HP FlexNetwork NJ5000 User Manual page 320

•
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 realtime
accounting requests and stop-accounting requests to the same accounting server. If you
remove the accounting server, realtime 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 realtime accounting interval based on the number of users.
Table 110 Recommended realtime accounting intervals
Number of users
1 to 99
100 to 499
500 to 999
≥1000
Realtime accounting interval (in
minutes)
3
6
12
≥15
308