Multicast - Implementing Multicast (MCAST V1.0) - PIM SSM (7)

- delivery modell for one-to-many distribution
- allows immediate use of shortest forwarding path to a specific source, without need to create shared tree
- only source-specific multicast distribution trees (not shared trees) are created
- RFC 3569
- IGMP Version 3 supports source filtering, which is required for SSM
- SSM must be supported by host, router and application
- receivers must subscribe or unsubscribe to (S, G) channels to receive or not receive traffic from specific sources
- does not require an RP, so there is no need for an RP mechanism such as Auto-RP, MSDP, or bootstrap router (BSR).
- IGMPv3 is used by host, to receive traffic only from specific sources
- only last-hop-router needs to be SSM capable
- you must use sparse-mode on


PIM SSM Configuration

Router1(config)#ip multicast-routing
Router1(config)#ip pim ssm default ! for all groups
Router1(config)#ip pim ssm range ACL123 ! for specifig groups
Router1(config-if)# ip igmp version 3 ! enable IGMP v3 on interface

Have a look at Cisco IOS Multicast Configuration Guide