User's Manual

518
ip igmp version
version_number
Changes the IGMP version running on the
current port.
73.3.1 Configuring IGMP Query Interval
No matter what version number of the current IGMP-Router protocol is, the multicast switch can send the
IGMP General Query message every a certain time on the port where the IGMP-Router function is started.
The transmission address is 224.0.0.1. The purpose of the multicast switch is to get the report message from
the IGMP host and therefore know which multicast group each IGMP host in the network belongs to. The
interval to send the General Query message is called as IGMP Query Interval. If the parameter IGMP Query
Interval is set to a big value, the switch cannot immediately receive the information about which multicast group
the current IGMP host belongs to. If the parameter IGMP Query Interval is set to a small value, the flow of the
IGMP message is to increase in the current network.
Run the following command in interface configuration mode to modify the IGMP query interval on
a port:
Command Purpose
ip igmp query-interval
time
Modifies the IGMP query interval on the
current interface (unit: second).
73.3.2 Configuring IGMP Querier Interval
As to version 2 and version 3 of the IGMP-Router protocol, if another switch that runs the IGMP-
Router protocol exists in the same network, you need to choose a querier. Querier stands for a
switch that can send the query message (In fact, it is a port of the switch where the IGMP-
Router protocol is enabled). Normally, one network has only one querier, that is, only one switch
sends the IGMP Query message. There is no querier choice for IGMP-Router V1 because the
multicast routing protocol decides which switch to send the IGMP Query message in IGMP-
Router V1.
IGMP-Router V2 and IGMP-Router V3 have the same querier choice mechanism, that is, the switch with the
minimum IP address is the querier in the network. The switch that is not the querier needs to save a clock to
record the existence of the querier. If the clock times out, the non-querier switch turns to be the querier until it
receives the IGMP Query message from the switch with a smaller IP address.
For IGMP-Router V2, you can configure other querier intervals using the following command:
Command Purpose
ip igmp
querier-timeout
time
Configures the interval for other queriers (unit:
second).
For IGMP-Router V1, the interval of other queriers is useless. For IGMP-Router V3, the interval cannot be
configured because it is decided by the protocol itself.
73.3.3 Configuring Maximum IGMP Response Time
For IGMP-Router V2 and IGMP-Router V3, special data field in the transmitted IGMP General Query message
regulates the maximum response time of the IGMP host. That is, the IGMP host has to send the response