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How Does Authentication Work When Radius Fails Over

  [KB7826] Show Article Properties


Summary:
An external authentication server using Radius with redundant radius servers.
Symptoms:
How does authentication flow when Radius fails on the primary server?
Solution:

By default, when authentication requires proxying to an external radius server, the radius request is first sent to the primary server.  If there is no acceptable response from the primary server, the NetScreen sends the request to the backup1 server.  If backup1 is not reachable, it sends the request to backup2. 

For all radius connections, the NetScreen tries to use the latest active Radius server.  For example, assume the primary radius server fails.  For all subsequent connections, it tries to use the backup1 server.  Even if the primary radius server comes back online, the radius request still goes to the backup1 server, until the backup1 server fails. Then, the primary radius server accepts the authentication requests.

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