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Re: Live Migration (L2 network)
From: |
Dr. David Alan Gilbert |
Subject: |
Re: Live Migration (L2 network) |
Date: |
Mon, 27 Jul 2020 20:09:09 +0100 |
User-agent: |
Mutt/1.14.5 (2020-06-23) |
* William Lima Reiznautt (willreli@gmail.com) wrote:
> Hi folks,
>
> I hope everything is well.
Hi,
> Sorry about that doubt in this channel.
No, it's the right place to ask!
> I have a doubt about live migration interacting with layer 2 network, when
> the live migration is running. How does the qemu signal the switch network
> that the qemu instance changes port ? Because when the qemu migration to
> another port switch, the switch has a time to understand that flow is
> changed.
>
> I saw the dump traffic in live migration and I noticed that one packet
> (RARP). "This packet is created by qemu."
>
> Does anyone know if there is documentation on this?
I'm not sure we have documentation, but the code is in net/announce.c in
recent qemu.
When the migration has finished we send an ARP and then, when it starts
running, we tell the guest to send a RARP; we send those a few times
to make sure we don't miss it.
Those are normally enough for the switch to realise that the VM
has moved port; some very complex switch setups are less forgiving - in
recent qemu's you can send the announce again later and/or change the
timing of it.
Dave
> Thanks
>
> - - -
> William Lima Reiznautt
> willreli@gmail.com
> www.ic.unicamp.br/~william
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK