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RE: [Xen-devel] arp during live migration

To: "Keir Fraser" <keir@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] arp during live migration
From: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>
Date: Wed, 7 Mar 2007 17:25:59 -0500
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Thread-topic: [Xen-devel] arp during live migration
> > All of this leads to a ~1s delay setting up the network path plus
> > gratuitous ARP is dropped so there can be a MUCH larger network
> > blackout. If you are trying to get sub-second blackout on migration
> this
> > is a big problem!
> >
> > It seems to me that the right thing to do here is to have the link
> on
> > the VIF in advance of the domain resuming on the target but I'm
> guessing
> > that this would cause netback to have conniptions...
> Changeset 14280 in xen-unstable fixes this by no longer using the
> netif_carrier flag. The patch will probably backport very
> straightforwardly
> onto older (or newer) 2.6 Linux kernels.

Just wanted to close the loop here -- We've tested with this fix and it
definitely fixes our problem -- network blackout times are way low again
and I see the gratuitous ARP being sent -- many thanks to Keir for the
swift fix.


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