PLANET WGSW-50040 - Manual (Page 161)

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Switch(config)#multicast destination-control
Switch(config)#ip multicast destination-control 10.0.0.0/8 access-group 6000
In this way, users of this network segment can only join groups other than 238.0.0.0/8.
3． Multicast strategy
Server 210.1.1.1 is distributing important multicast data on group 239.1.2.3, we can configure on its join-in
switch as follows:
Switch(config)#ip multicast policy 210.1.1.1/32 239.1.2.3/32 cos 4
In this way, the multicast stream will have a priority of value 4 (Usually this is pretty higher, the higher possible
one is protocol data; if higher priority is set, when there is too many multicast data, it might cause abnormal
behavior of the switch protocol) when it gets to other switches through this switch.
21.2.4 DCSCM Troubleshooting
The effect of DCSCM module itself is similar to ACL, and the problems occurred are usually related to
improper configuration. Please read the descriptions above carefully. If you still can not determine the cause
of the problem, please send your configurations and the effects you expect to the after-sale service staff of our
company.
21.3 IGMP Snooping
21.3.1 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.