From owner-freebsd-net@FreeBSD.ORG Wed Mar 16 13:26:58 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6B5D31065675 for ; Wed, 16 Mar 2011 13:26:58 +0000 (UTC) (envelope-from korvus@comcast.net) Received: from qmta12.westchester.pa.mail.comcast.net (qmta12.westchester.pa.mail.comcast.net [76.96.59.227]) by mx1.freebsd.org (Postfix) with ESMTP id 2A2B68FC1D for ; Wed, 16 Mar 2011 13:26:57 +0000 (UTC) Received: from omta24.westchester.pa.mail.comcast.net ([76.96.62.76]) by qmta12.westchester.pa.mail.comcast.net with comcast id Kp4c1g0041ei1Bg5CpSynS; Wed, 16 Mar 2011 13:26:58 +0000 Received: from [192.168.2.164] ([206.210.89.202]) by omta24.westchester.pa.mail.comcast.net with comcast id KpSb1g01R4Mx3R23kpSjC1; Wed, 16 Mar 2011 13:26:52 +0000 Message-ID: <4D80BA89.1080300@comcast.net> Date: Wed, 16 Mar 2011 09:26:33 -0400 From: Steve Polyack User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.13) Gecko/20110125 Lightning/1.0b2 Thunderbird/3.1.7 MIME-Version: 1.0 To: Jeremy Chadwick References: <4D7F69FF.2020608@comcast.net> <20110315182603.GA37095@icarus.home.lan> In-Reply-To: <20110315182603.GA37095@icarus.home.lan> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-net@freebsd.org, freebsd-stable Subject: Re: MAC address / per-proto ARP caching in 8.1-RELEASE X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Mar 2011 13:26:58 -0000 On 03/15/11 14:26, Jeremy Chadwick wrote: > On Tue, Mar 15, 2011 at 09:30:39AM -0400, Steve Polyack wrote: >> Is anyone aware of some sort of facility in either FreeBSD >> 8.1-RELEASE or the em(4) driver which would cause it to cache MAC >> addresses / ARP entries for hosts on a per-protocol basis? >> >> [snipping remaining details; readers can read it here instead:] >> [http://lists.freebsd.org/pipermail/freebsd-stable/2011-March/061908.html] > The only thing I can think of would be flowtable, but I'm not sure > if it's enabled by default on 8.1-RELEASE-p2. You can try the following > sysctl to disable it (I would recommend setting this in sysctl.conf and > rebooting; I don't know what happens in the case you set it on a live > system that's already experiencing the MAC issue you describe). > > net.inet.flowtable.enable=0 > > Details: > > http://conferences.sigcomm.org/sigcomm/2009/workshops/presto/papers/p37.pdf > I gave this a shot again this morning. It's definitely related to the flowtable: [spolyack@web01 ~]$ time host web00.lab00 ; sudo sysctl net.inet.flowtable.enable=0 ; time host web00.lab00 ;; connection timed out; no servers could be reached real 0m10.017s user 0m0.000s sys 0m0.008s net.inet.flowtable.enable: 1 -> 0 web00.lab00 has address 10.0.1.129 real 0m0.069s user 0m0.000s sys 0m0.003s I'm still curious as to why this is only breaking new outgoing UDP traffic. New TCP connections aren't affected in the same way at all. There also does not seem to be any relevant changes to flowtable code between 8.1-RELEASE and 8.2-RELEASE or 8-STABLE.