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Date: Thu, 29 Mar 2007 09:37:09 +1200
From: Andrew Thompson <thompsa@freebsd.org>
To: Jeremy Chadwick <koitsu@FreeBSD.org>
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Cc: freebsd-stable@freebsd.org
Subject: Re: em(4) losing link when if_bridge(4) addm/deletem are used
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On Tue, Mar 27, 2007 at 08:33:27PM -0700, Jeremy Chadwick wrote:
> In the midst of the madness, I found that when doing either of the
> following commands...
> 
>   ifconfig bridge0 addm em1
>   ifconfig bridge0 deletem em1
> 
> ...I see the entire em1 interface completely reset, bringing down link,
> then up again shortly after.  The logs on my switch also confirm this.
> 
> For sake of comparison, the bge(4) driver does not behave this way.
> 
> I am aware that if_bridge(4) enables promiscuous mode on whatever
> interface is being added, ditto with -promisc on deletem.  However, this
> does not appear to be the cause of the problem, because I can do
> "ifconfig em1 promisc" and "ifconfig em1 -promisc" without loss of link.
 
The only other thing the bridge does to the interface when removing it
is to reinstate IFCAP_TXCSUM, which is disabled when the interface is
bridged. If you manually toggle this with ifconfig do you get the same
result?


Andrew