Importance

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Abstract

The invention provides a method for resolving a data packet collision in a local network where a plurality of nodes which respectively comprise processors and terminal equipment utilize a single transmission line in accordance with a contention system. A contention phase is initiated unless a collision occurs. When a collision occurs, a resolution phase is initiated. The nodes which have been performing transmission immediately stop transmission. They discriminate their positions on the transmission line before a time interval (2.times.maximum transmission delay time interval) elapses from the start of transmission. If no signal is received by a given node from the left, the given node is regarded as the leftmost node among the conflicting nodes. The leftmost node immediately starts transmitting a packet. Other nodes except for the leftmost node stop retransmitting the packets. The nodes which have performed retransmission are stopped until the resolution phase is completed. The nodes except for the leftmost node receive retransmitted packets and immediately send out short reservation signals to the right. A node which does not receive the reservation signal from any other node during the reservation signal transmission is the leftmost node among the nodes which may not perform retransmission, and performs retransmission immediately after the reservation signal is sent out. Retransmission of the packet and transmission of the reservation signal are repeated. When the final conflicting node finishes retransmission, all of the nodes complete transmission. Each node continuously monitors the transmission line. When a nonsignalling period continues for more than a given time period (2.times.maximum propagating delay time interval), another contention phase is initiated.

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First Claim