From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [Bugme-new] [Bug 36602] New: Bridge fails to work normally without net.ipv4.ip_forward=1 Date: Fri, 03 Jun 2011 23:37:46 +0100 Message-ID: <1307140667.22348.120.camel@localhost> References: <20110603123632.139f83ca.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org, bugme-daemon@bugzilla.kernel.org, Stephen Hemminger , Neil Horman , Andrew Morton To: igor@novg.net Return-path: Received: from exchange.solarflare.com ([216.237.3.220]:30169 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754247Ab1FCWhv (ORCPT ); Fri, 3 Jun 2011 18:37:51 -0400 In-Reply-To: <20110603123632.139f83ca.akpm@linux-foundation.org> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 2011-06-03 at 12:36 -0700, Andrew Morton wrote: [...] > > At the bridge, on each interface i've created a vlan, and then bridged them: > > # vconfig add eth0 102 > > # vconfig add eth1 102 > > # brctl addbr br0 > > # brctl addif br0 eth0.102 > > # brctl addif br0 eth1.102 > > # ip link set br0 mtu 9000 up > > ...etc... > > > > At this point, the bridge seems to be working, i can ping between host1 & > > host2, even with jumbo frames without fragmentation. > > > > BUT when i am trying to use iperf & friends to measure raw tcp speed between > > hosts 1/2, i'm getting something weird like 7-10 MEGABITS per second, or even > > an iperf hang until ctrl+c. This sounds like a symptom of doing LRO on a bridged device. Normally we turn off LRO for bridge members automatically, but we haven't been doing that when the bridge members are VLAN devices. > > If i attach an ip address to the bridge, and measure between hosts and the > > bridge, it works flawlessly, rendering 9.8Gbit/s in both directions. > > > > While trying to find a solution, when i ran out of options, i've set > > net.ipv4.ip_forward to 1, and, SURPRISE, the bridge started to work like a > > charm, at almost 10gig speed. [...] Right, that should force LRO off for all devices with IPv4 set up. This should be fixed by: commit f11970e383acd6f505f492f1bc07fb1a4d884829 Author: Neil Horman Date: Tue May 24 08:31:09 2011 +0000 net: make dev_disable_lro use physical device if passed a vlan dev (v2) which is in 3.0-rc1. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.