RackSwitch G8000 Application Guide
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Chapter 1: Accessing the Switch BMD00041, November 2008
TACACS+ Authentication
Blade OS supports authentication and authorization with networks using the Cisco Systems
TACACS+ protocol. The G8000 functions as the Network Access Server (NAS) by interacting
with the remote client and initiating authentication and authorization sessions with the
TACACS+ access server. The remote user is defined as someone requiring management
access to the G8000 through a data port.
TACACS+ offers the following advantages over RADIUS:
TACACS+ uses TCP-based connection-oriented transport; whereas RADIUS is UDP-
based. TCP offers a connection-oriented transport, while UDP offers best-effort delivery.
RADIUS requires additional programmable variables such as re-transmit attempts and
time-outs to compensate for best-effort transport, but it lacks the level of built-in support
that a TCP transport offers.
TACACS+ offers full packet encryption whereas RADIUS offers password-only encryp-
tion in authentication requests.
TACACS+ separates authentication, authorization and accounting.
How TACACS+ authentication works
TACACS+ works much in the same way as RADIUS authentication as described on page 26.
1. Remote administrator connects to the switch and provides user name and password.
2. Using Authentication/Authorization protocol, the switch sends request to authentication
server.
3. Authentication server checks the request against the user ID database.
4. Using TACACS+ protocol, the authentication server instructs the switch to grant or deny
administrative access.
During a session, if additional authorization checking is needed, the switch checks with a
TACACS+ server to determine if the user is granted permission to use a particular command.
