Cisco Cisco Aironet 1600e Access Point 설치 가이드

If your access point does not indicate normal operation, turn it off and repeat the 
pre-installation configuration.

When you are installing a Layer 3 access point on a different subnet than the Cisco 
wireless LAN controller, be sure that a DHCP server is reachable from the subnet on 
which you will be installing the access point, and that the subnet has a route back to 
the Cisco wireless LAN controller. Also be sure that the route back to the Cisco 
wireless LAN controller has destination UDP ports 5246 and 5247 open for CAPWAP 
communications. Ensure that the route back to the primary, secondary, and tertiary 
wireless LAN controller allows IP packet fragments. Finally, be sure that if address 
translation is used, that the access point and the Cisco wireless LAN controller have 
a static 1-to-1 NAT to an outside address.