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Cisco Bug: CSCvi54256 - Stale MAC seen when dot1x is enabled on the switchport and IP phone is looped between to interfaces

Last Modified

Dec 13, 2018

Products (1)

  • Cisco Catalyst 2960-X Series Switches

Known Affected Releases

15.2(2)E6 15.2(4)E

Description (partial)

A stale MAC will be learned as static when ports of an IP Phone are looped to the switch causing BPDUguard and Err-disable recovery to bounce the interfaces several times.

The issue is seen no matter if authentication mac-move permit is present or not.

1. Issue is seen in a 7841 and a 7945 IP phone and the phone is looped between two switchport interfaces. Issue not isolated to a specific phone model.
2. Err-disabled auto-recovery enables the ports again every 5 or 1 minutes.
3. 802.1x is enabled on the switchport interfaces.
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