Connectivity Guide

Terminology Denition
Outgoing interface (OIF) The OIF is the interface through which a multicast packet is sent out towards the receiver.
Incoming interface (IIF) The IIF is the interface through which a multicast packet is received towards the source or
the RP.
Reverse path forwarding (RPF) The RPF is the path the router uses to reach the RP or the multicast source.
Standards compliance
OS10 complies to the following standards:
• RFC 4601 for PIM-SM
• RFC 3569 for PIM-SSM
PIM-SM
PIM sparse mode (PIM-SM) is a multicast routing protocol for networks with receivers that are sparsely distributed. Receivers have to
explicitly send a join message to join particular groups or sources. PIM join and prune messages are used to join and leave multicast
distribution trees.
PIM-SM uses shared trees with the root node being the rendezvous point (RP). All multicast sources use the RP to route the trac to the
receiver. The last hop router (LHR) sends an (*,G) join message towards the RP. The designated router connected to the rst hop router
(FHR) encapsulates multicast data that comes from the multicast source in PIM control messages and sends it via unicast to the RP as
PIM register messages. The RP sends an (S, G) join towards the source. When the RP receives native data trac from the source, it sends
a register stop message to the FHR.
OS10 supports static conguration of an RP address for a multicast group.
To keep the PIM-SM state alive, all PIM join messages are periodically re-transmitted.
You must enable PIM-SM on each of the participating interfaces. Be sure to have multicast routing enabled on the system. To do this, use
the ip multicast-routing command from CONFIGURATION mode.
OS10# configure terminal
OS10(config)# interface vlan 100
OS10(conf-if-vl-100)# ip pim sparse-mode
PIM-SSM
PIM-SSM uses source-based trees. A separate multicast distribution tree is built for each multicast source that sends data to a multicast
group. Each multicast distribution tree has as its root node a router adjacent to the source. Sources send data directly to the root of the
tree. PIM-SSM allows receivers to specify the source from which to receive data as well as the multicast group they want to join. The
receiver identies a multicast data stream using the source and group address pair (S, G) instead of the group address alone (*, G).
NOTE
:
• PIM-SSM requires receivers to support IGMP version 3.
• The default PIM-SSM range is 232.0.0.0/8. The default range is always supported and the range can never be smaller than the
default.
Multicast 645