H3C S5100-SI Operation Manual page 280

Clients: This database stores information about RADIUS clients (such as shared key).
Dictionary: The information stored in this database is used to interpret the attributes and attribute
values in the RADIUS protocol.
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.
Figure 1-2 depicts the message exchange procedure between
1-3