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C5/B5/A4-Series f/w 6.71.02.0008 L2 Querier state Transitions between Non-Querier and Querier


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Article ID: 15105

Products
C5-Series, firmware 6.71.01.0067 and higher
B5-Series, firmware 6.71.01.0067 and higher
A4-Series, firmware 6.71.01.0067 and higher

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

code:
set igmpsnooping adminmode enable

code:
set igmpsnooping querier enable

code:
set igmpsnooping 196 enable

code:
set igmpsnooping querier 196 enable

code:
set igmpsnooping querier 196 address 10.26.196.23

code:
set igmpsnooping querier election participate 196 enable


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

Symptoms
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 10.26.196.1 v2
197 10.26.197.1 v2
198 10.26.198.1 v2
199 10.26.199.1 v2

Global IGMP Snooping querier status
-----------------------------------
IGMP Snooping Querier Mode Enable
Querier Address 0.0.0.0
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 10.26.196.23
Operational State Non-Querier
Last Querier Address 10.26.196.1
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
. . .

C5(su)->[/code]Cause
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.

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

Workaround:
On each affected system, issue the command '
code:
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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