6-21
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-03
Chapter6 Administering the Swi tc h Controlling Switch Access with RADIUS
If two different host entries on the same RADIUS server are configured for the same service—for
example, accounting—the second host entry configur ed acts as a fail-over backup to the first one. Using
this example, if the first host entry fails to provide accounting services, the switch tries the second host
entry configured on the same device for accounting services. (The RADIUS host entri es are tried in the
order that they are configured.)
A RADIUS server and the switch use a shared secret text string to encrypt passwords and exchan ge
responses. To configure RADIUS to use the AAA security commands, you must specify the host running
the RADIUS server daemon and a secret text (key) string that it shares with the switch.
The timeout, retransmission, and encryption key values ca n b e conf ig ured glob al ly for al l RA DIU S
servers, on a per-server basis, or in some combination of global and per-server s ettings. To apply these
settings globally to all RADIUS servers communicating with the switch, use the three unique global
configuration commands: radius-server timeout, radius-server retransmit, and radius-server key.
To apply these values on a specific RADIUS server, use the radius-server host global configuration
command.
Note If you configure both global and per-server functions (timeout, re transm issi on, a nd key
commands) on the switch, the per-server timer, retransmission, and key value commands
override global timer, retransmission, and key value commands. For information on
configuring these setting on all RADIUS servers, see the “Configuring Settings for All
RADIUS Servers” section on page 6-28.
You can configure the switch to use AAA server g roups to gr oup existing se rver hosts for authentic ation.
For more information, see the “Defining AAA Server Groups” section on page 6-24.
Beginning in privileged EXEC mode, follow these steps to confi gure pe r-server RAD IUS se rv er
communication. This procedure is required.