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Method of and apparatus for realizing priority data transmissions for CSMA/CD system

  • US 6,501,764 B1
  • Filed: 11/18/1998
  • Issued: 12/31/2002
  • Est. Priority Date: 03/11/1998
  • Status: Expired due to Fees
First Claim
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1. A method of realizing priority data transmission for a CSMA/CD system, comprising the steps of:

  • checking to see if a transmission line has a free space in response to a data transmission request from a node serving as a source node;

    transmitting, if the transmission line has a free space, a priority transmission notice carried by a data-link-layer protocol signal of the CSMA/CD system from the source node directly to the other nodes;

    putting the nodes except the source node in a transmission-disabled, reception-enabled state when the priority transmission notice is received by the nodes; and

    transmitting data for which the data transmission request has been made from the source node to a node serving as a destination node, the method being performed without the use of an arbitration device external to the source node and the other nodes, wherein;

    the data-link-layer protocol signal of the CSMA/CD system is a MAC frame signal; and

    the MAC frame signal has a frame type field or an LLC header field, either of the fields being used to carry at least one of;

    (1) the priority transmission notice, (2) a priority assigned to the source node, and (3) a release notice releasing the nodes from the transmission-disabled, reception-enabled state when the transmission of data, for which the data transmission request has been made, has been completed.

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