Overview of PIM
Purpose
A multicast network requires multicast protocols to replicate and forward multicast data. PIM is a widely used intra-domain multicast protocol that builds MDTs to transmit multicast data between routers in the same domain.
PIM can create multicast routing entries on demand, forward packets based on multicast routing entries, and dynamically respond to network topology changes.
Definition
If IPv4 PIM and IPv6 PIM implement a feature in the same way, details are not provided in this chapter. For details about implementation differences, see Appendixes.
PIM is a multicast routing protocol that uses unicast routing protocols to forward data, but PIM is independent of any specific unicast routing protocols.
PIM has three implementation modes: PIM-SM, and PIM-SSM. These modes apply to both IPv4 and IPv6 networks.
Protocol |
Full Name |
Model |
Deployment Scenario |
|---|---|---|---|
Protocol Independent Multicast-Dense Mode |
Any-Source Multicast (ASM) model |
Small-scale networks on which multicast data receivers are densely distributed | |
Protocol Independent Multicast-Sparse Mode |
ASM model |
Large-scale networks on which multicast data receivers are sparsely distributed. |
|
Protocol Independent Multicast-Source-Specific Multicast |
SSM model |
Networks on which multicast data receivers can learn source locations before they join multicast groups and require multicast data from specific multicast sources. |
Benefits
- Multimedia and media streaming applications
- Training and tele-learning communication
- Data storage and financial management applications
IP multicast is being widely used in Internet services, such as online broadcasts, network TV, e-learning, telemedicine, network TV stations, and real-time video/voice conferencing services.
