3.2.6.1 Open Timer Expires

If the Open timer expires, it means that no MSB packets or Beacon packets were received for at least 10 seconds. In this case, the client SHOULD attempt to open the failover URL that is specified in the "Unicast URL" property in the .nsc file. If the "Unicast URL" property is not present or is an empty string, the client SHOULD report a network time-out error to the higher layer.