Multiplex communications – Wide area network – Packet switching
Patent
1989-03-20
1991-03-12
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
371 32, H04J 326
Patent
active
049998340
ABSTRACT:
A method of communicating between a primary station and a secondary station wherein variable sized packets of information are transferred asynchronously (or in start/stop mode) between the primary station and the secondary station. A communication control (e.g., "BREAK" in the preferred embodiment) indicates the end of each packet. To permit the high speed transfer of data, the secondary station receives a high-speed clocking signal externally, from the primary in the preferred embodiment. The primary station generates and transmits a sequence number in connection with each packet, and the secondary responds to each packet with a status, but without generating a sequence number of its own or transmitting a sequence number. The primary station responds to the lack of a response from the secondary station by resending a transmission, while the secondary station responds to a duplicate transmission by ignoring the second transmission, and responds by resending the status from the previous transmission (which may not be the current status). This method using a minimum of overhead insures that the secondary station only proceeds after it has successfully transmitted its last status to the primary, thus guaranteeing that dynamically changing status will not be lost.
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patent: 4601035 (1986-07-01), Marzec et al.
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Data Communications Concepts . . . IBM GC21-5169-6.
Leo Robert P.
McColgan Mark W.
Stockman, III James E.
Young Jeffrey H.
International Business Machines - Corporation
Marcelo Melvin
Olms Douglas W.
Seaman Kenneth A.
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