Re: congestion control? - (was Re: Appointment of a Transport Area Director)
Spencer Dawkins <spencer@wonderhamster.org> Tue, 05 March 2013 15:40 UTC
Return-Path: <spencer@wonderhamster.org>
X-Original-To: ietf@ietfa.amsl.com
Delivered-To: ietf@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id D195321F88EF for <ietf@ietfa.amsl.com>; Tue, 5 Mar 2013 07:40:12 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -102.599
X-Spam-Level:
X-Spam-Status: No, score=-102.599 tagged_above=-999 required=5 tests=[AWL=0.000, BAYES_00=-2.599, USER_IN_WHITELIST=-100]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 0n-kZ-ZGGAF8 for <ietf@ietfa.amsl.com>; Tue, 5 Mar 2013 07:40:12 -0800 (PST)
Received: from mout.perfora.net (mout.perfora.net [74.208.4.194]) by ietfa.amsl.com (Postfix) with ESMTP id E9BF121F8869 for <ietf@ietf.org>; Tue, 5 Mar 2013 07:40:11 -0800 (PST)
Received: from [192.168.1.79] (99-108-174-213.lightspeed.rcsntx.sbcglobal.net [99.108.174.213]) by mrelay.perfora.net (node=mrus3) with ESMTP (Nemesis) id 0Le5rg-1UaARM48BI-00qFV2; Tue, 05 Mar 2013 10:40:09 -0500
Message-ID: <513611D0.4080504@wonderhamster.org>
Date: Tue, 05 Mar 2013 09:40:00 -0600
From: Spencer Dawkins <spencer@wonderhamster.org>
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130215 Thunderbird/17.0.3
MIME-Version: 1.0
To: Brian E Carpenter <brian.e.carpenter@gmail.com>
Subject: Re: congestion control? - (was Re: Appointment of a Transport Area Director)
References: <5134EFEB.2090104@isi.edu> <20130305004135.34CCA1A5F4@ld9781.wdf.sap.corp> <B31EEDDDB8ED7E4A93FDF12A4EECD30D2502A316@GLKXM0002V.GREENLNK.net> <5135FE1F.3030308@gmail.com>
In-Reply-To: <5135FE1F.3030308@gmail.com>
Content-Type: text/plain; charset="UTF-8"; format="flowed"
Content-Transfer-Encoding: 7bit
X-Provags-ID: V02:K0:ieTFrLM9Uug5Li1QPeoegDW9W0K8hxA7wY75Lra19Ur F6gueUerg4eOsk7IVl6o6BsSfgt9c5dGMy2Wf208k5AwtFmQVN 73cRIbdoSlqjmwSqIee8JtoDxcXwRJiRl1bCKYmNz2p3ZbIW8G YeYQ01iWWlXnzFjC8hjH0Bm0RywuaqBHmSbwDfhatDaBlMDgdB cq5WesOIJHxCD6fBW/SKlbpl0Gs7+xeEPa68EWGLrqfuGgbRfk pspyLw0eY5IuC5WYGns9y7Sp6TC71hMWVpDze/A2lPwyocENSR EhHoqBsWJS8laH8DzIMvvur+ly9YWMEOooWF7USi5HAC2Lim9M 9wpnBKKUSYQPUdVOZupWHLYhHXoZeeflyEh0FPFit
Cc: "braden@isi.edu" <braden@isi.edu>, "ietf@ietf.org" <ietf@ietf.org>
X-BeenThere: ietf@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: IETF-Discussion <ietf.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ietf>, <mailto:ietf-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/ietf>
List-Post: <mailto:ietf@ietf.org>
List-Help: <mailto:ietf-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ietf>, <mailto:ietf-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 05 Mar 2013 15:40:12 -0000
On 3/5/2013 8:15 AM, Brian E Carpenter wrote: > On 05/03/2013 11:55, Dearlove, Christopher (UK) wrote: >> I've no idea about the example quoted, but I can see some of their motivation. >> >> TCP's assumptions (really simplified) that loss of packet = congestion => backoff >> aren't necessarily so in a wireless network, where packets can be lost without >> congestion. This means that TCP into, out of, or across, a MANET using TCP can be >> bad. It then tends to happen that the MANET people don't fully understand TCP, >> and the TCP people don't fully understand MANETs. > > The effects you mention were definitely discussed in PILC. > http://www.ietf.org/wg/concluded/pilc.html > Maybe the PILC documents need revision? > > Brian TRIGTRAN tried to nail this down in more detail after PILC concluded (I co-chaired both PILC and the TRGTRAN BOFs). This quote from the IETF 56 minutes pretty much captured where that ended up: <quote> Spencer summarized a private conversation with Mark Allman as, "Gee, maybe TCP does pretty well often times on its own. You may be able to find cases where you could do better with notifications, but by the time you make sure the response to a notification doesn't have undesirable side effects in other cases, TCP doesn't look so bad" </quote> If we had to have all the TCP responding-to-loss mechanisms in an implementation anyway, and we could tell a sender to slow down, but not to speed up, it wasn't clear that additional mechanisms would buy you much. References are at http://www.ietf.org/proceedings/55/239.htm and http://www.ietf.org/proceedings/56/251.htm The high order bit on this may have been that TRIGTRAN wasn't IETF-ready and should have gone off to visit IRTF-land, but in the early 2000s, I (at least) had no idea how to make that happen. Spencer >> >> I don't have a single good reference for what I say above, in particular have >> things got better (or worse) as TCP evolves, and therefore which references >> are still valid? But the obvious Google search (TCP MANET) throws up various >> discussions.
- Re: congestion control? - (was Re: Appointment of… Michael Richardson
- congestion control? - (was Re: Appointment of a T… Roger Jørgensen
- Re: congestion control? - (was Re: Appointment of… Bob Braden
- Re: congestion control? - (was Re: Appointment of… Martin Rex
- Re: congestion control? - (was Re: Appointment of… Eggert, Lars
- Re: congestion control? - (was Re: Appointment of… Eliot Lear
- RE: congestion control? - (was Re: Appointment of… Dearlove, Christopher (UK)
- RE: congestion control? - (was Re: Appointment of… l.wood
- Re: congestion control? - (was Re: Appointment of… Brian E Carpenter
- Re: congestion control? - (was Re: Appointment of… Spencer Dawkins
- Re: congestion control? - (was Re: Appointment of… Wesley Eddy
- Re: congestion control? - (was Re: Appointment of… Cameron Byrne
- Re: congestion control? - (was Re: Appointment of… Wesley Eddy
- Re: congestion control? - (was Re: Appointment of… t.p.
- Re: congestion control? - (was Re: Appointment of… Brian E Carpenter
- Re: congestion control? - (was Re: Appointment of… Masataka Ohta
- RE: congestion control? - (was Re: Appointment of… l.wood
- Re: congestion control? - (was Re: Appointment of… Masataka Ohta
- Re: congestion control? - (was Re: Appointment of… Cameron Byrne
- RE: congestion control? - (was Re: Appointment of… John E Drake
- Re: congestion control? - (was Re: Appointment of… Masataka Ohta
- Re: congestion control? - (was Re: Appointment of… Toerless Eckert
- Re: congestion control? - (was Re: Appointment of… Toerless Eckert
- Re: congestion control? - (was Re: Appointment of… t.p.