Re: [Qemu-devel] [PATCH v2] net: Add support of VIRTIO_NET_F_GUEST_ANNOUNCE for vhost-net/vhost-user

[Stefan Hajnoczi]

On Mon, Jun 08, 2015 at 05:32:38PM +0200, Thibaut Collet wrote:
> > 3. The easiest solution - nop .receive()
> 
> The solution 3 is similar of my implementation and does not solve issue
> pointed by Jason: legacy guest do not send a gratuitous ARP.

Yes, but it prints a warning so the user is aware they are operating in
a degraded state.

Sending gratuitous ARP packets minimizes the time that network
infrastructure forwards packets to the old host.  But the network
infrastructure will learn about the new host as long as the guest
sends outgoing packets after migration.

Putting these two things together, it seems acceptable to do #3.  Most
users should be running a modern virtio-net that supports the announce
feature anyway.

Stefan

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