BGP underlay sessions are up, but one leaf’s loopback used as a VTEP address is missing from remote routing tables. What underlay routing gap should be investigated first?
Select an answer to reveal the explanation.
Short Explanation
Sessions up but no loopback route is like having phone signal and no phone number published. The VTEP address has to be advertised in the underlay or remote leaves cannot build the tunnel. Do not go hunting STP on a loopback.
Full Explanation
Overlay tunnels require underlay reachability to VTEP (typically loopback) addresses. Missing loopback advertisement is a common root cause when BGP sessions are otherwise established. STP does not block loopback interfaces as fabric ports, and disabling VXLAN does not publish VTEP reachability. Redistributing arbitrary server VLANs is not the clean way to inject infrastructure loopbacks.