3Com 4200G 12-Port Configuration Manual page 183

Figure 54 Databases in RADIUS server
In addition, the RADIUS server can act as the client of some other AAA server to
provide the authentication or accounting proxy service.
Basic message exchange procedure of RADIUS
The messages exchanged between a RADIUS client (a switch, for example) and the
RADIUS server are verified by using a shared key. This enhances the security. The
RADIUS protocol combines the authentication and authorization processes together
by sending authorization information in the authentication response message.
Figure 55 depicts the message exchange procedure between user, switch and RADIUS
server.
Figure 55 Basic message exchange procedure of RADIUS
PC PC PC PC
(1) The user inputs the user name and password (1) The user inputs the user name and password (1) The user inputs the user name and password (1) The user inputs the user name and password
(9) Inform the user the access is ended (9) Inform the user the access is ended (9) Inform the user the access is ended (9) Inform the user the access is ended
The basic message exchange procedure of RADIUS is as follows:
1 The user enters the user name and password.
2 The RADIUS client receives the user name and password, and then sends an
authentication request (Access-Request) to the RADIUS server.
RADIUS server RADIUS server
Users Users Clients Clients
RADIUS RADIUS RADIUS RADIUS
client Client client Client
(2) Access -Request (2) Access -Request (2) Access -Request (2) Access -Request
(3) Access -Accept (3) Access -Accept (3) Access -Accept (3) Access -Accept
(4) Accounting -Request (start) (4) Accounting -Request (start) (4) Accounting -Request (start) (4) Accounting -Request (start)
(5) Accounting -Response (5) Accounting -Response (5) Accounting -Response (5) Accounting -Response
(6) The user starts to access the resources (6) The user starts to access the resources (6) The user starts to access the resources (6) The user starts to access the resources
(7) Accounting - Request (stop) (7) Accounting - Request (stop) (7) Accounting - Request (stop) (7) Accounting - Request (stop)
(8) Accounting -Response (8) Accounting -Response (8) Accounting -Response (8) Accounting -Response
Overview 169
Dictionary Dictionary
RADIUS RADIUS RADIUS RADIUS
server Server server Server