From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: Was change to ip_push_pending_frames intended to break udp (more specifically, WCCP?) Date: Mon, 22 May 2006 14:22:32 -0400 Message-ID: <1148322152.15322.299.camel@galen.zko.hp.com> References: <20060520191153.GV3776@stingr.net> <20060520140434.2139c31b.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: Received: from atlrel8.hp.com ([156.153.255.206]:12440 "EHLO atlrel8.hp.com") by vger.kernel.org with ESMTP id S1751124AbWEVSWg (ORCPT ); Mon, 22 May 2006 14:22:36 -0400 To: Paul P Komkoff Jr In-Reply-To: <20060520140434.2139c31b.akpm@osdl.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Sat, 2006-05-20 at 14:04 -0700, Andrew Morton wrote: > Paul P Komkoff Jr wrote: > > > > Hello! > > > > I have a userspace application, which talks WCCP2 with cisco routers. > > It sends and receives UDP packets on port 2048. After I've updated my > > server to 2.6.16, it stopped working. > > > > Examining logs and packet dumps of previous (2.6.15 kernel) vs. > > current, I found, that cisco will not understand packets generated by > > 2.6.16. The only difference in that packets was IP id field, which was > > increasing (1, 2, ...) with old kernel, and always 0 with 2.6.16. > > > > Looking thru the changelog, I've found a suspect. It was this commit: > > http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=1a55d57b107c3e06935763905dc0fb235214569d > > > > Reverting this patch fixes my problems - the router understands > > packets again. > > > > I took a look through the code and ip_select_ident codepath but still > > don't understand why it setting id to 0. IP id is set to 0 on unconnected sockets when the DF bit is set (path mtu discovery is enabled). Try issuing a connect() in your application and see if the ids are increasing again. -vlad