A township still runs an underlay multicast group for VXLAN BUM delivery between civic VTEPs. What role does that multicast underlay play in a classic VXLAN design?
Select an answer to reveal the explanation.
Short Explanation
Think of underlay multicast as the township’s shared megaphone for flood traffic—one BUM shout fans out to every VTEP that joined the group. That is the classic way VXLAN shared broadcast, unknown unicast, and multicast without building a unicast copy per remote leaf. It is not an encryption feature and it is not limited to Type-5 routes.
Full Explanation
In traditional multicast-based VXLAN, VTEPs map overlay BUM traffic to underlay multicast groups so a single encapsulated BUM packet can reach interested remote VTEPs. That mechanism supported flood-and-learn style discovery and BUM delivery without head-end replication to each peer. Multicast does not eliminate VNIs, encrypt MACs, or apply only to EVPN IP-prefix (Type-5) routes. Modern EVPN fabrics often replace underlay multicast with ingress replication, but understanding multicast BUM signaling remains a core VXLAN control/data distribution concept.