Two vlans on the ap: vlan1 (native) and vlan4. Bridge wirless to vlan1. The ap is not addressed in vlan1 (int bvi1, no ip address). An ethernet subinterface has been created, assigned to vlan4 and addressed. Communication to the subinterface address fails. The switch port to which the ap is connected to is properly configured (encap dot1q, mode trunk). My intention is to provide out-of-band management. I'm really a bit stumped at this point.
switch
interface FastEthernet0/18 switchport trunk encapsulation dot1q switchport mode trunk no ip address interface Vlan4 ip address 192.168.1.2 255.255.255.0
ap
interface FastEthernet0.4 encapsulation dot1Q 4 ip address 192.168.1.21 255.255.255.0