Internet DRAFT - draft-berger-manet-dlep-ether-credit-extension
draft-berger-manet-dlep-ether-credit-extension
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
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This Internet-Draft will expire on 30 January 2022.
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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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