Patent ID: 6501764
Filing Date: 2002-12-31
Classification: H04L

Abstract:
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.