FW: [e2e] Can feedback be generated more fast in ECN?

[K. K. Ramakrishnan]

Renjish,
There is more discussion of this issue on the ECN web page:
http://www.aciri.org/floyd/ecn.html

We have discussed this issue extensively before. One of the issues that
has concerned me is the lack of an appropriate incentive for ECN
compliance, with marking the CE bit in the ack. A receiver could
ignore the CE bit in the ack with impunity because of the nature of
cumulative acknowledgments.

With data packets, if I ignore ECN, then there is the possibility
that I  would begin to experience more packet loss, and hence
reduced performance. If I ignore ECN indications in the ACK,
then even if acks. are lost, the cumulative ack would provide
me enough information.

There have been proposals for reacting to congestion in the
ack path, but we've felt that we need to understand the
situation more thoroughly before suggesting deployment.

  K. K. Ramakrishnan

Kaleelazhicathu R R Kumar wrote:

> The RFC 2481 talks about sending a pure ack with ECT bit set to 0. Can we
> not set the ECT bit for a pure ack as well?? This could help in avoiding
> ack loss in the reverse direction to a greater extent. The receiver of
> the pure ack can be modified  to behave appropriately  when a CE bit is
> found or don't react at all.
>
> Renjish