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CHAPTER 5: SYSTEM CONFIGURATION
Secondary Radius Server Setup – Configure a secondary RADIUS server to provide
a backup in case the primary server fails. The access point uses the secondary
server if the primary server fails or becomes inaccessible. Once the access point
switches over to the secondary server, it periodically attempts to establish
communication again with primary server. If communication with the primary
server is re-established, the secondary server reverts to a backup role.
VLAN ID Format – A VLAN ID (a number between 1 and 4094) can be assigned to
each client after successful authentication using IEEE 802.1X and a central
RADIUS server. The user VLAN IDs must be configured on the RADIUS server for
each user authorized to access the network. VLAN IDs can be entered as
hexadecimal numbers or as ASCII strings.
AUTHENTICATION
Wireless clients can be authenticated for network access by checking their MAC
address against the local database configured on the access point, or by using a
database configured on a central RADIUS server. Alternatively, authentication can
be implemented using the IEEE 802.1X network access control protocol.
A client’s MAC address provides relatively weak user authentication, since MAC
addresses can be easily captured and used by another station to break into the
network. Using 802.1X provides more robust user authentication using user
names and passwords or digital certificates. You can configure the access point to
use both MAC address and 802.1X authentication, with client station MAC
authentication occurring prior to IEEE 802.1X authentication. However, it is better
to choose one or the other, as appropriate.
IEEE 802.1X is a standard framework for network access control that uses a
central RADIUS server for user authentication. This control feature prevents
unauthorized access to the network by requiring an 802.1X client application to
submit user credentials for authentication. The 802.1X standard uses the
Extensible Authentication Protocol (EAP) to pass user credentials (either digital
certificates, user names and passwords, or other) from the client to the RADIUS
server. Client authentication is then verified on the RADIUS server before the
access point grants client access to the network.
The 802.1X EAP packets are also used to pass dynamic unicast session keys and
static broadcast keys to wireless clients. Session keys are unique to each client and
are used to encrypt and correlate traffic passing between a specific client and the
access point. You can also enable broadcast key rotation, so the access point
provides a dynamic broadcast key and changes it at a specified interval.