Network availability status detection device and method

Abstract

According to an embodiment of the present invention, a device configured to send and receive messages over a first network and a second network includes a network status detector unit and a network disabling unit. The network status detector unit is configured to detect the availability of the first network and output a first network status signal indicating the availability or unavailability of the first network. The network disabling unit is configured to receive the first network status signal and disable the sending and receiving of messages on the second network when the first network status signal indicates the first network is unavailable.

1 . A first network device, comprising:
 a message sending and receiving unit configured to send a status request message to a target network device, the message sending and receiving unit being configured to receive a status reply message from the target network device having received the status request message, the first network device being disposed at a predetermined first location in a hierarchical network comprising a plurality of interconnected network segments, the target network device being disposed at a predetermined second location in the hierarchical network that is different from the first location along a first network path; and   a timer unit configured to determine an elapsed time between the sending of the status request message and the receiving of the status reply message along the first network path, the timer unit being configured to output a first network path status signal indicating one of the availability and unavailability of the first network path based on the elapsed time.   
     
     
         2 . The first network device of  claim 1 , wherein the first network path includes at least two predetermined network segments for sending and receiving network messages being disposed between the first network device and the target network device. 
     
     
         3 . The first network device of  claim 1 , wherein the status request message is sent at a predetermined periodic interval. 
     
     
         4 . The first network device of  claim 1 , wherein the first network path status signal indicates availability when the elapsed time is less than a predetermined timer limit value. 
     
     
         5 . The first network device of  claim 1 , wherein the first network path includes at least one essential network comprising the only possible interconnecting network segment between the first network device and the target network device. 
     
     
         6 . The first network device of  claim 1 , further comprising:
 a status indicator configured to portray the availability of the first network path based on the first network path status signal.   
     
     
         7 . In a first network device configured to send and receive messages over a first network, a method comprising:
 sending a status request message to a target network device, the first network device being disposed at a predetermined first location in a hierarchical network comprising a plurality of interconnected network segments, the target network device being disposed at a predetermined second location in the hierarchical network that is different from the first location along a first network path;   initializing a timer count value to a first timer count value; and   repeating a second method until a first network path status signal is asserted as one of available or unavailable, the second method comprising:
 comparing the timer count value to a timer limit value; 
 asserting a first network path status signal as unavailable when the timer count value is greater than the timer limit value; 
 detecting the receipt of a status reply message from the target network device; 
 asserting a first network path status signal as available when the timer count value is less than the timer limit value and the status reply message is received from the target network device; and 
 advancing the timer count value. 
   
     
     
         8 . The method of  claim 7 , wherein the sending of a status request message occurs at a predetermined periodic interval. 
     
     
         9 . The method of  claim 7 , wherein the first network path includes at least two predetermined network segments for sending and receiving network messages disposed between the first network device and the target network device. 
     
     
         10 . The method of  claim 7 , further comprising:
 asserting a status indicator configured to portray the availability status of the first network path when the first network path status signal indicates availability of the first network path.   
     
     
         11 . The method of  claim 7 , wherein the first network path includes at least one essential network segment comprising the only possible interconnecting network segment between the network device and the target device.