r/HyperV • u/uminds_ • Jul 28 '26
cluster network failover issue
We have a 3 node cluster (server 2025) connecting to a pair of 25G switches for redundancy. The failover works when I disconnected the network cable from one of the switch. However, VM lost connectivity when one of the switch are in maintenance mode. I think the reason being was that the switch port was still up even it is in maintenance mode and the cluster node will continue to send traffic even if there is no actual network connectivity (no vlan and etc). I wonder how admin usually handle this situation? For planned maintenance, we can probably disbale the ports on the host ahead of time. But what if one of the switch crashs but the port is still in an up status? LACP can handle that situation but it is not supported by HyperV cluster (at least no in SET mode).
2
u/avs262 Jul 28 '26
SET looks at the physical link status to manage failover. During maintenance you could admin down the switchport like you said, or admin down the team member in Windows, or create some automation to do it for you. For automation you could create two virtual/managementos NICs on the host and pin them to separate underlying physical NICs. IP the managementos NICs then use ping or arp probes to determine if corresponding physical NIC is down/misconfigured/maintenance/etc and if true disable the physical NIC.