Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureHard
A network engineer is designing a multicast solution for a video conferencing system that uses a single source and multiple receivers spread across different subnets. The receivers dynamically join and leave the multicast groups. The network uses OSPF as its unicast routing protocol. Which multicast routing protocol is most appropriate for this scenario?
- AMOSPF
- BPIM Dense Mode (PIM-DM)
- CDVMRP
- DPIM Sparse Mode (PIM-SM)
Show answer & explanationAnswer & explanation
Correct answer: D. PIM Sparse Mode (PIM-SM)
PIM Sparse Mode (PIM-SM) is best suited for environments with widely dispersed multicast receivers that dynamically join and leave groups. It uses an explicit join model, where receivers explicitly request multicast streams from a Rendezvous Point (RP), making it efficient for sparse groups. This fits the 'single source, multiple receivers, dynamically join/leave' description.
Why the other options are wrong
- A. MOSPF (Multicast OSPF) is an extension to OSPF that is difficult to scale and rarely used in modern networks compared to PIM.
- B. PIM Dense Mode (PIM-DM) uses a flood-and-prune model, which is inefficient for sparse groups where receivers are few and far between.
- C. DVMRP (Distance Vector Multicast Routing Protocol) is an older, less scalable protocol, typically used for early internet multicast.
PIM Sparse Mode (PIM-SM)
A multicast routing protocol that uses an explicit join model, where receivers explicitly request multicast streams, making it efficient for environments with widely dispersed and dynamic multicast groups.
- Explicit join model.
- Uses a Rendezvous Point (RP).
- Efficient for sparse groups (few receivers, widely distributed).
- Suitable for dynamic group memberships.
Memory trick: PIM-SM: Sparse means asking nicely for the stream.