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Specifying Alternate Semantics for the Explicit Congestion Notification (ECN) Field
RFC 4774

Approval announcement
Draft of message to be sent after approval:


From: The IESG <>
To: IETF-Announce <>
Cc: Internet Architecture Board <>,
    RFC Editor <>
Subject: Protocol Action: 'Specifying Alternate Semantics for 
         the Explicit Congestion Notification (ECN) Field' to BCP 

The IESG has approved the following document:

- 'Specifying Alternate Semantics for the Explicit Congestion 
   Notification (ECN) Field '
   <draft-ietf-tsvwg-ecn-alternates-03.txt> as a BCP

This document is the product of the Transport Area Working Group. 

The IESG contact persons are Lars Eggert and Magnus Westerlund.

A URL of this Internet-Draft is:

Ballot Text

Technical Summary
This document discusses how alternate semantics of the ECN field can 
co-exist where not all routers in a network are configured for a single 
interpretation of codepoints. Also discussed are the issues raised by 
nodes, including endsystems, configured for alternate-ECN usages. This 
document can be used as a means of migration from one alternate-ECN to 
another, where not all nodes can be configured to change at the same 
time. Additionally, means for a node (router) to determine which alternate

to use with which packet is specified. And finally, this document 
discusses how well alternate-ECN traffic performs where it co-exists with
competing traffic on a path.

Working Group Summary
There is strong consensus in the WG to publish this document. It has been
reviewed by several people prior to the WG last call. Comments raised 
earlier have all been addressed. There are no outstanding open issues wrt
this document.

Protocol Quality
This document has been well reviewed in the WG and comments raised have 
been addressed.

James Polk ( has acted as PROTO Document Shepherd for
this document.

Lars Eggert ( has reviewed this document for the

RFC Editor Note