City operators enable VXLAN on two leaves, but the underlay cannot…

Question

City operators enable VXLAN on two leaves, but the underlay cannot reach the remote VTEP loopback. What happens to the overlay data plane?

Accepted Answer

Encapsulated VXLAN packets cannot be delivered, so the overlay data plane fails until underlay IP reachability to the remote VTEP is restored — No road to the other warehouse means no deliveries—period. VXLAN rides IP in the underlay, so if you can’t ping the remote VTEP, you can’t ship encapsulated frames there. Fix underlay reachability before blaming the VNI paint job.

Answer

VXLAN automatically falls back to spanning-tree flooding across access ports only

Answer

Overlay unicast still works because VNIs are carried in LLDP regardless of IP reachability

Answer

Only multicast BUM fails; all known-unicast overlay traffic is unaffected by underlay loss

City operators enable VXLAN on two leaves, but the underlay cannot reach the remote VTEP loopback. What happens to the overlay data plane?

Short Explanation

Full Explanation