Hyper-V: Loss of network connectivity
Many people have been reporting network connectivity issues once a Hyper-V Virtual Network Switch is created, but the symptoms vary so widely that it can be tough to find a solution. There are issues like:
- A few packets getting lost every 6-8 hours.
- Complete loss of connectivity on the host operating system.
- VMs work for 3-4 days, then a complete loss of connectivity to the VMs.
This list goes on and on. I've been using Microsoft's Virtualization Technologies since before Virtual Server was first released, and network connectivity has been an issue with every build. Every time Microsoft thinks that they've fixed the issues, they creep right back in. Microsoft has been known to respond with their normal, "We can't reproduce the issue." response, as well. That being said, I think that I've finally found a solution that works for me in each and every case, turning off the "offload" setting(s) of anything IPv4 related within the properties of the driver itself.
If you are using Intel network controllers, then you will most likely not have any issues, as Microsoft does the majority of their testing with intel network controllers. If you are using some other make like Broadcom or Marvell (these 2 in particular), you will most likely run into issues, some of which may even occur without Hyper-V being installed. People using HP servers have also been reporting a large number of issues, but I don't know what chipsets they use. If you are having connectivity issues, turn off all the IPv4 offload settings and see if that fixes your issues. If doing that fixes your issues, or makes a dent, you've found the source.
You can keep disabling properties until you find a combination that works best in your situation, or you can disable/remove the network controller and replace it with a different make and model that is known to be free of issues. The number of features that have been disabled, and the impact that it has on system performance, should determine whether or not disabling features is preferable to replacing the controller altogether. Microsoft needs to get together with these chip manufactures and figure out what the problem is. This is like the old days of DOS, SCSI, and no real standard.