Using the privilege-mode option for login

When using TACACS+ to control user access to the switch, first login with your username at the operator privilege level using the password for operator privileges, then login again with the same username but using the Manger password to obtain manager privileges. You can avoid this double login process by entering the privilege-mode option with the aaa authentication login command to enable TACACS+ for a single login. The switch authenticates your username/password, then requests the privilege level (operator or manager) that was configured on the TACACS+ server for this username/password. The TACACS+ server returns the allowed privilege level to the switch. You are placed directly into operator or manager mode, depending on your privilege level.

switch(config)#aaa authentication login privilege-mode

The no version of the above command disables TACACS+ single login capability.