Hi,

It seems my Hyper-V 2008 R2 two nodes cluster has a communication problem since at least two days (I don't know when it started)

Virtual machines on one node have lost the ability to ping virtual machines on the other node.

Has anyone ever had this problem?

Thanks for your answer.

Is it only one way?

Have you determined any way to 'wake them up'?

Did you just apply the latest set of patches (I know there was a recent one) and not reboot the machines - I see this as a pattern lately.

Did you take a driver update?

What is the OS in the VMs?

Have you verified the physical

Well What I have tested so far is:

NODE1 pings NODE2 / NODE2 pings NODE1

virtual machines on NODE1 ping NODE1 / NODE1 pings virtual machines on NODE1 

virtual machines on NODE2 ping NODE2 / NODE2 pings virtual machines on NODE2

Virtual Machines on NODE1 can ping NODE2

Virtual Machines on NODE1 can not ping  virtual machines on NODE2

Virtual machines on NODE2 can not ping NODE1

Virtual machines on NODE2 can not ping Virtual machines on NODE1

All patches are up to date, all drivers up to date, physical layer has been verified and it's ok, hosted machines are linux or windows machines and the results are always the same. 

Also, I believe live migration is kind of slow (20 to 30 seconds /server)

Can the VMs communicate to other systems outside the cluster without any issues?

"Also, I believe live migration is kind of slow (20 to 30 seconds /server)"

Live migration has a lot of variables.  How much memory in the VM.  How often memory changes in the VM during the live migration process. Network speed of the live migration network.  Network bandwidth available of the live migration network.  20-30 seconds could be exactly what should be expected, or it could be fast, or it could be slow.  Don't know with more information.

Yes, the Vms can communicate fully with any other equipements or servers outside the cluster. 

they can do so independenly of the node they are on.