Adjusting The Igmp Querier Timeout Value; Configuring A Static Igmp Group; Enabling Igmp Immediate-Leave - Dell Force10 S4810P Configuration Manual

Adjusting the IGMP Querier Timeout Value

If there is more than one multicast router on a subnet, only one is elected to be the querier, which is the
router that sends queries to the subnet.
1. Routers send queries to the all multicast systems address, 224.0.0.1. Initially, all routers send queries.
2. When a router receives a query it compares the IP address of the interface on which it was received
with the source IP address given in the query. If the receiving router IP address is greater than the
source address given in the query, the router stops sending queries. By this method, the router with the
lowest IP address on the subnet is elected querier and continues to send queries.
3. If a specified amount of time elapses during which other routers on the subnet do not receive a query,
those routers assume that the querier is down, and a new querier is elected.
The amount of time that elapses before routers on a subnet assume that the querier is down is the Other
Querier Present Interval. Adjust this value using the command
mode.

Configuring a Static IGMP Group

Configure a static IGMP group using the command
is always forwarded to the subnet even if there are no members in the group.
View the static groups using the command
have an expiration value of
IGMP Groups.

Enabling IGMP Immediate-leave

If the querier does not receive a response to a group-specific or group-and-source query, it sends another
(Querier Robustness Value). Then, after no response, it removes the group from the outgoing interface for
the subnet.
IGMP Immediate Leave reduces leave latency by enabling a router to immediately delete the group
membership on an interface upon receiving a Leave message (it does not send any group-specific or
group-and-source queries before deleting the entry). Configure the system for IGMP Immediate Leave
using the command
View the enable status of this feature using the command
mode, as shown in the example in
show ip igmp groups
and a Last Reporter value of
Never
ip igmp immediate-leave
Selecting an IGMP
ip igmp querier-timeout
ip igmp static-group
from EXEC Privilege mode. Static groups
, as shown in the example in
CLI
.
show ip igmp interface
Version.
Internet Group Management Protocol (IGMP) | 467
from INTERFACE
. Multicast traffic for static groups
from EXEC Privilege
Viewing