Configuration steps of remote Tacacs+ authentication mode:
1. Create an authentication template -> configure authentication mode
OLT(config-aaa)# authentication-scheme 3
OLT(config-aaa-authen-2)# authentication-mode tac-plus

2. Create Tacacs+ server template -> configure server parameters
OLT(config)# tac-plus-server template 1
OLT(config-tac-plus-1)# tac-plus-server authentication 192.168.222.104 port 49
OLT(config-tac-plus-1)# tac-plus-server shared-key ***
To
3. Create domain -> bind authentication template -> bind Tacacs + server template
OLT(config-aaa)# domain isp
OLT(config-aaa-domain-isp)# authentication 3
OLT(config-aaa-domain-isp)# tac-plus-server 1