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RE: [Xen-devel] arp during live migration

  • To: "Keir Fraser" <keir@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>
  • Date: Wed, 7 Mar 2007 17:25:59 -0500
  • Delivery-date: Wed, 07 Mar 2007 14:25:21 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcdfPJTYp3d71aDxRxK0gccT+4xaGgAQl6OgADB089AAJEqVNQANWTcQ
  • 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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