Hyper-V Virtual Machine stops responding to network traffic if VMQ (Virtual Machine Queues) are enabled on a 1GB physical NIC

vmqI recently took on a new customer who’s IT infrastructure was a mess.  They have good hardware but the setup they had was just awful (it was an internal guy who had great ideas but little skill).  They had Hyper-V running on a nice new Gen9 HP Server on Windows Server 2012 R2, which is a nice combination.  Once they were on boarded they let us know that the server kept on crashing (they had no idea their setup was virtualised or that they had more than one server…).    Virtual Machine Queuing or VMQ allows the “virtualization” of the network allowing for the NIC to create paths to each virtual NIC to offload the traffic.

After about a week, I got the call I was waiting for to tell me their server had stop responding, the virtual machine was still up but wasn’t responding to pings or allowing access to network resources (it was their SBS server).   So as a quick fix, I disabled and re-enabled the NIC on the server (as a best practice you should have a dedicated Management NIC to allow access to the host), this brought things back online.  After having a quick look at the Broadcom NIC it had VMQ enabled, I then set it to disabled and restarted the server out of hours.  Since then there hasn’t been any issues with the servers dropping off the network.

The issue hasn’t resurfaced since and is documented in the following Microsoft KB article https://support.microsoft.com/en-us/kb/2986895

It is interesting to note that the server had the latest drivers and firmware installed but was still having the issue, so I’d recommend leaving VMQ Disabled completely as the benefits aren’t that great (unless your high-traffic 10 Gbps).

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