Cisco IE 4000, Руководство по настройке программного обеспечения

Страница: 200 / 1066

196
Configuring IEEE 802.1x Port-Based Authentication
Information About Configuring IEEE 802.1x Port-Based Authentication
authenticated, the port changes to the authorized state, allowing all traffic for the client to flow normally. If the port is
configured as a voice VLAN port, the port allows VoIP traffic and 802.1x protocol packets before the client is successfully
authenticated.
If a client that does not support 802.1x authentication connects to an unauthorized 802.1x port, the switch requests the
client’s identity. In this situation, the client does not respond to the request, the port remains in the unauthorized state,
and the client is not granted access to the network.
In contrast, when an 802.1x-enabled client connects to a port that is not running the 802.1x standard, the client initiates
the authentication process by sending the EAPOL-start frame. When no response is received, the client sends the
request for a fixed number of times. Because no response is received, the client begins sending frames as if the port is
in the authorized state.
You control the port authorization state by using the authentication port-control interface configuration command and
these keywords:

force-authorized —Disables 802.1x authentication and causes the port to change to the authorized state without any
authentication exchange required. The port sends and receives normal traffic without 802.1x-based authentication
of the client. This is the default setting.

force-unauthorized —Causes the port to remain in the unauthorized state, ignoring all attempts by the client to
authenticate. The switch cannot provide authentication services to the client through the port.

auto —Enables 802.1x authentication and causes the port to begin in the unauthorized state, allowing only EAPOL
frames to be sent and received through the port. The authentication process begins when the link state of the port
changes from down to up or when an EAPOL-start frame is received. The switch requests the identity of the client
and begins relaying authentication messages between the client and the authentication server. Each client
attempting to access the network is uniquely identified by the switch by using the client MAC address.
If the client is successfully authenticated (receives an Accept frame from the authentication server), the port state
changes to authorized, and all frames from the authenticated client are allowed through the port. If the authentication
fails, the port remains in the unauthorized state, but authentication can be retried. If the authentication server cannot be
reached, the switch can resend the request. If no response is received from the server after the specified number of
attempts, authentication fails, and network access is not granted.
When a client logs off, it sends an EAPOL-logoff message, causing the switch port to change to the unauthorized state.
If the link state of a port changes from up to down, or if an EAPOL-logoff frame is received, the port returns to the
unauthorized state.
802.1x Host Mode
You can configure an 802.1x port for single-host or for multiple-hosts mode. In single-host mode (see Figure 18 on
page 189 ), only one client can be connected to the 802.1x-enabled switch port. The switch detects the client by sending
an EAPOL frame when the port link state changes to the up state. If a client leaves or is replaced with another client, the
switch changes the port link state to down, and the port returns to the unauthorized state.
In multiple-hosts mode, you can attach multiple hosts to a single 802.1x-enabled port. Figure 22 on page 197 shows
802.1x port-based authentication in a wireless LAN. In this mode, only one of the attached clients must be authorized
for all clients to be granted network access. If the port becomes unauthorized (reauthentication fails or an EAPOL-logoff
message is received), the switch denies network access to all of the attached clients. In this topology, the wireless
access point is responsible for authenticating the clients attached to it, and it also acts as a client to the switch.