Congestion control method and apparatus for end-to-end packetcommunication

Claim 2

A congestion control method for an end-to-end packet switched communications system in which packets are sent from a source terminal in response to an acknowledgment packet from a destination terminal signalling correct receipt of previous packets from said souce terminal, the method comprising the steps of (a) detecting if a traffic congestion occurs in said system and (b) introducing a delay between receipt of an acknowledgment packet by said system from said destination terminal and transmission of said acknowledgment packet from said system to said source terminal if a traffic congestion is detected by the step (a).

Claim 3

A congestion control method as claimed in claim 1, further comprising detecting a level of said traffic congestion and controlling the amount of said delay as a function of the detected level of traffic congestion.

Claim 4

A congestion control method as claimed in claim 1 or 2, further comprising detecting priority of said acknowledgment packet and controlling the amount of said delay with the detected priority.

Claim 5

A congestion control method as claimed in any one of claims 1 to 3, wherein the step (b) comprises recirculating said acknowledgment packet through a buffer.

Claim 6

A congestion control method as claimed in claim 4, further comprising detecting a level of said traffic congestion and controlling the number of times said acknowledgment packet recirculates through said buffer.

Claim 7

A congestion control method as claimed in claim 4 or 5, further comprising detecting priority of said packets and controlling the number of times said acknowledgment packet recirculates through said buffer.

Claim 8

A congestion control apparatus in a packet switched communications system which serves a plurality of data terminal equipments each sending an acknowledgment packet from a destination side of said system signalling correct receipt of packets from a source side of said system, comprising: congestion detector means for detecting a traffic congestion in said system; packet detector means operable in response to the detection of a traffic congestion by said congestion detector means for detecting receipt of said acknowledgment packet form a destination data terminal equipment; and delay means for holding said detected acknowledgment packet for a period of time and forwarding same toward a source data terminal equipment upon termination of said period of time.

Claim 9

A congestion control apparatus in a packet switched communications system which serves a plurality of data terminal equipments each sending an acknowledgment packet from a destination side of said system signalling correct receipt of packets from a source side of said system, comprising: congestion detector means for detecting a traffic congestion in said system; packet detector means operable in response to the detection of a traffic congestion by said congestion detector means for detecting receipt of said acknowledgment packet form a destination data terminal equipment; and delay means for holding said detected acknowledgment packet for a period of time and forwarding same toward a source data terminal equipment upon termination of said period of time.

Claim 10

A congestion control apparatus as claimed in claim 7, wherein said congestion detector means generates a signal indicating a level of said traffic congestion and wherein said delay means holds said acknowledgment packet for a variable length of time in accordance with said level indicating signal.

Claim 11

A congestion control apparatus as claimed in claim 7 or 8, further comprising means for detecting priority of said acknowledgment packet and wherein said delay means holds said acknowledgment packet for a variable length of time in accordance with the detected priority.

Claim 12

A congestion control apparatus as claimed in claim 7, wherein said delay means comprises a timer for measuring the length of time in response to the detection of said acknowledgment packet by said packet detector means and generating an output signal when said measured length of time reaches a predetermined value and a buffer for storing said detected acknowledgment packet therein until said output signal is supplied from said timer and then forwarding said acknowledgment packet to said source data terminal equipment.

Claim 13

A congestion control apparatus as claimed in claim 10, wherein said congestion detector means generates a signal indicating a level of said traffic congestion and wherein said predetermined value of said timer is preset according to said level indicating signal.

Claim 14

A congestion control apparatus as claimed in claim 10 or 11, further comprising means for detecting priority of said detected acknowledgment packet and wherein said predetermined value of said timer is preset according to the detected priority.

Claim 15

A congestion control apparatus as claimed in claim 7, wherein said delay means comprises a buffer for storing therein message packets, acknowledgment packets not detected by said packet detector means and said detected acknowledgment packet, and means for recirculating said detected acknowledgment packet through said buffer and forwarding the recirculated acknowledgment packet, the acknowledgment packets not detected by said packet detector means and said message packets toward said source data terminal equipment.

Claim 16

A congestion control apparatus as claimed in claim 13, wherein said congestion detector means generates a signal indicating a level of said detected congestion, and wherein said recirculating means causes said acknowledgment packet to recirculate through said buffer a number of times depending on the level of congestion indicated by said signal.

Claim 17

A congestion control apparatus as claimed in claim 13 or 14, further comprising means for detecting the level of priority of said acknowledgment packet and wherein said recirculating means causes said acknowledgment packet to recirculate through said buffer a number of times depending on the detected level of priority.

Claim 18

A congestion control apparatus as claimed in any one of claims 13 to 15, wherein said packet detector means is connected to the output of said buffer to detect if a flag is contained in said acknowledgment packet and generate a first output signal if said flag is not detected or a second output signal if said flag is detected in said acknowledgment packet, said recirculating means comprising: a flag generator for writing said flag into each acknowledgment packet leaving said buffer in response to said first output signal from said packet detector means; and switch means for feeding said acknowledgment packet from said buffer back to an input terminal thereof in response to said first output signal from said packet detector means and forwarding said acknowledgment packet from said buffer toward said source data terminal equipment in response to said second output signal from said packet detector means.

Claim 19

A congestion control apparatus as claimed in any one of claims 13 to 15, wherein said packet detector means is connected to the output of said buffer to examine the value of a flag in said acknowledgment packet and generate a first output signal if said flag is of a least value or a second ouput signal if said flag is of a highest value, said recirculating means comprising: a flag generator for incrementing the value of said flag in each acknowledgment packet leaving said buffer in response to said first output signal from said packet detector means; and switch means for feeding said acknowledgment packet from said buffer back to an input terminal thereof in response to said first output signal from said packet detector means and forwarding said acknowledgment packet from said buffer toward said source data terminal equipment in response to said second output signal from said packet detector means.