Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureHard
A network architect is designing a multicast solution for a video streaming application in a large enterprise. The application requires efficient distribution of video streams to receivers that are sparsely distributed across different VLANs and subnets. The multicast routing protocol should minimize unnecessary traffic flooding and only forward streams to segments with active listeners. Which multicast routing protocol is best suited for this scenario?
- AIGMP Snooping
- BPIM Dense Mode (PIM-DM)
- CPIM Sparse Mode (PIM-SM)
- DDVMRP
Show answer & explanationAnswer & explanation
Correct answer: C. PIM Sparse Mode (PIM-SM)
PIM Sparse Mode (PIM-SM) is designed for environments where multicast receivers are sparsely distributed, meaning there are few receivers relative to the total number of subnets. It explicitly builds distribution trees from a Rendezvous Point (RP) to active receivers, minimizing unnecessary traffic flooding.
Why the other options are wrong
- A. IGMP Snooping is a Layer 2 feature that prevents multicast flooding within a VLAN by monitoring IGMP messages, but it does not perform Layer 3 multicast routing across subnets.
- B. PIM Dense Mode (PIM-DM) operates on a 'flood and prune' model, initially flooding multicast traffic to all segments and then pruning branches without receivers. This is inefficient for sparsely distributed receivers.
- D. DVMRP (Distance Vector Multicast Routing Protocol) is an older, less scalable multicast routing protocol that uses a flood-and-prune mechanism, similar to PIM-DM, and is generally not used in modern enterprise networks.
PIM Sparse Mode (PIM-SM)
PIM Sparse Mode (PIM-SM) is a multicast routing protocol optimized for environments with sparsely distributed receivers. It builds explicit shortest-path trees from a Rendezvous Point (RP) to active receivers, avoiding unnecessary traffic flooding.
- Explicit join model.
- Uses a Rendezvous Point (RP).
- Minimizes unnecessary traffic flooding.
- Suited for sparsely distributed receivers.
- Scalable for large networks.
Memory trick: Sparse receivers? PIM-SM's the choice, to deliver streams with a quiet voice.