Re: [dpdk-dev] [PATCH 0/4 for 2.3] vhost-user live migration support

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Mon, Dec 14, 2015 at 09:00:22PM +0800, Peter Xu wrote:
> On Mon, Dec 14, 2015 at 08:09:37PM +0800, Yuanhan Liu wrote:
> > It seems that we have exactly the same test environment set up: I have
> > one server (where I normally do vhost test there) and one desktop (my
> > dev box), 
> > 
> > On both hosts, there is an ovs bridge, with IP address 192.168.100.1
> > assigned manually. Later, I started a VM on the server, and manually
> > assigned IP to 192.168.100.10. I then run "ping 192.168.100.1" for
> > live migration testing.
> > 
> > The migration to my desktop somehow works (even though there are some
> > bugs in this patch set), however, I did see what Pavel saw: about 12
> > packets has been lost, which means about 12 seconds the network is not
> > working well.
> 
> Hi, Yuanhan,
> 
> I _guess_ the problem for ping might be: guest ARP entry for
> 192.168.100.1 is not updated. Or say, after guest migrated to host2
> from host1, guest is still trying to send packet to host1's NIC (no
> one is telling it to update, right?), so no one is responding the
> ping. When the entry is expired, guest will resend the ARP request,
> and host2 will respond this time, with mac address on host2 provided
> this time. After that, ping works again.

Peter,

Thanks for your input, and that sounds reasonable. You just reminded
me that the host1's NIC is indeed different with host2's NIC: the ovs
bridge mac address is different.

I then had a quick try, setting the two ovs bridge with same mac
address, and it works like a charm: the gap is gone :)

	--yliu
> 
> (not familiar with OVS too, so am just taking it as a "vritual"
> switch)
> 
> Thanks.
> Peter