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Cisco Bug: CSCtc42659 - Static MAC written to running-config not removed when behind IP phone

Last Modified

Feb 05, 2017

Products (1)

  • Cisco 2800 Series Integrated Services Routers

Known Affected Releases

12.4(15)T9

Description (partial)

Symptom:

Static MAC written to running-config not removed/changed, when a PC initially connected behind an IP phone moves directly connected to another port of the same switch or of another switch in the same LAN.

Conditions:

1. PC connected behind an IP phone:

sh mac-address-table stat
Static Address Table:
Destination Address  Address Type  VLAN  Destination Port
-------------------  ------------  ----  --------------------
0016.35a8.a6f3		Static	      2	    FastEthernet1/3 < PC
001e.7a25.7e0a		Static	     50	    FastEthernet1/3 < phone

sh run | i mac
mac-address-table static 0016.35a8.a6f3 interface FastEthernet1/3 vlan 2
mac-address-table static 001e.7a25.7e0a interface FastEthernet1/3 vlan 50

2. The PC is disconnected from behind the phone and reconnected to a different interface (Fa1/2 in the example):

Sep 29 10:21:12.112: %LINK-3-UPDOWN: Interface FastEthernet1/2, changed state to up
Sep 29 10:21:13.112: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/2, changed state to up

sh mac-address-table stat
Static Address Table:
Destination Address  Address Type  VLAN  Destination Port
-------------------  ------------  ----  --------------------
0016.35a8.a6f3		Static	      2	    FastEthernet1/3	
001e.7a25.7e0a		Static	     50	    FastEthernet1/3	

sh run | i mac-
mac-address-table static 0016.35a8.a6f3 interface FastEthernet1/3 vlan 2
mac-address-table static 001e.7a25.7e0a interface FastEthernet1/3 vlan 50
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