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New Member

wireless link flapping issue

Hi all,

Having a wireless link flapping issue happen on the network. Would like to find out the possible root cause on this case.

(a) Problem statement

I found these at logging.

Symptom 1

Sep  8 07:55:27: %MAC_MOVE-SW1_SP-4-NOTIF: Host 28cc.0102.xxxx in vlan 7 is flapping between port Po201 and port Po200

Sep  8 07:55:31: %MAC_MOVE-SW1_SP-4-NOTIF: Host 28cc.0102.xxxx in vlan 7 is flapping between port Po200 and port Po201

Host MAC address is normal PC Wireless NIC.

Symptom 2

Sep  8 09:25:56: %MAC_MOVE-SW1_SP-4-NOTIF: Host e8b7.4828.f9dc in vlan 120 is flapping between port Po102 and port Te1/6/3

Sep  8 11:59:56: %MAC_MOVE-SW1_SP-4-NOTIF: Host e8b7.4828.f9dc in vlan 120 is flapping between port Te1/6/3 and port Po102

This a bit weird, Host e8b7.4828.f9dc is the logical MAC reside at ASASM, which is install at module 6.

I  am now clueless in troubleshooting these issue. Can anyone explain what  will cause wireless link flapping, and what the log shown at second  symptom, what happen on ASASM?

(b) Platform

1. Core switch s72033-adventerprisek9_wan-mz.122-33.SXJ1.bin

2. Access switch c2960s-universalk9-mz.122-55.SE3

3. ASASM asa851-smp-k8.bin

4. LC 7.3.101.0

5. AP 3500

attached 01.topology.png as reference.

Million thanks

Noel

5 REPLIES
Hall of Fame Super Silver

Re: wireless link flapping issue

That is normal in an autonomous environment. The reason is because the MAC address is cached on the switch somewhen the device roams to a new Ap, the AP sends out the device MAC address and now you have multiple MAC address until the other MAC address is removed from the switch.

Sent from Cisco Technical Support iPhone App

-Scott
*** Please rate helpful posts ***
New Member

wireless link flapping issue

Hi Scott,

Thanks for the reply.

This is install in lightweight environment, with WLC as central configuration controller.

What is the normal behaviour for switch in order to solve this issue? Can we fine tune our configuration on netwrok access device (ex: switch, WLC) to eliminate this issue happen?

Million thanks

Noel

VIP Purple

Re: wireless link flapping issue

Are you running VSS between two core switches ? Where is Te1/6/3 in your topology ? Are two WLCs serving client all the time or is it primary/secondary set up ?

Rasika

New Member

wireless link flapping issue

Hi Rasika

Yes, VSS configure on the core switch.

Wireless configuration is in all time Active/Active mode.

And about the Te1/6/3, this is the miserable part. Cause ASASM is the service module install at C6500 chassis, there's no physical interface can be found. I have no idea why only this logical interface having this error log,

thanks

Noel

VIP Purple

wireless link flapping issue

Client MAC adrees is flapping between Po200 & Po201 indicating when client roam, those two APs controlled by two different controller. It is always good practice to put all the AP geographically close by on to one controller as primary. In that way most of the roaming would be intra controller roaming & would not have issues like  you are facing.

What is vlan 120, does it need to go to Access switches ? Since you have layer 2 trunk link across access layer port channel, there is possiblity MAC learn via two path. Is it possble to block vlan 120 on P102 ?

HTH

Rasika

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