Variable speed local area network
First Claim
1. A method for transferring data on a communication medium between a plurality of data processing devices ("agents"), including a sending agent and a receiving agent, comprising the steps of:
- said sending agent transmitting a first signal(RTS) to said receiving agent coupled to said data communication medium at a first speed;
said receiving agent receiving said first signal and generating a second signal(CTS), said second signal including an CTS control character corresponding to a speed for data transfer over said medium, said receiving agent transmitting said control signal on said medium to said sending agent;
said sending agent receiving said second signal and transmitting a data packet to said receiving agent at the speed which corresponds to said CTS control character;
whereby data is transfer between said sending and receiving agents coupled to said communication medium.
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Accused Products
Abstract
A local area network is disclosed including apparatus and methods for transmitting data between a plurality of data processing resources (agents) coupled to a cable. An agent desiring to send data to a receiving agent transmits a request to send (RTS) data packet which includes a control character requesting to either high or low speed data communication. Utilizing the teachings of the present invention, absent other predefined conditions a transmitting agent capable of high speed communication requests a high speed data exchange with the receiving agent. The RTS data packet itself is transmitted at low speed. Upon receiving the RTS packet, the receiving agent must transmit a clear to send (CTS) packet to the transmitting agent within a predetermined time after the receipt of the RTS packet. The CTS packet also includes a control character which either confirms that the data exchange will take place at high speed, or alternatively, a control character which requires a transmitting agent to use the low speed data rate. The transmitting agent, upon receipt of the CTS packet, generates and transmits a data packet to the receiving agent at either a high speed or low speed, depending upon the value of the control character with the CTS packet. The present invention further includes a status table maintained by each agent for tracking the address and communication capability of other agents coupled to the cable.
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Citations
46 Claims
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1. A method for transferring data on a communication medium between a plurality of data processing devices ("agents"), including a sending agent and a receiving agent, comprising the steps of:
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said sending agent transmitting a first signal(RTS) to said receiving agent coupled to said data communication medium at a first speed; said receiving agent receiving said first signal and generating a second signal(CTS), said second signal including an CTS control character corresponding to a speed for data transfer over said medium, said receiving agent transmitting said control signal on said medium to said sending agent; said sending agent receiving said second signal and transmitting a data packet to said receiving agent at the speed which corresponds to said CTS control character; whereby data is transfer between said sending and receiving agents coupled to said communication medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. In a data communication system having a communications medium coupled between a plurality of data processing devices ("agents"), including a sending agent and a receiving agent, an apparatus for transferring data between said agents, comprising:
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transmitting means coupled to each agent to permit said sending agent to transmit a first signal(RTS) at a first speed from said sending agent to said receiving agent coupled to said communications medium; receiving means coupled to each agent to permit said receiving agent to receive said first signal and generate a second signal (CTS), said second signal including an CTS control character corresponding to a speed for data transfer over said medium, said receiving agent transmitting said second signal on said medium to said sending agent; data packet generation means coupled to each agent to permit said sending agent receiving said second signal to generate and transmit a data packet to said receiving agent at the speed which corresponds to said CTS control character; whereby data is transferred between said sending and receiving agents coupled to said communication medium. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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Specification