Tuesday, March 20, 2012

Cisco IOS IGMP Timers and Fine Tuning

Cisco IGMP Timers and Fine Tuning

ip igmp immediate-leave: Multicast router will not send IGMP group-specific host queries when an IGMP leave  message is received.Then the multicast router removes the interface from multicast routing table outgoing interface list(OIL).
ip igmp last-member-query-interval: The multicast router removes the interface from multicast routing table outgoing interface list(OIL) when there is no group specific reply to the query messages.These query messages occur after a IGMP leave message is received by the router.
ip igmp last-member-query-count: Count of the group specific query messages of the multicast router after it receives IGMP Leave message.
ip igmp limit: Limit for the IGMP group membership for the interfaces of the multicast router.
ip igmp querier-timeout: The timeout period before the router recalculates IGMP querier selection for the interface.By default the router which has the lowest IP address on the subnet is selected as IGMP Querier.
ip igmp query-interval: The time interval at which the IGMP querier sends IGMP host-query messages.
ip igmp query-max-response-time: the time interval that the client can respond to an IGMP query message before the router deletes the group
Here is default values:
Router#show ip igmp interface F0/0
FastEthernet0/0 is up, line protocol is up
  Internet address is 192.168.123.2/24
  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 not set
  IGMP activity: 1 joins, 0 leaves
  Multicast routing is enabled on interface
  Multicast TTL threshold is 0
  Multicast designated router (DR) is 192.168.123.3 
  IGMP querying router is 192.168.123.2 (this system)
  Multicast groups joined by this system (number of users):