Overview of PIM
Definition
Unless otherwise specified, IPv4 PIM and IPv6 PIM implement a feature in the same way. For details about implementation differences, see Appendix.
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 (PIM-DM) |
Any-Source Multicast (ASM) model |
Small-scale networks with densely distributed multicast group members. |
|
PIM-Sparse Mode (PIM-SM) |
ASM model |
Large-scale networks on which multicast data receivers are sparsely distributed. |
|
PIM-specific multicast (PIM-SSM) |
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. |
Purpose
On a network, multicast data is replicated and forwarded through a multicast network from a multicast source to receivers. PIM is a widely used intra-domain multicast protocol that builds MDTs to transmit multicast data.
PIM can create multicast routing entries on demand, forward packets based on these entries, and dynamically respond to network topology changes.
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 broadcast, network TV, remote education, telemedicine, network TV stations, and real-time video/voice conferencing services.