Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755504AbYKGEqq (ORCPT ); Thu, 6 Nov 2008 23:46:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751595AbYKGEqb (ORCPT ); Thu, 6 Nov 2008 23:46:31 -0500 Received: from swm.pp.se ([212.247.200.143]:37134 "EHLO uplift.swm.pp.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751447AbYKGEqa (ORCPT ); Thu, 6 Nov 2008 23:46:30 -0500 Date: Fri, 7 Nov 2008 05:46:28 +0100 (CET) From: Mikael Abrahamsson To: David Miller cc: daniel.blueman@gmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-net@vger.kernel.org Subject: Re: time for TCP ECN defaulting to on? In-Reply-To: <20081105.151015.206163697.davem@davemloft.net> Message-ID: References: <6278d2220811040632u7a36d68ekad5de517fd0671bb@mail.gmail.com> <20081105.151015.206163697.davem@davemloft.net> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1512 Lines: 33 On Wed, 5 Nov 2008, David Miller wrote: > This kind of thinking just perpetuates the problem forever. Well, I also think IPv6 breaks things for some people (mostly buggt DNS resolvers) but I wholly support this being default on. The ISP business is going in the direction of faster links and smaller interface buffers, meaning WRED is used less and less, thus lessening the benefit of ECN. I see that in there is a recommendation to not use ECN on retransmits, is there code right now (or planned) to do some kind of "ECN blackhole detection", ie if no response is received to SYN with ECN set, continue by sending the second SYN without ECN and keep this information for the duration of the TCP session? If there is, I do agree with you that enabling ECN by default is a good idea. Without such code, I still believe there are enough broken devices out there that will create problems for people. It's like the TCP option order "bug", where some devices would drop the packets because of buggy implementations, that was changed in Linux to work around others buggy code, and I see "ECN blackhole detection" as a similar measure. -- Mikael Abrahamsson email: swmike@swm.pp.se -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/