providing a specific AAA service. This unique identifier enables RADIUS requests to be sent to multiple
UDP ports on a server at the same IP address.
If two different host entries on the same RADIUS server are configured for the same service—for example,
accounting—the second host entry configured acts as a fail-over backup to the first one. Using this example,
if the first host entry fails to provide accounting services, the %RADIUS-4-RADIUS_DEAD message appears,
and then the switch tries the second host entry configured on the same device for accounting services. (The
RADIUS host entries 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 exchange 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 can be configured globally for all RADIUS servers,
on a per-server basis, or in some combination of global and per-server settings.
Related Topics
Identifying the RADIUS Server Host, on page 83
Defining AAA Server Groups, on page 88
Configuring Settings for All RADIUS Servers, on page 93
Configuring RADIUS Login Authentication, on page 86
RADIUS Login Authentication
To configure AAA authentication, you define a named list of authentication methods and then apply that list
to various ports. The method list defines the types of authentication to be performed and the sequence in which
they are performed; it must be applied to a specific port before any of the defined authentication methods are
performed. The only exception is the default method list. The default method list is automatically applied to
all ports except those that have a named method list explicitly defined.
A method list describes the sequence and authentication methods to be queried to authenticate a user. You
can designate one or more security protocols to be used for authentication, thus ensuring a backup system for
authentication in case the initial method fails. The software uses the first method listed to authenticate users;
if that method fails to respond, the software selects the next authentication method in the method list. This
process continues until there is successful communication with a listed authentication method or until all
defined methods are exhausted. If authentication fails at any point in this cycle—meaning that the security
server or local username database responds by denying the user access—the authentication process stops, and
no other authentication methods are attempted.
Related Topics
Configuring RADIUS Login Authentication, on page 86
AAA Server Groups
You can configure the switch to use AAA server groups to group existing server hosts for authentication. You
select a subset of the configured server hosts and use them for a particular service. The server group is used
with a global server-host list, which lists the IP addresses of the selected server hosts.
Server groups also can include multiple host entries for the same server if each entry has a unique identifier
(the combination of the IP address and UDP port number), allowing different ports to be individually defined
as RADIUS hosts providing a specific AAA service. This unique identifier enables RADIUS requests to be
Catalyst 2960-X Switch Security Configuration Guide, Cisco IOS Release 15.0(2)EX
70 OL-29048-01
Configuring RADIUS
RADIUS Login Authentication
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