The strangest problem in the world, ever!

[british_government]

This problem has dragged my back to edgeek, not necessarily for an answer just to share my pain.

 

We have an NEC Flex server running a hyper-v cluster on 2008 R2 and the server with the fault is also 2008 R2.

 

I came in Monday morning and one of our physical hosts was unreachable so I rebooted it and everything seemed to be back up, then I noticed that all traffic being sent to the virtual servers that were on it is being duplicated.

 

For example, if I send a ping to the server running wireshark I see these results.

 

On my machine: 4 pings sent, 8 replies received.

On the VM: 8 pings received, 8 replies sent.

 

This is only happening with the virtual servers and not the hardware hosts.

 

Fun

[jinnantonnixx]

Check your network cards on the host. Are they in promiscuous mode? If you don't need this, switch off promiscuous mode.

 

I'm guessing the host is duplicating the ping request of its client.

You can check this on the wireshark trace by looking at the destination MAC addresses of the ping replies.

 

Also, do you have a bridge in the equation? Perhaps the bridge IP is being routed. If you don't need an IP address for the bridge, remove it.

Edited April 9, 2013 by jinnantonnixx

[british_government]

For anybody that comes across this thread. It seemed to be a fault in the switch in the flex, total powerdown of the networking was the way to solve the problem!