DLEP IEEE 802.1Q Aware Credit Window Extension
draft-ietf-manet-dlep-ether-credit-extension-08

MANET                                                         D. Wiggins
Internet-Draft                                                          
Intended status: Standards Track                               L. Berger
Expires: 18 June 2025                            LabN Consulting, L.L.C.
                                                        D. Eastlake, Ed.
                                                             Independent
                                                        15 December 2024

             DLEP IEEE 802.1Q Aware Credit Window Extension
            draft-ietf-manet-dlep-ether-credit-extension-08

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 18 June 2025.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Key Words . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Extension Usage and Identification  . . . . . . . . . . . . .   3
   3.  Management Considerations . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
   This protocol provides the exchange of 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 include any flow control capability.
   There are various flow control techniques theoretically possible with
   DLEP.  This document defines a DLEP extension which provides an
   Ethernet-based flow control mechanism for traffic sent from a router
   to a modem.  Flow control is provided using one or more logical
   "Credit Windows", each of which will typically be supported by an
   associated virtual or physical queue.  A router will use traffic flow
   classification information provided by the modem to identify which
   traffic is associated with each credit window.  Credit windows may be
   shared or dedicated on a per flow basis.  See
   [I-D.ietf-manet-dlep-da-credit-extension] for a DiffServ-based
   version of credit window flow control.  As specified in Section 2.3.1
   of [I-D.ietf-manet-dlep-traffic-classification], when both DiffServ
   and Ethernet traffic classification are specified for a flow, the
   Ethertype information takes precedence.

   This document uses the traffic classification and credit window
   control mechanisms defined in
   [I-D.ietf-manet-dlep-traffic-classification] and
   [I-D.ietf-manet-dlep-credit-flow-control] to provide credit window
   based flow control based on DLEP destinations and Ethernet VLANs and
   Priority Code Points.  Ethernet Priority Code Point support is
   defined as part of the IEEE 802.1Q [IEEE8021Q] tag format and
   includes a 3-bit "PCP" field.  The tag format also includes a 12-bit
   VLAN identifier (VID) field.  The defined mechanism allows for credit
   windows to be shared across traffic sent to multiple DLEP

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   destinations, Virtual Area Netwokrs (VLANs), and Priority Code Points
   (PCPs), or used exclusively for traffic sent to a particular
   destination and/or VLAN and/or PCP.  The extension also supports the
   "wildcard" matching of any PCP or VID.

   The extension defined in this document is referred to as "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] and
   [I-D.ietf-manet-dlep-credit-flow-control].

   This document defines a new DLEP Extension Type Value in Section 2
   which is used to indicate support for the extension.

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] and
   [I-D.ietf-manet-dlep-credit-flow-control].  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.  The Extensions Supported Data Item
   is sent and processed according to [RFC8175].  Any implementation
   that indicates use of the IEEE 802.1Q Aware Credit Window Extension
   MUST support all Messages, Data Items, the Ethernet Traffic
   Classification Sub-Data Item, and all related processing defined in
   [I-D.ietf-manet-dlep-traffic-classification] and
   [I-D.ietf-manet-dlep-credit-flow-control].

   The IEEE 802.1Q Aware Credit Window Extension Type Value is TBA1, see
   Section 5.

3.  Management Considerations

   This section provides several network management guidelines to
   implementations supporting the IEEE 802.1Q Aware Credit Window
   Extension.

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   If this extension is supported, that support MUST be declared using
   the Extensions Supported Data Item (see Section 13.6 of [RFC8175])
   which is configurable on both modens and routers.  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 PCP to credit window
   (queue) mapping.

   Modems MAY support the configuration of PCP to credit window (queue)
   mapping on a per VLAN basis.  VID value zero (0) is used by
   [I-D.ietf-manet-dlep-traffic-classification] to indicate that 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 VLAN to credit window
   (queue) mapping.

   Modems MAY support the configuration of the number of credit windows
   (queues) to advertise to a router.

   Routers may have limits on the number of queues that they can support
   and limits on supported credit window combinations.  Per destination
   queues might not be supported at all.  When modem-provided credit
   window information exceeds the capabilities of a router, the router
   SHOULD use a subset of the provided credit windows.  Alternatively, a
   router MAY reset the session and indicate that the extension is not
   supported.  In either case, the mismatch of capabilities SHOULD be
   reported to the user via normal network management mechanisms such as
   user interface messages or error logging.

   In all cases, if credit windows are in use, traffic for which credits
   are not available MUST NOT be sent to the modem by the router.

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] and
   [I-D.ietf-manet-dlep-credit-flow-control].  The defined extension is
   exposed to vulnerabilities similar to existing DLEP messages and
   discussed in the Security Considerations section of [RFC8175] such as
   an injected message resizing a credit window to a value that results
   in a denial of service.  Wildcards for matching PCP and VID fields
   are provided which may be convenient to match a number of packet
   flows but could inadvertently match unexpected flows or new flows

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   that appear after the wildcard matching has been set up.  It is
   therefore RECOMMENDED that wildcards not be used unless clearly
   needed.  The security mechanisms documented in [RFC8175] can be
   applied equally to the mechanism defined in this document.

5.  IANA Considerations

   IANA is requested to assign one code point in the "Extension Type
   Values" registry in the "Dynamic Link Exchange Protocol (DLEP)
   Parameters" registry group as follows:

                +======+=================================+
                | Code | Description                     |
                +======+=================================+
                | TBA1 | 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-16, 19 November 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-manet-
              dlep-credit-flow-control-16>.

   [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-13, 19 November 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-manet-
              dlep-traffic-classification-13>.

   [IEEE8021Q]
              IEEE, "IEEE Standard for Local and Metropolitan Area
              Networks--Bridges and Bridged Networks",
              DOI 10.1109/IEEESTD.2022.10004498, IEEE 802.1Q-2022, July
              2022, <https://ieeexplore.ieee.org/document/8403927>.

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   [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>.

6.2.  Informative References

   [I-D.ietf-manet-dlep-da-credit-extension]
              Cheng, B., Wiggins, D., Berger, L., and D. E. E. 3rd,
              "DLEP DiffServ Aware Credit Window Extension", Work in
              Progress, Internet-Draft, draft-ietf-manet-dlep-da-credit-
              extension-20, 15 December 2024,
              <https://datatracker.ietf.org/api/v1/doc/document/draft-
              ietf-manet-dlep-da-credit-extension/>.

Appendix A.  Acknowledgments

   The document was motivated by discussions in the MANET working group.
   Many useful comments were received from contributors to the MANET
   working group, notably Ronald 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 DLEP implementation have been
   critical to the acceptance of DLEP.  We mourn his passing on November
   23, 2023.  We wish to recognize his guidance, 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

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   Donald E. Eastlake 3rd (editor)
   Independent
   2386 Panoramic Circle
   Apopka, Florida 32703
   United States of America
   Phone: +1-508-333-2270
   Email: d3e3e3@gmail.com

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