H3C Technologies H3C SecPath F1000-E - Manual (Page 411)

3
5. The RADIUS server returns a start-accounting response (Accounting-Response) and starts
accounting.
6. The user accesses the network resources.
7. The host requests the RADIUS client to tear down the connection and the RADIUS client sends a
stop-accounting request (Accounting-Request) to the RADIUS server.
8. The RADIUS server returns a stop-accounting response (Accounting-Response) and stops
accounting for the user.
9. The user stops access to network resources.
RADIUS Packet Format
RADIUS uses UDP to transmit messages. It ensures the smooth message exchange between the RADIUS
server and the client through a series of mechanisms, including the timer management mechanism,
retransmission mechanism, and slave server mechanism. Figure 3 shows the RADIUS packet format.
Figure 3 RADIUS packet format
Descriptions of the fields are as follows:
1. The Code field (1-byte long) is for indicating the type of the RADIUS packet. Table 1 gives the
possible values and their meanings.
Table 1 Main values of the Code field
Code Packet type Description
1 Access-Request
From the client to the server. A packet of this type carries user
information for the server to authenticate the user. It must contain the
User-Name attribute and can optionally contain the attributes of
NAS-IP-Address, User-Password, and NAS-Port.
2 Access-Accept
From the server to the client. If all the attribute values carried in the
Access-Request are acceptable, that is, the authentication succeeds, the
server sends an Access-Accept response.
3 Access-Reject
From the server to the client. If any attribute value carried in the
Access-Request is unacceptable, the server rejects the user and sends an
Access-Reject response.
4 Accounting-Request
From the client to the server. A packet of this type carries user
information for the server to start/stop accounting for the user. It
contains the Acct-Status-Type attribute, which indicates whether the
server is requested to start the accounting or to end the accounting.