[libvirt-users] Windows 2008r2 guest tcp retransmit hangs

Andrey Korolyov andrey at xdel.ru
Thu Apr 10 18:06:53 UTC 2014

On 04/08/2014 06:38 PM, Dennis Jacobfeuerborn wrote:
> Hi,
> I'm currently investigating a problem with our windows 2008r2 guest on
> centos 6 hosts. The issue is that the windows system sometimes sees a
> SYN packet for a tcp connection but doesn't respond. Three seconds later
> the retransmitted packet arrives and this time windows decides to
> proceed normally with the connection.
> This is with the virtio drivers but I have now switched to the e1000
> driver where the problem also occurs but not quite as badly as with
> virtio which leads me to speculate that the driver isn't really the
> problem but only affects whatever the real issue is.
> Also this does not happen when the systems primary IP is addressed
> directly but only when an IP on the loopback device is addressed through
> a load-balancer.
> I've also provisioned a linux guest on the same host and put that into
> the load balancer as well but there everything is fine.
> Has anyone run into this and can provide a pointer in the right direction?
> Regards,
>   Dennis


I observed simular issue but was unable to resolve it until migration of
the entire network to OpenFlow, so it was caused by some quirk in the
bridge topology as I think. You may ask in the kvm/qemu list but I
suppose nobody will give a right answer for Centos version because it
cannot relate to any of generic qemu releases.
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