3Com 7700 Configuration Manual page 248

240 C 9: AAA
HAPTER AND
RADIUS O
PERATION
There are two types of ports for the Authenticator. One is the Uncontrolled Port,
and the other is the Controlled Port. The Uncontrolled Port is always in a
bi-directional connection state. The user can access and share the network
resources any time through the ports. The Controlled Port will be in a connecting
state only after the user passes the authentication. Then the user is allowed to
access the network resources.
Figure 1 802.1x System Architecture
Requester
system
Services offered by
Authenticator
Requester
system
Controlled
port
EAPol
802.1x Authentication Process
802.1x configures EAP frame to carry the authentication information. The
Standard defines the following types of EAP frames:
EAP-Packet: Authentication information frame, used to carry the
■
authentication information.
EAPoL-Start: Authentication originating frame, actively originated by the
■
Supplicant.
EAPoL-Logoff: Logoff request frame, actively terminating the authenticated
■
state.
EAPoL-Key: Key information frame, supporting to encrypt the EAP packets.
■
EAPoL-Encapsulated-ASF-Alert: Supports the Alerting message of Alert
■
Standard Forum (ASF).
The EAPoL-Start, EAPoL-Logoff and EAPoL-Key only exist between the Supplicant
and the Authenticator. The EAP-Packet information is re-encapsulated by the
Authenticator System and then transmitted to the Authentication Server System.
The EAPoL-Encapsulated-ASF-Alert is related to the network management
information and terminated by the Authenticator.
802.1x provides an implementation solution of user ID authentication. However,
802.1x itself is not enough to implement the scheme. The administrator of the
access device should configure the AAA scheme by selecting RADIUS or local
authentication to assist 802.1x in implementing the user ID authentication. For
detailed description, refer to the corresponding AAA configuration.
Authenticator system
Authenticator PAE
Unauthorized
port
LAN
Authenticator
server system
Authenticator
server
EAP protocol exchanges
carried in higher layer
protocol