HP 1920 Gigabit Ethernet Switch Series User Manual page 392

If you remove the accounting server used for online users, the device cannot send real-time
•
accounting requests and stop-accounting messages for the users to the server, and the
stop-accounting messages are not buffered locally.
• The status of RADIUS servers, blocked or active, determines which servers the device will
communicate with or turn to when the current servers are not available. In practice, you can specify
one primary RADIUS server and multiple secondary RADIUS servers, with the secondary servers
that function as the backup of the primary servers. Typically, the device chooses servers based on
these rules:
When the primary server is in the active state, the device communicates with the primary server.
If the primary server fails, the device changes the state of the primary server to blocked, starts
a quiet timer for the server, and turns to a secondary server in the active state (a secondary
server configured earlier has a higher priority). If the secondary server is unreachable, the
device changes the state of the secondary server to blocked, starts a quiet timer for the server,
and continues to check the next secondary server in the active state. This search process
continues until the device finds an available secondary server or has checked all secondary
servers in the 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 device does not check the server again during the authentication or
accounting process. If no server is found reachable during one search process, the device
considers the authentication or accounting attempt a failure.
Once the accounting process of a user starts, the device 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
can no longer be delivered to the server.
If you remove an authentication or accounting server in use, the communication of the device
with the server will soon time out, and the device will look for a server in the active state by
checking any primary server first and then the secondary servers in the order they are
configured.
When the primary server and secondary servers are all in the blocked state, the device
communicates with the primary server. If the primary server is available, its statues changes to
active. Otherwise, its status remains to be blocked.
If one server is in the active state but all the others are in the blocked state, the device only tries
to communicate with the server in the active state, even if the server is unavailable.
After receiving an authentication/accounting response from a server, the device 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.
Set a proper real-time accounting interval based on the number of users.
•
Table 117 Recommended real-time accounting intervals
Number of users
1 to 99
100 to 499
500 to 999
≥1000
Real-time accounting interval (in minutes)
3
6
12
≥15
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