DLEP DiffServ Aware Credit Window Extension
draft-ietf-manet-dlep-da-credit-extension-18

Network Working Group                                           B. Cheng
Internet-Draft                                    MIT Lincoln Laboratory
Intended status: Standards Track                              D. Wiggins
Expires: 23 January 2025                                                
                                                               L. Berger
                                                 LabN Consulting, L.L.C.
                                                            22 July 2024

              DLEP DiffServ Aware Credit Window Extension
              draft-ietf-manet-dlep-da-credit-extension-18

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 23 January 2025.

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
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   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.

Cheng, et al.            Expires 23 January 2025                [Page 1]
Internet-Draft          DLEP DA Credit Extension               July 2024

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].
   This protocol 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 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.

Cheng, et al.            Expires 23 January 2025                [Page 2]
Internet-Draft          DLEP DA Credit Extension               July 2024

   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.

Cheng, et al.            Expires 23 January 2025                [Page 3]
Internet-Draft          DLEP DA Credit Extension               July 2024

   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 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
   exposes vulnerabilities similar to existing DLEP messages, e.g., an
   injected message resizes 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.

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

Cheng, et al.            Expires 23 January 2025                [Page 4]
Internet-Draft          DLEP DA Credit Extension               July 2024

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>.

   [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>.

   [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>.

   [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>.

Cheng, et al.            Expires 23 January 2025                [Page 5]
Internet-Draft          DLEP DA Credit Extension               July 2024

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
   Email: david@none.org

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

Cheng, et al.            Expires 23 January 2025                [Page 6]