Communication control unit switched between active and stand-by functions automatically in response to monitored status of a different communication control unit connected to a common network

A communication control system, comprising:

• a first communication control unit functioning as an active unit and connected through a corresponding line to a communications network;
• a second communication control unit connected through a corresponding, different line to the communication network and functioning as a stand-by unit and to monitor the active communication control unit;
• and
• the stand-by second communication control unit switches with the active, different communication control unit and functions as the active unit, without disconnecting the corresponding line, when the active, different, first communication control unit does not return an expected response to an ID check request.

A method for controlling the switching of communication control units connected over a common network, comprising:

• sending an ID verification request from a stand-by, first communication control unit to the communication network with an address identifying an active, second communication control unit;
• monitoring if the active, second communication control unit has responded to an ID check request from the communication network;
• and
• switching from the active, first communication control unit to the stand-by, second communication control unit to function as the active unit and without disconnecting the first communication control unit from the communication network when it is found, as a result of the monitoring, that the active, first communication control unit has not returned the expected response.

A communication control unit connected to a communication network and selectively functioning as an active unit or a stand-by unit, comprising:

• means for sending a signal to the communication network with an address identifying a different communication control unit as the active unit when the respective unit is used as the stand-by unit;
• means for monitoring if the different, active communication control unit responds with a response signal to the signal from the communication network;
• and
• means for switching from the active, different communication control unit to the stand-by, respective unit and using the respective unit as the active unit without disconnecting the active, different communication control unit from the network when it is found, as a result of the monitoring, that the active, different communication control unit has not returned the expected response.

A communication control unit connectable to a communication network, having an ID verification function and used as an active unit or a stand-by unit, comprising:

• a send unit sending an ID verification request to the communication network with an address identifying a different communication control unit, connected to the communication network as an active communication control unit, when the respective communication control unit is used as a stand-by unit;
• a monitor monitoring if the active, different communication control unit responds to an ID check request from the communication network in response to the ID verification request;
• and
• a switch switching the respective communication control unit, when used as a stand-by unit, to take over the process of the active, different communication control unit and without disconnecting the active, different communication control unit from the communication network, when the active, different communication control unit does not return the expected response.

A communication control apparatus, comprising:

• at least one communication control unit operating as an initial active unit;
• at least one communication control unit operating as an initial stand-by unit wherein said stand-by communication control unit is used to monitor the initial active communication control unit;
• and
• said initial stand-by communication control unit switches with the initial active communication control unit and is used as a current active unit without disconnecting the initial active unit when the initial active communication control unit does not return an expected response to an ID check request.

A method for controlling the switching of communication control units, comprising:

• connecting an active communication control unit and a stand-by communication control unit to a common network;
• sending an ID verification request from the stand-by communication control unit to the communication network with an address identifying the active communication control unit;
• monitoring if the active communication control unit has responded to an ID check request from the communication network;
• and
• switching from the active communication control unit to the stand-by communication control unit without disconnecting the active communication control unit from the communication network when it is found, as a result of the monitoring, that the active communication control unit has not returned the expected response.

A communication control unit connected to a communication network and used as an active unit or a stand-by unit, comprising:

• a unit sending a signal to the communication network with an address identifying another communication control unit connected to the communication network as an active communication control unit when the subject communication control unit is used as a stand-by unit;
• a monitor monitoring if the active communication control unit responds with a response signal to the signal from the communication network;
• and
• a switch operating, when the subject communication control unit is used as a stand-by unit, to cause the subject communication control unit to take over the process of the active communication control unit without disconnecting the active communication control unit from the communication network when it is found as a result of the monitoring that the active communication control unit does not return the expected response.