3Com 5500-EI PWR Install Manual page 471

Figure 1-1 Databases in a RADIUS server
In addition, a RADIUS server can act as a client of some other AAA server to provide authentication or
accounting proxy service.
Basic message exchange procedure in RADIUS
The messages exchanged between a RADIUS client (a switch, for example) and a RADIUS server are
verified through a shared key. This enhances the security. The RADIUS protocol combines the
authentication and authorization processes together by sending authorization information along with
the authentication response message.
user, switch and RADIUS server.
Figure 1-2 Basic message exchange procedure of RADIUS
The basic message exchange procedure of RADIUS is as follows:
1) The user enters the username and password.
2) The RADIUS client receives the username and password, and then sends an authentication
request (Access-Request) to the RADIUS server.
3) The RADIUS server compares the received user information with that in the Users database to
authenticate the user. If the authentication succeeds, the RADIUS server sends back to the
RADIUS client an authentication response (Access-Accept), which contains the user's
authorization information. If the authentication fails, the server returns an Access-Reject response.
Figure 1-2 depicts the message exchange procedure between
1-3