Manual

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Switch(config)#ip pim multicast-routing
Switch(config)#interface vlan1
Switch(Config-if-Vlan1)#ip address 12.1.1.2 255.255.255.0
Switch(Config-if-Vlan1)#ip pim dense-mode
Switch(Config-if-Vlan1)#exit
Switch(config)#interface vlan2
Switch(Config-if-Vlan1)#ip address 20.1.1.1 255.255.255.0
Switch(Config-if-Vlan2)#ip pim dense-mode
Switch(Config-if-Vlan2)#ip igmp version 3
28.9.4 IGMP Troubleshooting
In configuring and using IGMP Protocol, IGMP Protocol might not operate normally caused by
physical connection or incorrect configuration. Therefore, user should pay attention to the
following issues:
Firstly to assure that physical connection is correct;
Next, to assure the Protocol of Interface and Link protocol is UP (use show interface
command);
Afterwards, to assure to start a kind of multicast protocol on the interface;
Multicast Protocol requires RPF Check using unicast routing; therefore the correctness of
unicast routing must be assured beforehand.
28.10 IGMP Snooping
28.10.1 Introduction to IGMP Snooping
IGMP (Internet Group Management Protocol) is a protocol used in IP multicast. IGMP is used
by multicast enabled network device (such as a router) for host membership query, and by
hosts that are joining a multicast group to inform the router to accept packets of a certain
multicast address. All those operations are done through IGMP message exchange. The router
will use a multicast address (224.0.0.1) that can address to all hosts to send an IGMP host
membership query message. If a host wants to join a multicast group, it will reply to the
multicast address of that a multicast group with an IGMP host membership reports a message.
IGMP Snooping is also referred to as IGMP listening. The switch prevents multicast traffic from
flooding through IGMP Snooping, multicast traffic is forwarded to ports associated to multicast
devices only. The switch listens to the IGMP messages between the multicast router and hosts,
and maintains multicast group forwarding table based on the listening result, and can then
decide to forward multicast packets according to the forwarding table.
Switch provides IGMP Snooping and is able to send a query from the switch so that the user
can use switch in IP multicast.