Cisco ASR 9000 Series Software Manual page 5

Implementing Layer-3 Multicast Routing on Cisco IOS XR Software
Multicast Routing Implementation
Cisco IOS XR Software supports the following protocols to implement multicast routing:
• IGMP is used between hosts on a LAN and the routers on that LAN to track the multicast groups of
which hosts are members.
• Protocol Independent Multicast in sparse mode (PIM-SM) is used between routers so that they can track
which multicast packets to forward to each other and to their directly connected LANs.
• Protocol Independent Multicast in Source-Specific Multicast (PIM-SSM) is similar to PIM-SM with the
additional ability to report interest in receiving packets from specific source addresses (or from all but
the specific source addresses), to an IP multicast address.
• PIM-SSM is made possible by IGMPv3 and MLDv2. Hosts can now indicate interest in specific sources
using IGMPv3 and MLDv2. SSM does not require a rendezvous point (RP) to operate.
• PIM Bidirectional is a variant of the Protocol Independent Multicast suit of routing protocols for IP
multicast. PIM-BIDIR is designed to be used for many-to-many applications within individual PIM
domains.
This image shows IGMP and PIM-SM operating in a multicast environment.
Figure 1: Multicast Routing Protocols
Cisco ASR 9000 Series Aggregation Services Router Multicast Configuration Guide, Release 5.1.x
Multicast Routing Functional Overview
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