Packet communication system

Claim 2

A packet communication system which sequentially receives packets each made up of a predetermined unit data, arranges the packets to form a packet queue, selects any one of the packets in the packet queue and sequentially transmits the selected packet, characterized in that said system comprising: timer means (30, 41) for starting its time measuring operation each time a packet is received and arranged in the packet queue to measure a stay time of the received packet staying in the packet queue; and selection means (28) for selecting one of the packets in the packet queue on the basis of the stay time of each packet.

Claim 3

A packet communication system as set forth in claim 1, further comprising a plurality of said packet queues and signal generating means (30) for generating signals having periods differently set to the plurality of packet queues, and wherein said timer means (41), when a packet is received and arranged in one of the packet queues, starts to count in synchronism with the signal of the period corresponding to the packet queue to find a count value for the packet, said selection means (28) compares the count values of the packets in the packet queues and selects one of the packets having maximum one of the count values.

Claim 4

A packet communication system as set forth in claim 2, wherein each of said plurality of packet queues belongs to any one of a plurality of predetermined immediateness classes, said signal generating means (30) generates the signals of different periods corresponding to the immediateness classes of the packet queues, said timer means (41), when a packet is received and arranged in the packet queue, starts to count in synchronism with the signal of the period corresponding to the immediateness class of the packet queue to find a count value for the packet.

Claim 5

A packet communication system as set forth in claim 1, further comprising memory means (35) for storing a plurality of packets and an address queue of arranged addresses for the packets in said memory means (35), and wherein said address queue is formed by sequentially arranging packets sequentially read out from the memory means (35).

Claim 6

A packet communication system which sequentially arranges packets each made up of a predetermined unit data to form a packet queue, selects any of the packets in the packet queue to sequentially transmit the selected packet, and when a remaining capacity of the packet queue becomes smaller than a predetermined value, discards any of the packets in the packet queue, characterized in that said system comprising: measuring means (37a, 37b) for discriminating a plurality of predetermined discard classes to which the packets of the packet queue respectively belong, and for measuring flow rates of the packets for the discriminated discard classes; product calculation means (37d) for calculating products of the respective packet flow rates of the discard classes measured by said measuring means (37a, 37b) and allowable discard rates previously set for the discard classes with respect to the respective discard classes: and discarding means (37e, 39a) for finding maximum one of the products of the discard classes calculated by said product calculation means (37d) and for discarding one of the packets of the packet queue belonging to the discard class corresponding to the found maximum product.

Claim 7

A packet communication system which sequentially arranges packets each made up of a predetermined unit data to form a packet queue, selects any of the packets in the packet queue to sequentially transmit the selected packet, and when a remaining capacity of the packet queue becomes smaller than a predetermined value, discards any of the packets in the packet queue, characterized in that said system comprising: measuring means (37a, 37b) for discriminating a plurality of predetermined discard classes to which the packets of the packet queue respectively belong, and for measuring flow rates of the packets for the discriminated discard classes; product calculation means (37d) for calculating products of the respective packet flow rates of the discard classes measured by said measuring means (37a, 37b) and allowable discard rates previously set for the discard classes with respect to the respective discard classes: and discarding means (37e, 39a) for finding maximum one of the products of the discard classes calculated by said product calculation means (37d) and for discarding one of the packets of the packet queue belonging to the discard class corresponding to the found maximum product.

Claim 8

A packet communication system as set forth in claim 5, further comprising compensation means (36, 38) for compensating for a remaining capacity of said packet queue during a time after the remaining capacity of the packet queue becomes smaller than a predetermined value until a packet is discarded from the packet queue.

Claim 9

A packet communication system as set forth in claim 5, further comprising memory means (39b) for storing a connection associated with the discarded packet for a predetermined time, and wherein said discarding means (39a) does not discard packets of the connection stored in said memory means from the packet queue.

Claim 10

A packet communication system as set forth in claim 5. further comprising memory means (39b) for storing up to a predetermined number of connections associated with discarded packets and at the time of storing a new connection after storage of said predetermined number of connections, for erasing first stored one of the predetermined number of connections to update its memory contents, and wherein said discarding means (39a) does not discard packets of the connection stored in said memory means (39b) from the packet queue.

Claim 11

A packet communication system as set forth in claim 5. further comprising memory means (35) for storing a plurality of packets and an address queue of arranged addresses for the packets stored in said memory means (35), and wherein the packets in the memory means are read out from the memory means (35) and sequentially arranged according to the addresses arranged in said address queue to form a packet queue.

Claim 12

A packet communication system which sequentially arranges packets each made up of a predetermined unit data to form a packet queue. selects any of the packets in the packet queue to sequentially transmit the selected packet. and when a remaining capacity of the packet queue becomes smaller than a predetermined value, discards any of the packets in the packet queue. characterized in that said system comprising: timer means (30, 41) for starting its time measuring operation each time a packet is received and arranged in the packet queue to measure a stay time of the received packet staying in the packet queue: selection means (28) for selecting one of the packets in the packet queue on the basis of the stay time of each packet; measuring means (37a, 37b) for discriminating a plurality of predetermined discard classes to which the packets of the packet queue respectively belong, and for measuring flow rates of the packets for the discriminated discard classes: product calculation means (37d) for calculating products of the respective packet flow rates of the discard classes measured by said measuring means (37a, 37b) and allowable discard rates previously set for the discard classes with respect to the respective discard classes; and discarding means (39) for finding maximum one of the products of the discard classes calculated by said product calculation means (37d) and when the packet selected by said selection means (28) belongs to the discard class corresponding to the found maximum product, for discarding the packet and for selecting another packet in place of the discarded packet through the selection means (28).

Claim 13

A packet communication system which sequentially arranges packets each made up of a predetermined unit data to form a packet queue. selects any of the packets in the packet queue to sequentially transmit the selected packet. and when a remaining capacity of the packet queue becomes smaller than a predetermined value, discards any of the packets in the packet queue. characterized in that said system comprising: timer means (30, 41) for starting its time measuring operation each time a packet is received and arranged in the packet queue to measure a stay time of the received packet staying in the packet queue: selection means (28) for selecting one of the packets in the packet queue on the basis of the stay time of each packet; measuring means (37a, 37b) for discriminating a plurality of predetermined discard classes to which the packets of the packet queue respectively belong, and for measuring flow rates of the packets for the discriminated discard classes: product calculation means (37d) for calculating products of the respective packet flow rates of the discard classes measured by said measuring means (37a, 37b) and allowable discard rates previously set for the discard classes with respect to the respective discard classes; and discarding means (39) for finding maximum one of the products of the discard classes calculated by said product calculation means (37d) and when the packet selected by said selection means (28) belongs to the discard class corresponding to the found maximum product, for discarding the packet and for selecting another packet in place of the discarded packet through the selection means (28).

Claim 14

A packet communication system as set forth in claim 10, further comprising a plurality of said packet queues and signal generating means (30) for generating signals having periods differently set to the plurality of packet queues, and wherein said timer means (41), when a packet is received and arranged in one of the packet queues, starts to count in synchronism with the signal of the period corresponding to the packet queue to find a count value for the packet, said selection means (28) compares the count values of the packets in the packet queues and selects one of the packets having maximum one of the count values.

Claim 15

A packet communication system as set forth in claim 11, wherein each of said plurality of packet queues belongs to any one of a plurality of predetermined immediateness classes, said signal generating means (30) generate the signals of different periods corresponding to the immediateness classes of the packet queues, said timer means (41), when a packet is received and arranged in the packet queue, starts to count in synchronism with the signal of the period corresponding to the immediateness class of the packet queue to find a count value for the packet.

Claim 16

A packet communication system as set forth in claim 10, further comprising compensation means (36, 38) for compensating for a remaining capacity of said packet queue during a time after the remaining capacity of the packet queue be comes smaller than a predetermined value until a packet is discarded from the packet queue.

Claim 17

A packet communication system as set forth in claim 10, further comprising memory means (39b) for storing a connection associated with the discarded packet for a predetermined time, and wherein said discarding means (39a) does not discard packets of the connection stored in said memory means (39b).

Claim 18

A packet communication system as set forth in claim 10, further comprising memory means (39b) for storing up to a predetermined number of connections associated with discarded packets and at the time of storing a new connection after storage of said predetermined number of connections, for erasing first stored one of the predetermined number of connections to update its memory contents, and wherein said discarding means (39a) does not discard packets of the connection stored in said memory means.

Claim 19

A packet communication system as set forth in claim 10, further comprising memory means (35) for storing a plurality of packets and an address queue of arranged addresses for the packets stored in said memory means, and wherein the packets in the memory means (35) are read out from the memory means (35) and sequentially arranged according to the addresses arranged in said address queue to form a packet queue.