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RE: [Xen-devel] arp during live migration

To: "Cristian Zamfir" <zamf@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] arp during live migration
From: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>
Date: Fri, 2 Mar 2007 17:22:14 -0500
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Thread-topic: [Xen-devel] arp during live migration
> I am having some trouble with the send_fake_arp in the netfront

Interesting - I was just composing an almost identical note; we've been
seeing some horrible network blackouts in migration that are caused by a
failure to send the gratuitous ARP (blackouts vary from 0-50+ seconds
when the domain is idle and just being pinged from outside).

In my case, I NEVER see the gratuitous ARP being sent (confirmed using
tcpdump on peth0 in Dom0) and the return value from dev_queue_xmit is
sometimes 0 and sometimes 2 (that's PLUS 2 -- congestion notification

My next step was going to be to add instrumentation to netback but I
thought I would ask if this is a known issue with 3.0.3 first...


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