Subject: [Tsvwg] Adding ECN Capability to TCP's SYN/ACK packets

From: Sally Floyd <[email-masked]>
Date: Mon, 03 Oct 2005 10:53:04 -0700

Allison and Jon -

Aleksandar, KK, and I have just submitted an internet-draft
on "Adding Explicit Congestion Notification (ECN) Capability to TCP's
SYN/ACK Packets", available from
"http://www.icir.org/floyd/papers/draft-kuzmanovic-ecn-syn-00.txt".
This is motivated by the SIGCOMM 2005 paper by Aleksandar on 
"The Power of Explicit Congestion Notification".
Any feedback would be appreciated.

If possible, I would like to talk about this briefly at TSVWG in
Vancouver, and see if there is agreement for this to become an
official tsvwg document.  This is a pretty straightforward draft,
and our hope is that it could go to Proposed Standard fairly soon.

Many thanks,

- Sally

Abstract:

   This draft specifies a modification to RFC 3168 to allow TCP SYN/ACK
   packets to be ECN-Capable.  For TCP, RFC 3168 only specified setting
   an ECN-Capable codepoint on data packets, and not on SYN and SYN/ACK
   packets.  However, because of the high cost to the TCP transfer of
   having a SYN/ACK packet dropped, with the resulting retransmit
   timeout, this document is specifying the use of ECN for the SYN/ACK
   packet itself, when sent in response to a SYN packet with the two ECN
   flags set in the TCP header, indicating a willingness to use ECN.
   Setting TCP SYN/ACK packets as ECN-Capable can be of great benefit to
   the TCP connection, avoiding the severe penalty of a retransmit
   timeout for a connection that has not yet started placing a load on
   the network.  The sender of the SYN/ACK packet must respond to an ECN
   mark by reducing its initial congestion window from two, three, or
   four segments to one segment, reducing the subsequent load from that
   connection on the network.

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From: Sally Floyd <[email-masked]>
Date: Mon, 03 Oct 2005 11:45:59 -0700

>"http://www.icir.org/floyd/papers/draft-kuzmanovic-ecn-syn-00.txt".

Sorry, the old copy only had the first two pages.  My fault.
It should all be there now.

- Sally
http://www.icir.org/floyd/