I have a rather strange networking issue that cropped up on one of our vsphere hosts yesterday. We got a call that one of the VM's was "mostly" unreachable. One person could get to it, another person couldn't. The monitoring software could get to it, but most other things could not. After trying a few things like rebooting the VM, etc., I migrated it to another host and it suddenly started working just fine. The various hosts have a good dozen different matching port groups (we aren't fancy enough to have distributed switches) and this particular VM is the only one that uses this certain port group and vlan. I spun up a new VM, put it on that host and port group and it exhibited the exact same problem. No other port groups on the host seem to be affected. The host has 2 nics and is configured for route by ip hash so my assumption is that, for whatever reason, it isn't able to send this particular VLAN down one of the NICS? Or is refusing to do so? No other VLANs or port groups seem to be affected and we can see nothing on the switch side. Anyone have any ideas on what might be causing this?
If other VLAN has no issue, so there is misconfiguration on switch port or vSwitch/PortGroup.
Double check all configuration.