Network Working Group                                         D. Wiggins
Internet-Draft                                    MIT Lincoln Laboratory
Intended status: Standards Track                               L. Berger
Expires: 30 January 2022                         LabN Consulting, L.L.C.
                                                            29 July 2021


             DLEP IEEE 802.1Q Aware Credit Window Extension
           draft-berger-manet-dlep-ether-credit-extension-07

Abstract

   This document defines an extension to the Dynamic Link Exchange
   Protocol (DLEP) that enables a Ethernet IEEE 802.1Q 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 30 January 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Simplified 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 . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Extension Type Value  . . . . . . . . . . . . . . . . . .   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].
   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 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.
















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   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 [IEEE.802.1Q_2014] 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
   destinations, VLANs, and 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].




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   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.

   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.  Note that VID value of 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, 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 MAY 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.

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.




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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 | 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., and S. Ratliff, "DLEP
              Credit-Based Flow Control Messages and Data Items", Work
              in Progress, Internet-Draft, draft-ietf-manet-dlep-credit-
              flow-control-08, 21 June 2021,
              <https://www.ietf.org/archive/id/draft-ietf-manet-dlep-
              credit-flow-control-08.txt>.

   [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-05, 21
              June 2021, <https://www.ietf.org/archive/id/draft-ietf-
              manet-dlep-traffic-classification-05.txt>.

   [IEEE.802.1Q_2014]
              IEEE, "IEEE Standard for Local and metropolitan area
              networks--Bridges and Bridged Networks", IEEE 802.1Q-2014,
              DOI 10.1109/ieeestd.2014.6991462, 18 December 2014,
              <http://ieeexplore.ieee.org/servlet/
              opac?punumber=6991460>.





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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., and L. Berger, "DLEP DiffServ
              Aware Credit Window Extension", Work in Progress,
              Internet-Draft, draft-ietf-manet-dlep-da-credit-extension-
              11, 21 June 2021, <https://www.ietf.org/archive/id/draft-
              ietf-manet-dlep-da-credit-extension-11.txt>.

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.

Authors' Addresses

   David Wiggins
   MIT Lincoln Laboratory
   Massachusetts Institute of Technology
   244 Wood Street
   Lexington

   Email: David.Wiggins@ll.mit.edu


   Lou Berger
   LabN Consulting, L.L.C.

   Email: lberger@labn.net







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