Re: [tcpm] Fwd: New Version Notification for draft-kuehlewind-tcpm-ecn-fallback-00.txt

Hi,

Without having read this draft yet, just from the description, I'd like to express that I applaud this approach. I have always thought that the TCP/IP suite is weak on "fallback" approaches - why do we have dismiss sooo many things once and for all, just because some middle-boxes or routers may play wrong with them? Why can't we simply *try* things, and fall back to a default behavior if something doesn't work?

ECN is one particular case where I was asking myself this question, so I'm happy to see this work appear - but I think that this method could probably be used to improve a lot of things at the transport layer.

Cheers,
Michael

On Jul 4, 2013, at 2:14 PM, Brian Trammell <trammell@tik.ee.ethz.ch> wrote:

> Greetings, all,
> 
> We've posted a draft on ECN path probing and fallback, which we'd like to discuss at the TCPM meeting in Berlin. In a recent work [1], we found that though the ECN-readiness of popular webservers has significantly increased even in the last couple of years, there still exist paths on which attempts to use ECN after successful ECN negotiation will cause connection disruption.
> 
> This draft proposes an experimental approach to determine at runtime whether a path is usable, by sending segments after connection startup and ECN negotiation with the CE codepoint set, and disabling ECN if all probe segments were lost, on a per-flow or per-destination basis.
> 
> Experiments with an implementation of the approach within the Linux kernel are underway; we plan to be able to present initial results in Berlin.
> 
> Best regards,
> 
> Mirja and Brian
> 
> [1] Kuehlewind, M., Neuner, S., and Trammell, B., “On the state of ECN and TCP Options on the Internet”, in Proceedings of the the 2013 Passive and Active Measurement Conference, Hong Kong SAR, China, 19 March 2013.
> 
> Begin forwarded message:
> 
>> From: internet-drafts@ietf.org
>> Subject: New Version Notification for draft-kuehlewind-tcpm-ecn-fallback-00.txt
>> Date: 3 July 2013 17:40:32 GMT+02:00
>> To: Mirja Kuehlewind <mirja.kuehlewind@ikr.uni-stuttgart.de>, Brian Trammell <trammell@tik.ee.ethz.ch>
>> 
>> 
>> A new version of I-D, draft-kuehlewind-tcpm-ecn-fallback-00.txt
>> has been successfully submitted by Mirja Kuehlewind and posted to the
>> IETF repository.
>> 
>> Filename:	 draft-kuehlewind-tcpm-ecn-fallback
>> Revision:	 00
>> Title:		 A Mechanism for ECN Path Probing and Fallback
>> Creation date:	 2013-07-02
>> Group:		 Individual Submission
>> Number of pages: 5
>> URL:             http://www.ietf.org/internet-drafts/draft-kuehlewind-tcpm-ecn-fallback-00.txt
>> Status:          http://datatracker.ietf.org/doc/draft-kuehlewind-tcpm-ecn-fallback
>> Htmlized:        http://tools.ietf.org/html/draft-kuehlewind-tcpm-ecn-fallback-00
>> 
>> 
>> Abstract:
>>  Explicit Congestion Notification (ECN) is a TCP/IP extension that is
>>  widely implemented but hardly used due to the perceived unusablilty
>>  of ECN on many paths through the Internet caused by ECN-ignorant
>>  routers and middleboxes.  This document specifies an ECN probing and
>>  fall-back mechanism in case ECN has be successfully negotiated
>>  between two connection endpoints, but might not be usable on the
>>  path.
>> 
>> 
>> 
>> 
>> The IETF Secretariat
> 
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