Re: Summary of responses so far and proposal moving forward[WasRe: [tcpm] Is this a problem?]

Joe Touch <touch@ISI.EDU> Tue, 27 November 2007 14:11 UTC

Return-path: <tcpm-bounces@ietf.org>
Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Ix19R-0006va-Re; Tue, 27 Nov 2007 09:11:01 -0500
Received: from tcpm by megatron.ietf.org with local (Exim 4.43) id 1Ix19Q-0006vO-Tf for tcpm-confirm+ok@megatron.ietf.org; Tue, 27 Nov 2007 09:11:00 -0500
Received: from [10.90.34.44] (helo=chiedprmail1.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Ix19Q-0006vC-Iw for tcpm@ietf.org; Tue, 27 Nov 2007 09:11:00 -0500
Received: from vapor.isi.edu ([128.9.64.64]) by chiedprmail1.ietf.org with esmtp (Exim 4.43) id 1Ix19Q-00029q-3k for tcpm@ietf.org; Tue, 27 Nov 2007 09:11:00 -0500
Received: from [12.170.144.92] (245ahost92.starwoodbroadband.com [12.170.144.92]) by vapor.isi.edu (8.13.8/8.13.8) with ESMTP id lAREATf4025253; Tue, 27 Nov 2007 06:10:30 -0800 (PST)
Message-ID: <474C2548.1060608@isi.edu>
Date: Tue, 27 Nov 2007 06:10:16 -0800
From: Joe Touch <touch@ISI.EDU>
User-Agent: Thunderbird 2.0.0.9 (Windows/20071031)
MIME-Version: 1.0
To: Lloyd Wood <L.Wood@surrey.ac.uk>
Subject: Re: Summary of responses so far and proposal moving forward[WasRe: [tcpm] Is this a problem?]
References: <20071126163305.326192FC402@lawyers.icir.org> <474AFB2A.9080504@isi.edu> <200711262103.VAA27187@cisco.com> <474B92FA.7020902@isi.edu> <200711271130.LAA11778@cisco.com>
In-Reply-To: <200711271130.LAA11778@cisco.com>
X-Enigmail-Version: 0.95.5
X-ISI-4-43-8-MailScanner: Found to be clean
X-MailScanner-From: touch@isi.edu
X-Spam-Score: 0.0 (/)
X-Scan-Signature: 92df29fa99cf13e554b84c8374345c17
Cc: tcpm@ietf.org, mallman@icir.org
X-BeenThere: tcpm@ietf.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: TCP Maintenance and Minor Extensions Working Group <tcpm.ietf.org>
List-Unsubscribe: <https://www1.ietf.org/mailman/listinfo/tcpm>, <mailto:tcpm-request@ietf.org?subject=unsubscribe>
List-Post: <mailto:tcpm@ietf.org>
List-Help: <mailto:tcpm-request@ietf.org?subject=help>
List-Subscribe: <https://www1.ietf.org/mailman/listinfo/tcpm>, <mailto:tcpm-request@ietf.org?subject=subscribe>
Content-Type: multipart/mixed; boundary="===============1203202947=="
Errors-To: tcpm-bounces@ietf.org


Lloyd Wood wrote:
...
>> 1122 says that connections that are active - i.e., actively exchanging
>> packets - MUST NOT be terminated. 
> 
> If only it said connections actively exchanging data...

See 1122 sec 4.2.2.17, as I cited before. Active exchange of probes is
sufficient.

>> Connections are terminated only when
>> applications indicate, OR when the endpoints cannot communicate.
>>
>> If you start "robbing Peter to pay Paul" - i.e., killing some
>> connections to make room for others - you end up with a very unreliable
>> kind of TCP. One where connections just disappear.
> 
> I'd argue we have that unreliable TCP already - e.g. varying # of
> SYNs
> repeated to ensure a connection is opened on different OSs, with
> different application behaviour as a result. Your connection just
> disappeared because the SYN and the sole repeat Windows sends were lost?
> Hit reload in your web browser! (How applications handle end-to-end
> reliability across TCP is a separate problem, but the end-to-end
> argument suggests that TCP can be unreliable - it's not the highest level.)

I agree that unpredictable OPEN behavior isn't good, but it's not
unreliable. TCP is reliable only after a connection is open, not on the
open itself.

>> Modern OS's don't kill apps to make room for new ones (presuming they're
>> static in resource use). This is the connection equivalant.
> 
> What's the connection equivalent of swapping an unused app out to virtual memory and forgetting about it?

Sounds like advertising a zero window would be similar; note that
starvation-free OS's don't "forget" about swapped processes, though --
so I wouldn't expect either to starve a process/connection indefinitely,
or to just kill a connection/process.

Joe

_______________________________________________
tcpm mailing list
tcpm@ietf.org
https://www1.ietf.org/mailman/listinfo/tcpm