Configuring IP Multicast Routing
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0 and 255. However, the value should be high enough to stop multicast
packets from exiting the interface. Here is an example:
RouterA#conf t
Enter configuration commands, one per line. End with
CNTL/Z.
RouterA(config)#interface FastEthernet0/0
RouterA(config-if)#ip multicast ttl-threshold 230
RouterA(config-if)#^Z
RouterA#
!
interface FastEthernet0/0
ip address 172.16.5.1 255.255.255.0
no ip directed-broadcast
ip multicast ttl-threshold 230
no ip route-cache
no ip mroute-cache
full-duplex
!
Joining a Multicast Group
Once the main configuration is done on the router to enable multicast, PIM,
rendezvous points, and RP Mapping Agents, the only other major task is
allowing hosts to join multicast groups.
Within Cisco IOS, the network administrator has the opportunity to ver-
ify functionality and connectivity before users use the multicast system and
applications. You can configure a router to join any number of IP multicast
groups and, thus, verify functionality.
This is achieved through the ip igmp join-group group-address com-
mand. The group-address is the multicast address of the group you want
the router to join. An example follows:
RouterA(config)#interface FastEthernet4/0
RouterA(config-if)#ip igmp join-group 224.2.127.254
RouterA(config-if)#^Z
RouterA#
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