Internet DRAFT - draft-ietf-manet-dlep-da-credit-extension

draft-ietf-manet-dlep-da-credit-extension







Network Working Group                                           B. Cheng
Internet-Draft                                    MIT Lincoln Laboratory
Intended status: Standards Track                              D. Wiggins
Expires: 4 September 2024                                               
                                                               L. Berger
                                                 LabN Consulting, L.L.C.
                                                            3 March 2024


              DLEP DiffServ Aware Credit Window Extension
              draft-ietf-manet-dlep-da-credit-extension-15

Abstract

   This document defines an extension to the Dynamic Link Exchange
   Protocol (DLEP) that enables a DiffServ aware credit-window scheme
   for destination-specific and shared flow control.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   This Internet-Draft will expire on 4 September 2024.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   Please review these documents carefully, as they describe your rights
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   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.



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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 . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Extension Type Value  . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
   It provides the exchange of link related control information between
   DLEP peers.  DLEP peers are comprised 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 base 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 a DiffServ-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.berger-manet-dlep-ether-credit-extension] for an Ethernet-based
   version of credit window flow control.

   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 DiffServ [RFC2475]
   DSCPs (differentiated services codepoints).  The defined mechanism
   allows for credit windows to be shared across traffic sent to
   multiple DLEP destinations and DSCPs, or used exclusively for traffic
   sent to a particular destination and/or DSCP.  The extension also
   supports the "wildcard" matching of any DSCP.





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   The extension defined in this document is referred to as "DiffServ
   Aware Credit Window" or, more simply, the "DA 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
   DiffServ Aware Credit Window Extension is to be used, an
   implementation MUST include the DiffServ 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 DiffServ Aware Credit
   Window Extension MUST support all Messages, Data Items, the DiffServ
   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 DiffServ 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 DiffServ Aware Credit Window
   Extension.

   The use of the extension defined in this document SHOULD be
   configurable on both modems and routers.

   Modems SHOULD support the configuration of DSCP to credit window
   (queue) mapping.



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   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, perhaps, even limits in supported credit window combinations,
   e.g., if per destination queues can even 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, e.g., user interface 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 base 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 use of those
   mechanisms, and the introduction of a new extension, do not
   inherently introduce any additional vulnerabilities above those
   documented in [RFC8175].  The approach taken to Security in that
   document applies equally to the mechanism defined in this document.

5.  IANA Considerations

   This document requests one assignment by IANA.  All assignments are
   to registries defined by [RFC8175].

5.1.  Extension Type Value

   This document requests 1 new assignment to the DLEP Extensions
   Registry named "Extension Type Values" in the range with the
   "Specification Required" policy.  The requested value is as follows:


                  +======+==============================+
                  | Code | Description                  |
                  +======+==============================+
                  | TBA1 | DiffServ Aware Credit Window |
                  +------+------------------------------+

                  Table 1: Requested Extension Type Value





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6.  References

6.1.  Normative References

   [I-D.ietf-manet-dlep-credit-flow-control]
              Cheng, B., Wiggins, D., Berger, L., and S. Ratliff, "DLEP
              Credit-Based Flow Control Messages and Data Items", Work
              in Progress, Internet-Draft, draft-ietf-manet-dlep-credit-
              flow-control-12, 11 July 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-manet-
              dlep-credit-flow-control-12>.

   [I-D.ietf-manet-dlep-traffic-classification]
              Cheng, B., Wiggins, D., and L. Berger, "DLEP Traffic
              Classification Data Item", Work in Progress, Internet-
              Draft, draft-ietf-manet-dlep-traffic-classification-09, 10
              July 2023, <https://datatracker.ietf.org/doc/html/draft-
              ietf-manet-dlep-traffic-classification-09>.

   [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.berger-manet-dlep-ether-credit-extension]
              Wiggins, D. and L. Berger, "DLEP IEEE 802.1Q Aware Credit
              Window Extension", Work in Progress, Internet-Draft,
              draft-berger-manet-dlep-ether-credit-extension-07, 29 July
              2021, <https://datatracker.ietf.org/doc/html/draft-berger-
              manet-dlep-ether-credit-extension-07>.

   [RFC2475]  Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
              and W. Weiss, "An Architecture for Differentiated
              Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
              <https://www.rfc-editor.org/info/rfc2475>.





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Appendix A.  Acknowledgments

   The Sub-Data item format was inspired by Rick Taylor's "Data Item
   Containers".  He also proposed the separation of credit windows from
   traffic classification at IETF98.  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 morn 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

   Bow-Nan Cheng
   MIT Lincoln Laboratory
   Massachusetts Institute of Technology
   244 Wood Street
   Lexington
   Email: bcheng@ll.mit.edu


   David Wiggins


   Lou Berger
   LabN Consulting, L.L.C.
   Email: lberger@labn.net



















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