Spanning Tree Issue

I’ve 2 PMP 430 APs and Multiple SMs, the 2 AP are bundeled on a management switch.

I’m using this design as a redundant connection in case of the fiber Connection is down.
but when I connect one of the SMs to a cisco switch I get VLAN flapping between the port connected to the AP and the port connected to the fiber Connection.

the connection between the SM and switch is trunk.
I enabled lldp on the switch, and it can see the SM without any Issue.

the error that appears is:
May 9 13:03:23.367: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d32.3c74 in vlan 50 is flapping between port Fa0/18 and port Gi0/1
May 9 13:03:24.575: %SW_MATM-4-MACFLAP_NOTIF: Host 24be.0528.d0da in vlan 109 is flapping between port Fa0/18 and port Gi0/1

my AP os is canopy 12.2.2 AP-DES Board Type P11
My SM os is Canopy 12.1 SM-DES Board Type P11

any resolution will be appreciated.


Can you post any of the port configuration related to Spanning Tree? Sounds like something is dropping BPDUs

I have experienced the same problem with the firmware of both AP and SM is 12.2.2. Spanning-tree is forwarding traffic instead of blocking  it.

the configuration on the trunk interface conncted to the SM is as follows:

switchport trunk encapsulation dot1q
 switchport trunk native vlan 5
 switchport mode trunk
 ip arp inspection trust
 ip dhcp snooping trust

can you advise?