Radius Protocol - 3Com 3032 Configuration Manual

Packet Structure of the

RADIUS protocol

Figure 166 Basic message interaction process of RADIUS
PSTN/ PSTN/
ISDN ISDN
PC PC
Enter username and password Enter username and password
Notify the end of access Notify the end of access
The basic operation is described as follows:
1 The user enters a username and password.
2 Having received the username and password, teh RADIUS client sends an
authentication request packet (Access-Request) to the RADIUS server.
3 The RADIUS server authenticates the user information in the user database. If the
authentication succeeds, it sends the user's right information in an authentication
response packet (Access-Accept) to the RADIUS client. If the authentication fails, it
returns the Access-Request packet.
4 According to the authentication result, the RADIUS client accepts or denies the
user. If it accepts, the RADIUS client sends an accounting start request packet
(Accounting-Request) to the RADIUS server. The value of Status-Type is start.
5 The RADIUS server returns an accounting start response packet
(Accounting-Response).
6 The RADIUS client sends an accounting stop request packet (Accounting-Request)
to the RADIUS server. The value of Status-Type is stop.
7 The RADIUS server returns an accounting stop response packet
(Accounting-Response).
RADIUS uses UDP to transmit messages. By employing a timer management
mechanism, retransmission mechanism, and slave server mechanism, it can ensure
that the interactive message between the RADIUS server and client can be
processed correctly. Figure 167 illustrates the contents of a RADIUS packet.
RADIUS Client RADIUS Client
Access-Request Access-Request
Access-Accept Access-Accept
Accounting-Request Accounting-Request
Accounting-Response Accounting-Response
The user visits the resource The user visits the resource
Accounting-Request £ ¨ stop Accounting-Request £ ¨ stop
Accounting-Response Accounting-Response
RADIUS Overview 531
RADIUS Server RADIUS Server
£ ¨ start £ © £ ¨ start £ ©
£ © £ ©