From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Quetchenbach Subject: Re: [PATCH][BUG] tcp: advertise MSS requested by user Date: Fri, 29 Aug 2008 09:48:03 -0700 Message-ID: <48B82843.4090707@gmail.com> References: <48B44768.3030208@gmail.com> <20080828.024617.117112334.davem@davemloft.net> <200808281250.35006.denys@visp.net.lb> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org, lachlan.andrew@gmail.com To: Denys Fedoryshchenko Return-path: Received: from rv-out-0506.google.com ([209.85.198.227]:61469 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752986AbYH2QsG (ORCPT ); Fri, 29 Aug 2008 12:48:06 -0400 Received: by rv-out-0506.google.com with SMTP id k40so954692rvb.1 for ; Fri, 29 Aug 2008 09:48:05 -0700 (PDT) In-Reply-To: <200808281250.35006.denys@visp.net.lb> Sender: netdev-owner@vger.kernel.org List-ID: Best I can tell, my mailer ate this reply, so apologies if you get it twice. >> Thanks for your patch, I'll mull over this and put in the fix >> once I understand exactly how this got broken. David, thanks a lot for looking into this. It will be really helpful for our TCP benchmarking work. > I am using, just i workaround this over iptables MSS option. You feel > discomfort, but most people start googling and see this trick with iptables, > and they use it. In my case I don't think the iptables workaround is the right solution. I'm working on a traffic generator (tmix, from the University of North Carolina), that starts many simultaneous flows between two endpoints, based on a set of "connection vectors" derived from a tcpdump. The MSS for each flow is specified in the connection vector file on a per-flow basis. So it's not so simple as clamping the MSS to the path MTU or setting it based on some simple criteria like destination or port number. I'm sure I could hack something together using iptables to approximate what I want to do, but it seems like a bit of a mess to me. I'm not that familiar with iptables so please correct me if I'm wrong. Thanks -Tom