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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="std"
     ipr="trust200902" docName="draft-ietf-bfcpbis-rfc4583bis-27" obsoletes="4583">

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     number="8856" obsoletes="4583" updates="" submissionType="IETF"
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  <front>
    <title abbrev="BFCP">Session abbrev="SDP Format for BFCP Streams">Session Description Protocol (SDP) Format for Binary
    Floor Control Protocol (BFCP) Streams</title>
    <seriesInfo name="RFC" value="8856"/>
    <author initials="G." surname="Camarillo" fullname="Gonzalo Camarillo">
      <organization>Ericsson</organization>
      <address>
        <postal>
          <street>Hirsalantie 11</street>
        <city>FI-02420 Jorvas</city>
          <code>02420</code>
          <city>Jorvas</city>
          <country>Finland</country>
        </postal>
        <email>Gonzalo.Camarillo@ericsson.com</email>
      </address>
    </author>
    <author fullname="Tom Kristensen" initials="T." surname="Kristensen">
    <organization>Cisco</organization>
      <organization abbrev="Jotron">Jotron AS</organization>
      <address>
        <postal>
        <street>Philip Pedersens vei 1</street>
        <city>NO-1366 Lysaker</city>
          <street>Ringdalskogen 8</street>
          <code>3270</code>
          <city>Larvik</city>
          <country>Norway</country>
        </postal>
      <email>tomkrist@cisco.com,
        <email>tom.kristensen@jotron.com, tomkri@ifi.uio.no</email>
      </address>
    </author>
    <author initials="C.H." initials="C." surname="Holmberg" fullname="Christer Holmberg">
      <organization>Ericsson</organization>
      <address>
        <postal>
          <street>Hirsalantie 11</street>
          <code>02420</code>
          <city>Jorvas</city>
          <country>Finland</country>
        </postal>
        <email>christer.holmberg@ericsson.com</email>
      </address>
    </author>
    <date year="2018"/>

  <area>Real-time Applications and Infrastructure</area>
  <workgroup>BFCPbis Working Group</workgroup> month="May" year="2020"/>

    <keyword>floor control</keyword>
    <keyword>BFCP</keyword>
    <keyword>SDP</keyword>

    <abstract>
      <t>This document defines the Session Description Protocol (SDP)
      offer/answer procedures for negotiating and establishing Binary Floor
      Control Protocol (BFCP) streams.</t>

      <t>This document obsoletes RFC 4583. Changes from RFC 4583 are summarized in Section 14.</t>
    <!--                                 Ensure correct section #, as xref is not allowed in abstract --> 4583.</t>
    </abstract>
  </front>
  <middle>
    <section title="Introduction"> numbered="true" toc="default">
      <name>Introduction</name>
      <t>As discussed in the BFCP (Binary Floor Control Protocol) specification <xref target="I-D.ietf-bfcpbis-rfc4582bis"/>, target="RFC8855" format="default"/>, a
    given BFCP client needs a set of data in order to establish a BFCP connection to a floor control server. This data includes
    the transport address of the server, the conference identifier, and the user identifier.</t>
      <t>One way for clients to obtain this information is to use an SDP a Session
      Description Protocol (SDP) offer/answer exchange <xref target="RFC3264"/> exchange. target="RFC3264" format="default"/>.
    This document specifies how to encode this information in the SDP session descriptions that are part of such an offer/answer
    exchange.</t>
      <t>User agents typically use the offer/answer model to establish a number of media streams of different types.
    Following this model, a BFCP connection is described as any other media stream by using an SDP 'm' "m=" line, possibly
    followed by a number of SDP lines that also apply to the BFCP connection.</t>
      <t><xref target="sec:m-line"/> target="sec_m-line" format="default"/> defines how the field
      values in 'm' an "m=" line representing a BFCP connection are set.</t>
      <t><xref target="sec:attributes"/> target="sec_attributes" format="default"/> defines SDP attributes that are used when negotiating a BFCP connection.</t>
      <t><xref target="sec:mux-cons"/> target="sec_mux-cons" format="default"/> defines multiplexing considerations for a BFCP connection.</t>
      <t><xref target="sec:bfcp-connection"/> target="sec_bfcp-connection" format="default"/> defines procedures for managing a BFCP connection.</t>
      <t><xref target="sec:authentication"/> target="sec_authentication" format="default"/> defines TLS and DTLS considerations when negotiating a BFCP connection.</t>
      <t><xref target="sec:ice-considerations"/> target="sec_ice-considerations" format="default"/> defines the
      considerations regarding Interactive Connectivity Establishment (ICE)
    <xref target="RFC8445"/> considerations target="RFC8445" format="default"/> when negotiating a BFCP connection.</t>
      <t><xref target="sec:oa-offer-answer-proc"/> target="sec_oa-offer-answer-proc" format="default"/> defines
      the SDP offer/answer procedures for negotiating a BFCP connection.</t>

      <t>This document obsoletes RFC 4583 <xref target="RFC4583"/>. <xref
      target="sec_changes"/> summarizes the changes
      from RFC 4583.</t>
    </section>
    <section title="Conventions">
    <t>
      The numbered="true" toc="default">
      <name>Conventions</name>
     <t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
      "MAY", "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
     "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>",
     "<bcp14>SHALL NOT</bcp14>", "<bcp14>SHOULD</bcp14>",
     "<bcp14>SHOULD NOT</bcp14>",
     "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
     "<bcp14>MAY</bcp14>", and "OPTIONAL" "<bcp14>OPTIONAL</bcp14>" in this document are
     to be interpreted as described in BCP 14 BCP&nbsp;14 <xref target="RFC2119"></xref> target="RFC2119"/>
     <xref target="RFC8174"></xref> target="RFC8174"/> when, and only when, they appear in all capitals,
     as shown here.
      </t> here.</t>
    </section>
    <section title="Floor anchor="sec_server-determination" numbered="true" toc="default">
      <name>Floor Control Roles" anchor="sec:server-determination"> Roles</name>
      <t>
       When two endpoints establish a BFCP stream, they need to determine which of them acts as a floor control client and which acts as a floor control server.
      </t>
      <t>
       Once the roles have been determined, the roles will apply to all BFCP-controlled streams associated with the BFCP stream.
      </t>
    </section>
    <section title="Fields anchor="sec_m-line" numbered="true" toc="default">
      <name>Fields in the 'm' Line" anchor="sec:m-line"> "m=" Line</name>
      <t>According to the SDP specification <xref target="RFC4566"/>, target="RFC4566" format="default"/>, the 'm' "m=" line format is the following:</t>
    <t><list style="hanging">
        <t><![CDATA[m=<media> as follows:</t>
   <sourcecode name="" type="sdp"><![CDATA[
   m=<media> <port> <proto> <fmt> ...]]></t>
    </list></t> ... ]]></sourcecode>
      <t>This section describes how to generate an 'm' "m=" line of an SDP Media Description ('m' ("m=" section) describing a BFCP stream.</t>
      <t>The media field MUST <bcp14>MUST</bcp14> have a value of "application".</t>
    <t>The port field is set depending
      <t>Depending on the value of the proto field, the port field is set as explained below.  A port field value of zero has the standard SDP meaning (i.e., rejection of the media stream) stream), regardless of the proto field.</t>
    <t><list style="hanging">
        <t>When
      <ul spacing="normal">
        <li>When TCP is used as the transport, the port field is set following
	the rules in <xref target="RFC4145"/>. target="RFC4145" format="default"/>. Depending on
	the value of the 'setup' attribute (discussed (defined in <xref
	target="RFC4145"/> and discussed in <xref target="sec:tcp-connection"/>), target="sec_tcp-connection" format="default"/>), the port field contains the port to which the remote endpoint will direct BFCP messages, or in the case where the endpoint will initiate the connection towards the remote endpoint, should be set to a value of 9.</t>
        <t>When 9.</li>
        <li>When UDP is used as the transport, the port field contains the port to which the remote endpoint will direct BFCP messages messages, regardless of the value of the 'setup' attribute.</t>
    </list></t> attribute.</li>
      </ul>
      <t>This document defines five values for the proto field: TCP/BFCP, TCP/DTLS/BFCP, TCP/TLS/BFCP, UDP/BFCP, 'TCP/BFCP', 'TCP/DTLS/BFCP', 'TCP/TLS/BFCP', 'UDP/BFCP', and UDP/TLS/BFCP.</t> 'UDP/TLS/BFCP'.</t>
      <t>The proto value values are used as described below:</t>
    <t><list style="hanging">
      <t>'TCP/BFCP'
      <ul spacing="normal">
        <li>'TCP/BFCP' is used for TCP transport of BFCP without TLS encryption,
	encryption and is backward compatible with RFC 4583 endpoints that are compliant endpoints.</t>
      <t>'TCP/TLS/BFCP' with RFC 4583.</li>
        <li>'TCP/TLS/BFCP' is used for TCP transport of BFCP with TLS encryption,
	encryption and is backward compatible with RFC 4583 compliant endpoints that are
	compliant with RFC 4583 and support TLS.</t>
      <t>'UDP/BFCP' TLS.</li>
        <li>'UDP/BFCP' is used for UDP transport of BFCP without DTLS encryption <xref target="RFC6347"/>.</t>
      <t>'UDP/TLS/BFCP' target="RFC6347" format="default"/>.</li>
        <li>'UDP/TLS/BFCP' is used for UDP transport of BFCP with DTLS
	encryption. This is one of the options when ICE is used (<xref target="sec:ice-considerations"/>). target="sec_ice-considerations" format="default"/>). It can also be used without ICE
          when backward compatibility with endpoints compliant with RFC 4583 compliant endpoints is not required.</t>
      <t>'TCP/DTLS/BFCP' required.</li>
        <li>'TCP/DTLS/BFCP' is used for TCP transport of BFCP with DTLS encryption, running on top of TCP using the framing method defined in <xref target="RFC4571"/>, target="RFC4571" format="default"/>, with DTLS packets being
          sent and received instead of RTP/RTCP packets using the shim defined in RFC 4571 RTP / RTP Control Protocol (RTCP)
          packets, such that the length LENGTH field defined in RFC 4571 precedes
	  each DTLS message. This is one of the options when
          ICE is used (<xref target="sec:ice-considerations"/>). target="sec_ice-considerations"
	  format="default"/>). It can also be used without ICE when backward
	compatibility with endpoints compliant with RFC 4583 compliant endpoints is not required.</t>
    </list></t> required.</li>
      </ul>
      <t>The fmt (format) list is not applicable to BFCP. The fmt list of 'm' "m=" lines in the case of any proto field value related to BFCP MUST <bcp14>MUST</bcp14> contain a single "*" character. If the the fmt list contains any other value value, it MUST <bcp14>MUST</bcp14> be ignored.</t>
      <t>The following is an example of an 'm' "m=" line for a BFCP connection:</t>
    <figure>
      <artwork>
   <sourcecode name="" type="sdp"><![CDATA[
   m=application 50000 TCP/TLS/BFCP *
      </artwork>
    </figure> ]]></sourcecode>
    </section>
    <section title="SDP Attributes" anchor="sec:attributes"> anchor="sec_attributes" numbered="true" toc="default">
      <name>SDP Attributes</name>
      <section title="SDP anchor="sec_floorctrl-attr" numbered="true" toc="default">
        <name>SDP 'floorctrl' Attribute" anchor="sec:floorctrl-attr"> Attribute</name>
        <t>
         This section defines the SDP 'floorctrl' media-level attribute. The attribute is used to determine the floor control roles (client and server) for the endpoints associated with
         the BFCP stream.
        </t>
    <figure>
      <artwork type='abnf'>
      Attribute Name: floorctrl

      Attribute Value: floor-control

      Usage Level: media

      Charset Dependent: No

      Mux Category: TBD

    The

<ul empty="true"><li>
<dl>
  <dt>Attribute Name:</dt><dd>floorctrl</dd>
  <dt>Attribute Value:</dt><dd>floor-control</dd>
  <dt>Usage Level:</dt><dd>media</dd>
  <dt>Charset Dependent:</dt><dd>No</dd>
  <dt>Mux Category:</dt><dd>TBD</dd>
</dl>
</li></ul>

    <t>The Augmented BNF syntax [RFC5234] <xref target="RFC5234"/> for the attribute is: is:</t>
   <sourcecode name="" type="abnf"><![CDATA[
   floor-control = role *(SP role)
   role = "c-only" / "s-only" / "c-s"
      </artwork>
     </figure> ]]></sourcecode>

     <t>An endpoint includes the attribute to indicate the role(s) it would be willing to perform for the BFCP-controlled media streams:</t>
      <t><list style="hanging">
          <t hangText="c-only:">The
       <ul empty="true"><li>
        <dl newline="false" spacing="normal">
          <dt>c-only:</dt>
          <dd>The endpoint is willing to act as a floor control client.</t>
          <t hangText="s-only:">The client.</dd>
          <dt>s-only:</dt>
          <dd>The endpoint is willing to act as a floor control server only.</t>
      </list></t> only.</dd>
        </dl></li></ul>
        <t>
        When inserted in an offer, the offerer MAY <bcp14>MAY</bcp14> indicate multiple attribute values ("c-only" and "s-only"). When inserted in an answer, the answerer MUST <bcp14>MUST</bcp14>
        indicate only one attribute value: "c-only" or "s-only". The answerer indicates the role taken by the answerer. The offerer will then take the
        opposite role.
        </t>
        <t>
        In <xref target="RFC4583"/>, target="RFC4583" format="default"/>, there was a third
	attribute specified, "c-s", which meant that an endpoint was willing
	to act as both a floor control client and a
        floor control server at the same time for the BFCP stream, taking different roles for different BFCP-controlled media streams. The feature was underspecified
        and implemented in different ways, ways; in particular particular, many implementations
	interpreted "c-s” "c-s" to mean that the endpoint is willing to act as
	either a client or a server
        (equivalent to “c-only s-only”). "c-only s-only"). An implementation compliant to with this specification MUST NOT <bcp14>MUST NOT</bcp14> include the "c-s" floorctl 'floorctrl' attribute value in an offer or in an answer, answer
        but MUST <bcp14>MUST</bcp14> accept the attribute value in an offer and
	process it as equivalent to "c-only s-only" (or "s-only c-only"). Also, as an implementation compliant to with
        this specification is only allowed to include one role, role -- either 'c-only'
	"c-only" or 's-conly', "s-only" -- in an answer, each endpoint will only take one role, and as a result
        the endpoint will take the same role for each BFCP-controlled media stream associated with the BFCP stream.
        </t>
        <t>
        <xref target="tab-roles"/> target="tab-roles" format="default"/> shows the roles that the answerer is allowed to take, based on what roles the offerer has
        indicated that it is willing to take.
        </t>
      <texttable title="Roles" anchor="tab-roles">
          <ttcol align="center">Offerer</ttcol>
          <ttcol align="center">Answerer</ttcol>

          <c>c-only</c>
          <c>s-only</c>

          <c>s-only</c>
          <c>c-only</c>

          <c>c-s</c>
          <c>c-only</c>

          <c>c-s</c>
          <c>s-only</c>
      </texttable>
        <table anchor="tab-roles" align="center">
          <name>Roles</name>
          <thead>
            <tr>
              <th align="center">Offerer</th>
              <th align="center">Answerer</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="center">c-only</td>
              <td align="center">s-only</td>
            </tr>
            <tr>
              <td align="center">s-only</td>
              <td align="center">c-only</td>
            </tr>
            <tr>
              <td align="center">c-s</td>
              <td align="center">c-only</td>
            </tr>
            <tr>
              <td align="center">c-s</td>
              <td align="center">s-only</td>
            </tr>
          </tbody>
        </table>
        <t>
        Endpoints compliant with <xref target="RFC4583"/> target="RFC4583" format="default"/> might not include the 'floorctrl' attribute in offers and answerer. answers.
        If the 'floorctrl' attribute is not present, in order to be
	interoperable with such endpoints, the offerer will act as a floor control client
        and the answerer will act as a floor control server.
        </t>
        <t>
        The SDP Offer/Answer procedures for the 'floorctrl' attribute are defined in <xref target="sec:oa-offer-answer-proc"/>. target="sec_oa-offer-answer-proc" format="default"/>.
        </t>
        <t>The following is an example of a 'floorctrl' attribute in an offer:</t>
      <figure>
        <artwork>

   <sourcecode name="" type="sdp"><![CDATA[
   a=floorctrl:c-only s-only
        </artwork>
      </figure> ]]></sourcecode>

      </section>
      <section title="SDP anchor="sec_confid-attr" numbered="true" toc="default">
        <name>SDP 'confid' Attribute" anchor="sec:confid-attr"> Attribute</name>

        <t>
      This section defines the SDP 'confid' media-level attribute. The attribute is used by a floor control server
      to convey the conference ID value to the floor control client, using decimal integer representation.
        </t>
    <figure>
      <artwork type='abnf'><![CDATA[
      Attribute Name: confid

      Attribute Value: conference-id

      Usage Level: media

      Charset Dependent: No

      Mux Category: TBD

    The

<ul empty="true"><li>
<dl>
      <dt>Attribute Name:</dt><dd>confid</dd>
      <dt>Attribute Value:</dt><dd>conference-id</dd>
      <dt>Usage Level:</dt><dd>media</dd>
      <dt>Charset Dependent:</dt><dd>No</dd>
      <dt>Mux Category:</dt><dd>NORMAL</dd>
</dl>
</li></ul>

    <t>The Augmented BNF syntax [RFC5234] <xref target="RFC5234"/> for the attribute is: is:</t>
   <sourcecode name="" type="abnf"><![CDATA[
   conference-id = 1*DIGIT

   DIGIT = <DIGIT as defined in [RFC5234]>

      The ]]></sourcecode>

      <t>The maximum value of the attribute is determined by the
      COMMON-HEADER format [I-D.ietf-bfcpbis-rfc4582bis].

      ]]></artwork>
    </figure> <xref target="RFC8855"/>.</t>

        <t>
      The SDP Offer/Answer procedures for the 'confid' attribute are defined in <xref target="sec:oa-offer-answer-proc"/>. target="sec_oa-offer-answer-proc" format="default"/>.
        </t>
      </section>
      <section title="SDP anchor="sec_userid-attr" numbered="true" toc="default">
        <name>SDP 'userid' Attribute" anchor="sec:userid-attr"> Attribute</name>
        <t>
      This section defines the SDP userid' 'userid' media-level attribute. The attribute is used by a floor control server
      to convey the user ID value to the floor control client, using decimal integer representation.
        </t>
    <figure>
      <artwork type='abnf'><![CDATA[
      Attribute Name: userid

      Attribute Value: user-id

      Usage Level: media

      Charset Dependent: No

      Mux Category: TBD

    The

<ul empty="true"><li>
<dl>
      <dt>Attribute Name:</dt><dd>userid</dd>
      <dt>Attribute Value:</dt><dd>user-id</dd>
      <dt>Usage Level:</dt><dd>media</dd>
      <dt>Charset Dependent:</dt><dd>No</dd>
      <dt>Mux Category:</dt><dd>NORMAL</dd>
</dl>
</li></ul>

    <t>The Augmented BNF syntax [RFC5234] <xref target="RFC5234"/> for the attribute is: is:</t>
   <sourcecode name="" type="abnf"><![CDATA[
   user-id = 1*DIGIT

   DIGIT = <DIGIT as defined in [RFC5234]>

      The ]]></sourcecode>

      <t>The maximum value of the attribute is determined by the
      COMMON-HEADER format [I-D.ietf-bfcpbis-rfc4582bis].

      ]]></artwork>
    </figure> <xref target="RFC8855"/>.</t>

        <t>
      The SDP Offer/Answer procedures for the 'userid' attribute are defined in <xref target="sec:oa-offer-answer-proc"/>. target="sec_oa-offer-answer-proc" format="default"/>.
        </t>
      </section>
      <section title="SDP anchor="sec_floorid-attr" numbered="true" toc="default">
        <name>SDP 'floorid' Attribute" anchor="sec:floorid-attr"> Attribute</name>
        <t>
      This section defines the SDP 'floorid' media-level attribute. The
      attribute conveys is used to convey a floor identifier, using decimal integer
      representation, and optionally and, optionally, pointers to one or more BFCP-controlled
      media streams.
    </t>
    <figure>
      <artwork type='abnf'><![CDATA[
      Attribute Name: floorid

      Attribute Value: floor-id

      Usage Level: media

      Charset Dependent: No

      Mux Category: TBD

    The streams.</t>

<ul empty="true"><li>
<dl>
      <dt>Attribute Name:</dt><dd>floorid</dd>
      <dt>Attribute Value:</dt><dd>floor-id</dd>
      <dt>Usage Level:</dt><dd>media</dd>
      <dt>Charset Dependent:</dt><dd>No</dd>
      <dt>Mux Category:</dt><dd>NORMAL</dd>
</dl>
</li></ul>

    <t>The Augmented BNF syntax [RFC5234] <xref target="RFC5234"/> for the attribute is: is:</t>
   <sourcecode name="" type="abnf"><![CDATA[
   floor-id = 1*DIGIT SP "mstrm:" token *(SP token)

   DIGIT = <DIGIT as defined in [RFC5234]>
   token = <token as defined in [RFC4566]>

      The ]]></sourcecode>

      <t>The maximum value of the attribute is determined by the
      FLOOR-ID format [I-D.ietf-bfcpbis-rfc4582bis].

      ]]></artwork>
    </figure>
    <t>
      The <xref target="RFC8855"/>.</t>

        <t>The floor identifier value is the integer representation of the Floor ID
        Floor&nbsp;ID field value <xref target="RFC8855"/> to be used in BFCP. Each media stream
      pointer value is associated with an SDP 'label' attribute <xref target="RFC4574"/> target="RFC4574" format="default"/> of a media stream.
        </t>
        <t>
      The SDP Offer/Answer procedures for the 'floorid' attribute are defined in <xref target="sec:oa-offer-answer-proc"/>. target="sec_oa-offer-answer-proc" format="default"/>.
        </t>
    <t><list style="empty">
    <t>
      Note:
    <aside><t>Note: In the first SDP example in
    <xref target="RFC4583"/> target="RFC4583" sectionFormat="of" section="9"/>, 'm-stream'
    was erroneously used in <xref target="sec:example"/>. listed. Although the example was non-normative, non&nbhy;normative, it is
      implemented by some vendors and occurs in cases where the endpoint is willing to act as a server. Therefore, it is RECOMMENDED <bcp14>RECOMMENDED</bcp14> to support parsing and
      interpreting 'm-stream' the same way as 'mstrm' when receiving.
    </t>
    </list></t> receiving.</t></aside>
      </section>
      <section title="SDP anchor="sec_bfcp-version-attr" numbered="true" toc="default">
        <name>SDP 'bfcpver' Attribute" anchor="sec:bfcp-version-attr"> Attribute</name>
        <t>
      This section defines the SDP 'bfcpver' media-level attribute. The
      attribute is used to negotiate the BFCP version, using decimal integer
      representation.
        </t>
    <t>
      The

<ul empty="true"><li>
<dl>
      <dt>Attribute Name:</dt><dd>bfcpver</dd>
      <dt>Attribute Value:</dt><dd>bfcp-version</dd>
      <dt>Usage Level:</dt><dd>media</dd>
      <dt>Charset Dependent:</dt><dd>No</dd>
      <dt>Mux Category:</dt><dd>TBD</dd>
</dl>
</li></ul>

    <t>The Augmented BNF syntax <xref target="RFC5234"/> for the attributes is:
    </t>
    <figure>
      <artwork type='abnf'><![CDATA[
      Attribute Name: bfcpver

      Attribute Value: bfcp-version

      Usage Level: media

      Charset Dependent: No

      Mux Category: TBD

    The Augmented BNF syntax [RFC5234] for the attribute is: is:</t>
   <sourcecode name="" type="abnf"><![CDATA[
   bfcp-version = version *(SP version)
   version = 1*DIGIT

   DIGIT = <DIGIT as defined in [RFC5234]>

      The ]]></sourcecode>

      <t>The maximum value of the attribute is determined by the
      COMMON-HEADER format [I-D.ietf-bfcpbis-rfc4582bis].

      ]]></artwork>
    </figure> <xref target="RFC8855"/>.</t>

        <t>
      An endpoint uses the 'bfcpver' attribute to convey the version(s) of BFCP supported by the endpoint, using integer values. For a given version, the attribute
      value representing the version MUST <bcp14>MUST</bcp14> match the "Version" version ("Ver") field that would be presented in the BFCP COMMON-HEADER COMMON&nbhy;HEADER <xref target="I-D.ietf-bfcpbis-rfc4582bis"/>. target="RFC8855" format="default"/>.
      The BFCP version that will eventually be used will be conveyed with a BFCP-level Hello/HelloAck.
        </t>
        <t>
      Endpoints compliant with <xref target="RFC4583"/> target="RFC4583" format="default"/> might not always include the 'bfcpver'
      attribute in offers and answers. The attribute value, if present, MUST <bcp14>MUST</bcp14> be in accordance with
      the definition of the Version version ("Ver") field in <xref target="I-D.ietf-bfcpbis-rfc4582bis"/>. target="RFC8855" format="default"/>. If the
      attribute is not present, endpoints MUST <bcp14>MUST</bcp14> assume a default value in accordance with
      <xref target="I-D.ietf-bfcpbis-rfc4582bis"/>: target="RFC8855" format="default"/>: when used over a reliable transport transport, the default
      attribute value is "1", and when used over an unreliable transport transport, the default attribute value
      is "2". The value is inferred from the transport specified in the 'm' "m=" line (<xref target="sec:m-line"/>) target="sec_m-line" format="default"/>)
      of the 'm' "m=" section associated with the stream.
        </t>
        <t>
      The SDP Offer/Answer procedures for the 'bfcpver' attribute are defined in <xref target="sec:oa-offer-answer-proc"/>. target="sec_oa-offer-answer-proc" format="default"/>.
        </t>
      </section>
    </section>
    <section title="Multiplexing Considerations" anchor="sec:mux-cons"> anchor="sec_mux-cons" numbered="true" toc="default">
      <name>Multiplexing Considerations</name>
      <t>
      <xref target="I-D.ietf-mmusic-sdp-bundle-negotiation"/> target="RFC8843" format="default"/> defines how multiplexing of multiple media streams can be negotiated. This specification does not define
      how BFCP streams can be multiplexed with other media streams. Therefore, a BFCP stream MUST NOT <bcp14>MUST NOT</bcp14> be associated with a BUNDLE group <xref target="I-D.ietf-mmusic-sdp-bundle-negotiation"/>. target="RFC8843" format="default"/>.
      Note that BFCP-controlled media streams might be multiplexed with other media streams.
      </t>
      <t>
      <xref target="I-D.ietf-mmusic-sdp-mux-attributes"/> target="RFC8859" format="default"/> defines the mux categories for the SDP
      attributes defined in this specification, except for the 'bfcpver' attribute. <xref target="tab:mux-tbd"/> target="tab_mux-tbd" format="default"/> defines the mux category
      for the 'bfcpver' attribute:
      </t>
    <texttable title="Multiplexing
      <table anchor="tab_mux-tbd" align="center">
        <name>Multiplexing Attribute Analysis" anchor="tab:mux-tbd">
      <ttcol>Name</ttcol>
      <ttcol>Notes</ttcol>
      <ttcol>Level</ttcol>
      <ttcol>Mux Category</ttcol>

      <c>bfcpver</c>
      <c>Needs Analysis</name>
        <thead>
          <tr>
            <th align="left">Name</th>
            <th align="left">Notes</th>
            <th align="left">Level</th>
            <th align="left">Mux Category</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td align="left">bfcpver</td>
            <td align="left">Needs further analysis in a separate specification</c>
      <c>M</c>
      <c>TBD</c>
    </texttable> specification</td>
            <td align="left">M</td>
            <td align="left">TBD</td>
          </tr>
        </tbody>
      </table>
    </section>
    <section title="BFCP anchor="sec_bfcp-connection" numbered="true" toc="default">
      <name>BFCP Connection Management" anchor="sec:bfcp-connection"> Management</name>
      <t>
      BFCP streams can use TCP or UDP as the underlying transport. Endpoints exchanging BFCP messages over UDP send the BFCP messages towards the peer
      using the connection address and port provided in the SDP 'c' "c=" and 'm' "m=" lines. TCP connection management is more complicated and is described in
      the following Section. section.
      </t>
    <t><list style="empty">
      <t>Note:
        <aside><t>Note: When using Interactive Connectivity Establishment
	(ICE) <xref target="RFC8445"/>, target="RFC8445" format="default"/>, TCP/DTLS/BFCP, or
	UDP/TLS/BFCP, the straight-forward straightforward procedures for connection management
	via UDP/BFCP, as UDP/BFCP described above above, apply.
      TCP/TLS/BFCP follows the same procedures as TCP/BFCP TCP&wj;/BFCP and is described below.</t>
    </list></t> below.</t></aside>
      <section title="TCP anchor="sec_tcp-connection" numbered="true" toc="default">
        <name>TCP Connection Management" anchor="sec:tcp-connection"> Management</name>
        <t>
        The management of the TCP connection used to transport BFCP messages is performed using the SDP 'setup' and 'connection' attributes <xref target="RFC4145"/>. target="RFC4145" format="default"/>.
        The 'setup' attribute indicates which of the endpoints initiates the TCP connection. The 'connection' attribute handles TCP connection re-establishment.
        </t>
        <t>
        The BFCP specification <xref target="I-D.ietf-bfcpbis-rfc4582bis"/> target="RFC8855" format="default"/> describes a number of situations when the TCP connection between a floor control client
        and the floor control server needs to be re-established. However, that specification
	<xref target="RFC8855"/> does not describe the re-establishment process
	process, because this process
        depends on how the connection was established in the first
	place. Endpoints using the offer/answer mechanism follow the following rules.
      </t>
	rules.</t>
        <t>
        When the existing TCP connection is closed and re-established following the rules in <xref target="I-D.ietf-bfcpbis-rfc4582bis"/>, target="RFC8855" format="default"/>, the floor control client
        MUST
        <bcp14>MUST</bcp14> send an offer towards the floor control server in order to re-establish the connection. If a TCP connection cannot deliver a BFCP message and times out,
        the endpoint that attempted to send the message (i.e., the one that detected the TCP timeout) MUST <bcp14>MUST</bcp14> send an offer in order to re-establish the TCP connection.
        </t>
        <t>
        Endpoints that use the offer/answer mechanism to negotiate TCP connections MUST <bcp14>MUST</bcp14> support the 'setup' and 'connection' attributes.
        </t>
      </section>
    </section>
    <section title="TLS/DTLS Considerations" anchor="sec:authentication"> anchor="sec_authentication" numbered="true" toc="default">
      <name>TLS/DTLS Considerations</name>
      <t>
       When DTLS is used with UDP, the generic procedures defined in Section 5 of <xref target="I-D.ietf-mmusic-dtls-sdp"/>
       MUST target="RFC8842" sectionFormat="of" section="5"/>
       <bcp14>MUST</bcp14> be followed.
      </t>
      <t>
       When TLS is used with TCP, once the underlying connection is established, the answerer always acts as the TLS server.
       If the TCP connection is lost, the active endpoint <xref target="RFC4583"/> target="RFC4583" format="default"/> is responsible for re-establishing the TCP connection. Unless a new
       TLS connection is negotiated, subsequent SDP offers and answers will not impact the previously negotiated TLS roles.
      </t>
    <t><list style="empty">
        <t>
          Note:
      <aside><t>Note: For TLS, it was decided to keep the original procedures in <xref target="RFC4583"/> target="RFC4583" format="default"/> to determine which endpoint
          acts as the TLS server server, in order to retain backwards compatibility.
        </t>
    </list></t> backward compatibility.</t></aside>
    </section>
    <section title="ICE Considerations" anchor="sec:ice-considerations"> anchor="sec_ice-considerations" numbered="true" toc="default">
      <name>ICE Considerations</name>
      <t>
      Generic SDP offer/answer procedures for Interactive Connectivity Establishment (ICE) ICE are defined in <xref target="I-D.ietf-mmusic-ice-sip-sdp"/>. target="RFC8839" format="default"/>.
      </t>
      <t>
      When BFCP is used with UDP based UDP-based ICE candidates <xref target="RFC8445"/> then target="RFC8445" format="default"/>, the procedures for UDP/TLS/BFCP are used.
      </t>
      <t>
      When BFCP is used with TCP based TCP-based ICE candidates <xref target="RFC6544"/> then target="RFC6544" format="default"/>, the procedures for TCP/DTLS/BFCP are used.
      </t>
      <t>
      Based on the procedures defined in <xref target="I-D.ietf-mmusic-dtls-sdp"/>, target="RFC8842" format="default"/>, endpoints treat all ICE candidate pairs associated with a BFCP stream on top of a DTLS association
      as part of the same DTLS association. Thus, there will only be one BFCP handshake and one DTLS handshake
  even if there are multiple valid candidate pairs, and even if BFCP media
  is shifted between candidate pairs (including switching between UDP to
  candidate pairs and TCP candidate pairs) prior to nomination.  If new
  candidates are added, they will also be part of the same DTLS association.
      </t>
      <t>
      In order to maximize the likelihood of interoperability between the endpoints, all ICE enabled ICE-enabled BFCP-over-DTLS endpoints SHOULD <bcp14>SHOULD</bcp14>
      implement support for UDP/TLS/BFCP.
      </t>
      <t>
      When an SDP offer or answer conveys multiple ICE candidates for a BFCP stream, UDP based UDP-based candidates SHOULD <bcp14>SHOULD</bcp14> be included and
      the default candidate SHOULD <bcp14>SHOULD</bcp14> be chosen from one of those UDP candidates. If UDP transport is used for the default candidate,
      then the 'm' "m=" line proto value MUST <bcp14>MUST</bcp14> be 'UDP/TLS/BFCP'. If TCP transport is used for the default candidate, the 'm' "m=" line proto
      value MUST <bcp14>MUST</bcp14> be 'TCP/DTLS/BFCP'.
      </t>
    <t><list style="empty">
      <t>Note:
        <aside><t>Note: Usage of ICE with protocols other than UDP/TLS/BFCP and TCP/DTLS/BFCP is outside out of scope for this specification.</t>
    </list></t> specification.</t></aside>
    </section>
    <section title="SDP anchor="sec_oa-offer-answer-proc" numbered="true" toc="default">
      <name>SDP Offer/Answer Procedures" anchor="sec:oa-offer-answer-proc"> Procedures</name>
      <t>
      This section defines the SDP offer/answer <xref target="RFC3264"/> target="RFC3264" format="default"/> procedures for negotiating and establishing a BFCP stream.
      Generic procedures for DTLS are defined in <xref target="I-D.ietf-mmusic-dtls-sdp"/>. target="RFC8842" format="default"/>. Generic procedures for TLS are defined
      in <xref target="RFC8122"/>. target="RFC8122" format="default"/>.
      </t>
      <t>
      This section only defines the BFCP-specific procedures. Unless explicitly stated otherwise, the procedures apply to an 'm' "m=" section describing a BFCP stream.
      If an offer or answer contains multiple 'm' "m=" sections describing BFCP streams, the procedures are applied independently to each stream.
      </t>
      <t>
      Within this document, 'initial offer' refers to the first offer, offer within
      an SDP session (e.g. (e.g., a SIP
      dialog when the Session Initiation Protocol (SIP)
      dialog when SIP <xref target="RFC3261"/> target="RFC3261" format="default"/> is used to carry SDP) in which the offerer
      indicates that it wants to negotiate the establishment of a BFCP stream.
      </t>
      <t>
      If the 'm' "m=" line 'proto' value is 'TCP/TLS/BFCP', 'TCP/DTLS/BFCP' 'TCP/DTLS/BFCP', or 'UDP/TLS/BFCP', the offerer and answerer follow the generic procedures
      defined in <xref target="RFC8122"/>. target="RFC8122" format="default"/>.
      </t>
      <t>
      If the 'm' "m=" line proto value is 'TCP/BFCP', 'TCP/TLS/BFCP', 'TCP/DTLS/TCP' 'TCP&wj;/DTLS&wj;/TCP', or 'UDP/TLS/BFCP', the offerer and answerer
      use the SDP 'setup' attribute according to the procedures in <xref target="RFC4145"/>. target="RFC4145" format="default"/>.
      </t>
      <t>
      If the 'm' "m=" line proto value is 'TCP/BFCP', 'TCP/TLS/BFCP' 'TCP/TLS/BFCP', or 'TCP/DTLS/BFCP', the offerer and anwerer answerer use
      the SDP 'connection' attribute according to the procedures in <xref target="RFC4145"/>. target="RFC4145" format="default"/>.
      </t>
    <t><list style="empty">
      <t>Note:
        <aside><t>Note: The use of source-specific SDP parameters <xref target="RFC5576"/> target="RFC5576" format="default"/> is not defined for BFCP streams.</t>
    </list></t> streams.</t></aside>
      <section title="Generating anchor="oa-gen-initial-offer" numbered="true" toc="default">
        <name>Generating the Initial SDP Offer" anchor="oa-gen-initial-offer"> Offer</name>
        <t>
        When the offerer creates an initial offer, the offerer MUST <bcp14>MUST</bcp14> include an SDP 'floorctrl' attribute (<xref target="sec:floorctrl-attr"/>) target="sec_floorctrl-attr" format="default"/>)
        and an SDP 'bfcpver' attribute (<xref target="sec:bfcp-version-attr"/>) target="sec_bfcp-version-attr" format="default"/>) in the 'm' "m=" section.
        </t>
        <t>
        In addition, if the offerer includes an SDP 'floorctrl' attribute with 's-only' "s-only" or 'c-s' "c-s" attribute values in the offer, the offerer: offerer
        </t>
      <t><list style="symbols">
          <t>MUST
        <ul spacing="normal">
          <li><bcp14>MUST</bcp14> include an SDP 'confid' attribute (<xref target="sec:confid-attr"/>) target="sec_confid-attr" format="default"/>) in the 'm' section; and</t>
          <t>MUST "m=" section,</li>
          <li><bcp14>MUST</bcp14> include an SDP 'userid' attribute (<xref target="sec:userid-attr"/>) target="sec_userid-attr" format="default"/>) in the 'm' section; and</t>
          <t>MUST "m=" section,</li>
          <li><bcp14>MUST</bcp14> include an SDP 'floorid' attribute (<xref target="sec:floorid-attr"/>) target="sec_floorid-attr" format="default"/>) in the 'm' section; and</t>
          <t>MUST "m=" section, and</li>
          <li><bcp14>MUST</bcp14> include an SDP 'label' attribute (<xref target="RFC4574"/>) <xref target="RFC4574" format="default"/> with the 'm' "m=" section of each BFCP-controlled media stream.</t>
      </list></t>
      <t><list style="empty">
        <t>
          Note: stream.</li>
        </ul>
        <aside><t>Note: If the offerer includes an SDP 'floorctrl' attribute with a 'c-s' "c-s" attribute value, or both a 'c-only' "c-only" and a 's-only' an "s-only" attribute value in the offer,
          the attribute values above will only be used if it is determined
	(<xref target="sec:floorctrl-attr"/>) target="sec_floorctrl-attr" format="default"/>) that the
	offerer will act as a floor control server.
        </t>
      </list></t> server.</t></aside>
      </section>
      <section title="Generating anchor="oa-gen-answer" numbered="true" toc="default">
        <name>Generating the SDP Answer" anchor="oa-gen-answer"> Answer</name>
        <t>
        When the answerer receives an offer that contains an 'm' "m=" section describing a BFCP stream, the answerer MUST <bcp14>MUST</bcp14> check whether it supports
        one or more of the BFCP versions supported by the offerer (<xref target="sec:bfcp-version-attr"/>). target="sec_bfcp-version-attr" format="default"/>). If the answerer does not support
        any of the BFCP versions, it MUST NOT <bcp14>MUST NOT</bcp14> accept the 'm' "m="
	section. Otherwise, if the answerer accepts the 'm' "m=" section, it: the answerer
        </t>
      <t><list style="symbols">
          <t>MUST
        <ul spacing="normal">
          <li><bcp14>MUST</bcp14> insert a corresponding 'm' "m=" section in the
	  answer, with an identical 'm' "m=" line proto value <xref target="RFC3264"/>; and</t>
          <t>MUST
	  target="RFC4566" format="default"/>,</li>
          <li><bcp14>MUST</bcp14> include a 'bfcpver' attribute in the 'm' section. The "m=" section; the versions indicated by the answer MUST <bcp14>MUST</bcp14> be the same or a subset of the versions indicated by the offerer in the corresponding offer; and</t>
          <t>MUST, offer, and</li>
          <li><bcp14>MUST</bcp14>, if the offer contained an SDP 'floorctrl' attribute, include a 'floorctrl' attribute in the 'm' section.</t>
      </list></t> "m=" section.</li>
        </ul>
        <t>
        In addition, if the answerer includes an SDP 'floorctrl' attribute with an 's-only' "s-only" attribute value in the answer, the answerer: answerer
        </t>
      <t><list style="symbols">
          <t>MUST
        <ul spacing="normal">
          <li><bcp14>MUST</bcp14> include an SDP 'confid' attribute in the 'm' section; and</t>
          <t>MUST "m=" section,</li>
          <li><bcp14>MUST</bcp14> include an SDP 'userid' attribute in the 'm' section; and</t>
          <t>MUST "m=" section,</li>
          <li><bcp14>MUST</bcp14> include an SDP 'floorid' attribute in the 'm' section; and</t>
          <t>MUST "m=" section, and</li>
          <li><bcp14>MUST</bcp14> include an SDP 'label' attribute in the 'm' "m=" section of each BFCP-controlled media stream.</t>
      </list></t>
      <t><list style="empty">
        <t>
          Note: stream.</li>
        </ul>
         <aside><t>Note: An offerer compliant with <xref target="RFC4583"/> target="RFC4583" format="default"/> might not include 'floorctrl' and 'bfcpver' attributes in offers, in which cases case
          the default values apply.
        </t>
      </list></t> apply.</t></aside>
        <t>
        Once the answerer has sent the answer, the answerer: answerer
        </t>
      <t><list style="symbols">
          <t>MUST,
        <ul spacing="normal">
          <li><bcp14>MUST</bcp14>, if the answerer is the active endpoint, endpoint and if a TCP connection associated with the 'm' "m=" section is to be established (or re-established),
             initiate the establishing establishment of the TCP connection; and</t>
          <t>MUST, connection, and</li>
          <li><bcp14>MUST</bcp14>, if the answerer is the active endpoint, endpoint and if an a TLS/DTLS connection associated with the 'm' "m=" section is to be established (or re-established),
             initiate the establishing establishment of the TLS/DTLS connection (by sending a ClientHello message).</t>
      </list></t> message).</li>
        </ul>
        <t>
        If the answerer does not accept the 'm' "m=" section in the offer, it MUST <bcp14>MUST</bcp14> assign a zero port value to the 'm' "m=" line of the corresponding 'm' "m=" section in the answer.
        In addition, the answerer MUST NOT <bcp14>MUST NOT</bcp14> establish a TCP connection or a TLS/DTLS connection associated with the 'm' "m=" section.
        </t>
      </section>
      <section title="Offerer anchor="oa-offerer-processing-answer" numbered="true" toc="default">
        <name>Offerer Processing of the SDP Answer" anchor="oa-offerer-processing-answer"> Answer</name>
        <t>
        When the offerer receives an answer that contains an 'm' "m=" section
        describing a BFCP stream and with a non-zero port value, describing a BFCP stream, value in the offerer:
      </t>
      <t><list style="symbols">
          <t>MUST,
        "m=" line, the offerer</t>
        <ul spacing="normal">
          <li><bcp14>MUST</bcp14>, if the offerer is the active endpoint, endpoint and if a TCP connection associated with the 'm' "m=" section is to be established (or re-established),
             initiate the establishing establishment of the TCP connection; and</t>
          <t>MUST, connection, and</li>
          <li><bcp14>MUST</bcp14>, if the offerer is the active endpoint, endpoint and if an a TLS/DTLS connection associated with the 'm' "m=" section is to be established (or re-established),
             initiate the establishing establishment of the TLS/DTLS connection (by sending a ClientHello message).</t>
      </list></t>
      <t>
        Note: message).</li>
        </ul>
        <aside><t>Note: An answerer compliant with <xref target="RFC4583"/> target="RFC4583" format="default"/> might not include 'floorctrl' and 'bfcpver' attributes in answers,
        in which cases case the default values apply.
      </t> apply.</t></aside>
        <t>
        If the 'm' "m=" line in the answer contains a zero port value, value or if the offerer for some other reason does not accept the answer (e.g., if the answerer only
        indicates support of BFCP versions not supported by the offerer), the offerer MUST NOT <bcp14>MUST NOT</bcp14> establish a TCP connection or a TLS/DTLS connection associated with the 'm' "m=" section.
        </t>
      </section>
      <section title="Modifying anchor="oa-mod-session" numbered="true" toc="default">
        <name>Modifying the Session" anchor="oa-mod-session"> Session</name>
        <t>
        When an offerer sends an updated offer, in order to modify a previously established BFCP stream, it follows the procedures
        in <xref target="oa-gen-initial-offer"/>, target="oa-gen-initial-offer" format="default"/>, with the following exceptions:
        </t>
      <t><list style="symbols">
          <t>If
        <ul spacing="normal">
          <li>If the BFCP stream is carried on top of TCP, TCP and if the offerer
	  does not want to re-establish an existing TCP connection, the
	  offerer MUST <bcp14>MUST</bcp14> include in the "m=" section
             an SDP 'connection' attribute with a value of "existing", in the 'm' section; and</t>
          <t>If and</li>
          <li>If the offerer wants to disable a previously established BFCP stream, it MUST <bcp14>MUST</bcp14> assign a zero port value to the 'm' "m=" line associated with the
             BFCP connection, following the procedures in <xref target="RFC3264"/>.</t>
      </list></t> target="RFC3264" format="default"/>.</li>
        </ul>
      </section>
    </section>
    <section title="Examples" anchor="sec:example"> anchor="sec_example" numbered="true" toc="default">
      <name>Examples</name>
      <t>For the purpose of brevity, the main portion of the session description is omitted in the examples, which only show 'm' "m=" sections and their 'm' "m=" lines and attributes.</t>
      <t>The following is an example of an offer sent by a conference server to a client.</t>
    <figure>
      <artwork>
      <sourcecode name="" type="sdp"><![CDATA[
m=application 50000 TCP/TLS/BFCP *
a=setup:actpass
a=connection:new
a=fingerprint:sha-256 \
     19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04: \
     BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2
a=floorctrl:c-only s-only
a=confid:4321
a=userid:1234
a=floorid:1 mstrm:10
a=floorid:2 mstrm:11
a=bfcpver:1 2
m=audio 50002 RTP/AVP 0
a=label:10
m=video 50004 RTP/AVP 31
a=label:11
      </artwork>
    </figure> ]]></sourcecode>
      <t>Note that due to RFC formatting conventions, this document splits the
      SDP entries across lines whose content would exceed 72 characters. the maximum line
      length. A backslash character ("\") marks where this line folding has taken place. This backslash and its trailing CRLF and whitespace would not appear in actual SDP content.</t>
      <t>The following is the answer returned by the client.</t>
    <figure>
      <artwork>
<sourcecode name="" type="sdp"><![CDATA[
m=application 9 TCP/TLS/BFCP *
a=setup:active
a=connection:new
a=fingerprint:sha-256 \
     6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35: \
     DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08
a=floorctrl:c-only
a=bfcpver:1
m=audio 55000 RTP/AVP 0
m=video 55002 RTP/AVP 31
      </artwork>
    </figure> ]]></sourcecode>

      <t>A similar example using an unreliable transport and DTLS is shown below, where the offer is sent from a client.</t>
    <figure>
      <artwork>
<sourcecode name="" type="sdp"><![CDATA[
m=application 50000 UDP/TLS/BFCP *
a=setup:actpass
a=dtls-id:abc3dl
a=fingerprint:sha-256 \
     19:E2:1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04: \
     BB:05:2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:88:A2
a=floorctrl:c-only s-only
a=confid:4321
a=userid:1234
a=floorid:1 mstrm:10
a=floorid:2 mstrm:11
a=bfcpver:1 2
m=audio 50002 RTP/AVP 0
a=label:10
m=video 50004 RTP/AVP 31
a=label:11
      </artwork>
    </figure> ]]></sourcecode>

      <t>The following is the answer returned by the server.</t>
    <figure>
      <artwork>
<sourcecode name="" type="sdp"><![CDATA[
m=application 55000 UDP/TLS/BFCP *
a=setup:active
a=dtls-id:abc3dl
a=fingerprint:sha-256 \
     6B:8B:F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35: \
     DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08
a=floorctrl:s-only
a=confid:4321
a=userid:1234
a=floorid:1 mstrm:10
a=floorid:2 mstrm:11
a=bfcpver:2
m=audio 55002 RTP/AVP 0
m=video 55004 RTP/AVP 31
      </artwork>
    </figure> ]]></sourcecode>
    </section>
    <section title="Security Considerations" anchor="sec:security"> anchor="sec_security" numbered="true" toc="default">
      <name>Security Considerations</name>
      <t>The BFCP specification <xref target="I-D.ietf-bfcpbis-rfc4582bis"/>, target="RFC8855" format="default"/>, SDP
      specification <xref target="RFC4566"/>, target="RFC4566" format="default"/>, and
      offer/answer specification <xref target="RFC3264"/>
    specifications target="RFC3264" format="default"/> discuss security issues related to BFCP, SDP, and offer/answer, respectively. In addition, <xref target="RFC4145"/> target="RFC4145" format="default"/>
    and <xref target="RFC8122"/> target="RFC8122" format="default"/> discuss security issues related to the establishment of TCP and TLS connections using an offer/answer
    model. Furthermore, when using DTLS over UDP, the generic offer/answer considerations defined in
    <xref target="I-D.ietf-mmusic-dtls-sdp"/> MUST target="RFC8842" format="default"/> <bcp14>MUST</bcp14> be followed.</t>
      <t>The usage of certain proto values in the SDP offer/answer negotiation will result in a BFCP stream that is not protected by
    TLS or DTLS. Operators will need to provide integrity protection and confidentiality protection of the BFCP stream using other means.</t>
      <t>The generic security considerations associated with SDP attributes are defined in <xref target="RFC3264"/>. target="RFC3264" format="default"/>. While the attributes
    defined in this specification do not reveal information about the content of individual BFCP controlled BFCP-controlled media streams, they do reveal
    which media streams will be BFCP controlled.</t>
    </section>
    <section title="IANA Considerations" anchor="sec:iana">
    <t><list style="empty">
      <t>[Editorial note: The changes in <xref target="sec:proto-reg"/> instruct the IANA to register the anchor="sec_iana" numbered="true" toc="default">
      <name>IANA Considerations</name>
<t>This document registers three new values TCP/DTLS/BFCP, UDP/BFCP and UDP/TLS/BFCP for in the SDP 'proto' field. The new section "proto"
subregistry within the "Session Description Protocol (SDP)
Parameters" registry: 'TCP/DTLS/BFCP', 'UDP/BFCP', and 'UDP/TLS/BFCP' (see <xref target="sec:bfcp-version-attr"/>
target="sec_proto-reg"/>).</t>
<t>This document also registers a new SDP "bfcpver" attribute. The rest is attribute in the "att-field"
subregistry within the "Session Description Protocol (SDP) Parameters"
registry: 'bfcpver' (see <xref target="sec_bfcp-version-attr"/>).</t>
<t>The remaining values are unchanged from <xref target="RFC4582"/>.]</t>
    </list></t> target="RFC4582"/>, except
that the references have been updated to refer to this document.</t>

      <section title="Registration anchor="sec_proto-reg" numbered="true" toc="default">
        <name>Registration of SDP 'proto' Values" anchor="sec:proto-reg"> Values</name>

        <t>The IANA is requested to register the following has registered three new values for in the SDP
	'proto' field under the Session "Session Description Protocol (SDP) Parameters registry:</t>

      <texttable title="Values
	Parameters" registry.</t>
        <table anchor="tab_proto-iana" align="center">
          <name>Values for the SDP 'proto' field" anchor="tab:proto-iana">
        <ttcol>Value</ttcol>
        <ttcol align="center">Reference</ttcol>

        <c>TCP/BFCP</c>
        <c>[RFC XXXX]</c>

        <c>TCP/DTLS/BFCP</c>
        <c>[RFC XXXX]</c>

        <c>TCP/TLS/BFCP</c>
        <c>[RFC XXXX]</c>

        <c>UDP/BFCP</c>
        <c>[RFC XXXX]</c>

        <c>UDP/TLS/BFCP</c>
        <c>[RFC XXXX]</c>
      </texttable> Field</name>
          <thead>
            <tr>
              <th align="left">Value</th>
              <th align="center">Reference</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">TCP/BFCP</td>
              <td align="center">RFC 8856</td>
            </tr>
            <tr>
              <td align="left">TCP/DTLS/BFCP</td>
              <td align="center">RFC 8856</td>
            </tr>
            <tr>
              <td align="left">TCP/TLS/BFCP</td>
              <td align="center">RFC 8856</td>
            </tr>
            <tr>
              <td align="left">UDP/BFCP</td>
              <td align="center">RFC 8856</td>
            </tr>
            <tr>
              <td align="left">UDP/TLS/BFCP</td>
              <td align="center">RFC 8856</td>
            </tr>
          </tbody>
        </table>
      </section>
      <section title="Registration numbered="true" toc="default">
        <name>Registration of the SDP 'floorctrl' Attribute"> Attribute</name>
        <t>
        This document defines the SDP attribute,'floorctrl'.
        The details of the 'floorctrl' attribute.
        Details regarding this attribute are defined provided in <xref target="sec:floorctrl-attr"/>. target="sec_floorctrl-attr" format="default"/>.
        </t>
      </section>
      <section title="Registration numbered="true" toc="default">
        <name>Registration of the SDP 'confid' Attribute"> Attribute</name>
        <t>
        This document defines the SDP attribute,'confid'.
        The details of the 'confid' attribute.
        Details regarding this attribute are defined provided in <xref target="sec:confid-attr"/>. target="sec_confid-attr" format="default"/>.
        </t>
      </section>
      <section title="Registration numbered="true" toc="default">
        <name>Registration of the SDP 'userid' Attribute"> Attribute</name>
        <t>
        This document defines the SDP attribute,'userid'.
        The details of the 'userid' attribute.
        Details regarding this attribute are defined provided in <xref target="sec:userid-attr"/>. target="sec_userid-attr" format="default"/>.
        </t>
      </section>
      <section title="Registration numbered="true" toc="default">
        <name>Registration of the SDP 'floorid' Attribute"> Attribute</name>
        <t>
        This document defines the SDP attribute,'floorid'.
        The details of the 'floorid' attribute.
        Details regarding this attribute are defined provided in <xref target="sec:floorid-attr"/>. target="sec_floorid-attr" format="default"/>.
        </t>
      </section>
      <section title="Registration numbered="true" toc="default">
        <name>Registration of the SDP 'bfcpver' Attribute"> Attribute</name>
        <t>
        This document defines the SDP attribute,'bfcpver'.
        The details of the 'bfcpver' attribute.
        Details regarding this attribute are defined provided in <xref target="sec:bfcp-version-attr"/>. target="sec_bfcp-version-attr" format="default"/>.
        </t>
      </section>
    </section>
    <section title="Changes anchor="sec_changes" numbered="true" toc="default">
      <name>Changes from RFC 4583" anchor="sec:changes">
    <t>Following is the list of 4583</name>
      <t>The technical changes and other fixes from <xref target="RFC4583"/>.</t>
    <t>Main
      target="RFC4583" format="default"/> are listed below.</t>
      <t>The main purpose of this work was to add signaling support necessary
      to support BFCP over an unreliable transport, as described in <xref target="I-D.ietf-bfcpbis-rfc4582bis"/>, target="RFC8855" format="default"/>, resulting in the following changes:</t>
    <t><list style="numbers">
        <t>Fields
<ul>
     <li><t>Fields in the 'm' line "m=" Line (<xref target="sec:m-line"/>):<vspace/>
          The target="sec_m-line" format="default"/>):</t>
         <t>This section is re-written has been rewritten to remove reference to the exclusivity
	 of TCP as a transport for BFCP streams. The proto field values TCP/DTLS/BFCP, UDP/BFCP
	 'TCP/DTLS/BFCP', 'UDP/BFCP', and UDP/TLS/BFCP added.</t>
        <t>Security 'UDP/TLS/BFCP' have been added.</t></li>
     <li><t>Security Considerations (<xref target="sec:security"/>):<vspace/>
          For target="sec_security" format="default"/>):</t>
         <t>For the DTLS over UDP DTLS-over-UDP case, mention we direct the reader to existing considerations
	 and requirements for the offer/answer offer&wj;/answer exchange as provided in <xref target="I-D.ietf-mmusic-dtls-sdp"/>.</t>
        <t>Registration target="RFC8842" format="default"/>.</t></li>
     <li><t>Registration of SDP 'proto' Values (<xref target="sec:proto-reg"/>):<vspace/>
          Register target="sec_proto-reg" format="default"/>):</t>
         <t>This document registers the three new values TCP/DTLS/BFCP, UDP/BFCP 'TCP/DTLS/BFCP', 'UDP/BFCP', and UDP/TLS/BFCP
	 'UDP/TLS/BFCP' in the SDP parameters registry.</t>
        <t>BFCP Version Negotiation "Session Description Protocol (SDP) Parameters" registry.</t></li>
     <li><t>SDP 'bfcpver' Attribute (<xref target="sec:bfcp-version-attr"/>):<vspace/>
          A target="sec_bfcp-version-attr" format="default"/>):</t>
         <t>A new 'bfcpver' SDP media-level attribute is added has been added, in order to
	 signal the supported version number.</t>
    </list></t> number.</t></li>
</ul>

      <t>In addition to the changes associated with support of BFCP over an
      unreliable transport, the possibility for that an endpoint to can act as both a
      floor control client and a floor control server at the same time has
    been removed. An endpoint will now take the same role for all BFCP-controlled streams associated with the BFCP stream.</t>
    <t>Clarification
      <t>Clarifications and bug fixes:</t>
    <t><list style="numbers">
        <t>Errata ID:

<ul>
         <li><t>Erratum ID 712 (<xref target="sec:server-determination"/> (Sections&nbsp;<xref target="RFC4583" section="3"
 sectionFormat="bare"/> and <xref target="sec:oa-offer-answer-proc"/>):<vspace/>
          Language clarification. Don't target="RFC4583" section="10"
 sectionFormat="bare"/> of <xref target="RFC4583"/>; see <xref target="Err712"/> for details):</t>

         <t>Do not use terms like an SDP attribute is "used language such as 'used in an 'm' line", instead "m=" line' when discussing an SDP attribute; instead, make clear that the attribute is a
	 media-level attribute.</t>
        <t>Fix typo attribute.</t></li>
         <li><t>Spelling corrected in the first SDP example (<xref target="sec:example"/>):<vspace/>
          Do in <xref target="RFC4583" sectionFormat="of" section="9"/>:</t>
         <t>Do not use 'm-stream' as listed in the first SDP example, example in <xref
	 target="RFC4583"/>; instead, use the correct 'mstrm'
	 as specified in <xref target="sec:example"/>. Recommend interpreting 'm-stream' target="sec_example" format="default"/> of this
	 document. However, we recommend continuing to interpret 'm-stream', if it is received, since
	 because it is still present in some implementations.</t>
        <t>Assorted implementations.</t></li>
         <li><t>Assorted clarifications (Across (throughout the document):<vspace/>
          Language document):</t>
         <t>Language clarifications were made as a result of reviews. Also, the
	 normative language where tightened was "tightened" where appropriate, i.e. i.e., changed
	 from SHOULD "<bcp14>SHOULD</bcp14>" strength to MUST "<bcp14>MUST</bcp14>" in a
	 number of places.</t>
    </list></t> places.</t></li>
      </ul>
    </section>
  </middle>
  <back>
    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5234.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3261.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3264.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4145.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4574.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8122.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4566.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6347.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4571.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6544.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4582.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4583.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8445.xml"/>

<!-- draft-ietf-mmusic-ice-sip-sdp-39  RFC-to-be 8839 -->

<reference anchor='RFC8839' target="https://www.rfc-editor.org/info/rfc8839">
<front>
<title>Session Description Protocol (SDP) Offer/Answer Procedures for Interactive Connectivity Establishment (ICE)</title>

<author initials='M' surname='Petit-Huguenin' fullname='Marc Petit-Huguenin'>
    <organization />
</author>

<author initials='S' surname='Nandakumar' fullname='Suhas Nandakumar'>
    <organization />
</author>

<author initials='C' surname='Holmberg' fullname='Christer Holmberg'>
    <organization />
</author>

<author initials='A' surname='Keränen' fullname='Ari Keränen'>
    <organization />
</author>

<author initials='R' surname='Shpount' fullname='Roman Shpount'>
    <organization />
</author>

<date month="May" year="2020"/>

</front>
<seriesInfo name="RFC" value="8839"/>
<seriesInfo name="DOI" value="10.17487/RFC8839"/>

</reference>

<!-- draft-ietf-bfcpbis-rfc4582bis  RFC-to-be 8855 -->
<reference anchor="RFC8855" target="https://www.rfc-editor.org/info/rfc8855">

  <front>
    <title>The Binary Floor Control Protocol (BFCP)</title>

    <author initials="G." surname="Camarillo" fullname="">
      <organization />
    </author>

    <author initials="K." surname="Drage" fullname="Keith Drage">
      <organization />
    </author>

    <author initials="T." surname="Kristensen" fullname="Tom Kristensen">
      <organization />
    </author>

    <author initials="J." surname="Ott" fullname="Jörg Ott">
      <organization />
    </author>

    <author initials="C." surname="Eckel" fullname="Charles Eckel">
      <organization />
    </author>

    <date month="May" year="2020" />
  </front>
  <seriesInfo name="RFC" value="8855" />
  <seriesInfo name="DOI" value="10.17487/RFC8855"/>

</reference>

<!-- draft-ietf-mmusic-dtls-sdp   RFC-to-be 8842 -->
<reference anchor="RFC8842" target="https://www.rfc-editor.org/info/rfc8842">

  <front>
    <title>Session Description Protocol (SDP) Offer/Answer Considerations for
Datagram Transport Layer Security (DTLS) and Transport Layer Security (TLS)</title>

    <author initials="C." surname="Holmberg" fullname="Christer Holmberg">
      <organization />
    </author>

    <author initials="R." surname="Shpount" fullname="Roman Shpount">
      <organization />
    </author>

    <date month="May" year="2020" />
  </front>
  <seriesInfo name="RFC" value="8842" />
  <seriesInfo name="DOI" value="10.17487/RFC8842"/>

</reference>

<!-- draft-ietf-mmusic-sdp-mux-attributes-17 (RFC 8859) -->
<reference anchor="RFC8859" target="https://www.rfc-editor.org/info/rfc8859">
  <front>
    <title>A Framework for SDP Attributes When Multiplexing</title>
    <author initials="S" surname="Nandakumar" fullname="Suhas Nandakumar">
      <organization/>
    </author>
    <date month="May" year="2020"/>
  </front>
    <seriesInfo name="DOI" value="10.17487/RFC8859"/>
    <seriesInfo name="RFC" value="8859"/>

</reference>
      </references>

      <references>
        <name>Informative References</name>
    <reference anchor="Err712" quote-title="false"
	       target="https://www.rfc-editor.org/errata/eid712">
       <front>
          <title>Erratum ID 712</title>
          <author><organization>RFC Errata</organization></author>
       </front>
       <refcontent>RFC 4583</refcontent>
    </reference>

<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5576.xml"/>

<!-- draft-ietf-mmusic-sdp-bundle-negotiation (RFC 8843) -->
<reference anchor="RFC8843" target="https://www.rfc-editor.org/info/rfc8843">
  <front>
    <title>Negotiating Media Multiplexing Using the Session Description Protocol (SDP)</title>
    <author initials="C" surname="Holmberg" fullname="Christer Holmberg">
      <organization/>
    </author>
    <author initials="H" surname="Alvestrand" fullname="Harald Alvestrand">
      <organization/>
    </author>
    <author initials="C" surname="Jennings" fullname="Cullen Jennings">
      <organization/>
    </author>
    <date month="May" year="2020"/>
  </front>
    <seriesInfo name="RFC" value="8843"/>
    <seriesInfo name="DOI" value="10.17487/RFC8843"/>
</reference>

      </references>
    </references>
    <section title="Acknowledgements" anchor="sec:acks">
    <t>Joerg Ott, Keith Drage, Alan Johnston, Eric Rescorla, Roni Even, and Oscar Novo anchor="sec_acks" numbered="false" toc="default">
      <name>Acknowledgements</name>
      <t><contact fullname="Joerg Ott"/>, <contact fullname="Keith Drage"/>,
      <contact fullname="Alan Johnston"/>, <contact fullname="Eric
      Rescorla"/>, <contact fullname="Roni Even"/>, and <contact
      fullname="Oscar Novo"/> provided useful ideas for the original <xref target="RFC4583"/>.
      target="RFC4583" format="default"/>. The authors also acknowledge
      contributions to the revision of BFCP for use over an unreliable
      transport from Geir <contact fullname="Geir Arne Sandbakken, Charles Eckel, Alan Ford, Eoin McLeod and Mark Thompson. Sandbakken"/>, <contact
      fullname="Charles Eckel"/>, <contact fullname="Alan Ford"/>, <contact
      fullname="Eoin McLeod"/>, and <contact fullname="Mark Thompson"/>. Useful
      and important final reviews were done by Ali C. Begen, Mary Barnes and Charles Eckel. <contact fullname="Ali
      C.&nbsp;Begen"/>, <contact fullname="Mary Barnes"/>, and <contact
      fullname="Charles Eckel"/>. In the final stages, Roman Shpount <contact fullname="Roman Shpount"/> made a considerable effort in adding proper ICE support and considerations.</t>
    </section>
</middle>

<back>
  <references title="Normative References">
    <?rfc include="reference.RFC.2119" ?>
    <?rfc include="reference.RFC.5234" ?>
    <?rfc include="reference.RFC.3261" ?>
    <?rfc include="reference.RFC.3264" ?>
    <?rfc include="reference.RFC.4145" ?>
    <?rfc include="reference.RFC.4574" ?>
    <?rfc include="reference.RFC.8122" ?>
    <?rfc include="reference.RFC.4566" ?>
    <?rfc include="reference.RFC.6347" ?>
    <?rfc include="reference.RFC.4571" ?>
    <?rfc include="reference.RFC.6544" ?>
    <?rfc include="reference.RFC.4582" ?>
    <?rfc include="reference.RFC.4583" ?>
    <?rfc include="reference.RFC.8174" ?>
    <?rfc include="reference.RFC.8445" ?>
    <?rfc include="reference.I-D.draft-ietf-mmusic-ice-sip-sdp-24"?>
    <?rfc include="reference.I-D.draft-ietf-bfcpbis-rfc4582bis-16" ?>
    <?rfc include="reference.I-D.draft-ietf-mmusic-dtls-sdp-32" ?>
    <?rfc include="reference.I-D.draft-ietf-mmusic-sdp-mux-attributes-17" ?>
  </references>
  <references title="Informational References">
    <?rfc include="reference.RFC.5576" ?>
    <?rfc include="reference.I-D.draft-ietf-mmusic-sdp-bundle-negotiation-53" ?>
  </references>
  </back>
</rfc>