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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.
38.2.4 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.
38.3 IGMP Snooping
38.3.1 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
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Troubleshooting
