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Host xx in vlan yy is flapping between port Gi1/0/32 and port Gi1/0/33

Marco Noviello
Level 4
Level 4

Hi everyone,

in a FlexConnect branch environment we report on the switch (3650 or 2960) several times this log entry:

%SW_MATM-4-MACFLAP_NOTIF: Host xx in vlan yy is flapping between port Gi1/0/32 and port Gi1/0/33

I can understand that this will happen when the client is roaming (but then I don't understand why the entry is written only some time and not every time the client is roaming) , but I can not understand why the client MAC is also flapping between the client VLAN (Mapped via FlexConnect configuration) and the VLAN where the AP reside (Native VLAN) .

Did someone report similar behaviour?

I'm running 8.3.120 on a vWLC, Catalyst switch was updated to the latest recommended version.

Regards

Marco

5 Replies 5

Hi Marco,

I would think it is due to mac address aging time of your switch. By default it is 300s 

HTH

Rasika

Hi guys,  thx for reply and sorry for delay.

1) if I have an aging time issue I expect to see al lot of entry.

2) we don't have any channel konfigured

3) the log entry is very randomly.

For troubleshooting purposes we installed locally an 2504 and switched all APs from Flex to local back.

WLAN client could work without any problem, all MAC clients are seen in only in only client lan.

So far so good, thenn we switched the AP to Flex back and register it to the controller on site and not in the HQ.

MAC flapping (between client and native VLAN) appear again, user report connection stuck again.

I think that something in the Flex AP is not working well.

Regards

Marco

You don't have other central switching SSIDs broadcast by the same AP? Could client connect to a central switch SSID and then back to the local switching SSID?

8.3.120.0 version does not exist, what is the actual version you are running?

Regards,

Leo Laohoo
Hall of Fame
Hall of Fame

Host xx in vlan yy is flapping between port Gi1/0/32 and port Gi1/0/33

Most of the time if we see this kind of error message it means that EtherChannel is not (properly) configured.  

What are the downstream clients connected to port 32 and 33?

Jaime Gonzalez Gomez
Cisco Employee
Cisco Employee

Hi Marco,

What do you mean by several times? several times per day, week, minute?

Device may be changing to another SSID central switching and returning back to this local switching?

Have you verified AP is not loosing connection with WLC (loosing the VLAN mapping probably)?

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