Inter-processor communication protocol

Claim 2

A station (101) for a system (FIG. 1) having a communication medium (150) and a plurality of the stations communicatively connected to the medium, the station characterized by: first means (100:1301-1305 and 1314), for seeking access to the medium according to either one of a first and a second priority associated with the station, the second priority being higher than the first priority; second means (110:1306-1308), responsive to gaining of sought access by the first means, for transmitting messages of either one of a first and a second type on the medium to other stations; third means (110:923 and 1410-1412) for storing messages of the first type received on the medium from other stations; fourth means (110:918 and 1410-1412), for storing, separately from messages of the first type, messages of the second type received on the medium from other stations; fifth means (144, FIGS. 8-11), for causing the first means to seek medium access according to the first priority and causing the second means to transmit a message of the first type: and sixth means (143, FIGS. 18-20), responsive to a message stored in the third means and received from a second station, for causing the first means to seek medium access according to the second priority and causing the second means to transmit a message of the second type to the second station.

Claim 3

The station of claim 1 characterized in that the third means include seventh means (1214:1411), for determining whether a message being stored in the third means is affected by a condition of a first type, and eighth means (1214:1412), cooperative with the seventh means, for sending a first signal on the medium when a message is determined to be affected by a condition of the first type; and the fifth means include ninth means (618, 620), responsive to receipt of a first signal on the medium for causing retransmission of a message of the first type transmitted by the second means during receipt of the first signal.

Claim 4

The station of claim 2 characterized in that the sixth means include: tenth means (143) for storing information representing messages removed from the third means; eleventh means (1504, 1515, FIG. 19) for removing from the third means a message stored therein and received from a second station; twelfth means (1514) for determining whether the removed message is affected by a condition of a second type; thirteenth means (FIG. 19), for selectively storing information representing the removed message in the tenth means if the removed message is determined to not be affected by a condition of the second type, and for discarding the removed message if it is determined to be affected by a condition of the second type; and fourteenth means (1532, 1545, 1547) for causing the first means to seek medium access according to the second priority and causing the second means to transmit to the second staton a message of the second type conveying a positive acknowlegment of the removed message if the remove message is determined to not be affected by a condition of the second type, and for causing the first means to seek medium access according to the second priority and causing the second means to transmit to the second station a message of the second type conveying a negative acknowledgment of the removed message if the removed message is determined to be affected by a condition of the second type and the eighth meands did not send a first signal on the medium during receipt of the affected message.

Claim 5

The station of claim 2 characterized in that the sixth means include: tenth means (143) for storing information representing messages removed from the third means; eleventh means (1504, 1515, FIG.19) for removing from the third means a message stored therein and received from a second station; twelfth means (1505, 1509, 1514, 1518) for determining whether the removed message is affected by a condition of a second type, the second type conditions including conditions of the first type; thirteenth means (1504, 1515, 1506, 1526, 1508, 1510, 1516, 1517, 1501 1550, 1519, 1520, 1508, 1530) for storing information representing the removed message in the tenth means if the removed message is determined to not be affected by a condition of the second type, and for discarding the removed message if it is determined to be affected by a condition of the second type; and fourteenth means (1502, 1532, 1545, 1547) for causing the first means to seek medium access according to the second priority and causing the second means to transmit a message of the second type to the second station if the removed message is determined to not be affected by a condition of the first type.

Claim 6

The staton of claim 3 characterized in that the fifth means include: a plurality of fifteenth means (144), each for association with a different tenth means of other stations, for storing information representing messages for transmission by the second means to associated tenth means; sixteenth means (621-623), responsive to storing by the fourth means of a message, for removing the stored message from the fourth means to determine which acknowledgment is conveyed thereby; seventeenth means (624, 625), cooperative with the sixteenth means, for deleting from a tenth means information represinting the message acknolwedged by the message removed from the fourth means, if the acknowledgment is determined to be positive, and for postponing transmission of messages represented by information stored by a tenth means storing information representing the message acknowledged by the message removed from the fourth means, if the acknowledgment is determined to be negative.

Claim 7

The staton of claim 1 characterized in that the sixth means comprise seventh means (1504, 1514, 1515, FIG. 19) for determining whether a message stored in the third means and received from a second station is affected by a condition of a first type, and eighth means (1502, 1532, 1545, 1547), cooperative with the seventh means, for causing the first means to seek medium access according to the second priority and causing the second means to transmit to the second station a message of the second type conveying a positive acknowledgment of the message stored in the third means and received from the second station if the acknowledged message is determined to not be affected by a condition of the first type, and further for causing the first means to seek medium access according to the second priority and causing the second means to transmit to the second station a message of the second type conveying a negative acknowledgment of the message stored in the third means and received from the second staton if the acknowledged message is determined to be affected by a condition of the first type; and the fifth means comprise ninth means (621-625) responsive to a message stored by the fourth means and conveying a negative acknowledgment of a message for causing retransmission of the negatively-acknowledged message.

Claim 8

The station of claim 6 characterized in that the sixth means comprise tenth means (143), for storing information representing messages removed from the third means; the seventh means comprise eleventh means (1504, 1515, FIG.19) for removing from the third means a message stored therein; twelfth means (1514), for determining whether the removed message is affected by a condition of a first type, and fourteenth means (FIG. 19), for selectively storing information representing the removed message in the tenth means if the removed message is determined to not be affected by a condition of the first type, and further for discarding the removed message if the removed message is determined to be affected by a condition of the first type.

Claim 9

The station of claim 7 characterized in that the fifth means comprise a plurality of fifteenth means (142), each for association with a different tenth means of other stations, for storing information representing messages for transmission by the second means to associated eight means; and the ninth means comprise sixteenth means (621-623), responsive to storing by the fourth means of a message, for removing the stored message from the fourth means to determine which acknowledgment is conveyed thereby, and seventeenth means (624, 625), cooperative with the sixteenth means, for deleting from a fifteenth means information representing the message acknowledged by the message removed from the fourth means, if the acknowledgment is determined to be positive, and for postponing transmission of messages represented by information stored by a fifteenth means storing information representing the message acknowledged by the message removed from the fourth means, if the acknowledgment is determined to be negative.

Claim 10

The station of claim 1 wherein the medium defines a plurality of logical communicaton paths (200,201), characterized in that the fifth means include a plurality of output queues (144), each for association with different logical paths extending to other stations of the plurality of stations of the communication system, each output queue for storing entries (317) each defining a packet of a first type for transmission across an associated logical path; the sixth means include a plurality of input queue (143), each for association with different logical paths extending from output queues of other stations of the plurality of stations of the communicaton system, each input queue for storing entries (354) each representing a packet of the first type received across an associated logical path; the second means include first memory means (921) for buffering packets for transmission on the medium; the third means include second memory means (923) for buffering packets of the first type received on the medium; the fourth means include third memory means (918) for buffering packets of a second type received on the medium; the fifth means further include seventh means (FIGS. 8-11), for storing in the first memory means a packet defined by an entry of an output queue and identifying the output queue's associated logical path; the first means include eighth means (1211, 1212, 1214:1301-1305 and 1314), responsive to storage in the first memory means of a packet of the first type, for contending for access to the medium according to a first priority associated with the station, and further responsive to storage in the first memory means of a packet of a second type, for contending for access to the medium according to a second priority associated with the station and higher than the first priority; the second means further include ninth means (1214:1306-1308), responsive to gaining of access to the medium by the second operative means, for transmitting on the medium the packet stored in the first memory means; the third means further include tenth means (1214:1410-1412), responsive to receipt on the medium of a packet of the first type, for storing the received packet in the second memory means, and responsive to receipt on the medium of a packet of the second type, for storing the received packet in the third memory means; and the sixth means further include eleventh means (FIGS. 18-20), for removing a received packet from the second memory means and in response to the removed packet forming in the input queue associated with the logical path identified by the removed packet an entry representing the removed packet, and twelfth means (1502, 1532, 1545-1547, FIG. 21), cooperative with the eleventh means, for storing in the first memory means a packet of the second type acknowledging the removed packet.

Claim 11

The station of claim 9 characterized in that the eleventh means comprise thirteenth means (1514), for determining whether the removed packet is affected by occurrence of a first condition, and fourteenth means (FIG. 19), cooperative with the thirteenth means, for storing in the input queue associated with the logical path identified by the removed packet an entry defining the removed packet, if the removed packet is determined to not be affected by occurrence of a first condition, and for discarding the removed packet, if the removed packet is determined to be affected by occurrence of a first condition; the twelfth means comprise fifteenth means (1532, 1545-1547, FIG. 21), cooperative with the thirteenth means, for storing in the first memory means a packet of the second type conveying a positive acknowledgment of the removed packet, if the removed packet is determined to not be affected by occurrence of a first condition, and for storing in the first memory means a packet of the second type conveying a negative acknowledgment of the removed packet, if the removed packet is determined to be affected by occurrence of a first condition; the fifth means further comprise sixteenth means (622-625), for removing a received packet of the second type from the third memory means and in response to the removed packet deleting from an output queue an entry defining the acknowledged packet of the first type, if the removed packet conveys a positive acknowledgment, and further in response to the removed packet postponing transmission of packets defined by entries of the output queue, if the removed packet conveys a negative acknowledgment.

Claim 14

The method of claim 11 characterized in that step (e) comprises the steps of (g) determing (154) whether the message received by the first storage means of the second staton is affected by a condition of a first type, (h) in response to determining at step (g) that the received message is affected, discarding (1530) the affected message at the second station, (i) upon gaining access to the medium, transmitting (1545, 1547, FIG. 21) from the second station to the first station a message of the second type conveying a positive acknowledgement of the receive message of the first type, if the received message is determined to not be affected by a condition of the first type, and (j) upon gaining access to the medium, transmitting (1532, FIG. 21) from the second station to the first station a message of the second type conveying a negative acknowledgment of the received message of the first type, if the received message is determined to be affected by a condition of the first type; and step (f) includes the step of (k) in response to receipt of the message of the second type conveying a negative acknowledgment, repeating (FIGS. 8-11) steps (a) and (b) at the first station to retransmit the negatively-acknowledged transmitted message to the second station.

Claim 15

The method of claim 11 wherein the plurality of statons have storage means (918, 921, 923) and input and output queues (143, 144) and the communication medium defines a plurality of logical communication paths (200, 201), characterized in that step (a) comprises the steps of forming (FIGS. 9-10) in first storage means (921) of a first station a packet of a first type from an entry of an output queue (144) of a plurality of output queues each associated with different logical paths extending from the first station to other stations, each output queue for storing entries each defining a packet of a first type for transmission across an associated logical path, the packet identifying the queue's associated logical path, and in response to formation of the packet in the first storage means, seeking access (1301-1305, 1314) at the first station to the medium according to a first priority, of the first and a higher second priority associated with the first station; step (b) comprises the step of upon gaining access to the medium, transmitting (1306-1308) the formed packet from the first storage means on the medium to a second station; step (c) comprises the steps of receiving (FIG. 17) the transmitted packet of the first type at the second station in a second storage means (923), the second station having the second storage means for receiving packets of the first type and having third storage means for separately receiving packets of a second type, and forming (FIG. 19) an entry, representing a packet of the first type received in the second storage means, in an input queue (143) associated with the logical path identified by the received packet, the input queue being of a plurality of input queues each associated with different logical communication paths extending to the second station from output queues of other stations, each input queue for storing entries each representing a packet of the first type received across an associated logical path; step (d) comprises the steps of forming (FIG. 21) in first storage means of the second station a packet of a second type acknowledging the packet of the first type received in the second storage means, and in response to formation of the packet in the first storage means, seeking access (1301-1305, 1314) at the second station to the medium according to a second priority, of a lower first and the second priority associated with the second station; step (e) comprises the step of upon gaining access to the medium, transmitting (1306-1308) the formed packet from the first storage means on the medium to the first station; and step (f) comprises the steps of receiving (FIG. 17) the transmitted packet of the second type at the first station in a third storage means (918), the first station having a second storage means for separately receiving packets of the first type and having the third storage means for receiving packets of the second type, and in response to receipt of the packet of the second type, deleting (FIGS. 10-11) from an output queue an entry representing the acknowledged packet of the first type.