A public-safety fabric team asks whether underlay PIM is still required if the pod uses EVPN-VXLAN with ingress replication for BUM. What is the sound conclusion?
Select an answer to reveal the explanation.
Short Explanation
If EVPN is building ingress-replication lists, the leaves already know whom to unicast BUM copies to—so you are not forced to keep a PIM megaphone in the underlay for that job. Turning PIM off does not magically delete bridging, and VXLAN absolutely can carry broadcast frames when the BUM path is designed.
Full Explanation
If a public-safety pod uses EVPN-VXLAN with ingress replication for BUM, underlay PIM is not required solely for that VXLAN BUM path. Ingress replication unicasts encapsulated BUM frames to remote VTEPs listed for the VNI, removing dependence on underlay multicast groups for that distribution method. PIM may still exist for other underlay services, but it is not inherent to EVPN-VXLAN whenever HER is the chosen BUM mode.
PIM remains mandatory only on the incorrect theory that EVPN cannot deliver any BUM without underlay multicast—HER is the counterexample taught in modern fabrics. Disabling PIM does not automatically convert every VNI into a Layer-3 VRF with no bridging left. PIM need not run on every host VLAN for VXLAN to encapsulate broadcast frames when HER or another BUM mechanism is configured.
Exam caveat: BUM mode determines multicast need; EVPN with ingress replication means PIM is not required for that VXLAN BUM path.
Operational check: confirm the pod’s BUM mode is ingress replication in configuration and state, verify PIM is unused for VXLAN groups, send ARP/ND, and capture unicast VXLAN BUM copies toward remote public-safety VTEPs.
In civic fabric operations, retain the correct idea—EVPN with ingress replication can handle BUM without depending on underlay multicast, so PIM is not required solely for that VXLAN BUM path—and reject distractors that confuse layers or tools. Specifically, do not treat “PIM remains mandatory because EVPN cannot deliver any BUM frames without underlay multicast groups.” as valid, do not accept “Disabling PIM automatically converts every VNI into a Layer-3 VRF with no bridging left.” as a substitute design, and do not operationalize “PIM must still run on every host VLAN because VXLAN cannot encapsulate broadcast frames.” in production runbooks. Re-validate after changes with show commands for sessions, routes, VTEP reachability, and a simple tenant traffic test appropriate to the VNI under review.