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Date: Wed, 28 Oct 2009 11:07:08 +0200
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] accidental mistyping of command line kills networking
Message-ID: <20091028090708.GT29477@redhat.com>
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To: Avi Kivity <avi@redhat.com>
Cc: Beth Kon <eak@us.ibm.com>, qemu-devel <qemu-devel@nongnu.org>

On Wed, Oct 28, 2009 at 10:55:50AM +0200, Avi Kivity wrote:
> On 10/28/2009 10:34 AM, Gleb Natapov wrote:
> >
> >>It shouldn't kill networking though.  If a guest has two nics
> >>connected to the same host bridge (a reasonable configuration), and
> >>then connects these two nics through its own bridge, it creates the
> >>same sort of loop.  If that kills networking, we have a
> >>guest-initiated DoS (not that the userspace-initiated DoS was much
> >>better).
> >>
> >That's what STP is for.
> >
> 
> The guest need not respect it.  The host must survive network loopbacks.
> 
I am not sure how STP handles situation when one bridge doesn't support
STP. If it disables one of the ports in such situation the setup will
work. If it does not then rate limiting traffic is the only solution I see.
 
--
			Gleb.