As far as troubleshooting, search CCO.

From CCO:

RTD-1-ADDR_FLAP [chars] relearning [dec] addrs per min

Explanation Normally, MAC addresses are learned once on a port.
Occasionally, when a switched network reconfigures, due to either
manual or STP reconfiguration, addresses learned on one port are
relearned on a different port. However, if there is a port anywhere in
the switched domain that is looped back to itself, addresses will jump
back and forth between the real port and the port that is in the path
to the looped back port. In this message, [chars] is the interface,
and [dec] is the number of addresses being learnt.

Action Determine the real path (port) to the MAC address. Use debug
ethernet-controller addr to see the alternate path-port on which the
address is being learned. Go to the switch attached to that port. Note
that show cdp neighbors is useful in determining the next switch.
Repeat this procedure until the port is found that is receiving what
it is transmitting, and remove that port from the network.

Sean Mathias
CCIE #12779

On Wed, 25 Feb 2004 12:01:41 +0800, "Woon" <kaori_michiru@hotmail.com>
wrote:

>Hi,
>
>We have a distribution switch (Cat2912MF) which is connected to several
>Cat1924s (i.e. each 100BaseFX interface -> 1 Cat1924). I'm used to seeing
>the following log messages appearing :
>
>RTD-1-ADDR_FLAP: fastEthernet0/5 relearning 13 addresses
>RTD-1-ADDR_FLAP: fastEthernet0/5 relearning 9 addresses
>RTD-1-ADDR_FLAP: fastEthernet0/5 relearning 13 addresses
>RTD-1-ADDR_FLAP: fastEthernet0/7 relearning 13 addresses
>
>How do i go about troubleshooting this? Should this be a matter of concern
>and will it affect the network?
>
>thanks,
>woon
>

Sean Mathias
CCIE #12779