CCNP Infrastructure Practice Question
A network administrator is configuring a VXLAN EVPN fabric. The administrator wants to optimize the forwarding of broadcast, unknown unicast, and multicast (BUM) traffic by using a multicast group per VLAN. Which VXLAN feature should be configured on the VTEPs to achieve this?
⚠ Common exam trap
The trap here is assuming that any VXLAN feature like ingress replication or anycast VTEP can optimize BUM traffic, but only multicast underlay with PIM Sparse Mode supports per-VLAN multicast groups.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Multicast underlay with PIM Sparse Mode
Using a multicast underlay with PIM Sparse Mode allows each VLAN to be mapped to a unique multicast group, so BUM traffic is replicated only to VTEPs that have joined that group. This optimizes bandwidth and reduces unnecessary flooding. Ingress replication and anycast VTEP do not provide per-VLAN multicast group mapping. EVPN IRB is for routing, not BUM optimization.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Multicast underlay with PIM Sparse Mode
Why this is correct
In VXLAN, BUM traffic can be replicated using multicast in the underlay. By mapping each VLAN to a unique multicast group address, VTEPs can efficiently forward BUM traffic only to interested VTEPs. Configuring PIM Sparse Mode in the underlay enables this multicast replication. This approach optimizes BUM traffic by avoiding unicast head-end replication and leverages the underlay multicast capabilities.
- ✗
Ingress replication
Why it's wrong here
Ingress replication is a method where the ingress VTEP replicates BUM traffic and sends unicast copies to all remote VTEPs. While it can be used without multicast, it does not use a multicast group per VLAN and can be less efficient in large fabrics. The requirement specifically asks for multicast group per VLAN, so ingress replication is not the correct choice.
- ✗
EVPN Integrated Routing and Bridging (IRB)
Why it's wrong here
EVPN IRB allows routing between subnets within the VXLAN fabric and is used for inter-VLAN routing. It does not directly handle BUM traffic replication or multicast group mapping. While important for EVPN, it does not address the optimization of BUM traffic using multicast groups per VLAN.
- ✗
Anycast VTEP
Why it's wrong here
Anycast VTEP allows multiple VTEPs to share the same IP address for redundancy and load balancing, but it does not directly map multicast groups to VLANs for BUM traffic optimization. It is used for distributed anycast gateways and does not control BUM replication. Thus, it does not fulfill the requirement of using a multicast group per VLAN.
Visual reference
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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