Subject: [Tsvwg] adding a transport layer nonce to TCP (and SCTP and DCCP)

From: Sally Floyd <[email-masked]>
Date: Tue, 7 Nov 2006 17:07:03 -0800

Bob -

I think it would be a good step if you did this (as you said at the 
tsvwg meeting).
If this was done, then it would leave the only role of the current ECN 
Nonce to be
about fairness between competing flows, and would take away the other 
role
of the ECN Nonce of playing a part in protecting against congestion 
collapse.

(Explanation: If packets are being dropped and receivers are not 
reporting the drops,
subverting congestion control, this raised the danger of high 
steady-state packet drop
rates and congestion collapse.  If receivers are not able to lie about 
packet drops
(because of a transport layer nonce), but are only able to lie about 
packet marks
(if there was no ECN Nonce and no re-ECN policers protecting that 
congested link),
this still would allow receivers to subvert end-to-end congestion 
control, but at least
it wouldn't threaten congestion collapse...)

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