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Webcast-Catalyst9k
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I am looking for a possible cause of the following error on a 2924 switch. It is not set up for HSRP. %RTD-1-ADDR_FLAP: FastEthernet0/5 relearning 8 addrs per min

A server on our lan losing conection to another server on the same subnet. They both connect to this 2924 switch. The log for the switch is full of the following error:

%RTD-1-ADDR_FLAP: FastEthernet0/5 relearning 8 addrs per min. The Cisco error decoder is telling me that this could be a hsrp issue but I am not using hsrp in this case.

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Anonymous
N/A

Re: I am looking for a possible cause of the following error on

It is not necessary an HSRP issue, 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.

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 the show cdp neighbors command 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.

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