what is RADIUS and TACACS+ in your own words.

For an excellent explanation please refer to the techexams.net post by Darril Gibson
Link:
 http://www.techexams.net/forums/security/48766-what-difference-between-tacacs-radius.html

Sorry Wolfe -- I was just trying to help and I did not know that there will be such objection.

 jazzIIIlove : Here is some info which I am writing with my own understanding and I hope you will find it useful.

 TACACS+ and RADIUS (RFC 2865 - Spec) are Security Protocols of Cisco to control access into networks.

RADIUS is an access server that uses AAA protocol. It secures remote access to networks and network services against unauthorized access. RADIUS has a client, a server and a protocol with a frame format that utilizes User Datagram Protocol (UDP)/IP. RADIUS uses UDP which is best effort transport.RADIUS encrypts only the password in the access-request packet, from the client to the server. The remainder of the packet is unencrypted, RADIUS does not multiprotocol protocols ((ARA,NetBIOS , NASI & •X.25 PAD ). RADIUS Request for Comments (RFCs) does not guarantee interoperability.RADIUS does not allow users control on routers. RADIUS combines authentication and authorization hence in router management it cannot decouple authentication, exec authorization, command authorization, exec accounting, and command accounting.

TACACS+ protocol has independent authentication, authorization, and accounting (AAA) architecture that is designed to support growing security markets, It uses TCP which is connection oriented transport.TACACS+ encrypts the entire body of the packet but leaves a standard TACACS+ header. TACACS+ offers multiprotocol support(ARA,NetBIOS , NASI & •X.25 PAD ). TACACS+ allows control on routers.TACACS+ decouples  authentication and authorization hence  in router management it can decouple authentication, exec authorization, command authorization, exec accounting, and command accounting.

Hi;

Thanks any fundamental difference between them?

Also are those protocols used by ISPs? Where is their place in OSI layer?

Best regards.