From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 29 Jan 2001 18:31:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 29 Jan 2001 18:31:31 -0500 Received: from webmail.metabyte.com ([216.218.208.53]:13319 "EHLO webmail.metabyte.com") by vger.kernel.org with ESMTP id ; Mon, 29 Jan 2001 18:31:12 -0500 Message-ID: <3A75F4D7.D7957633@metabyte.com> Date: Mon, 29 Jan 2001 14:55:19 -0800 From: Pete Zaitcev X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.2.14-5.0 i686) X-Accept-Language: en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: Maxwell strikes the heart (ECN: Clearing the air) Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 29 Jan 2001 22:55:46.0894 (UTC) FILETIME=[9DF72EE0:01C08A46] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > From: Gregory Maxwell (greg@linuxpower.cx) > Date: Sun Jan 28 2001 - 14:42:04 EST > > On Sun, Jan 28, 2001 at 01:29:52PM +0000, James Sutherland wrote: > > > There is nothing silly with the decision, davem is simply a modern day > > > internet hero. > > > > No. If it were something essential, perhaps, but it's just a minor > > performance tweak to cut packet loss over congested links. It's not > > IPv6. It's not PMTU. It's not even very useful right now! > > No. ECN is essential to the continued stability of the Internet. Without > probabilistic queuing (i.e. RED) and ECN the Internet will continue to have > retransmit synchronization and once congested stay congested until people get > frustrated and give it up for a little bit. > > It's a real issue, and it's actually important to have it implemented. It's > not just a performance hack. I always "knew" that the stability of the Internet is secured by the exponential backoff in TCP. A small packet loss on uncongested links is a part of this technique, and it existed long before ATM studies produced RED (which infiltrated backwards). It also requires sending stacks to "give up for a little bit" (actually to give up a lot, and together with the slow start it produced the well known "saw" of the window size). So far I fail to see how a repainted NAK, kludged into a NAKless protocol, would improve stability of the Internet. If anything, it is going to exaggerate traffic oscillations. I would appreciate couple of links to reputable studies or discussions on the subject. -- Pete - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/