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Explanation of multiple potential igmp queriers – Allied Telesis AR400 User Manual

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Page 17 | AlliedWare™ OS How To Note: IGMP

Multiple potential IGMP queriers > Explanation of Multiple potential IGMP queriers

Explanation of

Multiple potential IGMP queriers

When there are no group members

Switch 1 and switch 2 are both possible Queriers, and an election determines which switch
becomes the actual Querier. We can see the results of the election by using the command
show ip igmp on each switch.

In the output from switch 2 above, switch 2 reports that it has become the Querier by
displaying (DR)—which stands for Designated Router—next to the interface name.

In the output from switch 1 above, switch 1 has an entry for Other Querier timeout, which
indicates that it is aware that another device is the IGMP Querier. If the timer expires,
switch 1 will decide that the other Querier no longer exists, and will become the Querier
itself. The timer is refreshed by a Membership Query or an IGMP Querier election.

Note:

Switch 2 shows an IGMP Proxy entry, which is set to Off (see

"IGMP proxy" on

page 21

). Switch 1 does not show a Proxy entry because the AT-8948 did not

support IGMP Proxy on Software Version 2.7.6 which this example used.

Manager Switch 1> show ip igmp

IGMP Protocol
------------------------------------------------------------------------
Status ........................... Enabled
Default Query Interval ........... 125 secs
Default Timeout Interval ......... 260 secs

Last Member Query Interval ....... 10 (1/10secs)
Last Member Query Count .......... 2
Robustness Variable .............. 2
Query Response Interval .......... 100 (1/10secs)
Disabled All-groups ports ........ None

Interface Name .......... vlan100
Other Querier timeout ... 209 secs
Group List ..............

------------------------------------------------------------------------

Manager Switch 2> show ip igmp

IGMP Protocol
------------------------------------------------------------------------
Status ........................... Enabled
Default Query Interval ........... 125 secs
Default Timeout Interval ......... 260 secs

Last Member Query Interval ....... 10 (1/10secs)
Last Member Query Count .......... 2
Robustness Variable .............. 2
Query Response Interval .......... 100 (1/10secs)
Disabled All-groups ports ........ None

Interface Name .......... vlan100 (DR)
IGMP Proxy .............. Off
Group List ..............

------------------------------------------------------------------------

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