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Cisco Bug: CSCvt49258 - 60 sec traffic drops seen on uplinks after doing "no enable/enable" and then a swithover

Last Modified

Oct 16, 2020

Products (1)

  • Cisco Catalyst 9400 Series Switches

Known Affected Releases

16.12.3 Amsterdam-17.2.1

Description (partial)

Upon doing "no enable/enable" and then switchover, on the uplink of the new standby SUP 60sec traffic drop is seen before the traffic is resumed. Applicable for 40G and 25G. Issue is also noted in 10G, but intermittently.

Please see the ENG-notes and attached PPT for detail description

The traffic loss, is because of  FMAN_RP standby is out of sync with FMAN_RP active on interface link status. Because of this after SWO, FED incorrectly get a link flap notification, causing to go through buffer drain sequence , causing the traffic loss.

Issue is cauing to the below reason : Instead of pm_port_cfg_message updating FMAN_RP ( introduced as part of CSCvd82060), the update should happen from ng3k_idbman_pm_port_physical_linkchange, so that both pm, FMAN_RP are in sync both in active and standby.

no enable/enable needs to be performed before switchover
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