Mac address flap

[vasanth_k08]

Hi all,

often i get mac address flap error in switches, but unable to identify the cause for some cases.

AS1---DS---AS2.

Two switches AS1 and AS2 are connected to DS and i am seeing host mac address connected to AS1 being learnt from AS2 connected port in DS under same vlan 100. There is no physical loop in this connectivity. While checking i found mac address aging timer higher in DS (480s) than in AS1(30s) and AS2(30s). Even when the host pc goes down it takes some time for the address to get flushed in DS mac table. Would this be causing this mac flap ?

[Syed Aman Hussain]

Vasanth ,

its happining only for one host or all host,make bubug and paste the output here

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[vasanth_k08]

Hi aman,

since this is a live production setup unable to share debug logs.

this issue is not particular to a vlan. getting same kind of error logs for other user vlans as well.

[Syed Aman Hussain]

Find out what those hosts which are falpping in the swichtes first.

Possibilities:

(1) Loop in the network (what is on the other end of those trunks in the connectivity ?  and are they
otherwise interconnected?)
(2) Port-channel incompatibility (your pasted configuration was not a channel-group, but
what about the other end?)
(3) If you have wireless that bridges AP traffic to the wired network, it could be
"roaming" clients

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