This error message signifies that a MAC address is moving consistently between different ports. This error message is
only applicable on the Catalyst 2900XL and 3500XL switches. The error message may indicate that two or more HSRP
routers have become active. However, the error message may indicate where an STP loop, duplicated frames, or
reflected packets are being sourced.
To gather further information about the error message, run the following debug:
switch#debug ethernet-controller address
Ethernet Controller Addresses debugging is on l
_Mar 9 08:06:06: Add address 0000.0c07.ac02, on port 35 vlan 2
_Mar 9 08:06:06: 0000.0c07.ac02 has moved from port 6 to port 35 in vlan 2
_Mar 9 08:06:07: Add address 0000.0c07.ac02, on port 6 vlan 2
_Mar 9 08:06:07: 0000.0c07.ac02 has moved from port 35 to port 6 in vlan 2
_Mar 9 08:06:08: Add address 0000.0c07.ac02, on port 35 vlan 2
_Mar 9 08:06:08: 0000.0c07.ac02 has moved from port 6 to port 35 in vlan 2
_Mar 9 08:06:10: Add address 0000.0c07.ac02, on port 6 vlan 2
_Mar 9 08:06:10: 0000.0c07.ac02 has moved from port 35 to port 6 in vlan 2
_Mar 9 08:06:11: Add address 0000.0c07.ac02, on port 35 vlan 2
_Mar 9 08:06:11: 0000.0c07.ac02 has moved from port 6 to port 35 in vlan 2
_Mar 9 08:06:12: %RTD-1-ADDR_FLAP: FastEthernet0/7 relearning 20 addrs per min
_Mar 9 08:06:13: Add address 0000.0c07.ac02, on port 6 vlan 2
_Mar 9 08:06:13: 0000.0c07.ac02 has moved from port 35 to port 6 in vlan 2
The ports referenced in the debug are off by one (that is, port 0 is fastethernet0/1). The above error messages indicate a
MAC address is flapping between ports 5 and 34 on the respective switch.
Note: The message, RTD-1-ADDR_FLAP, may not be correct. Review the following bugs to rule out this possibility. See
the Tools Information section for more information.
CSCdp81680: Incorrect RTD-1-ADDR_FLAP message
CSCds27100/CSCdr30113: Fastetherchannel Issues causing RTD-1-ADDR_FLAP
The most common cause for MAC addresses moving around is Spanning-Tree Problems or Physical Layer Problems.
When troubleshooting this error message, follow the steps outlined below and also in the HSRP Troubleshooting Modules
section of this document:
1.Determine the correct source (port) of the host MAC address.
2.Disconnect the port that should not be sourcing the host MAC address.
3.Document the STP topology on a per VLAN basis and check for STP failure.
4.Verify port-channeling configuration. An incorrect port-channel configuration may result in the host MAC
address flapping error messages, due to the load-balancing nature of port-channeling.
