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Cisco Bug: CSCuq75081 - N7K: 3 to 5 seconds traffic loss on pim6 process restart SSM config

Last Modified

Jan 24, 2017

Products (1)

  • Cisco Nexus 7000 Series Switches

Known Affected Releases

7.1(0)D1(0.246)

Description (partial)

The issue happens when a non-default PIM6 SSM range configured happens to be a subset of the default SSM range ff30::/12. Hence because the MLD group in question falls within both these ranges, on restarting PIM6, PIM6 1st communicates a force delete of the SSM SG's to M6RIB for the older default SSM range, which results in deletion of the SG entry since group matches the default SSM range. Soon afterwards, it gets re-created by data packet getting punted to SUP IPV6 add route. Hence the loss is seen for this intermediate minute time-interval. The issue will be seen only with the trigger of restart PIM6. It doesn't happen in steady state.

Symptom:
Traffic loss seen for 3-5 seconds on restart pim6 trigger for SSM config only when a non-default PIM6 SSM range configured happens to be a subset of the default SSM range ff30::/12

Conditions:
The issue happens only when a non-default PIM6 SSM range configured happens to be a subset of the default SSM range ff30::/12. Hence because the MLD group in question falls within both these ranges, on restarting PIM6, PIM6 1st communicates a force delete of the SSM SG's to M6RIB for the older default SSM range, which results in deletion of the SG entry since group matches the default SSM range. Soon afterwards, it gets re-created by data packet getting punted to SUP IPV6 add route. Hence the loss is seen for this intermediate minute time-interval. The issue will be seen only with the trigger of restart PIM6. It doesn't happen in steady state.
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