From mboxrd@z Thu Jan 1 00:00:00 1970 From: Corey Hickey Subject: Re: strange routing issue--packets stop getting forwarded for a live connection Date: Thu, 25 Aug 2011 20:50:03 -0700 Message-ID: <4E5717EB.6030304@fatooh.org> References: <4E506A46.6060407@fatooh.org> <4E50BDFB.7050502@fatooh.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Linux Netdev List To: Julian Anastasov Return-path: Received: from juniper.fatooh.org ([173.255.221.30]:49690 "EHLO juniper.fatooh.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751243Ab1HZDuG (ORCPT ); Thu, 25 Aug 2011 23:50:06 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 2011-08-21 02:02, Julian Anastasov wrote: >>>> 3. MTU size; 1500 on eth0 and 1406 on tun0. Bigger packets have been >>>> transferred fine. >>> >>> Lower MTU, it can be PMTUD problem. At 04:50:24.112658 >>> I see 7801:9169 is 1420 bytes and no ICMP FRAG NEEDED is generated. >>> May be these two regressions explain it: >>> >>> http://marc.info/?l=linux-netdev&m=131342172722536&w=2 >>> >>> There are 2 fixes you can try or more recent kernel >>> tree, for example 3.1-rc2 has the fixes. >> >> Many thanks for your reply--it looks like you're on to something. You >> didn't specify which interface to lower the MTU on, so I tried them each >> in turn, and found that lowering the MTU on the client machine to 1406 >> (matching tun0 on the router) did indeed solve the problem. That makes >> sense in retrospect. > > I just wanted to note the difference in MTUs > as a possible cause that triggers the problem. And after > your confirmation I think the new/patched kernel should work > without playing with MTUs. I finally got a chance to test this, and the patched kernel works fine. Thank you! -Corey