MANET
Internet Engineering Task Force (IETF) D. Wiggins
Internet-Draft
Intended status:
Request for Comments: 9895
Category: Standards Track L. Berger
Expires: 25 September 2025
ISSN: 2070-1721 LabN Consulting, L.L.C.
D. Eastlake, Eastlake 3rd, Ed.
Independent
24 March
November 2025
DLEP
Dynamic Link Exchange Protocol (DLEP) IEEE 802.1Q Aware Credit Window
Extension
draft-ietf-manet-dlep-ether-credit-extension-09
Abstract
This document defines an extension to the Dynamic Link Exchange
Protocol (DLEP) that enables an Ethernet IEEE 802.1Q aware credit-
window scheme for destination-specific and shared flow control.
Status of This Memo
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This Internet-Draft will expire on 25 September 2025.
https://www.rfc-editor.org/info/rfc9895.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Extension Usage and Identification . . . . . . . . . . . . . 3
3. Management Considerations . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A.
Acknowledgments . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
The protocol provides the exchange of link related link-related control
information between DLEP peers. DLEP peers consist of a modem and a
router. DLEP defines a base set of mechanisms as well as support for
possible extensions. This document defines one such extension.
The DLEP specification does not define any flow control mechanisms.
While in theory various flow control techniques could be theoretically implemented
with DLEP, this document specifies a DLEP extension that introduces
an Ethernet-based flow control mechanism for traffic transmitted from
a router to a modem. This mechanism utilizes one or more logical
"Credit Windows", each of which is typically associated with a
virtual or physical queue. The router leverages traffic flow
classification information provided by the modem to determine the
appropriate credit window for a given traffic flow. Credit windows
may be allocated on either a shared or a per-flow basis. For a
DiffServ-based
Diffserv-based approach to credit window flow control, refer to
[I-D.ietf-manet-dlep-da-credit-extension].
[RFC9894]. As specified in Section 2.3.1 of [I-D.ietf-manet-dlep-traffic-classification], [RFC9892], when both DiffServ
Diffserv and Ethernet traffic classification are applied to a flow,
Ethernet-based classification takes precedence.
This document leverages the traffic classification and credit window
control mechanisms defined in
[I-D.ietf-manet-dlep-traffic-classification] [RFC9892] and
[I-D.ietf-manet-dlep-credit-flow-control] [RFC9893] to enable credit window-
based
credit-window-based flow control based on DLEP destinations, Ethernet VLANs,
Virtual Local Area Networks (VLANs), and Priority Code Points (PCPs).
Ethernet PCP support is specified as part of the IEEE 802.1Q [IEEE8021Q] tag format,
format [IEEE8021Q], which includes a 3-bit "PCP" field. The tag
format also incorporates a 12-bit "VLAN Identifier (VID)" field.
The defined mechanism allows credit windows to be shared across
traffic destined for multiple DLEP destinations, Virtual Local Area
Networks (VLANs), VLANs, and PCPs, or
to be dedicated exclusively to traffic associated with a specific
destination, VLAN, and/or PCP. Additionally, this extension supports
"wildcard" matching for any PCP or VID.
The extension defined in this document is referred to as the "IEEE
802.1Q Aware Credit Window" or, more simply, the "Ethernet Credit"
extension. The reader should be familiar with both the traffic
classification and credit window control mechanisms defined in
[I-D.ietf-manet-dlep-traffic-classification]
[RFC9892] and
[I-D.ietf-manet-dlep-credit-flow-control]. [RFC9893].
This document defines a new DLEP Extension Type Value in Section 2
which that is used to
indicate support for the extension. See Section 2.
1.1. Key Words
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
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Extension Usage and Identification
The extension defined in this document is composed of the mechanisms
and processing defined in
[I-D.ietf-manet-dlep-traffic-classification] [RFC9892] and
[I-D.ietf-manet-dlep-credit-flow-control]. [RFC9893]. To indicate that
the IEEE 802.1Q Aware Credit Window Extension is to be used, an
implementation MUST include the IEEE 802.1Q Aware Credit Window Type
Value in the Extensions Supported Data Item. Item (see Section 13.6 of
[RFC8175]). The Extensions Supported Data Item is sent and processed
according to [RFC8175]. Any implementation that indicates the use of
the IEEE 802.1Q Aware Credit Window Extension MUST support all Messages,
message types, Data Items, the Ethernet Traffic Classification Sub-Data Sub-
Data Item, and all related processing defined in
[I-D.ietf-manet-dlep-traffic-classification] [RFC9892] and
[I-D.ietf-manet-dlep-credit-flow-control].
[RFC9893].
The IEEE 802.1Q Aware Credit Window Extension Type Value is TBA1, see 5. See
Section 5.
3. Management Considerations
This section provides several network management guidelines to for
implementations supporting the IEEE 802.1Q Aware Credit Window
Extension.
If this extension is supported, that support MUST be declared using
the Extensions Supported Data Item (see Section 13.6 of [RFC8175]) [RFC8175]),
which is configurable on both modems and routers. DiffServ Diffserv Aware
Credit Window Extension Data Items MUST NOT be emitted by a DLEP
participant unless such support was specified in the initialization
message received from its peer. The use of the extension defined in
this document SHOULD be configurable on both modems and routers.
Modems SHOULD support the configuration of mapping a PCP to a credit
window
(queue) mapping. (queue).
Modems MAY support the configuration of mapping a PCP to a credit
window (queue)
mapping on a per VLAN per-VLAN basis. VID value zero (0) is used by
[I-D.ietf-manet-dlep-traffic-classification]
[RFC9892] to indicate that the VID is ignored and any VID value is
used in traffic classification.
When VLANs are supported by a modem without support from PCPs, the
modem SHOULD support the configuration of mapping a VLAN to a credit
window
(queue) mapping. (queue).
Modems MAY support the configuration of the number of credit windows
(queues) that they advertise to a router.
Routers may impose limitations on the number of queues they can
support and on the allowable credit window configurations. In some
cases, per-destination queues may not be supported. If the credit
window information provided by the modem exceeds the router's
capabilities, the router SHOULD utilize a subset of the advertised
credit windows. Alternatively, the router MAY reset the session and
indicate that the extension is not supported. In either case, any
mismatch in capabilities SHOULD be reported to the user through
standard network management mechanisms, such as user interface
notifications or error logging.
Regardless of implementation, if credit windows are in use, the
router MUST NOT send traffic to the modem unless sufficient credits
are available.
4. Security Considerations
This document defines a DLEP extension that uses DLEP mechanisms and
the credit window control and flow mechanisms defined in
[I-D.ietf-manet-dlep-traffic-classification] [RFC9892]
and
[I-D.ietf-manet-dlep-credit-flow-control]. [RFC9893]. See also the Security Considerations sections of
those documents.
The defined extension is exposed to vulnerabilities similar to
existing DLEP messages and discussed in the Security Considerations
section of [RFC8175] [RFC8175], such as an injected message resizing a credit
window to a value that results in a denial of service. The security
mechanisms documented in [RFC8175] can be applied equally to the
mechanism defined in this document.
Wildcards for matching PCP and VID fields are provided which provided. Note that
wildcards may be convenient to match for matching a number of packet flows but
could inadvertently match unexpected flows or new flows that appear
after the wildcard matching has been set up. It is therefore
RECOMMENDED that wildcards not be used unless clearly needed.
5. IANA Considerations
IANA is requested to assign one has assigned the following code point in the "Extension Type
Values" registry in the "Dynamic Link Exchange Protocol (DLEP)
Parameters" registry group as follows: group:
+======+=================================+
| Code | Description |
+======+=================================+
| TBA1 5 | IEEE 802.1Q Aware Credit Window |
+------+---------------------------------+
Table 1: Requested Extension Type Value
6. References
6.1. Normative References
[I-D.ietf-manet-dlep-credit-flow-control]
Cheng, B., Wiggins, D., Berger, L., Ratliff, S., and E.
Kinzie, "Dynamic Link Exchange Protocol (DLEP) Credit-
Based Flow Control Messages and Data Items", Work in
Progress, Internet-Draft, draft-ietf-manet-dlep-credit-
flow-control, 3 January 2025,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
credit-flow-control>.
[I-D.ietf-manet-dlep-traffic-classification]
Cheng, B., Wiggins, D., Berger, L., and D. Fedyk, "Dynamic
Link Exchange Protocol (DLEP) Traffic Classification Data
Item", Work in Progress, Internet-Draft, draft-ietf-manet-
dlep-traffic-classification, 19 November 2024,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
traffic-classification>.
[IEEE8021Q]
IEEE, "IEEE Standard for Local and Metropolitan Area
Networks--Bridges and Bridged Networks",
DOI 10.1109/IEEESTD.2022.10004498, IEEE Std 802.1Q-2022, July
December 2022, <https://ieeexplore.ieee.org/document/8403927>.
<https://ieeexplore.ieee.org/document/10004498>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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>.
[RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175,
DOI 10.17487/RFC8175, June 2017,
<https://www.rfc-editor.org/info/rfc8175>.
[RFC9892] Cheng, B., Wiggins, D., Berger, L., and D. Fedyk, Ed.,
"Dynamic Link Exchange Protocol (DLEP) Traffic
Classification Data Item", RFC 9892, DOI 10.17487/RFC9892,
November 2025, <https://www.rfc-editor.org/info/rfc9892>.
[RFC9893] Cheng, B., Wiggins, D., Ratliff, S., Berger, L., and E.
Kinzie, Ed., "Dynamic Link Exchange Protocol (DLEP)
Credit-Based Flow Control Messages and Data Items",
RFC 9893, DOI 10.17487/RFC9893, November 2025,
<https://www.rfc-editor.org/info/rfc9893>.
6.2. Informative References
[I-D.ietf-manet-dlep-da-credit-extension]
[RFC9894] Cheng, B., Wiggins, D., Berger, L., and D. E. Eastlake,
"DLEP DiffServ Eastlake 3rd,
Ed., "Dynamic Link Exchange Protocol (DLEP) Diffserv Aware
Credit Window Extension", Work in
Progress, Internet-Draft, draft-ietf-manet-dlep-da-credit-
extension, 15 December 2024,
<https://datatracker.ietf.org/doc/draft-ietf-manet-dlep-
da-credit-extension/>.
Appendix A. RFC 9894, DOI 10.17487/RFC9894,
November 2025, <https://www.rfc-editor.org/info/rfc9894>.
Acknowledgments
The
This document was motivated by discussions in the MANET working group. Working
Group. Many useful comments were received from contributors to the
MANET
working group, Working Group, notably Ronald in't in 't Velt.
We had the honor of working too briefly with David Wiggins on this
and related DLEP work. His contribution to the IETF and publication
of the first and definitive open source open-source DLEP implementation have been
critical to the acceptance of DLEP. We mourn his passing on November
23,
26, 2023. We wish to recognize his guidance, leadership leadership, and
professional excellence. We were fortunate to benefit from his
leadership and friendship. He shall be missed.
Authors' Addresses
David Wiggins
Email: david@none.org
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
Donald E. Eastlake 3rd (editor)
Independent
2386 Panoramic Circle
Apopka, Florida FL 32703
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com