Date: Wed, 10 Dec 2014 13:25:33 -0500 From: Ryan Stone <rysto32@gmail.com> To: "David P. Discher" <dpd@dpdtech.com> Cc: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: EM(4) - Link flap when bridged and adding members (em bridge flap) Message-ID: <CAFMmRNyVFtaZW0cu30f8_s8ABZJpnH%2ByPKSa67s%2BngNueWHhfw@mail.gmail.com> In-Reply-To: <BF885CAD-6A3A-4B79-B3E3-52BDF2C1497D@dpdtech.com> References: <BF885CAD-6A3A-4B79-B3E3-52BDF2C1497D@dpdtech.com>
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>From a quick look at the code, whenever an interface is added to a bridge, if that interface does not support a feature currently enabled on the bridge then it has to disable that feature on all member interfaces of that bridge. That would re-init the em interface, which would cause a link flap. Take a look at the ifconfig output for em0 and epair0 before epair0 is added to the bridge. You will probably see that one or more features that em supports is not supported by epair (I would bet on something like LRO or TSO).. The solution would be to disable those features from em0 before adding it to the bridge (you can persist this in rc.conf with ifconfig_em0="...")
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