topic Hi Spooster in Wireless

MAC Flapping between WLC and flexconnect AP

saifeddinehakim — Mon, 05 Jul 2021 14:00:21 GMT

Hello,

We are facing a MAC flapping issue between WLC 2504 version 8.2.151.0 and flexconnect APs

The logs in the access switch connected to APs:

*May 4 21:59:16.369: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 21:59:53.162: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:00:11.440: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:00:12.682: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/1 and port Fa0/13
*May 4 22:01:00.992: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:01:19.581: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:02:09.460: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/1 and port Fa0/13
*May 4 22:02:33.258: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/1 and port Fa0/13
*May 4 22:02:45.799: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:03:07.182: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:03:37.364: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:03:50.962: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:05:26.810: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/1 and port Fa0/13
*May 4 22:05:33.152: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/1 and port Fa0/13
*May 4 22:06:35.790: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:06:51.460: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:07:10.468: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Fa0/13 and port Gi0/1
*May 4 22:08:30.437: %SW_MATM-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/1 and port Fa0/13

The port Fa0/13 is connected to an AP and Gi0/1 is the uplink of the switch

The logs in the switch connected to the WLC:

000285: *May 4 01:42:40: %SW_MATM-CLUSTER_MEMBER_4-4-MACFLAP_NOTIF: Host 4cbb.585d.3c6b in vlan 255 is flapping between port Gi0/21 and port Gi0/24
000286: *May 4 01:43:33: %SW_MATM-CLUSTER_MEMBER_4-4-MACFLAP_NOTIF: Host 4cbb.585d.3c6b in vlan 255 is flapping between port Gi0/24 and port Gi0/21
000287: *May 4 01:56:59: %SW_MATM-CLUSTER_MEMBER_4-4-MACFLAP_NOTIF: Host 3894.96ed.b776 in vlan 255 is flapping between port Gi0/24 and port Gi0/21
000288: *May 4 21:06:06: %SW_MATM-CLUSTER_MEMBER_4-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/24 and port Gi0/21
000289: *May 4 21:33:41: %SW_MATM-CLUSTER_MEMBER_4-4-MACFLAP_NOTIF: Host e094.6778.7b34 in vlan 255 is flapping between port Gi0/24 and port Gi0/21

The port Gi0/21 is connected to the WLC and Gi0/24 is the uplink of the switch

Any ideas how to resolve this problem? Thanks

Hi saifeddinehakim,

Spooster IT Services — Thu, 11 May 2017 17:17:55 GMT

Hi saifeddinehakim,

Vlan 255 is used for management or Wireless client traffic?

Is your AP configured for local authentcation?

Hi Spooster

saifeddinehakim — Thu, 11 May 2017 19:34:45 GMT

Hi Spooster

Vlan 255 is used for Wireless client traffic and the AP is configured for local authentication

Here is the mapping of VLANs in the AP

And this is the configuration of the WLAN

I see the Mac flapping alerts

Spooster IT Services — Thu, 11 May 2017 19:34:46 GMT

I see the Mac flapping alerts are only for Vlan 255 and there are total four ssid's configured with different vlans.

Are the other SSID's also in use?

Are the other SSID's also set for flexconnect local switching?

Did you enable the flex connect at AP level too?

Hey Saifeddinehakim

Kundan Prasad — Fri, 12 May 2017 08:35:34 GMT

Hey Saifeddinehakim

Your AP is in flexconnect mode, and it uses local switching which means traffic does not come to WLC, try changing AP mode into local, but as i see you have many ssid's running with different VLANs meaning you want all ssid to work with this AP, you should select flexconnect when your AP is located not in your network, like in branch offices or in other location. In that case you can map vlan as per the switchport.

In your case AP and WLC is located in same place because of which you have looping/MAC Flapping (when you receive packets from two different interfaces with the same source MAC address), the solution would be either you change the AP in local mode, create AP group and place that AP in the group and select the SSIDs whichever you would like to broadcast.

Create interfaces for each SSID as per the required VLAN and map it with the SSID.

or the simplest solution would be to change the inheritance to AP-SPECIFIC and change the VLAN, create different VLAN for your SSID, assign it to switchport...if you want AP to be in flexconnect mode...!!

Hey Saifeddinehakim

Kundan Prasad — Fri, 12 May 2017 08:37:00 GMT

Hey Saifeddinehakim

Create interfaces for each SSID as per the required VLAN and map it with the SSID.

Hey Kundan,

saifeddinehakim — Fri, 12 May 2017 09:45:58 GMT

Hey Kundan,

In fact, it was working without any problem in local mode. But we change it to flexconnect to protect the network from being down when the controller is down.

The problem is happening only in the WLAN "G-HOST" which is for guests.

We don't have any problem in the WLAN "G-AIR" for example which uses local switching too with Vlan based Central Switching for dynamic VLAN attribution.

Create interfaces for each SSID as per the required VLAN and map it with the SSID.

We already did it

the WLAN "G-AIR" is mapped to management interface and the WLAN "G-HOST" is mapped to guest interface

the management interface is associated to VLAN 4

and the guest interface is associated to VLAN 255

Are the other SSID's also in

saifeddinehakim — Fri, 12 May 2017 09:49:10 GMT

Are the other SSID's also in use?

Only G-AIR (with dynamic VLAN attribution) and G-HOST (for guest users)

Are the other SSID's also set for flexconnect local switching?

yes, all of its

Did you enable the flex connect at AP level too?

yes, it is enabled and every SSID is mapped to a VLAN

Re: MAC Flapping between WLC and flexconnect AP

lavance.davis — Fri, 14 Sep 2018 20:54:26 GMT

You ever get this resolved? I having the same problem with my flexconnected AP's

Re: MAC Flapping between WLC and flexconnect AP

Thierry C — Tue, 11 Feb 2025 13:25:59 GMT

I think those flapping messages are normal as it happens because that's the FlexConnect behaviour who is responsible.
FlexConnect mean that you do not make Central Switching on you WLC, but well Local switching on your switches.
Roaming from one ap to another located on an another switch, or another interface on the same switch, make that flapping.
What is annoying in this behavior is the pollution of the logs.
There is a way to target these messages with the DISCRIMINATOR function on the buffered logs, and not take them into account.
exemple to get rid of your flapping messages on vlan 255, and on vlan 256 (to threat multiple case):

sw(config)# logging discriminator wififlap msg-body drops (255 is flapping|256 is flapping)

sw(config)# logging buffered discriminator wififlap

That's it, no more flapping msg on those vlans