Multicast-IGMP Filtering and Boundary

IGMP, which runs at Layer 3 on a multicast router, generates Layer 3 IGMP queries in subnets where the multicast traffic needs to be routed, protocol used by multicast receivers to communicate their willingness to listen to a particular multicast group.When a host wants to join a multicast group, it sends an IGMP membership report message to the multicast address heard by all routers on the segment. This report contains the multicast group that the host wants to join.

Command  ip igmp access-group

The multicast boundary feature allows for setting administrative borders for multicast
traffic.
Command  ip multicast boundary [filter-autorp]

R2#sho run int f0/1
ip access-list standard IGMP-FILTER
 deny   239.1.1.0 0.0.0.255
 permit any
!
interface FastEthernet0/1
 ip address 23.1.1.2 255.255.255.0
 ip pim sparse-mode
 ip igmp access-group IGMP-FILTER
 duplex auto
 speed auto
end

R3(config)#
!
interface FastEthernet0/0
 ip address 23.1.1.3 255.255.255.0
 ip pim sparse-mode
 ip igmp join-group 224.1.1.1
 ip igmp join-group 239.1.1.1
 ip igmp join-group 239.1.1.2
 ip igmp join-group 224.4.4.4
 duplex auto
 speed auto
end
 





 #ip igmp limit 10
it limits the aggregate number of multicast groups joined by directly connected receivers on all multicast interfaces. When applied per-interface, it limits the number of different
multicast groups that can be joined on this particular interface.

R2(config)#int f0/1
R2(config-if)#ip igmp limit 10
 
R2(config-if)#do show ip igmp int f0/1
FastEthernet0/1 is up, line protocol is up
  Internet address is 23.1.1.2/24
  IGMP is enabled on interface
  Current IGMP host version is 2
  Current IGMP router version is 2
  IGMP query interval is 60 seconds
  IGMP querier timeout is 120 seconds
  IGMP max query response time is 10 seconds
  Last member query count is 2
  Last member query response interval is 1000 ms
  Inbound IGMP access group is IGMP-FILTER
  IGMP activity: 6 joins, 3 leaves
  Interface IGMP State Limit : 3 active out of 10 max
  Multicast routing is enabled on interface
  Multicast TTL threshold is 0
  Multicast designated router (DR) is 23.1.1.3
  IGMP querying router is 23.1.1.2 (this system)
  No multicast groups joined by this system