igmp
CCIE

IGMP filtering on switches

03/02/11 21:04
IGMP filtering on switches is performed by profiles as described on DocCD.

Example of filter:

ip igmp profile 1
	permit
	range 232.0.0.0 232.255.255.255

If action is "deny" all the others groups are permitted. If action is "permit" all the other groups are denied.

Apply filter to interface:

inte f0/0
	ip igmp filter 1

As reported on Cisco docs, igmp filters cannot be applied to routed, SVI or etherchannel member interfaces. Only plain L2 interfaces can be filtered.


LINKS

A Networker Blog
CCIE to be Blog

IGMP timers and tweaking

03/02/11 16:09
QUERIER: lowest IP of multicast-enabled router on the subnet

DEFAULTS:

R2#sh ip igmp interface f0/0
FastEthernet0/0 is up, line protocol is up
  Internet address is 10.0.123.2/24
  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: 4 joins, 2 leaves
  Multicast routing is enabled on interface
  Multicast TTL threshold is 0
  Multicast designated router (DR) is 10.0.123.2 (this system)
  IGMP querying router is 10.0.123.2 (this system)
  Multicast groups joined by this system (number of users):
      224.0.1.40(1)

QUERY INTERVAL - default 60s
How often the querier request membership reports from multicast clients

R2(config-if)#ip igmp query-interval ?
  <1-18000>  Query interval in seconds

QUERIER TIMEOUT - default 120s
If query message timeout is missed a new querier is elected

R2(config-if)#ip igmp querier-timeout ?
  <60-300>  timeout value in seconds


MAX QUERY RESPONSE - default 10s
Amount of time the querier waits for membership responses from clients.
When timeout reached, if no response came router removes mroute state.

R2(config-if)#ip igmp query-max-response-time  ?
  <1-25>  query response value in seconds


LAST MEMBER QUERY COUNT AND INTERVAL - default 2 messages every 1000ms
When the last member of a group is removed, the querier sends C messages each I interval if there's any other memeber in the subnet. If no answer group is removed.

R2(config-if)#ip igmp last-member-query-count ?
  <1-7>  Last member query count

R2(config-if)#ip igmp last-member-query-interval ?
<100-25500> Last member query interval in milliseconds

It is possible to disable the last member query for specific groups:

R2(config-if)#ip igmp immediate-leave group-list ?
  <1-99>       Access list number
  <1300-1999>  Access list number (expanded range)
  WORD         IP Named Standard Access list


IGMP LIMIT - default no limit
Limits che number of active groups membership on a interface

R2(config-if)#ip igmp limit ?
  <1-64000>  Max Allowed State on this interface