[Iccrg] Re: [tcpm] ECN feedback discussion

[Scheffenegger, Richard]

I'm back at a decent computer; this is the paper which mentions how the highest congestion rate on one of multiple congested routers can be determined (needs to know the number of hops though; with L2-to-L3 mapping of marks, simple TTL assumtions may not be enough).

"ECN verbose mode: a statistical method for network path congestion estimation", Remi Diana, Emmanuel Lochin, 2010

http://arxiv.org/pdf/0910.4455v2.pdf


I think Emmanuel is listening on one of these groups;


For the signaling aspect, using ECT1 as the initial signal of a high-density marking scheme, and CE for both low-density and when two high-density schemes overlap (mark the same packet) would be an improvement along the lines mentioned in that paper.

However, even the current TCP ECN Nonce feedback wouldn't work properly, as a feedback channel from the receiver to the sender. I'm deliberately excluding other protocols for now...

As Matt suggested, if such a scheme were to be standardized, the balance between feedback for CE and ECT(1) would generally shift more to ECT(1); the codepoint scheme described in draft-kuehlewind-tcpm-accurate-ecn could be adapted to that easily...

Best regards,


Richard Scheffenegger



> -----Original Message-----
> From: John Leslie [mailto:john at jlc.net]
> Sent: Montag, 12. November 2012 14:48
> To: Scheffenegger, Richard
> Cc: Ingemar Johansson S; tcpm at ietf.org; iccrg at cs.ucl.ac.uk
> Subject: Re: [Iccrg] Re: [tcpm] ECN feedback discussion
> 
> Scheffenegger, Richard <rs at netapp.com> wrote:
> >
> > Alternative to using ect1 by the sender (allowing high density ecn
> > marking), what about the sender continuing to use ect0, but high
> > density ecn marking by routers changing that from ect0 to ect1 andi
> > ect1 to ce (or ect0 directl to ce on very high load)?
> 
>    A truly interesting idea! Deployable...
> 
>    Of course, we'd need research to determine a good thresshold for
> marking ect0 to ect1.
> 
> --
> John Leslie <john at jlc.net>