3Com Switch 4800G 24-Port - Page 751

AAA/RADIUS/HWTACACS Overview 751
6 The subscriber 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.
9 The subscriber stops network resource accessing.
RADIUS packet structure
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 230 shows the RADIUS packet structure.
Figure 230 RADIUS packet structure
Descriptions of fields are as follows:
1 The Code field (1-byte long) is for indicating the type of the RADIUS packet.
Table 58 gives the possible values and their meanings.
Code
Attribute
Identifier
0
7
Length
Authenticator (16bytes)
715 31
Table 58 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 on 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.