(Revised 2011-07-13)
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The query management function enables the switch to generate IGMP “Query” messages: never, always, or
automatically.
Example of Configure Query Generation screen:
CLI\SWITCH\IGMP>query
Configure Query Generation.
Query mode is auto.
Query Frame Source IP: 192.168.69.102.
Enter: <(ESC)> to keep this configuration, OR
'A' to Auto query, OR
'O' for query On, OR
'F' for query oFF.
Enter A, O, F , (or ESC to exit) >
Note that by RFC, there should be only one entity issuing IGMP queries in a LAN and in the event of
conflict the one with the lowest IGMP Source IP Address should continue and the others should stop sending
queries. The Query Frame carries the unique switch MAC address as the physical layer “Source Address”.
A default “Source IP” Address for deeper within the Query frame is calculated from the lower bits of the
unique MAC address of the switch itself. It is unlikely, but possible, that the calculated (default) “Source IP
Address” is redundant to another in your topology and that this could create an issue in a device that is
monitoring IGMP Queries AND mapping these Addresses to some other parameter. In case you need to
change the “Source IP” for the Query frame, when you select Query On or Auto, you will be shown the
calculated address and asked if you‟d like to change it (yes or no).
In 500 series switches, the “IGMP
Query Source IP Address” is only for IGMP purposes. It cannot be „pinged‟, for example.
Example of changing IGMP Query Source IP Address:
(N-Tron is not aware of anyone ever having to change this, but the ability is provided..)
CLI\SWITCH\IGMP>query
Configure Query Generation.
Query mode is auto.
Query Frame Source IP: 192.168.69.102.
Enter: <(ESC)> to keep this configuration, OR
'A' to Auto query, OR
'O' for query On, OR
'F' for query oFF.
Enter A, O, F , (or ESC to exit) > a
Query mode is auto.
Query Frame Source IP: 192.168.69.102.
Would you like to change that ? Enter 'YES' or (NO):
CLI> yes
Enter a Source IP Address for IGMP Queries (or ESC to exit):191.23.12.15
Query mode is auto.
Query Frame Source IP: 191.23.12.15.
CLI\SWITCH\IGMP>
