ISR-LAB(config)#aaa new-model

radius server rad01
address ipv4 10.1.1.50 auth-port 1812 acct-port 1813
key testpass
!
radius server rad02
address ipv4 10.1.2.50 auth-port 1812 acct-port 1813
key testpass
!
radius server rad03
address ipv4 10.1.3.50 auth-port 1812 acct-port 1813
key testpass