hostflapping events due to a roaming wireless client

[vancampdax]

I've been investigating some hostflapping issues on my switches and discovered that this was caused by 2 access points where a client was roaming in between.

These AP's are standalone installations.

Is there any setting which will prevent this hostflapping ?

[James D Hensley]

It depends on the platform.   It is disabled by default on the 6500 running native IOS.  It is enabled on the 3750/3560/2960 platforms and cannot be disabled.

On the 6500, if it has mac address move notification enabled, you can disable it with the command "no mac address-table notification mac-move" command in the global config.

How to tell if it is enabled on the 6500:

#sh run | i notification
mac-address-table notification mac-move

How to disable it on the 6500:

(config)#no mac address-table notification mac-move

Again, on the 3750/3560/2960 platform you cannot disable this feature.

[vancampdax]

It's a 4506 model running IOS 12.2(25).

The system doesn't accept the command

Doesn't this "flapping" have an impact spanning tree on the system ?

[Yogesh Ramdoss]

Command in discussion is supported in 12.2(31)SG or later releases.

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/54sg/command/reference/int_sess.html#wp2097977

Please be aware, the recommended command just stops the switch from reporting mac-move notification and do NOT stop mac-move itself.

Mac-move should NOT have impact on the spanning-tree. In reverse, mac-move may be a symptom of Layer2 instability.

If have confirmed the mac-address reported belongs to a wireless client, and two ports in the error message are connecte to APs, then I believe this is an expected behavior/symptom.

- Yogesh