Subject: I-D Action:draft-ietf-tsvwg-ecn-tunnel-05.txt

From: [email-masked]
Date: Fri, 18 Dec 2009 08:15:05 -0800 (PST)

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Transport Area Working Group Working Group of the IETF.

	Title           : Tunnelling of Explicit Congestion Notification
	Author(s)       : B. Briscoe
	Filename        : draft-ietf-tsvwg-ecn-tunnel-05.txt
	Pages           : 41
	Date            : 2009-12-18

This document redefines how the explicit congestion notification
(ECN) field of the IP header should be constructed on entry to and
exit from any IP in IP tunnel.  On encapsulation it updates RFC3168
to bring all IP in IP tunnels (v4 or v6) into line with RFC4301 IPsec
ECN processing.  On decapsulation it updates both RFC3168 and RFC4301
to add new behaviours for previously unused combinations of inner and
outer header.  The new rules ensure the ECN field is correctly
propagated across a tunnel whether it is used to signal one or two
severity levels of congestion, whereas before only one severity level
was supported.  Tunnel endpoints can be updated in any order without
affecting pre-existing uses of the ECN field (backward compatible).
Nonetheless, operators wanting to support two severity levels (e.g.
for pre-congestion notification--PCN) can require compliance with
this new specification.  A thorough analysis of the reasoning for
these changes and the implications is included.  In the unlikely
event that the new rules do not meet a specific need, RFC4774 gives
guidance on designing alternate ECN semantics and this document
extends that to include tunnelling issues.

Status of This Memo

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