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Enabling IP Multicast Routing
Dec 18,2008 00:00
by
alperen
Enabling IP Multicast Routing As we have said, multicast routing must be enabled on the router. This step is very straightforward, but without it, multicast will not work. Let’s look at a configuration of a router that does not have multicast enabled: Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname Terry_3640 ! aaa new-model aaa authentication login default tacacs+ line aaa authentication login oldstyle line aaa accounting exec default start-stop tacacs+ enable secret 5 $1$G7Dq$em.LpM4Huem9uqjZDHLe4. ! ! ! ip subnet-zero ip telnet source-interface FastEthernet3/0 [output truncated] Notice that no multicast information is running on this machine. If we were to try to execute a multicast-related command, we wouldn’t get any information returned. For example, look at what happens when the show ip mroute command is issued: Terry_3640#sho ip mroute IP Multicast Routing Table Flags: D - Dense, S - Sparse, C - Connected, L - Local, P - Pruned R - RP-bit set, F - Register flag, T - SPT-bit set,J - Join SPT, M - MSDP created entry, X - Proxy Join Timer Running A - Advertised via MSDP Timers: Uptime/Expires Interface state: Interface, Next-Hop or VCD, State/Mode Terry_3640# The command is ip multicast-routing, and an example of the execution follows: Terry_3640#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Terry_3640(config)#ip multicast-routing Terry_3640(config)#^Z Terry_3640# This enables the multicast on the router. Notice that it was executed while in global configuration mode. However, the router still cannot exchange multicast information with any neighbors because none of the interfaces have been enabled. This step is next. |