H3C S5100-SI Operation Manual page 281

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.
4) The RADIUS client accepts or denies the user depending on the received authentication result. If it
accepts the user, the RADIUS client sends a start-accounting request (Accounting-Request, with
the Status-Type attribute value = start) to the RADIUS server.
5) The RADIUS server returns a start-accounting response (Accounting-Response).
6) The user starts to access network resources.
7) The RADIUS client sends a stop-accounting request (Accounting-Request, with the Status-Type
attribute value = stop) to the RADIUS server.
8) The RADIUS server returns a stop-accounting response (Accounting-Response).
9) The access to network resources is ended.
RADIUS message format
RADIUS messages are transported over UDP, which does not guarantee reliable delivery of messages
between RADIUS server and client. As a remedy, RADIUS adopts the following mechanisms: timer
management, retransmission, and backup server.
Figure 1-3 RADIUS message format
1) The Code field (one byte) decides the type of RADIUS message, as shown in
Table 1-1 Description on the major values of the Code field
Code
1 Access-Request
2 Access-Accept
Message type
Figure 1-3 depicts the format of RADIUS messages.
Message description
Direction: client->server.
The client transmits this message to the server to
determine if the user can access the network.
This message carries user information. It must contain
the User-Name attribute and may contain the following
attributes: NAS-IP-Address, User-Password and
NAS-Port.
Direction: server->client.
The server transmits this message to the client if all the
attribute values carried in the Access-Request
message are acceptable (that is, the user passes the
authentication).
1-4
Table 1-1.