TRILL: ECN (Explicit Congestion Notification) Support
draft-ietf-trill-ecn-support-03
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draft-eastlake-trill-ecn-support
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TRILL Working Group Donald Eastlake
INTERNET-DRAFT Huawei
Intended status: Proposed Standard Bob Briscoe
Simula Research Lab
Expires: November 27, 2017 May 28, 2017
TRILL: ECN (Explicit Congestion Notification) Support
<draft-ietf-trill-ecn-support-03.txt>
Abstract
Explicit congestion notification (ECN) allows a forwarding element to
notify downstream devices, including the destination, of the onset of
congestion without having to drop packets. This can improve network
efficiency through better flow control without packet drops. This
document extends ECN to TRILL switches, including integration with IP
ECN, and provides for ECN marking in the TRILL Header Extension Flags
Word (see RFC 7179).
Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Distribution of this document is unlimited. Comments should be sent
to the TRILL working group mailing list <trill@ietf.org>.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
D. Eastlake & B.Briscoe [Page 1]
INTERNET-DRAFT TRILL ECN Support
Table of Contents
1. Introduction............................................3
1.1 Conventions used in this document......................4
2. The ECN Specific Extended Header Flags..................6
3. ECN Support.............................................7
3.1 Ingress ECN Support....................................7
3.2 Transit ECN Support....................................7
3.3 Egress ECN Support.....................................8
4. TRILL Support for ECN Variants.........................10
4.1 Pre-Congestion Notification (PCN).....................10
4.2 Low Latency, Low Loss, Scalable Throughput (L4S)......11
5. IANA Considerations....................................12
6. Security Considerations................................13
7. Acknowledgements.......................................13
Normative References......................................14
Informative References....................................15
Appendix A. TRILL Transit RBridge Behavior to Support L4S.16
Authors' Addresses........................................18
D. Eastlake & B.Briscoe [Page 2]
INTERNET-DRAFT TRILL ECN Support
1. Introduction
Explicit congestion notification (ECN [RFC3168]) allows a forwarding
element, such as a router, to notify downstream devices, including
the destination, of the onset of congestion without having to drop
packets. This can improve network efficiency through better flow
control without packet drops. The forwarding element can explicitly
mark a proportion of packets in an ECN field instead of dropping the
packet. For example, a two-bit field is available for ECN marking in
IP headers.
.............................
. .
+---------+ .
+------+ | Ingress | .
|Source| +->| RBridge | . +----------+
+---+--+ | | RB1 | . |Forwarding|
| | +------+--+ +----------+ . | Element |
v | . | | Transit | . | Y |
+-------+--+ . +---->| RBridges | . +--------+-+
|Forwarding| . | RBn | . ^ |
| Element | . +-------+--+ +---------+ | v
| X | . | | Egress | | +-----------+
+----------+ . +---->| RBridge +-+ |Destination|
. | RB9 | +-----------+
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