Date: Wed, 16 Mar 2011 09:26:33 -0400 From: Steve Polyack <korvus@comcast.net> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-net@freebsd.org, freebsd-stable <freebsd-stable@FreeBSD.org> Subject: Re: MAC address / per-proto ARP caching in 8.1-RELEASE Message-ID: <4D80BA89.1080300@comcast.net> In-Reply-To: <20110315182603.GA37095@icarus.home.lan> References: <4D7F69FF.2020608@comcast.net> <20110315182603.GA37095@icarus.home.lan>
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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.
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