(PECL radius >= 1.1.0)
radius_add_server — Adds a server
$radius_handle
   , string $hostname
   , int $port
   , string $secret
   , int $timeout
   , int $max_tries
   )
   radius_add_server() may be called multiple times, and it
   may be used together with radius_config(). At most 10
   servers may be specified. When multiple servers are given, they are tried
   in round-robin fashion until a valid response is received, or until each
   server's max_tries limit has been reached.
  
radius_handle
hostname
       The hostname parameter specifies the server host,
       either as a fully qualified domain name or as a dotted-quad IP address
       in text form.
      
port
       The port specifies the UDP port to contact on
       the server. If port is given as 0, the library looks up the
       radius/udp or
       radacct/udp service in the
       network services database, and uses the port found there.  If no entry
       is found, the library uses the standard Radius ports, 1812 for
       authentication and 1813 for accounting. 
      
secret
       The shared secret for the server host is passed to the
       secret parameter. The Radius protocol ignores
       all but the leading 128 bytes of the shared secret.
      
timeout
       The timeout for receiving replies from the server is passed to the
       timeout parameter, in units of seconds.  
      
max_tries
       The maximum number of repeated requests to make before giving up is
       passed into the max_tries.
      
   Returns TRUE on success or FALSE on failure.
  
Example #1 radius_add_server() example
<?php
if (!radius_add_server($res, 'radius.example.com', 1812, 'testing123', 3, 3)) {
    echo 'RadiusError:' . radius_strerror($res). "\n<br>";
    exit;
}
?>