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are no longer available. In practice, you can specify one primary RADIUS server and multiple secondary
RADIUS servers, with the secondary servers functioning as the backup of the primary servers. Generally,
the switch chooses servers based on these rules:
•
When the primary server is in active
state, the switch communicates with the primary server. If the
primary server fails, the switch changes the server’s status to blocked and starts a quiet timer for the
server, and then turns to a secondary server in active state (a secondary server configured earlier
has a higher priority). If the secondary server is unreachable, the switch changes the server’s status
to blocked, starts a quiet timer for the server, and continues to check the next secondary server in
active state. This search process continues until the switch finds an available secondary server or
has checked all secondary servers in active state. If the quiet timer of a server expires or an
authentication or accounting response is received from the server, the status of the server changes
back to active automatically, but the switch does not check the server again during the
authentication or accounting process. If no server is found reachable during one search process,
the switch considers the authentication or accounting attempt a failure.
•
Once the accounting process of a user starts, the switch keeps sending the user’s real-time
accounting requests and stop-accounting requests to the same accounting server. If you remove the
accounting server, real-time accounting requests and stop-accounting requests for the user are no
longer delivered to the server.
•
If you remove an authentication or accounting server in use, the communication of the switch with
the server soon times out, and the switch looks for a server in active state from scratch by checking
any primary server first and then secondary servers in the order they are configured.
•
When the primary server and secondary servers are all in blocked
state, the switch communicates
with the primary server. If the primary server is available, its status changes to active. Otherwise, its
status remains to be blocked.
•
If one server is in active state and all the others are in blocked state, the switch only tries to
communicate with the server in active state, even if the server is unavailable.
•
After receiving an authentication/accounting response from a server, the switch changes the status
of the server identified by the source IP address of the response to active if the current status of the
server is blocked.
The device does not change the status of an unreachable authentication or accounting server if the server
quiet timer is set to 0. Instead, the device keeps the server status as active and sends authentication or
accounting packets to another server in active state, so subsequent authentication or accounting packets
can still be sent to that server. For more information about the server quiet timer, see "
controlling communication with HWTACACS servers
By default, the switch sets the status of all RADIUS servers to active. In cases such as a server failure, you
can change the status of the server to blocked to avoid communication with the server.
To set the status of RADIUS servers in a RADIUS scheme:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RADIUS scheme
view.
radius scheme
radius-scheme-name
N/A
