In message <v03110714b05ff5a14e1c@[206.235.19.198]>, Steve Goldstein writes:
> At 8:45 AM -0400 10/7/97, Mark Allman wrote:
> >... Some people have said that
> >we can/should design mechanisms whereby we can tell why a packet was
> >dropped (congestion or corruption). Personally, I remain
> >unconvinced this will work well (it can never completely work; who
> >does a machine tell when it receives a corrupted packet? it can
> >never be sure the right host is being told, as the packet is
> >corrupt). I may be wrong, it is a research area at best. In the
> >absence of such a mechanism, we must choose conservativly and
> >therefore take the drop as congestion and backoff.
>
> I hear from the IPv6 folk that the latest protocol spec's talk of the
> routers setting a congestion bit. If that were done, and if everybody were
> to speak IPv6 (let's not hold our breath) TCP would be able to tell the
> difference between a packet dropped because of congestion and one lost to
> corruption.
>
> --Steve G.
>
> ____________________________________________
> Steve Goldstein, National Science Foundation
> +1(703)306-1949 Ext. 1119
> "Let's not procrastinate until next week!"
Steve,
A RED Gateway implementation would need to be a requirements (ala
Sally Floyd's TCP-ECN proposal) otherwise this could degrade into
DECBIT (or ATM FECN) performance which can be quite poor with long
delays. See:
ftp://ftp.ee.lbl.gov/papers/tcp_ecn.4.ps.Z
Floyd, S., TCP and Explicit Congestion Notification. ACM Computer
Communication Review, V. 24 N. 5, October 1994, p. 10-23. [This
issue of CCR incorrectly has "1995" on the cover instead of
"1994".] Abstract.
Curtis
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