This is really just a question about best practices as there seems to be a little confusion. The physical hosts of our Hyper-V cluster have 4 Nic interfaces relating to the 4 subnets.
Now, when running the best practices analyzer, it loves to complain that most of these interfaces can't talk to each other. This is because all but one of the Nics have no gateway defined in the static settings. I was under the impression that best practice was to define only the one gateway, but I could be wrong.
So, the question:
Is it best practice to define one gateway per server, per subnet or per nic (in a cluster environment)? And, What are the effects of defining multiple gateways on a cluster environment?
Best Answer
For every network that the cluster members have in common (having a NIC in the same subnet), the cluster will create a cluster network and enable cluster communication for that cluster network (cluster heartbeat traffic, CSV metadata traffic and redirected CSV traffic). The cluster validation wizard will attempt to communicate from all cluster networks to all other cluster networks across all cluster members (such that if any single cluster network is unavailable on any cluster member, the cluster can still communicate with that cluster member across the other cluster networks). The fact that it can't communicate from a routed cluster network to a non-routed cluster network is expected. What you should do is determine which cluster networks you want the cluster to communicate on and disable cluster communication on all the others. You can do this in the properties of each cluster network. For instance, your iSCSI network doesn't need to be enabled for cluster communication (and in fact, you don't want cluster communication occurring on your iSCSI network).
If you assigned an ip address to each physical NIC (presumably in different subnets and presumably in different VLAN's) then that's why you have multiple cluster networks and that's why the cluster is trying to communicate across all of them.
Are you using a dedicated NIC for iSCSI traffic? Do you have a dedicated NIC for LiveMigration traffic? How about for CSV traffic?
Can you tell us how you have your Hyper-V virtual switches configured? Are you allowing the management operating system to share all of your virtual switches? How many virtual switches have you created? Have you created one for each physical NIC?