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Monitoring system of network

  • US 4,891,639 A
  • Filed: 06/23/1988
  • Issued: 01/02/1990
  • Est. Priority Date: 07/01/1987
  • Status: Expired due to Term
First Claim
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1. A network monitoring system in which a plurality of data transmitting apparatuses are connected to a communication medium and only one of said plurality of data transmitting apparatuses to which a communication right was transferred can acquire a transmission right of data, each of said plurality of data transmitting apparatuses being capable of operating in a normal operating mode and a communication medium monitoring mode, wherein each data transmitting apparatus can receive and transmit data in the normal mode, and can receive data determined to be transmitted to any one of said plurality of data transmitting apparatuses but cannot transmit data in the communication medium monitoring mode, each of said plurality of data transmitting apparatus comprising:

  • first discriminating means for discriminating, in the normal operating mode, whether received data is addressed to said data transmitting apparatus;

    second discriminating means for discriminating whether the received data discriminated to be addressed to said data transmitting apparatus by said first discriminating means includes a communication right transfer instruction;

    memory means for discriminating and storing a communication medium monitoring instruction; and

    control means for, when the communication medium monitoring instruction is stored in said memory means, changing from the normal operating mode to the communication medium monitoring mode, transmitting the communication right transfer instruction to a downward data transmitting apparatus, and instructing an upward data transmitting apparatus previously having said data transmitting apparatus as the destination of the communication right transfer instruction to change the destination of the communication right transfer instruction.

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