The civic NOC asks what head-end replication means for VXLAN BUM when the underlay has no multicast. Which explanation is accurate?
Select an answer to reveal the explanation.
Short Explanation
Head-end replication is the leaf doing the photocopying itself—one BUM frame in, a unicast VXLAN copy out to every remote VTEP on the list. You use it when the underlay has no multicast megaphone. It is ordinary tenant BUM handling, not a SPAN-only trick, and spines are not turning those frames into OSPF LSAs.
Full Explanation
Head-end replication (ingress replication) lets an ingress VTEP deliver overlay BUM by encapsulating and unicasting a copy to each remote VTEP interested in that VNI when underlay multicast is unavailable or undesired. EVPN commonly builds and distributes the replication list so leaves know which VTEPs should receive copies. Multicast is not mandatory for every VXLAN design, and BUM handling is not accomplished by injecting OSPF LSAs. Understanding HER is essential for EVPN-VXLAN fabrics that avoid PIM in the underlay.