From owner-freebsd-current@FreeBSD.ORG Sun Apr 24 16:21:31 2005 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 89F4B16A4CE for ; Sun, 24 Apr 2005 16:21:31 +0000 (GMT) Received: from c00l3r.networx.ch (c00l3r.networx.ch [62.48.2.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id B26C843D1D for ; Sun, 24 Apr 2005 16:21:30 +0000 (GMT) (envelope-from andre@freebsd.org) Received: (qmail 1893 invoked from network); 24 Apr 2005 16:22:47 -0000 Received: from unknown (HELO freebsd.org) ([62.48.0.54]) (envelope-sender ) by c00l3r.networx.ch (qmail-ldap-1.03) with SMTP for ; 24 Apr 2005 16:22:47 -0000 Message-ID: <426BC78A.3E56D99B@freebsd.org> Date: Sun, 24 Apr 2005 18:21:30 +0200 From: Andre Oppermann X-Mailer: Mozilla 4.8 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: David Malone References: <426426AE.2060406@uq.edu.au> <20050420084413.GA27304@walton.maths.tcd.ie> <42663EA1.3020409@uq.edu.au> <426A3F49.6090203@uq.edu.au> <20050424150211.GA87520@walton.maths.tcd.ie> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit cc: Matthew Sullivan cc: freebsd-current@freebsd.org Subject: Re: DF (Don't frag) issues X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 24 Apr 2005 16:21:31 -0000 David Malone wrote: > > On Sat, Apr 23, 2005 at 10:27:53PM +1000, Matthew Sullivan wrote: > > Ok well thanks to Andrew @ Supernews and a lot of debugging it appears > > there is a bug.... > > > > sys/netinet/ip_icmp.c: line 440 > > if (!mtu) > > mtu = ip_next_mtu(mtu, 1); > > Problem is ip_next_mtu will always return 0 when called with (0, 1) ... > > I think this might be a bug, but Andre would know better. Andre - > it looks to me as if the first argument to ip_next_mtu here should > be the current MTU for the path, but it is being set to the mtu > from the ICMP message, which (in this case) is zero. This is a bug indeed. Let me think how to fix this most efficiently... > (This is in the code that has just been moved to tcp_ctlinput.) > > > Apparently the gateway should be suggesting a MTU value for use.... the > > gateway is also FreeBSD 5.3 so something needs fixing .. :-/ > > Are you using ip fast forwarding on the gateway? It calculates the > size that is put into the ICMP message in a slightly different way > to the other forwrd path. The quoted code above is used only for incoming ICMP packets. It does not generate them? What is the problem being observed exactly? -- Andre