From: simon hart (simon@harttel.com)
Date: Fri Sep 23 2005 - 16:59:29 GMT-3
The commands are pretty different,
ip igmp query-timeout
When you have more than one router on a subnet configured for multicast,
then one router will need to establish who will be sending General Queries
and Group Specific Queries. The router with highest IP address will be the
querier.
However any other attached multicast router will be listening to the queries
on the subnet. If it fails to hear any queries after a specified amount of
time it will take on the responsibility of being the querier for the subnet.
This time can be changed by the command ip igmp query-timeout
ip igmp query-max-response-time
The router will periodically send out an igmp query - default 60 seconds.
Once a query is sent out on the subnet, any hosts that wish to join an mcast
group, or wish to continue receiving an mcast group will respond with a
membership report.
Now if a router is forwarding to an mcast group on the subnet due to a
previous join, it will as stated above send out a query every 60 seconds.
If it hears no response from any hosts that wish to continue to recieve this
mcast group, then the router will delete the group and stop forwarding the
traffic. The time before it takes this action is the:
ip igmp query-max-response-time
HTH
Simon
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Private Ryan
Sent: 23 September 2005 20:19
To: Cisco certification
Subject: Command meaning on "ip igmp"
Can any explain the difference between the following?
- ip igmp query-max-response-time
- ip igmp query-timeout
I checked the CCO but I don't understand "it takes over as the
querier" for "ip igmp query-timeout". Sorry for my poor knowledge on
Multicast.
Ryan
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