Manual
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238.0.0.0/8, so we can make the following configuration: 
Firstly enable IGMP snooping in the VLAN it is located (Here it is assumed to be in VLAN2) 
EC(config)#ip igmp snooping 
EC(config)#ip igmp snooping vlan 2 
  After that, configure relative destination control access-list, and configure specified IP 
address to use that access-list. 
Switch(config)#access-list 6000 deny ip any 238.0.0.0 0.255.255.255 
Switch(config)#access-list 6000 permit ip any any 
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. 
36.2.4 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. 
36.3 IGMP Snooping 
36.3.1 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 










