Method of transmitting information between stations attached to a _unidirectional transmission ring
First Claim
1. Method of transmitting information between stations attached to a unidirectional transmission ring, access to the ring for sending addressed information being given to stations, without frame synchronization, by a circulating frame header and a token indication, characterized in that for allowing both non-periodic transmission of asynchronously furnished data packets as well as periodic transmission of synchronously furnished data blocks:
- a particularly marked frame header for circuit-switched transmission is released as CS frame header by a CS monitor station in periodic intervals,a CS frame header and a free token indication enable only previously authorized stations to send a block of synchronous data,a non-marked frame header with a free token indication, enabling any station to transmit directly over the said unidirectional transmission ring a packet of asynchronous data of arbitrary length is released by the CS monitor station as PS frame header after all blocks of synchronous data due to be sent within a periodic interval from authorized stations were transmitted.
1 Assignment
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Accused Products
Abstract
In a ring communication system comprising several stations, access to the ring is granted to one station at a time by a circulating token indication. A method is provided guaranteeing a transmission opportunity for synchronous or circuit-switched data in periodic time intervals to authorized stations. A CS monitor station issues a frame header which is marked in a specific bit position to allow only authorized stations to transmit their synchronous data together with a destination address. In a first embodiment, a single frame comprises a plurality of slots each having a free/busy indication, a destination address field and a field for synchronous data, and each authorized station can occupy one such slot. In a second embodiment, a marked frame can be used by only one authorized station for transmitting synchronous data, but a new marked frame header is reissued until all authorized stations around the ring have transmitted synchronous data.
101 Citations
11 Claims
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1. Method of transmitting information between stations attached to a unidirectional transmission ring, access to the ring for sending addressed information being given to stations, without frame synchronization, by a circulating frame header and a token indication, characterized in that for allowing both non-periodic transmission of asynchronously furnished data packets as well as periodic transmission of synchronously furnished data blocks:
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a particularly marked frame header for circuit-switched transmission is released as CS frame header by a CS monitor station in periodic intervals, a CS frame header and a free token indication enable only previously authorized stations to send a block of synchronous data, a non-marked frame header with a free token indication, enabling any station to transmit directly over the said unidirectional transmission ring a packet of asynchronous data of arbitrary length is released by the CS monitor station as PS frame header after all blocks of synchronous data due to be sent within a periodic interval from authorized stations were transmitted. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Method of exchanging asynchronous data packets as well as synchronous data blocks in frames between stations attached to a unidirectional transmission ring, which includes for each said station the steps of:
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recognizing a circulating frame header, testing a first control bit (TK) in said header, and setting said first control bit to a first binary value (1) if the station has an asynchronous data packet to be transmitted, and transmitting said data packet if said first control bit had a second binary value (0), and releasing a new frame header including a first control bit having said given first binary value; characterized by the following additional steps; in each said station testing a second control bit (P1) in said frame header, and preventing issuance of a new frame header after transmission of said data packet if said second control bit had a first binary value (1); and in a particular circuit-switch monitor station; issuing a timing signal at periodic intervals, setting said second control bit to said first binary value in the next frame header received after each said periodic timing signal, and issuing a frame header in which a third control bit (CS) is set to a first binary value (1) after receiving a frame end delimiter.
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8. A method of operating a serial data transmission ring which includes a plurality of stations operating at different class of service levels connected in series circuit with each other to form an endless series circuit ring in which data messages emanating from one station traverse the ring and are received in sequence by all of the stations on the ring including the originating station after the data message has passed through all of the other stations said method comprising the steps of:
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generating a message frame which includes a header section having a first indicia (CS) for indicating more than one class of service level, a second indicia (P) for indicating more than one priority or reservation level and a third token indicia (TK) for indicating the state of occupancy of the frame said third token indicia being set at the time of generation to indicate availability of the frame said class of service indicia being set to a predetermined level and said priority or reservation indicia being set to a level corresponding to the predetermined class of service level, at a station requiring transmission capacity examining the header to determine the state of the class of service indicia creating a changed header by and the token indicia, changing the token indicia state, if available, to a not available state when the class of service level indicated by the said first indicia corresponds to the stations class and following the transmission of the said changed header transmitting a data message of variable length, at the said station examining the data received from the serial ring circuit for receipt of the header previously transmitted which has traversed all of the ring stations and issuing a frame header including a free token indicia if the priority or reservation indicia and the class of service indicia correspond. - View Dependent Claims (9, 10, 11)
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Specification