Authentication Initiation And Message Exchange - Cisco Catalyst 4500 series Administration Manual
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Also See for Catalyst 4500 series:
- Software configuration manual (2086 pages) ,
- Configuration manual (1610 pages) ,
- Command reference manual (1230 pages)
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Chapter 46
Configuring 802.1X Port-Based Authentication
About 802.1X Port-Based Authentication
Antivirus posture includes such elements as the operating system running on the device, the operating
system version, whether antivirus software is installed and what version of antivirus signatures is
available. If the authenticating device has a NAC-aware 802.1X supplicant and the authentication server
is configured to support NAC using 802.1X, antivirus posture information is automatically included as
part of the 802.1X authentication exchange.
For information on NAC, refer to the URL:
http://www.cisco.com/en/US/products/ps6128/index.html
Authentication Initiation and Message Exchange
The switch or the client can initiate authentication. If you enable authentication on a port by using the
authentication port-control auto interface configuration command (dot1x port-control auto
command in Cisco IOS Release 12.2(46)SG and earlier releases), the switch must initiate authentication
when it determines that the port link state has changed. It then sends an EAP-request/identity frame to
the client to request its identity (typically, the switch sends an initial identity/request frame followed by
one or more requests for authentication information). Upon receipt of the frame, the client responds with
an EAP-response/identity frame.
However, if during bootup, the client does not receive an EAP-request/identity frame from the switch,
the client can initiate authentication by sending an EAPOL-start frame, which prompts the switch to
request the client's identity.
If 802.1X is not enabled or supported on the network access switch, any EAPOL frames from the client
are dropped. If the client does not receive an EAP-request/identity frame after three attempts to start
authentication, the client transmits frames as if the port is in the authorized state. A port in the authorized
state means that the client was successfully authenticated. When the client supplies its identity, the
switch begins its role as the intermediary, passing EAP frames between the client and the authentication
server until authentication succeeds or fails. If the authentication succeeds, the switch port becomes
authorized.
The specific exchange of EAP frames depends on the authentication method being used.
Figure 46-2
shows a message exchange that is initiated by the client using the One-Time Password (OTP)
authentication method with an authentication server.
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
46-4
OL_28731-01
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