TMS zl Management and Configuration Guide ST.1.2.100916

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Routing
Multicast
Figure 9-23. Multicasting with IGMP
You should enable IGMP on each interface (TMS VLAN or GRE tunnel) that
includes endpoints that might need to join a multicast group.
Multicast Routing Protocol, PIM-SM
PIM-SM, which is a multicast routing protocol, which enables TMS zl Module
to route multicast traffic that arrives on one interface (TMS VLAN or GRE
tunnel) into other interfaces.
PIM-SM creates trees for each multicast group. The tree includes a rendezvous
point (RP). When a multicast source for a particular group begins streaming,
the source’s multicast router sends the multicast traffic to the RP. The RP
distributes the multicast traffic over the tree until it reaches every router that
belongs to the tree for that group.
The TMS zl Module automatically finds its RP, but you can configure a static
RP address from the CLI.
The TMS zl Module uses IGMP in conjunction with PIM-SM. As you learned,
it uses IGMP to determine for which groups it needs to receive multicast
traffic. It can then joins a unique multicast tree for each active multicast group.
IGMP also lets the module know on which interfaces it needs to forward
multicasts downstream.