802.1X Fundamentals; 802.1X Architecture; Controlled/Uncontrolled Port And Pot Authorization Status - HP 5120 EI Switch Series Configuration Manual

802.1X fundamentals

802.1X is a port-based network access control protocol initially proposed by the IEEE 802 LAN/WAN
committee for securing wireless LANs (WLANs), and it has also been widely used on Ethernet networks
for access control.
802.1X controls network access by authenticating the devices connected to 802.1X-enabled LAN ports.

802.1X architecture

802.1X operates in the client/server model. It comprises three entities: client (the supplicant), network
access device (the authenticator), and the authentication server.
Figure 23 802.1X architecture
Client
The client is a user terminal seeking access to the LAN. It must have 802.1X software to authenticate

to the network access device.
 The network access device authenticates the client to control access to the LAN. In a typical 802.1X
environment, the network access device uses an authentication server to perform authentication.
The authentication server is the entity that provides authentication services for the network access

device. It authenticates 802.1X clients by using the data sent from the network access device, and
returns the authentication results for the network access device to make access decisions. The
authentication server is typically a Remote Authentication Dial-in User Service (RADIUS) server. In a
small LAN, you can also use the network access device as the authentication server.
Controlled/uncontrolled port and pot authorization
status
802.1X defines two logical ports for the network access port: controlled port and uncontrolled port. Any
packet arriving at the network access port is visible to both logical ports.
The controlled port allows incoming and outgoing traffic to pass through when it is in the authorized

state, and denies incoming and outgoing traffic when it is in the unauthorized state, as shown in
Figure 24. The controlled port is set in the authorized state if the client has passed authentication,
and in the unauthorized state, if the client has failed authentication.
The uncontrolled port is always open to receive and transmit EAPOL frames.

EAPOL
Device
RADIUS
Server
63