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Cisco Bug: CSCvt21796 - C2960L/C1000 - Traffic blackhole due to wrongly programmed trunk port

Last Modified

Sep 01, 2020

Products (1)

  • Cisco Catalyst 2960-L Series Switches

Known Affected Releases

15.2(7.1.67)E2

Description (partial)

Symptom:
Switch may fail to program its trunk link as tagged and keep it in access mode, hence causing traffic blackhole as all traffic will be forwarded out of that trunk without a vlan dot1q tag.

Conditions:
Issue may be observed when a link is disconnected/connected multiple times. The failure may not be limited to only link OIR, other actions that invoke VLAN/Trunk programming on a port may also trigger the issue.
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