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Cisco Bug: CSCvv42889 - SVI up/down event causes outage with L2 multicast

Last Modified

Sep 25, 2020

Products (1)

  • Cisco Nexus 9000 Series Switches

Known Affected Releases

9.3(5)

Description (partial)

Symptom:
During SVI up/down event, there is disruption to multicast flow due to two symptoms:

1. IGMP snooping groups are getting cleared together with IGMP groups.

2. IGMP general queries from uplink interfaces being ignored for ~20 seconds after the SVI up/down event. Considering that IGMP queries are being sent out relatively rarely and all initial queries (configured with startup-query-interval and startup-query-count) are dropped, it leads to issues with re-building control plane state for L2 forwarding.
Approximately after 20-25 seconds, IGMP general queries start to get processed and group table for IGMP snooping is re-built.

Conditions:
Up/down event for SVI
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