User's Manual

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message before the regulated maximum response time expires, indicating that the General Query message is
received. If the maximum response time is set to a big value, the change of multicast group members delays.
If the maximum response time is set to a small value, the flow of the IGMP message will be increased in the
current network.
Note:
The maximum IGMP response time must be shorter than the IGMP query interval. If the value of
the maximum response time is bigger than the query interval, the system will automatically set the
maximum response time to
query-interval – 1
.
For IGMP-Router V2 and IGMP-Router V3, run the following command in interface configuration mode to set
the maximum IGMP response time:
Command Purpose
ip igmp query-max-response-time
time
Configures the maximum IGMP response
time (unit: second).
For IGMP-Router V1, the maximum IGMP response time is decided by the protocol itself. Therefore, the
previous command is useless to IGMP-Router V1.
73.3.4 Configuring IGMP Query Interval for the Last Group Member
For IGMP-Router V2 and IGMP-Router V3, When the Group Specific Query message for a specific multicast
group is sent, the query interval of the last group member will be used as the maximum response time of the
host. That is, the IGMP host has to send the response message before the maximum response time of the last
group member expires, indicating that the Group Specific Query message is received. If the IGMP host finds
that it need not respond to the query message, it will not respond to the message after the interval. In this case,
the multicast switch is to update the saved multicast group member information. If the query interval of the last
group member is set to a big value, the change of the multicast group member delays. If the query interval of
the last group member is set to a small value, the flow of the IGMP message is to increase in the current
network.
For IGMP-Router V2 and IGMP-Router V3, run the following command in interface configuration mode to
configure the IGMP query interval of the last group member:
Command Purpose
ip igmp last-member-query-interval
time
Configures the IGMP query interval of the last
group member (unit: ms).
The previous command is useless for IGMP-Router V1.
73.3.5 Static IGMP Configuration
Besides the functions regulated by the IGMP-Router protocol, BODCOM’s switches support the static multicast
group configuration on the port. For the IGMP host, its multicast group member relationship may vary. Suppose
the IGMP host only belongs to the multicast group group1, it receives the multicast message from and sends
the multicast message to the multicast group group1. After a period of time, it may belong to the multicast
group group2, and receives the multicast message from and sends the multicast message to the multicast
group group2. After another period of time, the IGMP host may not belong to any multicast group. Therefore,