How does Tacacs server forward the credentials from client to Authentication server?

Question

How does Tacacs server forward the credentials from client to Authentication server?

Does a decryption and Encryption of creds takes place? Or is it just a packet forward ?

Edit: The authentication server, i refer to would be a LDAP server to which tacacs would forward the credentials.

Answer 1

RADIUS was designed to authenticate and log dial-up remote users to a network, and TACACS+ is used most commonly for administrator access to network devices like routers and switches.

http://www.tacacs.net/docs/TACACS_Advantages.pdf