C5/B5/A4-Series f/w L2 Querier state Transitions between Non-Querier and Querier

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Article ID: 15105 

C5-Series, firmware and higher
B5-Series, firmware and higher
A4-Series, firmware and higher 

Enabled IGMP Snooping with L2 Querier election; for example on VLAN 196:

set igmpsnooping adminmode enable
set igmpsnooping querier enable
set igmpsnooping 196 enable
set igmpsnooping querier 196 enable
set igmpsnooping querier 196 address
set igmpsnooping querier election participate 196 enable

Deployed two or more such systems into the network, so that they negotiate for the Querier role. 

Each non-querier system cycles between Non-Querier and Querier states; remaining Non-Querier for about 60 seconds, briefly moving to Querier, then reverting back to Non-Querier to repeat the cycle. 

For example: 
    C5(su)->show igmpsnooping querier detail
Last Querier
VLAN ID Address IGMP Version
------- ---------------- ------------
196 v2
197 v2
198 v2
199 v2

Global IGMP Snooping querier status
IGMP Snooping Querier Mode Enable
Querier Address
IGMP Version 2
Querier Query Interval 125
Querier Expiry Interval 60

VLAN 196 : IGMP Snooping querier status
IGMP Snooping Querier VLAN Mode Enable
Querier Election Participate Mode Enable
Querier VLAN Address
Operational State Non-Querier
Last Querier Address
Operational version 2
Operational Max Resp Time 11

C5(su)->show igmpsnooping querier detail
. . .
Operational State Querier
. . .

C5(su)->show igmpsnooping querier detail
. . .
Operational State Non-Querier
. . .

The Querier Expiry Interval (default 60 seconds) should not be less than the Querier Query Interval (default 125 seconds). 

The Querier Expiry Interval is expiring all local knowledge of a previously established active querier before the Querier Query Interval triggers that active querier to send out a general query refresh. As a result, there is a period of time when this Non-Querier becomes what it believes is the sole Querier, resulting in multiple queriers on the VLAN. 

To be corrected in a future firmware release.
Contact the GTAC for an update, as necessary. 

On each affected system, issue the command 'set igmpsnooping querier timer expiry 255', which will make the local device the querier only if the previously known querier is no longer performing that function.
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Posted 4 years ago

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