Default Authentication Methodes

• General steps:
• enable AAA authentication with the aaa new-model global command.
• If using RADIUS or TACACS+, define the ip addresses & encryption keys used by servers by using the following  commands.
• radius-server host, 
• radius-server key, 
• tacacs-server host 
• tacacs-server key 
• Define the default set of authentication methodes used for all CLI access by using command
• aaa authentication login default
• Define the default set of authentication method used for enable-mode access by using command
• aaa authentication enable default
• For example by using above steps configure 2 RADIUS servers are configured.
• One of the serveres uses ios default port 1645
• Other one uses the reserved well known port 1812.