Method for transmitting a data stream with anticipation of acknowledgments, correspondence input device and computer-readable storage medium

• US 8,169,911 B2
• Filed: 01/20/2009
• Issued: 05/01/2012
• Est. Priority Date: 01/30/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Viger, Pascal, Baron, Stéphane
• Primary Examiner(s): Shah, Chirag
• Assistant Examiner(s): Patel, Jay P
• Application Number:
  US12/356,516
• Publication Number:
  US 20090213850A1
• Time in Patent Office: 1,197 Days
• Field of Search: 370/235, 370/236
• US Class Current: 370/235
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/40 using split connections

Abstract

Data of a stream to be stimulated is transmitted from a sender device to a receiver device through a network segment. An input device of the network segment determines a starting packet in transit (packets transmitted but not yet acknowledged by the receiver device), selects, as a function of a consumption of a target bandwidth for the stream, packets of the stream following the starting packet, temporarily stores selected packets received from the sender device, transmits to the sender device an anticipated positive acknowledgement message for each selected packet on behalf of the receiver device, transmits the selected packets to the receiver device, and discards stored selected packets corresponding to positive acknowledgements of transmitted selected packets.

Claims

1. A method for transmitting data of a stream, the stream coming from a sender device and intended for a receiver device through an input device of a network segment included in a communications network and according to a packet transport protocol with acknowledgement, each packet being associated with a sequence number, wherein said method comprises the following steps implemented by the input device:

upon detection of an increase of bandwidth available on said network segment, determining a starting packet associated with a sequence number higher than the sequence numbers of packets in transit, where the packets in transit are packets transmitted by said input device via the network segment but for which the input device has not yet received a positive acknowledgement message coming from the receiver device;

selecting, as a function of a consumption of a target bandwidth for the transmission of said stream, packets of said stream following said starting packet;

temporarily storing selected packets received from the sender device, and transmitting to the sender device an anticipated positive acknowledgement message for each selected packet;

transmitting the selected packets to the receiver device via the network segment; and

discarding stored selected packets corresponding to positive acknowledgements of transmitted selected packets, wherein the positive acknowledgments are received from the receiver device.

2. The method according to claim 1, wherein said step of selecting packets following said starting packet comprises the following steps:

obtaining, as a function of said target bandwidth, a target value of transmission window size, which represents a maximum number of packets authorized to be simultaneously in transit between the sender device and the receiver device;

obtaining a current value of transmission window size, which is a current number of packets in transit between the sender device and the receiver device; and

determining the number of selected packets necessary to enable an increase in said current value up to said target value of transmission window size.

3. The method according to claim 1, wherein said storing packets phase is interrupted in an anticipated way in the event of detection of a use by the sender device of at least one predetermined part of said target bandwidth.

4. The method according to claim 1, wherein, in the event of detection of a loss of one of said packets in transit, said method is reset by a return to said step for determining a starting packet.

5. The method according to claim 1, wherein, with a set of data streams going through the input device to access the network segment, the method preliminarily comprises a step of selecting at least one data stream from said set of data streams, each selected stream being a stream to be stimulated, and wherein said step of selecting at least one data stream is based on at least one selection criterion belonging to the group comprising:

a stream of TCP type in the slow starting phase is rejected from the selection;

a stream being encrypted is rejected from the selection; and

a stream proposing a margin, greater than a predetermined threshold, for an increase in network resources consumed to transmit said stream is favored.

6. The method according to claim 5, wherein, with the network segment being a tunnel between a first sub-network to which the sender device is connected and a second sub-network to which the receiver device is connected, said tunnel comprising a set of channels each associated with a transport protocol, the group of selection criteria further comprises:

with said target bandwidth resulting from a stopping of a stream transmitted via a given channel of the tunnel, another stream being transmitted via said given channel is favored.

7. The method according one to claim 5, wherein, in the event of detection of a loss of one of said packets in transit, said method is reset by return to said step for selecting at least one data stream.

8. The method according to claim 1, wherein said storing packets comprises a step of reliably transmitting via the network segment the starting packet and each selected packet and wherein said reliably transmitting step comprises at least one step belonging to the group comprising:

using a reliable transport mode of the network segment to transmit the starting packet and each selected packet;

increasing the priority level associated with the starting packet and with each selected packet; and

storing the starting packet and each selected packet in order to be able to retransmit them in the event of poor transmission via the network segment.

9. The method according one to claim 1, wherein said storing of selected packets comprises a step of reliably transmitting via the network segment the starting packet and each selected packet, and wherein the network segment being a tunnel between a first sub-network to which the sender device is connected and a second sub-network to which the receiver device is connected, said tunnel comprising a set of channels each associated with a transport protocol, said reliably transmitting step comprises a step of:

transmitting at least two copies, on at least two channels of said tunnel, of the starting packet and of each selected packet.

10. The method according to claim 1, wherein it comprises the following steps:

receiving a positive acknowledgement message for said starting packet or for one of said selected packets, said received message comprising a piece of information sent by the receiver device to the sender device, said piece of information being a piece of protocol information encapsulated by said transport protocol with which said data stream is associated; and

transmitting said piece of information in an acknowledgement message to be sent subsequently to the sender device.

11. The method according to claim 10, wherein said piece of information sent by the receiver device is a command for the control of said data stream intended for said sender device.

12. The method according to claim 1, wherein it comprises a step of managing the scheduling of transmission of anticipated positive acknowledgement messages during said storing of selected packets, said step of managing comprising the following step:

for the selected packets for which the sequence number is greater than or equal to a determined number which is a function of the sequence number of said starting packet and of an estimation of a number of said packets in transit between the sender device and the receiver device, transmitting the anticipated positive acknowledgement messages within a time limit that takes account of an estimation of a round-trip time between the sender device and the receiver device.

13. A non-transitory computer-readable storage medium, storing a computer program comprising a set of instructions executable by a computer in order to implement a method for transmitting data of a stream to be stimulated coming from a sender device and intended for a receiver device through an input device of a network segment included in a communications network and according to a packet transport protocol with acknowledgement, each packet being associated with a sequence number, wherein said method comprises the following steps implemented by the input device:

upon detection of an increase of bandwidth available on said network segment, determining a starting packet associated with a sequence number higher than the sequence numbers of packets in transit, where the packets in transit are packets transmitted by said input device via the network segment but for which the input device has not yet received a positive acknowledgement message coming from the receiver device;

selecting, as a function of a consumption of a target bandwidth for the transmission of said stream, packets of said stream following said starting packet;

temporarily storing selected packets received from the sender device, and transmitting to the sender device an anticipated positive acknowledgement message for each selected packet;

transmitting the selected packets to the receiver device via the network segment; and

discarding stored selected packets corresponding to positive acknowledgements of transmitted selected packets, wherein the positive acknowledgments are received from the receiver device.

14. An input device of a network segment included in a communications method enabling the transmission of data of a stream coming from a sender device and intended for a receiver device through said network segment and according to a packet transport protocol with acknowledgement, each packet being associated with a sequence number, wherein said input device comprises:

determining means for, upon detection of an increase of bandwidth available on said network segment, determining a starting packet associated with a sequence number higher than the sequence numbers of packets in transit, wherein packets in transit are packets transmitted by said input device via the network segment but for which the input device has not yet received a positive acknowledgement message coming from the receiver device;

first selecting means for selecting, as a function of a consumption of a target bandwidth for the transmission of said stream, packets of said stream following said starting packet;

means for temporarily storing selected packets received from the sender device, and for transmitting to the sender device an anticipated positive acknowledgement message for each selected packet;

transmitting means for transmitting the selected packets to the receiver device via the network segment; and

discarding means for discarding stored selected packets corresponding to positive acknowledgements of transmitted selected packets, wherein the positive acknowledgments are received from the receiver device.

15. The device according to claim 14, wherein said first selecting means for selecting packets following said starting packet, comprises:

means for obtaining, as a function of said target bandwidth, a target value of transmission window size, which represents a maximum number of packets authorized to be simultaneously in transit between the sender device and the receiver device;

means for obtaining a current value of transmission window size, which represents a number of packets in transit between the sender device and the receiver device, called a current value of transmission window size; and

means for determining the number of packets, called selected packets, necessary to enable an increase in said current value up to said target value of transmission window size.

16. The device according to claim 14, further comprising interruption means, enabling the interruption of said storing packets in an anticipated way in the event of detection of a use by the sender device of at least one predetermined part of said target bandwidth.

17. The device according to claim 14, wherein, with a set of data streams going through the input device to access the network segment, the device comprises second selecting means for selecting at least one data stream from said set of data streams, each selected stream being a stream to be stimulated, and

wherein said second selecting means for selecting at least one data stream, use at least one selection criterion belonging to the group comprising:

a stream of TCP type in the slow starting phase is rejected from the selection;

an encrypted stream is rejected from the selection; and

a stream proposing a margin, greater than a predetermined threshold, for an increase in network resources consumed to transmit said stream is favored.

18. The device according to claim 17, the network segment being a tunnel between a first sub-network to which the sender device is connected and a second subnetwork to which the receiver device is connected, said tunnel comprising a set of channels each associated with a transport protocol, wherein the group of selection criteria furthermore comprises:

said target bandwidth resulting from a stopping of a stream transported via a given channel of the tunnel, another stream transported via said given channel is favored.

19. The device according to claim 14, wherein it comprises reliably transmitting means, activated during said storing of selected packets, for reliably transmitting via the network segment the starting packet and each selected packet, and wherein said reliable transmitting means comprises at least means belonging to the group comprising:

means for using a reliable transport mode of the network segment to transmit the starting packet and each selected packet;

means for increasing a priority level associated with the starting packet and with each selected packet; and

means for storing the starting packet and each selected packet in order to be able to retransmit them in the event of poor transmission via the network segment.

20. The device according to claim 14, wherein it comprises reliably transmitting means, activated during said storing of selected packets, for reliably transmitting via the network segment the starting packet and each selected packet, and wherein, the network segment being a tunnel between a first subnetwork to which the sender device is connected and a second sub-network to which the receiver device is connected, said tunnel comprising a set of channels each associated with a transport protocol, said reliable transmitting means comprises:

means for transmitting at least two copies, on at least two channels of said tunnel, of the starting packet and of each selected packet.