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
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provisions of BCP 78 and BCP 79.
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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.
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Please review these documents carefully, as they describe your rights
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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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