Here is simple steps to setup RADIUS access for Cisco Aironet AP1242AG model.
1. External RADIUS server ready(i.e; 192.168.77.5)
2. Verifiy a Firewall rule if RADIUS traffic is passing thru any firewall.
– Port number ; TCP 1812~1813(1812 for authentication and 1813 for accounting)
3. Configururation on Cisco Aironet AP1242AG
Cisco_AP1242AG#
Cisco_AP1242AG# conf t
Cisco_AP1242AG(config)# aaa new-model
Cisco_AP1242AG(config)# aaa authentication login default group radius local
Cisco_AP1242AG(config)# aaa authorization exec default group radius local
Cisco_AP1242AG(config)# radius-server host 192.168.77.5 auth-port 1812 acct-port 1813 key 7 [your key]
* This is a simple and basic configuration for authenticate thru RADIUS server.
** You could use internal radius-server as well.