Method and apparatus for local area networks
First Claim
1. In a local area network (LAN) wherein a plurality of participating bus interface units (BIUs) are coupled for intercommunication such that each said BIU is permitted to transmit message information in accordance with a network protocol, and wherein each said BIU includes a buffer memory for temporarily storing said information to be transmitted, a method for transmitting said information comprising the steps of:
- (a) each said BIU determining its BIU service time, said service time being the time since the BIU last had access to the bus for transmitting information; and
(b) if said time is at or below a preselected value, transmitting all or up to a first quantum of said stored information and, if said time is above said preselected value, transmitting less than all or up to a second quantum of information, said second quantum being smaller than said first.
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Abstract
An improved method for transmitting messages from the buffers of a bus interface unit participating in a local area network is disclosed wherein the bus interface units are permitted to completely empty their buffers upon each possession of the token and thereby decrease the mean bus waiting time of the network. Further, to optimize network bus waiting time while maintaining an upper limit on BIU service time and thereby guaranteeing each bus interface unit of the network one opportunity to transmit during this upper limit time interval, each bus interface unit of the network monitors the BIU service time to determine when this time reaches the upper limit time interval and, thereafter, limits the quantum of information transmitted from its buffer to thereby prevent the BIU service time from increasing beyond the upper limit time interval.
11 Citations
7 Claims
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1. In a local area network (LAN) wherein a plurality of participating bus interface units (BIUs) are coupled for intercommunication such that each said BIU is permitted to transmit message information in accordance with a network protocol, and wherein each said BIU includes a buffer memory for temporarily storing said information to be transmitted, a method for transmitting said information comprising the steps of:
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(a) each said BIU determining its BIU service time, said service time being the time since the BIU last had access to the bus for transmitting information; and (b) if said time is at or below a preselected value, transmitting all or up to a first quantum of said stored information and, if said time is above said preselected value, transmitting less than all or up to a second quantum of information, said second quantum being smaller than said first. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A bus interface unit (BIU) for interfacing a user with a transmission bus of a token passing local area network, said apparatus comprising:
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(a) transceiver means for transmitting and receiving information to and from said bus; (b) interface means for transmitting and receiving information to and from said user; (c) buffer memory means for temporarily storing information received from said user to be transmitted in said network; (d) control means including means for measuring the rotation time of a token, said token rotation time being the time interval necessary for said token to traverse said bus, and means for controlling the flow of information to and from said transceiver, interface and buffer memory means to permit the transmission of an unlimited quantum of information stored in said buffer memory when said token rotation time is below a predetermined value and to decrease the quantum of information transmitted from said buffer memory when said token rotation time exceeds said predetermined value.
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Specification