From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 5 Dec 2001 15:24:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 5 Dec 2001 15:24:21 -0500 Received: from z.thunderworx.net ([217.27.32.64]:25874 "EHLO francoudi.com") by vger.kernel.org with ESMTP id ; Wed, 5 Dec 2001 15:22:49 -0500 Date: Wed, 5 Dec 2001 22:22:35 +0200 From: Vladimir Ivaschenko To: Andi Kleen Cc: linux-kernel@vger.kernel.org Subject: Re: sendmsg() leaves Identification field in IP header empty Message-ID: <20011205222235.A7572@francoudi.com> In-Reply-To: <3C0E6F8B.A6C85AB6@francoudi.com.suse.lists.linux.kernel> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: ; from ak@suse.de on Wed, Dec 05, 2001 at 09:04:27PM +0100 X-Operating-System: Linux Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote about "Re: sendmsg() leaves Identification field in IP header empty": > > In theory the hack from TCP could be ported to UDP too, but I'm not sure if it is > worth it for WCCP (to be honest I don't know what WCCP is so I cannot assess if > it's important enough to add a workaround for it) Andi, thanks a lot for the insight, I will try your suggestions. WCCP is a Web Cache Communication Protocol; it is used by Cisco routers to forward traffic to proxies. What is confusing is that send() generates an ID for packets with DF set, at least when used in a way like Squid uses it. I briefly checked Squid source code and didn't find any places where it would disable MTU Path discovery. > > Sorry if I'm wrong but I think this is a kernel problem because > > sendmsg() is a system call. On RH6.2 with 2.2.19 this doesn't happen, > > It's strictly not a bug because the RFCs don't require an IPID for !DF. Ok, an intercompatibility issue. :-) -- Best Regards Vladimir Ivaschenko Certified Linux Engineer (RHCE)