |
   +--------------------------+------------------+
   | secondary-realm          | TRANSPORT        |
   +--------------------------+------------------+
   | omr-s-cksum              | NORMAL           |
   +--------------------------+------------------+
   | omr-m-cksum              | NORMAL           |
   +--------------------------+------------------+
   | omr-codecs               | NORMAL           |
   +--------------------------+------------------+
   | omr-m-att                | NORMAL           |
   +--------------------------+------------------+
   | omr-s-att                | NORMAL           |
   +--------------------------+------------------+
   | omr-m-bw                 | NORMAL           |
   +--------------------------+------------------+
   | omr-s-bw                 | NORMAL           |
   +--------------------------+------------------+
   | msrp-cema                | TBD              |
   +--------------------------+------------------+
   | dccp-port                | CAUTION          |
   +--------------------------+------------------+
   | resource                 | NORMAL           |
   +--------------------------+------------------+
   | channel                  | NORMAL           |
   +--------------------------+------------------+
   | cmid                     | NORMAL           |
   +--------------------------+------------------+
   | content                  | NORMAL           |
   +--------------------------+------------------+
   | lcfg                     | SPECIAL          |
   +--------------------------+------------------+
   | loopback                 | NORMAL           |
   +--------------------------+------------------+
   | loopback-source          | NORMAL           |
   +--------------------------+------------------+
   | loopback-mirror          | NORMAL           |
   +--------------------------+------------------+
   | chatroom                 | TBD              |
   +--------------------------+------------------+
   | altc                     | TRANSPORT        |
   +--------------------------+------------------+
   | T38FaxMaxIFP             | TBD              |
   +--------------------------+------------------+
   | T38FaxUdpECDepth         | TBD              |
   +--------------------------+------------------+
   | T38FaxUdpFECMaxSpan      | TBD              |
   +--------------------------+------------------+
   | T38ModemType             | TBD              |
   +--------------------------+------------------+
   | cs-correlation           | TBD              |
   +--------------------------+------------------+
   | rtcp-idms                | NORMAL           |
   +---------------------------+-------------------+

15.2.5.  Table: att-field (source level)

   The following values are to be added to the "att-field (source
   level)" registry in the "Session Description Protocol (SDP)
   Parameters" registry.  The references should be updated to point at
   this RFC as well as the previous references.

   +----------------+-------------------+
   | SDP Name       | Mux Category      |
   +----------------+-------------------+
   +--------------------------+------------------+
   | cname                    | NORMAL           |
   +--------------------------+------------------+
   | previous-ssrc            | NORMAL           |
   +--------------------------+------------------+
   | fmtp                     | IDENTICAL-PER-PT |
   +--------------------------+------------------+
   | ts-refclk                | NORMAL           |
   +--------------------------+------------------+
   | mediaclk                 | NORMAL           |
   +----------------+-------------------+

15.2.6.
   +--------------------------+------------------+

                       Table 81

15.2.3.  Table: content SDP Parameters

   The following values are to be have been added to the "content SDP Parameters"
   subregistry in of the "Session Description Protocol (SDP) Parameters"
   registry.  The references should be have been updated to point at to this RFC as
   well as the previous references.

   +----------+--------------+

   +------------+--------------+
   | SDP Name   | Mux Category |
   +----------+--------------+
   +============+==============+
   | slides     | NORMAL       |
   +------------+--------------+
   | speaker    | NORMAL       |
   +------------+--------------+
   | sl         | NORMAL       |
   +------------+--------------+
   | main       | NORMAL       |
   +------------+--------------+
   | alt        | NORMAL       |
   +----------+--------------+

15.2.7.
   +------------+--------------+
   | g.3gpp.cat | NORMAL       |
   +------------+--------------+

              Table 82

15.2.4.  Table: Semantics for the 'group' "group" SDP Attribute

   The following values are to be have been added to the "Semantics for the
   "group"
   'group' SDP Attribute" subregistry in of the "Session Description
   Protocol (SDP) Parameters" registry.  The references should be have been
   updated to point at to this RFC as well as the previous references.

   +---------+--------------+

   +--------+--------------+
   | Token  | Mux Category |
   +---------+--------------+
   +========+==============+
   | LS     | NORMAL       |
   +--------+--------------+
   | FID    | NORMAL       |
   +--------+--------------+
   | SRF    | NORMAL       |
   +--------+--------------+
   | ANAT   | CAUTION      |
   +--------+--------------+
   | FEC    | NORMAL       |
   +--------+--------------+
   | FEC-FR | NORMAL       |
   +--------+--------------+
   | CS     | NORMAL       |
   +--------+--------------+
   | DDP    | NORMAL       |
   +--------+--------------+
   | DUP    | NORMAL       |
   +---------+--------------+

15.2.8.
   +--------+--------------+

            Table 83

15.2.5.  Table: 'rtcp-fb' "rtcp-fb" Attribute Values

   The following values are to be have been added to the " 'rtcp-fb' "'rtcp-fb' Attribute
   Values" subregistry in of the "Session Description Protocol (SDP)
   Parameters" registry.  The references should be have been updated to point at to
   this RFC as well as the previous references.

   +------------+-------------------+

   +------------+------------------+
   | Value Name | Mux Category     |
   +------------+-------------------+
   +============+==================+
   | ack        | IDENTICAL-PER-PT |
   +------------+------------------+
   | app        | SPECIAL          |
   +------------+------------------+
   | ccm        | IDENTICAL-PER-PT |
   +------------+------------------+
   | nack       | IDENTICAL-PER-PT |
   +------------+------------------+
   | trr-int    | IDENTICAL-PER-PT |
   +------------+-------------------+

15.2.9.
   +------------+------------------+

                Table 84

15.2.6.  Table: 'ack' "ack" and 'nack' "nack" Attribute Values

   The following values are to be have been added to the " 'ack' "'ack' and 'nack'
   Attribute Values" subregistry in of the "Session Description Protocol
   (SDP) Parameters" registry.  The references should be have been updated to
   point at to this RFC as well as the previous references.

   +------------+-------------------+

   +------------+------------------+
   | Value Name | Mux Category     |
   +------------+-------------------+
   +============+==================+
   | sli        | IDENTICAL-PER-PT |
   +------------+------------------+
   | pli        | IDENTICAL-PER-PT |
   +------------+------------------+
   | rpsi       | IDENTICAL-PER-PT |
   +------------+------------------+
   | app        | SPECIAL          |
   +------------+------------------+
   | rai        | IDENTICAL-PER-PT |
   +------------+------------------+
   | tllei      | IDENTICAL-PER-PT |
   +------------+------------------+
   | pslei      | IDENTICAL-PER-PT |
   +------------+------------------+
   | ecn        | IDENTICAL        |
   +------------+-------------------+

15.2.10.
   +------------+------------------+

                Table 85

15.2.7.  Table: 'depend' "depend" SDP Attribute Values

   The following values are to be have been added to the " 'depend' "'depend' SDP Attribute
   Values" subregistry in of the "Session Description Protocol (SDP)
   Parameters" registry.  The references should be have been updated to point at to
   this RFC as well as the previous references.

   +-------+-------------------+

   +-------+------------------+
   | Token | Mux Category     |
   +-------+-------------------+
   +=======+==================+
   | lay   | IDENTICAL-PER-PT |
   +-------+------------------+
   | mdc   | IDENTICAL-PER-PT |
   +-------+-------------------+

15.2.11.
   +-------+------------------+

             Table 86

15.2.8.  Table: 'cs-correlation' "cs-correlation" Attribute Values

   The following values are to be have been added to the " "cs-correlation" "'cs-correlation'
   Attribute Values" subregistry in of the "Session Description Protocol
   (SDP) Parameters" registry.  The references should be have been updated to
   point at to this RFC as well as the previous references.

   +-----------+--------------+

   +----------+--------------+
   | Value    | Mux Category |
   +-----------+--------------+
   +==========+==============+
   | callerid | TBD          |
   +----------+--------------+
   | uuie     | TBD          |
   +----------+--------------+
   | dtmf     | TBD          |
   +----------+--------------+
   | external | TBD          |
   +-----------+--------------+

15.2.12.
   +----------+--------------+

             Table 87

15.2.9.  Table: Semantics for the 'ssrc-group' "ssrc-group" SDP Attribute

   The following values are to be have been added to the Semantics for the "Semantics for the "ssrc-group" 'ssrc-
   group' SDP Attribute" subregistry in of the "Session Description
   Protocol (SDP) Parameters" registry.  The references should be have been
   updated to point at to this RFC as well as the previous references.

   +---------+--------------+

   +--------+--------------+
   | Token  | Mux Category |
   +---------+--------------+
   +========+==============+
   | FID    | NORMAL       |
   +--------+--------------+
   | FEC    | NORMAL       |
   +--------+--------------+
   | FEC-FR | NORMAL       |
   +--------+--------------+
   | DUP    | NORMAL       |
   +---------+--------------+

15.2.13.
   +--------+--------------+

            Table 88

15.2.10.  Table: SDP/RTSP key management protocol identifiers Key Management Protocol Identifiers

   The following values are to be have been added to the "SDP/RTSP key management
   protocol identifiers" subregistry in of the "Session Description
   Protocol (SDP) Parameters" registry.  The references should be have been
   updated to point at to this RFC as well as the previous references.

   +------------+--------------+
   | Value Name | Mux Category |
   +------------+--------------+
   +============+==============+
   | mikey      | IDENTICAL    |
   +------------+--------------+

15.2.14.

              Table 89

15.2.11.  Table: Codec Control Messages

   The following values are to be have been added to the "Codec Control Messages"
   subregistry in of the "Session Description Protocol (SDP) Parameters"
   registry.  The references should be have been updated to point at to this RFC as
   well as the previous references.

   +------------+-------------------+

   +------------+------------------+
   | Value Name | Mux Category     |
   +------------+-------------------+
   +============+==================+
   | fir        | IDENTICAL-PER-PT |
   +------------+------------------+
   | tmmbr      | IDENTICAL-PER-PT |
   +------------+------------------+
   | tstr       | IDENTICAL-PER-PT |
   +------------+------------------+
   | vbcm       | IDENTICAL-PER-PT |
   +------------+-------------------+

15.2.15.
   +------------+------------------+

                Table 90

15.2.12.  Table: QoS Mechanism Tokens

   The following values are to be have been added to the "QoS Mechanism Tokens"
   subregistry in of the "Session Description Protocol (SDP) Parameters"
   registry.  The references should be have been updated to point at to this RFC as
   well as the previous references.

   +---------------+--------------+
   | QoS Mechanism | Mux Category |
   +---------------+--------------+
   +===============+==============+
   | rsvp          | TRANSPORT    |
   +---------------+--------------+
   | nsis          | TRANSPORT    |
   +---------------+--------------+

15.2.16.

               Table 91

15.2.13.  Table: SDP Capability Negotiation Option Tags

   The following values are to be have been added to the "SDP Capability
   Negotiation Option Tags" subregistry in of the "Session Description
   Protocol (SDP) Parameters" registry.  The references should be have been
   updated to point at to this RFC as well as the previous references.

   +------------+--------------+
   | Option Tag | Mux Category |
   +------------+--------------+
   +============+==============+
   | cap-v0     | NORMAL       |
   +------------+--------------+
   | med-v0     | NORMAL       |
   +------------+--------------+
   | bcap-v0    | NORMAL       |
   +------------+--------------+
   | ccap-v0    | NORMAL       |
   +------------+--------------+
   | icap-v0    | NORMAL       |
   +------------+--------------+

15.2.17.

              Table 92

15.2.14.  Table: Timestamp Reference Clock Source Parameters

   The following values are to be have been added to the "Timestamp Reference
   Clock Source Parameters" subregistry in of the "Session Description
   Protocol (SDP) Parameters" registry.  The references should be have been
   updated to point at to this RFC as well as the previous references.

   +----------+--------------+

   +---------+--------------+
   | Name    | Mux Category |
   +----------+--------------+
   +=========+==============+
   | ntp     | NORMAL       |
   +---------+--------------+
   | ptp     | NORMAL       |
   +---------+--------------+
   | gps     | NORMAL       |
   +---------+--------------+
   | gal     | NORMAL       |
   +---------+--------------+
   | glonass | NORMAL       |
   +---------+--------------+
   | local   | NORMAL       |
   +---------+--------------+
   | private | NORMAL       |
   +----------+--------------+

15.2.18.
   +---------+--------------+

            Table 93

15.2.15.  Table: Media Clock Source Parameters

   The following values are to be have been added to the "Media Clock Source
   Parameters" subegistry in subregistry of the "Session Description Protocol (SDP)
   Parameters" registry.  The references should be have been updated to point at to
   this RFC as well as the previous references.

   +-----------+--------------+

   +----------+--------------+
   | Name     | Mux Category |
   +-----------+--------------+
   +==========+==============+
   | sender   | NORMAL       |
   +----------+--------------+
   | direct   | NORMAL       |
   +----------+--------------+
   | IEEE1722 | NORMAL       |
   +-----------+--------------+
   +----------+--------------+

             Table 94

16.  Security Considerations

   The primary security considerations for RTP RTP, including the way it is
   used here is here, are described in [RFC3550] and [RFC3711].

   When multiplexing SDP attributes with the category "CAUTION", the
   implementations should be aware of possible issues as described in this
   specification.

19.

17.  References

19.1.

17.1.  Normative References

   [I-D.ietf-mmusic-sdp-bundle-negotiation]
              Holmberg, C., Alvestrand, H., and C. Jennings,
              "Negotiating Media Multiplexing Using the Session
              Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle-
              negotiation-48 (work in progress), January 2018.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997. 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, 4566, DOI 10.17487/RFC4566,
              July 2006, <https://www.rfc-editor.org/info/rfc4566>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8843]  Holmberg, C., Alvestrand, H., and C. Jennings,
              "Negotiating Media Multiplexing Using the Session
              Description Protocol (SDP)", RFC 8843,
              DOI 10.17487/RFC4566,
              July 2006, <https://www.rfc-editor.org/info/rfc4566>.

   [RFC5226]  Narten, T. 10.17487/RFC8843, April 2020,
              <https://www.rfc-editor.org/info/rfc8843>.

17.2.  Informative References

   [FLUTE]    Walsh, R., Peltotalo, J., Peltotalo, S., Curcio, I., and
              H. Alvestrand, "Guidelines Mehta, "SDP Descriptors for Writing an
              IANA Considerations Section FLUTE", Work in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008, <https://www.rfc-
              editor.org/info/rfc5226>.

19.2.  Informative References Progress,
              draft-ietf-rmt-flute-sdp-03, 12 September 2012.

   [H.248.15] ITU-T, "Gateway control protocol: SDP ITU-T H.248 package
              attribute",
              <http://www.itu.int/rec/T-REC-H.248.15>.

   [I-D.ietf-mmusic-rfc4566bis]
              Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
              Session Description Protocol", draft-ietf-mmusic-
              rfc4566bis-25 (work in progress), February 2018. ITU-T Recommendation H.248.15, March 2013,
              <https://www.itu.int/rec/T-REC-H.248.15>.

   [IANA]     IANA, "Session Description Protocol (SDP) Parameters",
              <http://www.iana.org/assignments/sdp-parameters/
              sdp-parameters.xml>.

   [Q.1970]   "Q.1970 : BICC IP bearer control protocol",
              <https://www.itu.int/rec/T-REC-Q.1970-200609-I/en>.

   [R3GPPTS183.063]
              "TISPAN - IMS based ITPV Stage 3 specification.",
              <http://www.etsi.org/deliver/
              etsi_ts/183000_183099/183063/02.01.00_60/
              ts_183063v020100p.pdf>.

   [R3GPPTS24.182]
              <https://www.iana.org/assignments/sdp-parameters/sdp-
              parameters.xml>.

   [IMS-CAT]  3GPP, "IP Multimedia Subsystem (IMS) Customized Alerting
              Tones (CAT); Protocol specification",
              <http://www.3gpp.org/ftp/Specs/html-info/24182.htm>.

   [R3GPPTS24.183]
              Specification 24.182, Specification 24.182, January 2015,
              <https://www.3gpp.org/ftp/Specs/html-info/24182.htm>.

   [IMS-CRS]  3GPP, "IP Multimedia Subsystem (IMS) Customized Ringing
              Signal (CRS); Protocol specification",
              <http://www.3gpp.org/ftp/Specs/html-info/24183.htm>.

   [R3GPPTS24.229]
              Specification 24.183, September 2016,
              <https://www.3gpp.org/ftp/Specs/html-info/24183.htm>.

   [IP-CALL]  3GPP, "IP multimedia call control protocol based on
              Session Initiation Protocol (SIP) and Session Description
              Protocol
              (SDP);",
              <http://www.3gpp.org/ftp/Specs/html-info/24229.htm>.

   [R3GPPTS26.114]
              "IP multimedia Subsystem : Media Handling and
              interaction", <http://www.3gpp.org/DynaReport/26114.htm>. (SDP); Stage 3", Specification 24.229, September
              2016,
              <https://www.3gpp.org/ftp/Specs/html-info/24229.htm>.

   [Q.1970]   ITU-T, "Q.1970: BICC IP bearer control protocol", ITU-T
              Recommendation Q.1970, September 2006,
              <https://www.itu.int/rec/T-REC-Q.1970-200609-I/en>.

   [RFC2326]  Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
              Streaming Protocol (RTSP)", RFC 2326,
              DOI 10.17487/RFC2326, April 1998, <https://www.rfc-
              editor.org/info/rfc2326>.
              <https://www.rfc-editor.org/info/rfc2326>.

   [RFC3108]  Kumar, R. and M. Mostafa, "Conventions for the use of the
              Session Description Protocol (SDP) for ATM Bearer
              Connections", RFC 3108, DOI 10.17487/RFC3108, May 2001,
              <https://www.rfc-editor.org/info/rfc3108>.

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264,
              DOI 10.17487/RFC3264, June 2002, <https://www.rfc-
              editor.org/info/rfc3264>.
              <https://www.rfc-editor.org/info/rfc3264>.

   [RFC3312]  Camarillo, G., Ed., Marshall, W., Ed., and J. Rosenberg,
              "Integration of Resource Management and Session Initiation
              Protocol (SIP)", RFC 3312, DOI 10.17487/RFC3312, October
              2002, <https://www.rfc-editor.org/info/rfc3312>.

   [RFC3407]  Andreasen, F., "Session Description Protocol (SDP) Simple
              Capability Declaration", RFC 3407, DOI 10.17487/RFC3407,
              October 2002, <https://www.rfc-editor.org/info/rfc3407>.

   [RFC3524]  Camarillo, G. and A. Monrad, "Mapping of Media Streams to
              Resource Reservation Flows", RFC 3524,
              DOI 10.17487/RFC3524, April 2003, <https://www.rfc-
              editor.org/info/rfc3524>.
              <https://www.rfc-editor.org/info/rfc3524>.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
              July 2003, <https://www.rfc-editor.org/info/rfc3550>.

   [RFC3556]  Casner, S., "Session Description Protocol (SDP) Bandwidth
              Modifiers for RTP Control Protocol (RTCP) Bandwidth",
              RFC 3556, DOI 10.17487/RFC3556, July 2003,
              <https://www.rfc-editor.org/info/rfc3556>.

   [RFC3605]  Huitema, C., "Real Time Control Protocol (RTCP) attribute
              in Session Description Protocol (SDP)", RFC 3605,
              DOI 10.17487/RFC3605, October 2003, <https://www.rfc-
              editor.org/info/rfc3605>.
              <https://www.rfc-editor.org/info/rfc3605>.

   [RFC3611]  Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed.,
              "RTP Control Protocol Extended Reports (RTCP XR)",
              RFC 3611, DOI 10.17487/RFC3611, November 2003,
              <https://www.rfc-editor.org/info/rfc3611>.

   [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
              Norrman, "The Secure Real-time Transport Protocol (SRTP)",
              RFC 3711, DOI 10.17487/RFC3711, March 2004,
              <https://www.rfc-editor.org/info/rfc3711>.

   [RFC3890]  Westerlund, M., "A Transport Independent Bandwidth
              Modifier for the Session Description Protocol (SDP)",
              RFC 3890, DOI 10.17487/RFC3890, September 2004,
              <https://www.rfc-editor.org/info/rfc3890>.

   [RFC4091]  Camarillo, G. and J. Rosenberg, "The Alternative Network
              Address Types (ANAT) Semantics for the Session Description
              Protocol (SDP) Grouping Framework", RFC 4091,
              DOI 10.17487/RFC4091, June 2005, <https://www.rfc-
              editor.org/info/rfc4091>.
              <https://www.rfc-editor.org/info/rfc4091>.

   [RFC4145]  Yon, D. and G. Camarillo, "TCP-Based Media Transport in
              the Session Description Protocol (SDP)", RFC 4145,
              DOI 10.17487/RFC4145, September 2005, <https://www.rfc-
              editor.org/info/rfc4145>.
              <https://www.rfc-editor.org/info/rfc4145>.

   [RFC4567]  Arkko, J., Lindholm, F., Naslund, M., Norrman, K., and E.
              Carrara, "Key Management Extensions for Session
              Description Protocol (SDP) and Real Time Streaming
              Protocol (RTSP)", RFC 4567, DOI 10.17487/RFC4567, July
              2006, <https://www.rfc-editor.org/info/rfc4567>.

   [RFC4568]  Andreasen, F., Baugher, M., and D. Wing, "Session
              Description Protocol (SDP) Security Descriptions for Media
              Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006,
              <https://www.rfc-editor.org/info/rfc4568>.

   [RFC4570]  Quinn, B. and R. Finlayson, "Session Description Protocol
              (SDP) Source Filters", RFC 4570, DOI 10.17487/RFC4570,
              July 2006, <https://www.rfc-editor.org/info/rfc4570>.

   [RFC4572]  Lennox, J., "Connection-Oriented Media Transport over the
              Transport Layer Security (TLS) Protocol in the Session
              Description Protocol (SDP)", RFC 4572,
              DOI 10.17487/RFC4572, July 2006, <https://www.rfc-
              editor.org/info/rfc4572>.
              <https://www.rfc-editor.org/info/rfc4572>.

   [RFC4574]  Levin, O. and G. Camarillo, "The Session Description
              Protocol (SDP) Label Attribute", RFC 4574,
              DOI 10.17487/RFC4574, August 2006, <https://www.rfc-
              editor.org/info/rfc4574>.
              <https://www.rfc-editor.org/info/rfc4574>.

   [RFC4583]  Camarillo, G., "Session Description Protocol (SDP) Format
              for Binary Floor Control Protocol (BFCP) Streams",
              RFC 4583, DOI 10.17487/RFC4583, November 2006,
              <https://www.rfc-editor.org/info/rfc4583>.

   [RFC4585]  Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
              "Extended RTP Profile for Real-time Transport Control
              Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
              DOI 10.17487/RFC4585, July 2006, <https://www.rfc-
              editor.org/info/rfc4585>.
              <https://www.rfc-editor.org/info/rfc4585>.

   [RFC4796]  Hautakorpi, J. and G. Camarillo, "The Session Description
              Protocol (SDP) Content Attribute", RFC 4796,
              DOI 10.17487/RFC4796, February 2007, <https://www.rfc-
              editor.org/info/rfc4796>.
              <https://www.rfc-editor.org/info/rfc4796>.

   [RFC4975]  Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed.,
              "The Message Session Relay Protocol (MSRP)", RFC 4975,
              DOI 10.17487/RFC4975, September 2007, <https://www.rfc-
              editor.org/info/rfc4975>.
              <https://www.rfc-editor.org/info/rfc4975>.

   [RFC5104]  Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
              "Codec Control Messages in the RTP Audio-Visual Profile
              with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
              February 2008, <https://www.rfc-editor.org/info/rfc5104>.

   [RFC5109]  Li, A., Ed., "RTP Payload Format for Generic Forward Error
              Correction", RFC 5109, DOI 10.17487/RFC5109, December
              2007, <https://www.rfc-editor.org/info/rfc5109>.

   [RFC5159]  Dondeti, L., Ed. and A. Jerichow, "Session Description
              Protocol (SDP) Attributes for Open Mobile Alliance (OMA)
              Broadcast (BCAST) Service and Content Protection",
              RFC 5159, DOI 10.17487/RFC5159, March 2008,
              <https://www.rfc-editor.org/info/rfc5159>.

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245,
              DOI 10.17487/RFC5245, April 2010, <https://www.rfc-
              editor.org/info/rfc5245>.

   [RFC5285]  Singer, D. and H. Desineni, "A General Mechanism for RTP
              Header Extensions", RFC 5285, DOI 10.17487/RFC5285, July
              2008, <https://www.rfc-editor.org/info/rfc5285>.

   [RFC5432]  Polk, J., Dhesikan, S., and G. Camarillo, "Quality of
              Service (QoS) Mechanism Selection in the Session
              Description Protocol (SDP)", RFC 5432,
              DOI 10.17487/RFC5432, March 2009, <https://www.rfc-
              editor.org/info/rfc5432>.
              <https://www.rfc-editor.org/info/rfc5432>.

   [RFC5506]  Johansson, I. and M. Westerlund, "Support for Reduced-Size
              Real-Time Transport Control Protocol (RTCP): Opportunities
              and Consequences", RFC 5506, DOI 10.17487/RFC5506, April
              2009, <https://www.rfc-editor.org/info/rfc5506>.

   [RFC5547]  Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S.,
              and P. Kyzivat, "A Session Description Protocol (SDP)
              Offer/Answer Mechanism to Enable File Transfer", RFC 5547,
              DOI 10.17487/RFC5547, May 2009, <https://www.rfc-
              editor.org/info/rfc5547>.
              <https://www.rfc-editor.org/info/rfc5547>.

   [RFC5576]  Lennox, J., Ott, J., and T. Schierl, "Source-Specific
              Media Attributes in the Session Description Protocol
              (SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009,
              <https://www.rfc-editor.org/info/rfc5576>.

   [RFC5583]  Schierl, T. and S. Wenger, "Signaling Media Decoding
              Dependency in the Session Description Protocol (SDP)",
              RFC 5583, DOI 10.17487/RFC5583, July 2009,
              <https://www.rfc-editor.org/info/rfc5583>.

   [RFC5760]  Ott, J., Chesterfield, J., and E. Schooler, "RTP Control
              Protocol (RTCP) Extensions for Single-Source Multicast
              Sessions with Unicast Feedback", RFC 5760,
              DOI 10.17487/RFC5760, February 2010, <https://www.rfc-
              editor.org/info/rfc5760>.
              <https://www.rfc-editor.org/info/rfc5760>.

   [RFC5761]  Perkins, C. and M. Westerlund, "Multiplexing RTP Data and
              Control Packets on a Single Port", RFC 5761,
              DOI 10.17487/RFC5761, April 2010, <https://www.rfc-
              editor.org/info/rfc5761>.
              <https://www.rfc-editor.org/info/rfc5761>.

   [RFC5762]  Perkins, C., "RTP and the Datagram Congestion Control
              Protocol (DCCP)", RFC 5762, DOI 10.17487/RFC5762, April
              2010, <https://www.rfc-editor.org/info/rfc5762>.

   [RFC5763]  Fischl, J., Tschofenig, H., and E. Rescorla, "Framework
              for Establishing a Secure Real-time Transport Protocol
              (SRTP) Security Context Using Datagram Transport Layer
              Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May
              2010, <https://www.rfc-editor.org/info/rfc5763>.

   [RFC5888]  Camarillo, G. and H. Schulzrinne, "The Session Description
              Protocol (SDP) Grouping Framework", RFC 5888,
              DOI 10.17487/RFC5888, June 2010, <https://www.rfc-
              editor.org/info/rfc5888>.
              <https://www.rfc-editor.org/info/rfc5888>.

   [RFC5939]  Andreasen, F., "Session Description Protocol (SDP)
              Capability Negotiation", RFC 5939, DOI 10.17487/RFC5939,
              September 2010, <https://www.rfc-editor.org/info/rfc5939>.

   [RFC5956]  Begen, A., "Forward Error Correction Grouping Semantics in
              the Session Description Protocol", RFC 5956,
              DOI 10.17487/RFC5956, September 2010, <https://www.rfc-
              editor.org/info/rfc5956>.
              <https://www.rfc-editor.org/info/rfc5956>.

   [RFC6064]  Westerlund, M. and P. Frojdh, "SDP and RTSP Extensions
              Defined for 3GPP Packet-Switched Streaming Service and
              Multimedia Broadcast/Multicast Service", RFC 6064,
              DOI 10.17487/RFC6064, January 2011, <https://www.rfc-
              editor.org/info/rfc6064>.
              <https://www.rfc-editor.org/info/rfc6064>.

   [RFC6128]  Begen, A., "RTP Control Protocol (RTCP) Port for Source-
              Specific Multicast (SSM) Sessions", RFC 6128,
              DOI 10.17487/RFC6128, February 2011, <https://www.rfc-
              editor.org/info/rfc6128>.
              <https://www.rfc-editor.org/info/rfc6128>.

   [RFC6189]  Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP:
              Media Path Key Agreement for Unicast Secure RTP",
              RFC 6189, DOI 10.17487/RFC6189, April 2011,
              <https://www.rfc-editor.org/info/rfc6189>.

   [RFC6193]  Saito, M., Wing, D., and M. Toyama, "Media Description for
              the Internet Key Exchange Protocol (IKE) in the Session
              Description Protocol (SDP)", RFC 6193,
              DOI 10.17487/RFC6193, April 2011, <https://www.rfc-
              editor.org/info/rfc6193>.
              <https://www.rfc-editor.org/info/rfc6193>.

   [RFC6230]  Boulton, C., Melanchuk, T., and S. McGlashan, "Media
              Control Channel Framework", RFC 6230,
              DOI 10.17487/RFC6230, May 2011, <https://www.rfc-
              editor.org/info/rfc6230>.
              <https://www.rfc-editor.org/info/rfc6230>.

   [RFC6236]  Johansson, I. and K. Jung, "Negotiation of Generic Image
              Attributes in the Session Description Protocol (SDP)",
              RFC 6236, DOI 10.17487/RFC6236, May 2011,
              <https://www.rfc-editor.org/info/rfc6236>.

   [RFC6284]  Begen, A., Wing, D., and T. Van Caenegem, "Port Mapping
              between Unicast and Multicast RTP Sessions", RFC 6284,
              DOI 10.17487/RFC6284, June 2011, <https://www.rfc-
              editor.org/info/rfc6284>.
              <https://www.rfc-editor.org/info/rfc6284>.

   [RFC6285]  Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax,
              "Unicast-Based Rapid Acquisition of Multicast RTP
              Sessions", RFC 6285, DOI 10.17487/RFC6285, June 2011,
              <https://www.rfc-editor.org/info/rfc6285>.

   [RFC6364]  Begen, A., "Session Description Protocol Elements for the
              Forward Error Correction (FEC) Framework", RFC 6364,
              DOI 10.17487/RFC6364, October 2011, <https://www.rfc-
              editor.org/info/rfc6364>.
              <https://www.rfc-editor.org/info/rfc6364>.

   [RFC6642]  Wu, Q., Ed., Xia, F., and R. Even, "RTP Control Protocol
              (RTCP) Extension for a Third-Party Loss Report", RFC 6642,
              DOI 10.17487/RFC6642, June 2012, <https://www.rfc-
              editor.org/info/rfc6642>.
              <https://www.rfc-editor.org/info/rfc6642>.

   [RFC6679]  Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P.,
              and K. Carlberg, "Explicit Congestion Notification (ECN)
              for RTP over UDP", RFC 6679, DOI 10.17487/RFC6679, August
              2012, <https://www.rfc-editor.org/info/rfc6679>.

   [RFC6714]  Holmberg, C., Blau, S., and E. Burger, "Connection
              Establishment for Media Anchoring (CEMA) for the Message
              Session Relay Protocol (MSRP)", RFC 6714,
              DOI 10.17487/RFC6714, August 2012, <https://www.rfc-
              editor.org/info/rfc6714>.
              <https://www.rfc-editor.org/info/rfc6714>.

   [RFC6773]  Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A
              Datagram Congestion Control Protocol UDP Encapsulation for
              NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November
              2012, <https://www.rfc-editor.org/info/rfc6773>.

   [RFC6787]  Burnett, D. and S. Shanmugham, "Media Resource Control
              Protocol Version 2 (MRCPv2)", RFC 6787,
              DOI 10.17487/RFC6787, November 2012, <https://www.rfc-
              editor.org/info/rfc6787>.
              <https://www.rfc-editor.org/info/rfc6787>.

   [RFC6849]  Kaplan, H., Ed., Hedayat, K., Venna, N., Jones, P., and N.
              Stratton, "An Extension to the Session Description
              Protocol (SDP) and Real-time Transport Protocol (RTP) for
              Media Loopback", RFC 6849, DOI 10.17487/RFC6849, February
              2013, <https://www.rfc-editor.org/info/rfc6849>.

   [RFC6871]  Gilman, R., Even, R., and F. Andreasen, "Session
              Description Protocol (SDP) Media Capabilities
              Negotiation", RFC 6871, DOI 10.17487/RFC6871, February
              2013, <https://www.rfc-editor.org/info/rfc6871>.

   [RFC6947]  Boucadair, M., Kaplan, H., Gilman, R., and S.
              Veikkolainen, "The Session Description Protocol (SDP)
              Alternate Connectivity (ALTC) Attribute", RFC 6947,
              DOI 10.17487/RFC6947, May 2013, <https://www.rfc-
              editor.org/info/rfc6947>.
              <https://www.rfc-editor.org/info/rfc6947>.

   [RFC7006]  Garcia-Martin, M., Veikkolainen, S., and R. Gilman,
              "Miscellaneous Capabilities Negotiation in the Session
              Description Protocol (SDP)", RFC 7006,
              DOI 10.17487/RFC7006, September 2013, <https://www.rfc-
              editor.org/info/rfc7006>.
              <https://www.rfc-editor.org/info/rfc7006>.

   [RFC7104]  Begen, A., Cai, Y., and H. Ou, "Duplication Grouping
              Semantics in the Session Description Protocol", RFC 7104,
              DOI 10.17487/RFC7104, January 2014, <https://www.rfc-
              editor.org/info/rfc7104>.
              <https://www.rfc-editor.org/info/rfc7104>.

   [RFC7195]  Garcia-Martin, M. and S. Veikkolainen, "Session
              Description Protocol (SDP) Extension for Setting Audio and
              Video Media Streams over Circuit-Switched Bearers in the
              Public Switched Telephone Network (PSTN)", RFC 7195,
              DOI 10.17487/RFC7195, May 2014, <https://www.rfc-
              editor.org/info/rfc7195>.
              <https://www.rfc-editor.org/info/rfc7195>.

   [RFC7197]  Begen, A., Cai, Y., and H. Ou, "Duplication Delay
              Attribute in the Session Description Protocol", RFC 7197,
              DOI 10.17487/RFC7197, April 2014, <https://www.rfc-
              editor.org/info/rfc7197>.
              <https://www.rfc-editor.org/info/rfc7197>.

   [RFC7266]  Clark, A., Wu, Q., Schott, R., and G. Zorn, "RTP Control
              Protocol (RTCP) Extended Report (XR) Blocks for Mean
              Opinion Score (MOS) Metric Reporting", RFC 7266,
              DOI 10.17487/RFC7266, June 2014, <https://www.rfc-
              editor.org/info/rfc7266>.
              <https://www.rfc-editor.org/info/rfc7266>.

   [RFC7272]  van Brandenburg, R., Stokking, H., van Deventer, O.,
              Boronat, F., Montagud, M., and K. Gross, "Inter-
              Destination Media Synchronization (IDMS) Using the RTP
              Control Protocol (RTCP)", RFC 7272, DOI 10.17487/RFC7272,
              June 2014, <https://www.rfc-editor.org/info/rfc7272>.

   [RFC7273]  Williams, A., Gross, K., van Brandenburg, R., and H.
              Stokking, "RTP Clock Source Signalling", RFC 7273,
              DOI 10.17487/RFC7273, June 2014, <https://www.rfc-
              editor.org/info/rfc7273>.
              <https://www.rfc-editor.org/info/rfc7273>.

   [RFC7657]  Black, D., Ed. and P. Jones, "Differentiated Services
              (Diffserv) and Real-Time Communication", RFC 7657,
              DOI 10.17487/RFC7657, November 2015, <https://www.rfc-
              editor.org/info/rfc7657>.
              <https://www.rfc-editor.org/info/rfc7657>.

   [RFC8122]  Lennox, J. and C. Holmberg, "Connection-Oriented Media
              Transport over the Transport Layer Security (TLS) Protocol
              in the Session Description Protocol (SDP)", RFC 8122,
              DOI 10.17487/RFC8122, March 2017,
              <https://www.rfc-editor.org/info/rfc8122>.

   [RFC8285]  Singer, D., Desineni, H., and R. Even, Ed., "A General
              Mechanism for RTP Header Extensions", RFC 8285,
              DOI 10.17487/RFC8285, October 2017,
              <https://www.rfc-editor.org/info/rfc8285>.

   [RFC8445]  Keranen, A., Holmberg, C., and J. Rosenberg, "Interactive
              Connectivity Establishment (ICE): A Protocol for Network
              Address Translator (NAT) Traversal", RFC 8445,
              DOI 10.17487/RFC8445, July 2018,
              <https://www.rfc-editor.org/info/rfc8445>.

   [RFC8856]  Camarillo, G., Kristensen, T., and C. Holmberg, "Session
              Description Protocol (SDP) Format for Binary Floor Control
              Protocol (BFCP) Streams", RFC 8856, DOI 10.17487/RFC8856,
              May 2020, <https://www.rfc-editor.org/info/rfc8856>.

   [SDP]      Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
              Session Description Protocol", Work in Progress, draft-
              ietf-mmusic-rfc4566bis-35, 3 May 2019.

   [T.38]     ITU-T, "Procedures for real-time Group 3 facsimile
              communication over IP networks", <http://www.itu.int/rec/T-REC-T.38/e>.

17.  Acknowledgments ITU-T
              Recommendation T.38, November 2015,
              <https://www.itu.int/rec/T-REC-T.38/e>.

   [TISPAN]   ETSI, "Telecommunications and Internet converged Services
              and Protocols for Advanced Networking (TISPAN); IMS-based
              IPTV stage 3 specification", Technical Specification 183
              063 V2.1.0, June 2008, <https://www.etsi.org/deliver/
              etsi_ts/183000_183099/183063/02.01.00_60/
              ts_183063v020100p.pdf>.

Acknowledgements

   I would like to thank Cullen Jennings, Jennings and Flemming Andreasen for
   suggesting the categories, contributing text text, and reviewing the draft. draft
   of this document.  I would also link like to thank Magnus Westerlund,
   Christer Holmberg, Jonathan Lennox, Bo Burman, Ari Keranen, and Dan
   Wing on for suggesting structural changes helping improve that improved the document document's
   readability.

   I would like also to thank the following experts on for their inputs and
   reviews as listed - listed:

      Flemming Andreasen(5.24,5.32,5.33,14), Andreasen (5.24, 5.32, 5.33, 14),
      Rohan
   Mahy(5.57), Mahy (5.56),
      Eric Burger(5.26),Christian Huitema(5.14), Burger (5.26),
      Christian Huitema (5.14),
      Christer
   Holmberg(5.21,5.26,5.51,5.52), Holmberg (5.21, 5.26, 5.50, 5.51),
      Richard Ejzak (5.44,5.53,5.54), (5.44, 5.52, 5.53),
      Colin
   Perkins(5.7,5.8,5.9,5.58), Perkins (5.7, 5.8, 5.9, 5.57),
      Magnus
   Westerlund(5.2,5.3,5.9,5.27,5.47,6.1,6.2,6.3,8.3,7), Westerlund (5.2, 5.3, 5.9, 5.27, 5.47, 6.1 - 6.3, 8.3, 7),
      Roni
   Evens(5.12,5.27,8.4), Evens (5.12, 5.27, 8.4),
      Subha Dhesikan(5.6,10), Dhesikan (5.6, 10),
      Dan
   Wing(5.7,5.12,5.35,5.39,5.45), Wing (5.7, 5.12, 5.35, 5.39, 5.45),
      Cullen Jennings (5.40),
      Ali C
   Begen(5.1,5.20,5.22,5.25,5.38,7.3,8.2,8.4,8.6,9.2,13.1), Begen (5.1, 5.20, 5.22, 5.25, 5.38, 7.3, 8.2, 8.4, 8.6, 9.2,
      13.1),
      Bo Burman
   (7.2,7.6), (7.2, 7.6),
      Charles Eckel(5.15,5.27,5.28,9.1,8.5), Eckel (5.15, 5.27, 5.28, 9.1, 8.5),
      Paul Kyzivat(5.24), Kyzivat (5.24),
      Ian Johansson(5.15), Johansson (5.15),
      Saravanan Shanmugham(5.11), Shanmugham (5.11),
      Paul E Jones(5.30), Jones (5.30),
      Rajesh Kumar(5.48), Kumar (5.48),
      Jonathan Lennox(5.36,5,15,9.1,11.1), Lennox (5.36, 5, 15, 9.1, 11.1),
      Mo
   Zanaty(5.4,5.5,5.23,8.1,8.3,8.5,12.1), Zanaty (5.4, 5.5, 5.23, 8.1, 8.3, 8.5, 12.1),
      Christian Huitema (5.14),
      Qin Wu (5.47 (5.47, PM-Dir review),
      Hans Stokking(5.43,5.16), Stokking (5.43, 5.16),
      Christian Groves
   (5.48,5.55), (5.48, 5.54), and
      Thomas Stach.

   I would like to thank Chris Lonvick for the SECDIR review, Dan
   Romascanu for th the Gen-ART review review, and Sabrina Tanamal for the IANA
   review.

   Thanks to Ben Campbell for AD Area Director review suggestions.  Thanks
   to Spencer Dawkins, Stephen Farrel, Alissa Cooper, Mirja Kuehlewind K├╝hlewind,
   and the entire IESG experts for their reviews.

Author's Address

   Suhas Nandakumar
   Cisco
   170 West Tasman Drive
   San Jose, CA 95134
   USA
   United States of America

   Email: snandaku@cisco.com