Hi. This is an odd issue. I've been noticing lately that the ESXi server that hosts the DLR and/or ESG control vm's will intermittently have only it's VXLAN interfaces disconnected. No other interfaces on the ESXi server are affected. If the ESXi server doesn't house those control vm's, no issues. I can't figure out what is causing this unusual behaviour, but it's not good as this causes a bunch of issues. Since it's not an ESXi failure (just specific network interfaces going down) HA doesn't kick in to migrate those vm's to another host. So, I end up having vm's on the affected host just sit there until I'm alerted (i.e. network interface redundancy lost) and then I vMotion vm's away from the host. A reboot of the affected ESXi host resolves the problem and the interfaces are magically back up.
My servers are Cisco UCS blades, and all interfaces are created as vnics in USCM and presented to ESXi as vmnics. As mentioned, no other vmnics on the ESXi host are affected.