flapping between port two interface on the same switch

[CISCOTUMBA]

ello everyone,

I'm getting falpping between port  Gi1/0/16 and Gi1/0/23. Here is my config on the those interface:

s16-smc-mdf-3750#sh run int gi1/0/16
Building configuration...

Current configuration : 206 bytes
!
interface GigabitEthernet1/0/16
description AP SMC_S1.31
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 51-54,56,60,70,80,90,504
switchport mode trunk
spanning-tree portfast
end

s16-smc-mdf-3750#sh run int gi1/0/23
Building configuration...

Current configuration : 203 bytes
!
interface GigabitEthernet1/0/23
description ICU-AP
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 51-54,56,57,60,70,80,90,504
switchport mode trunk
spanning-tree portfast
end

The interfaces are configured for APs. I’m using the same interface configuration on 120 other APs, and this issue is only happening with these two.

Could it possibly there is a bad AP? 

Any help would be much appreciated.

[Mark Elsen]

   - @CISCOTUMBA    For access points , that is normal ; if a client starts roaming between them ,

  M.

[Jonatan Jonasson]

It could be a wifi client that is roaming back and forth between the APs.

So on one hand it could be normal, but can also be an indicator that this client is experiencing wifi issues, maybe due to equally bad signal to both APs or something else. 

Is this happening to only mac address or multiple mac addresses between these APs?

[CISCOTUMBA]

Hello Jonatan, 

I didn’t check whether the MAC address is different, but they are experiencing Wi-Fi issues. Bouncing the interface resolves the problem, but after a few days the same issue occurs again.

[pieterh]

there is a mismatch in the "allowed vlan"  list of both AP's

switchport trunk allowed vlan 51-54,56,60,70,80,90,504
switchport trunk allowed vlan 51-54,56,57,60,70,80,90,504

do you have an explicit reason for this? if not I advise to keep them equal.