Data communication system capable of bypassing malfunctioning relay units

A communication control unit for a data communication system having a network comprising a central facility, a plurality of relay units, and a plurality of terminal units, wherein bi-directional data communication is established between at least one of said central facility and each of said plurality of relay units, two of said plurality of relay units, and each of said plurality of relay units and each of said plurality of terminal units, and wherein at least one of said plurality of relay units relays down-stream data originated from said central facility to a designated terminal unit or up-stream data originated from said designated terminal unit to said central facility, the communication control unit comprising:

• reception means for receiving traffic information from each of said plurality of relay units, said traffic information representative of a condition of data transmission;
• threshold value storage means for storing at least one predetermined threshold value, each predetermined threshold value corresponding to at least one of said plurality of relay units;
• high-load determining means for comparing, for at least one of said plurality of relay units, said traffic information received through said reception means with a corresponding one of the at least one threshold value stored in said threshold value storage means and for determining whether the at least one relay unit is in a high-load condition;
• detection means for detecting relay units and terminal units that are programmed to send data to a high-load relay unit which is determined by said high-load determining means to be in the high-load condition;
• and
• bypassing means for bypassing said high-load relay unit when said relay units and terminal units attempt to send the data to said high-load relay unit.

A data communication system, comprising:

• a network in which a plurality of relay units connect a central facility with a plurality of terminal units, each of said plurality of relay units and each of said plurality of terminal units provided with a predetermined internal program according to which ones of said relay units and terminal units that can communicate are determined, wherein at least one of said plurality of relay units relays down-stream data originated from said central facility to a designated terminal unit or up-stream data originated from said designated terminal unit to said central facility;
• and
• a communication control unit comprising:
• reception means for receiving traffic information from each of said plurality of relay units, said traffic information representative of a condition of data transmission,
• threshold value storage means for storing at least one predetermined threshold value, each predetermined threshold value corresponding to at least one of said plurality of relay units,
• high-load determining means for comparing, for at least one of said plurality of relay units, said traffic information received through said reception means with a corresponding threshold value stored in said threshold value storage means and for determining whether the at least one relay unit is in a high-load condition,
• detection means for detecting relay units and terminal units that are programmed to send data to a high-load relay unit which is determined by said high-load determining means to be in the high-load condition, and
• setting means for setting at least one alternative relay unit for the high-load relay unit, said relay units and terminal units sending the data to said at least one alternative relay unit in place of said high-load relay unit.

A communication control unit for a data communication system having a network comprising a central facility, a plurality of relay units, and a plurality of terminal units, wherein bi-directional data communication is established between at least one of said central facility and each of said plurality of relay units, two of said plurality of relay units, and each of said plurality of relay units and each of said plurality of terminal units, and wherein at least one of said plurality of relay units relays at least one of down-stream data originated from said central facility to a designated terminal unit and up-stream data originated from said designated terminal unit to said central facility, the communication control unit comprising:

• reception means for receiving traffic information at a predetermined interval from each of said plurality of relay units, said traffic information representative of a condition of data communication;
• threshold value storage means for storing at least one predetermined threshold value, each predetermined threshold value corresponding to at least one of said plurality of relay units;
• high-load determining means for comparing, for at least one subject relay units, said traffic information received through said reception means with a corresponding threshold value stored in said threshold value storage means and for determining whether each of the at least one relay unit is in a high-load condition;
• detection means for detecting ones of said central facility, said plurality of relay units and said plurality of terminal units that are programmed to send data to each of said at least one subject relay unit that is in the high-load condition;
• and
• setting means for setting at least one alternative relay unit in place of each of said at least one subject relay unit which is determined by said high-load determining means to be in the high-load condition, and for reprogramming said ones of said central facility, said plurality of relay units and said plurality of terminal units to select said at least one alternative relay unit for each of said at least one subject relay unit that is in the high-load condition.