Hyper-V 2012 and BSOD with WLAN

 

Hyper-v 2012 and BSOD with WLAN
so lately I have had some strange issues with my Hyper-V Server (Running Server 2012) and this server is connected to my intranet using WLAN. Why you ask? Because in 2012 WLAN is supported and it is the only way I can connect my server to the network without using EoP.
I am using the wireless adapter as a bridge adapter to my virtual interfaces. So all my virtual machines connect to the internet using the wireless adapter.
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So at random times my server got a BSOD.
With the regular DRIVER_IRQL_NOT_LESS_OR_EQUAL error message. (Not like the picture shown above)
I started looking at the normal places, is something wrong with a driver? I haven’t installed anything recently and it has been working fine for a couple of months so I couldn’t be that. Could It be that Windows update has updated a driver and didn’t notify me? According to the event log of the drivers that was a no to.
Next I checked my memory modules they also have a tendency to create BSOD. No faults there either, and the BSOD was happening at random times. So troubleshooting 101, what did you change before the first BSOD? I added my WLAN as a connection to the virtual switch, so I removed the wireless adapter from the server and no BSOD. So now I am one step closer and I found out what was creating the BSOD, I tried updating the drivers for the wireless adapter but there were no new drivers available.
So therefore I needed to resort to debugging the memory dump using WinDbg. (You can find the memory dump from c:\windows\memory.dmp

First I added the symbol path from Microsoft online,
SRV*C:\SymCache*http://msdl.microsoft.com/download/symbols
(if you do this after you open the memory dump do a .reload )
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Looks like the sinner here is bridge.sys, but what is that?
Hyper-v creates a bridge between your virtual interface (virtual switch) and your physical interface when you choose “Allow management operating system to share this network adapter” and this bridge (You can see it under network adapters) is the source of the problems.
So by choosing this option the parent host can still be online using the same physical interface as the virtual hosts use.
I know there are a lot of features which are not supported using a wireless connection, but since Microsoft says WLAN are supported in 2012 it better work in time for the RTM.
FYI: The only way I found out so far to fix this was to remove the “Allow management Operating system to share this network adapter” This disables the bridge and I haven’t had any BSOD after that.

#hyper-v-2012, #wlan-bridge