WO2022233383A1

WO2022233383A1 - Method for negotiating a reliable transport protocol

Info

Publication number: WO2022233383A1
Application number: PCT/EP2021/061551
Authority: WO
Inventors: Reuven Cohen; Ben-Shahar BELKAR
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-05-03
Filing date: 2021-05-03
Publication date: 2022-11-10
Also published as: CN117321939A

Abstract

Provided is a computer-implemented method for communicating one or more data packets. The method includes sending, from a first device (104, 202, 302, 402, 502, 602, 702, 802, 902) to a second device (106, 204, 304, 404, 504, 604, 704, 804, 904), a connect message to establish a connection with the second device. The message includes a first set of one or more retransmission scheme parameters. The method includes receiving, by the first device from the second device, an acknowledgement message including a second set of retransmission scheme parameters. The method includes establishing the connection with the second device using a retransmission scheme based on a lowest parameter set. A set of retransmission scheme parameters indicating a go-back-N scheme, GBN, is lower than a set of retransmission scheme parameters indicating a selective repeat scheme, SR.

Description

METHOD FOR NEGOTIATING A RELIABLE TRANSPORT PROTOCOL

TECHNICAL FIELD

The disclosure relates generally to a computer-implemented method for communicating one or more data packets. Moreover, the disclosure also relates a system for communicating one or more data packets.

BACKGROUND

In data networks, data reliability has to be ensured when two computers communicate with each other. A sender attaches a sequence number to each data packet that sends to a receiver. A receiver informs the sender which data packets are received and are missing. The sender retransmits the missing data packets until the receiver receives all the data packets. The data reliability is ensured using protocols that may be classified into two categories (for example, go-back N (GBN) and Selective-Repeat (SR)).

In the go-back N protocol, the receiver that has received all data packets up to packet number i accepts only packet number i+1. If packet i+1 is not received, but a packet with a higher sequence number is received, e.g. i+2, the receiver drops this out-of-order packet. When the sender is informed that data packet i+1 was lost, the sender retransmits not only the data packet i+1, but all the succeeding data packets.

In the selective-repeat protocol, the receiver also accepts data packets that are received out of order. The receiver keeps out of order data packets in a reordering buffer, or directly places them in the memory, if a Direct Data Placement (DDP) header exists. The receiver then informs the sender only about missing data packets, and the sender retransmits only missing data packets. For example, suppose that the sender sends packets 1-5, and only packet number 3 is lost. In the go-back N protocol, the sender retransmits packets 3-5 while in the selective-repeat protocol, the sender retransmits the only packet number 3. The selective-repeat protocol is more efficient than go-back-N as only the lost data packets are retransmitted. However, the implementation of a selective-repeat protocol is more difficult than of a go-back N protocol, because the selective-repeat protocol requires the receiver to store the out-of-order packets, and both the sender and the receiver need to maintain a data- structure (e.g. a bitmap) that indicates the status of the transmission. At the receiver, the data-structures indicate which data packet is received and which data packet is missing. At the sender, the data- structures indicates the data packets for which an acknowledgement (ACK) is received, the data packets for which the acknowledgement (ACK) is not received, and the data packets that need to be retransmitted due to a time-out or due to the receipt of an implicit or explicit negative- acknowledgement (NACK) or selective acknowledgment (SACK). Resources needed for running the selective-repeat protocol are scarce and expensive, especially when the protocol is implemented by a Network Interface Card (NIC). Thus, the sender and the receiver may not always implement the selective-repeat protocol.

Therefore, there arises a need for improved solutions or technologies for communicating the data packets with high data reliability.

SUMMARY

It is an object of the disclosure to provide a method for communicating one or more data packets and a system for communicating one or more data packets while avoiding one or more disadvantages of prior art approaches.

This object is achieved by the features of the independent claims. Further, implementation forms are an apparent form of the dependent claims, the description, and the figures.

The disclosure provides a computer-implemented method for communicating one or more data packets and a system for communicating one or more data packets.

According to a first aspect, there is provided a computer-implemented method for communicating one or more data packets. The method includes sending, from a first device to a second device, a connect message to establish a connection with the second device. The message includes a first set of one or more retransmission scheme parameters. The method includes receiving, by the first device from the second device, an acknowledgement message including a second set of retransmission scheme parameters. The method includes establishing the connection with the second device using a retransmission scheme based on a lowest parameter set. A set of retransmission scheme parameters indicating a go-back-N scheme, GBN, is lower than a set of retransmission scheme parameters indicating a selective repeat scheme, SR.

The method provides an option to the first device and the second device to decide whether to use the go-back-N scheme or the selective-repeat scheme for the connection. The connection may be established to communicate the one or more data packets between the first device to the second device or the second device to the first device. The first device and the second device may negotiate for the set of retransmission scheme parameters for each connection in a full- duplex communication independently. The method allows two nodes (e.g. the first device and the second device) of a reliable transport connection to change a type or parameters of the connection when the connection is already active. The method enables the first device and the second device to use at least one of the go-back-N scheme, GBN, or the selective repeat scheme, SR, fully at both the connection. The method compromises between cost and value of various transport protocols, for each connection dynamically, based on the resources available at both the first device and the second device and their network status. The method further improves performance of a data center, by utilizing the available resources most efficiently.

Optionally, a set of retransmission scheme parameters indicating a smaller receiver window for a selective repeat scheme is lower than a set of retransmission scheme parameters indicating a larger receiver window for a selective repeat scheme.

The first device may be a sending device, and establishing the connection includes sending a further acknowledgement message and one or more data packets. Optionally, one or more initial data packets are transmitted with the connect message. The initial data packets may be transmitted using GBN and establishing connection includes determining whether to upgrade the retransmission scheme from GBN to SR. Alternatively, he first device may be a receiving device, and establishing the connection includes sending a further acknowledgement message.

Optionally, the invitation is for a duplex connection and the first set of retransmission scheme parameters includes transmission parameters and reception parameters. The connection is established using a first retransmission scheme and a second retransmission scheme. The connection may be already established, and the invitation includes a request to change the agreed set of retransmission scheme parameters. Optionally, the devices agree on a higher set of retransmission scheme parameters, and the connection is upgraded to a corresponding retransmission scheme when the acknowledgement message is received. Optionally, the devices agree on a lower set of retransmission scheme parameters, and a receiving device continues working with a larger window size corresponding to the higher set of retransmission scheme parameters until the number of missing packets is lower than a smaller window size corresponding to the agreed lower set of retransmission scheme parameters. In this case, a set of retransmission parameters indicating GBN corresponds to a window size of 1.

Optionally, if the lower set of retransmission scheme parameters indicates GBN, a sending device is configured to begin operating according to GBN, and the receiving device is configured to drop any packets that have already been successfully delivered.

According to a second aspect, there is provided a computer-readable medium configured to store instructions which, when executed by a processor, cause the processor to execute the above-mentioned method.

According to a third aspect, there is provided a system including at least a first device and a second device. The system is configured to execute the above-mentioned method.

The system provides an option to the first device and the second device to decide whether to use the go-back-N scheme or the selective-repeat scheme for the connection. The connection may be established to communicate the one or more data packets between the first device to the second device or the second device to the first device. In a full-duplex communication between two devices, where there are typically two connections (one from the first device to the second and the other from the second to the first), the first device and the second device may negotiate for the set of retransmission scheme parameters for each connection in the full-duplex communication independently. The system allows two nodes (e.g. the first device and the second device) of a reliable transport connection to change a type or parameters of the connection when the connection is already active. The system enables the first device and the second device to use either of the go-back-N scheme, GBN, or the selective repeat scheme, SR. The system compromises between cost and value of various transport protocols, for each connection dynamically, based on the resources available at both the first device and the second device and their network status. The system further improves performance of a data center, by utilizing the available resources most efficiently. A technical problem in the art is resolved, where the technical problem is that utilizing available resources to communicating the data packets with high data reliability.

Therefore, in contradistinction to the prior art, according to the computer-implemented method and the system, the data packets are communicated between the first device and the second device with high data reliability. The method enables the first device and the second device to decide for each connection whether to use the go-back-N scheme, GBN, or the selective repeat scheme, SR, vice-versa based on the available resources.

These and other aspects of the disclosure will be apparent from and the implementation(s) described below.

BRIEF DESCRIPTION OF DRAWINGS

Implementations of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram that illustrates a system for communicating one or more data packets in accordance with an implementation of the disclosure;

FIG. 2 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a first device to a second device in accordance with an implementation of the disclosure;

FIG. 3 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a second device to a first device in accordance with an implementation of the disclosure;

FIG. 4 is an exemplary interaction diagram that illustrates a method of communicating one or more data packets with a connect message from a first device to a second device in accordance with an implementation of the disclosure;

FIG. 5 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a first device to a second device using one or more set of retransmission scheme parameters in accordance with an implementation of the disclosure; FIG. 6 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a first device to a second device using a two set of retransmission scheme parameters in accordance with an implementation of the disclosure;

FIG. 7 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a second device to a first device in accordance with an implementation of the disclosure;

FIG. 8 is an exemplary interaction diagram that illustrates a method of establishing a two-way connection to communicate one or more data packets between a first device and a second device in accordance with an implementation of the disclosure;

FIG. 9 is an exemplary interaction diagram that illustrates a method of communicating one or more data packets using a controller in accordance with an implementation of the disclosure;

FIG. 10 is an exemplary bitmap of a receiver in accordance with an implementation of the disclosure; and

FIG. 11 is a flow diagram that illustrates a computer-implemented method for communicating one or more data packets in accordance with an implementation of the disclosure.

DETAILED DESCRIPTION OF THE DRAWINGS

Implementations of the disclosure provide a computer-implemented method for communicating one or more data packets and a system for communicating the one or more data packets.

To make solutions of the disclosure more comprehensible for a person skilled in the art, the following implementations of the disclosure are described with reference to the accompanying drawings.

Terms such as "a first", "a second", "a third", and "a fourth" (if any) in the summary, claims, and foregoing accompanying drawings of the disclosure are used to distinguish between similar objects and are not necessarily used to describe a specific sequence or order. It should be understood that the terms so used are interchangeable under appropriate circumstances, so that the implementations of the disclosure described herein are, for example, capable of being implemented in sequences other than the sequences illustrated or described herein. Furthermore, the terms "include" and "have" and any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, a method, a system, a product, or a device that includes a series of steps or units, is not necessarily limited to expressly listed steps or units but may include other steps or units that are not expressly listed or that are inherent to such process, method, product, or device.

FIG. 1 is a block diagram that illustrates a system 102 for communicating one or more data packets in accordance with an implementation of the disclosure. The system 102 includes at least a first device 104, and a second device 106. The system 102 is configured to send a connect message, from the first device 104 to the second device 106, to establish a connection with the second device 106. The message includes a first set of one or more retransmission scheme parameters. The first device 104 receives an acknowledgement message including a second set of retransmission scheme parameters from the second device 106. The system 102 establishes the connection with the second device 106 using a retransmission scheme based on a lowest parameter set. A set of retransmission scheme parameters indicating a go-back-N scheme, GBN, is lower than a set of retransmission scheme parameters indicating a selective repeat scheme, SR.

The system 102 provides an option to the first device 104 and the second device 106 to decide whether to use the go-back-N scheme or the selective-repeat scheme for the connection. The connection may be established to communicate the one or more data packets between at least one of the first device 104 to the second device 106 or the second device 106 to the first device 104. The first device 104 and the second device 106 may negotiate for the set of retransmission scheme parameters for each connection in a full-duplex communication independently. The system 102 allows two nodes (e.g. the first device 104 and the second device 106) of a reliable transport connection to change a type or parameters of the connection when the connection is already active. The system 102 enables the first device 104 and the second device 106 to use at least one of go-back-N scheme, GBN or selective repeat scheme, SR fully at both the connection. The system 102 compromises between cost and value of various transport protocols, for each connection dynamically, based on the resources available at both the first device 104 and the second device 106 and their network status. The system 102 method further improves performance of a data center, by utilizing the available resources most efficiently. Optionally, when a new connection is established, for each traffic direction, the first device 104 and the second device 106 may negotiate whether to use the go-back-N scheme, GBN or the selective repeat scheme, SR. Optionally, when using the selective repeat scheme, SR, a window’s length for the connection is negotiated. Optionally, the decision is made while taking a status of a network (i.e. a packet loss rate and a number of connections the first device 104 that has) and an availability of resources at the first device 104 and at the second device 106 into account. Optionally, the negotiation is performed in three ways that include (i) distributedly, using a conservative approach (as described above), (ii) distributedly, using an optimistic approach and (iii) using a centralized controller.

Optionally, a set of retransmission scheme parameters indicating a smaller receiver window for the selective repeat scheme, SR is lower than a set of retransmission scheme parameters indicating a larger receiver window for the selective repeat scheme, SR.

The set of retransmission scheme parameters may include a binary parameter and a length of a receiver window. The binary parameter indicates whether the set of retransmission scheme parameters are used by the go-back-N scheme, GBN, or the selective repeat scheme, SR. Optionally, the set of retransmission scheme parameters for the selective repeat scheme, SR, is the length of the receiver window.

Optionally, the set of retransmission scheme parameters of a sender device (e.g. the first device 104) is larger than or equal to the set of retransmission scheme parameters of a receiving device, e.g. the second device 106 for a best performance. For example, considering 2 sets of retransmission scheme parameters, set 1 and set 2. Optionally, set 1 is equal to set 2. The set 1 may be greater than the set 2. The set 2 may be greater than the set 1. Optionally, the set 1 is greater than the set 2 when (i) the set 1 requires the selective repeat scheme, SR, while the set 2 requires the go-back-N scheme, GBN or (ii) both requires the selective repeat scheme, SR. A size of the receiver window in the set 1 is larger than the size of the receiver window in the set 2

Optionally, the set 2 is greater than the set 1 when (i) the set 1 requires the go-back-N scheme or (ii) both requires the selective repeat scheme, SR, and a size of the receiver window in the set 2 is larger than the size of the receiver window in the set 1. Optionally, the set 1 is equal to the set 2 when both require the go-back-N scheme or the selective repeat scheme, SR, with a same size of the receiver window. Optionally, the set of retransmission scheme parameters is used for each direction of the connection. Optionally, the set of retransmission scheme parameters is different for a reverse direction of the connection. Optionally, the set of retransmission scheme parameters is added into a connection establishment phase. Optionally, the set of retransmission scheme parameters is added independently when an execution of a connection establishment protocol.

Optionally, the first device 104 is a sending device, and establishing the connection comprises sending a further acknowledgement message and one or more data packets. Optionally, one or more initial data packets are transmitted with the connect message. Optionally, the initial data packets are transmitted using the go-back-N scheme, GBN and establishing connection comprises determining whether to upgrade the retransmission scheme from the go-back-N scheme, GBN to the selective repeat scheme, SR. Optionally, the first device 104 is a receiving device, and establishing the connection comprises sending a further acknowledgement message.

Optionally, the invitation is for a duplex connection and the first set of retransmission scheme parameters includes transmission parameters and reception parameters, and the connection is established using a first retransmission scheme and a second retransmission scheme. Optionally, the connection is already established and the invitation includes a request to change the agreed set of retransmission scheme parameters.

Optionally, the devices agree on a higher set of retransmission scheme parameters, and the connection is upgraded to a corresponding retransmission scheme when the acknowledgement message is received. Optionally, the devices agree on a lower set of retransmission scheme parameters, and a receiving device continues working with a larger window size corresponding to the higher set of retransmission scheme parameters until the number of missing packets is lower than a smaller window size corresponding to the agreed lower set of retransmission scheme parameters. A set of retransmission parameters indicating the go-back-N scheme, GBN corresponds to a window size of 1.

Optionally, if the lower set of retransmission scheme parameters indicates the go-back-N scheme, GBN, a sending device is configured to begin operating according to the go-back-N scheme, GBN, and the receiving device is configured to drop any packets that have already been successfully delivered. FIG. 2 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a first device 202 to a second device 204 in accordance with an implementation of the disclosure. The first device 202 may be a sender device. The second device 204 may be a receiver device. At a step 206, a connect message is sent from the first device 202 to the second device 204 to establish a connection with the second device 204. The connect message includes a set of retransmission scheme parameters. At a step 208, the set of retransmission scheme parameters selected by the second device 204 is sent to the first device 202. At a step 210, an acknowledgement message is sent to the second device 204 to establish the connection by the first device 202. Optionally, the acknowledgement message is piggybacked on a first data packet sent by the first device 202 or even be eliminated. At a step 212, the one or more data packets are communicated to the second device 204 by the first device 202.

Optionally, the first device 202 requests the second device 204 to include a receiving window of 256 to use the selective repeat scheme, SR. Optionally, the second device 204 agrees to run the selective repeat scheme, SR, and the second device 204 allocates resources only for a receiving window of 128. The second device 204 may agree to use only the go-back-N scheme, GBN, when the resources are low for the selective repeat scheme, SR.

FIG. 3 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a second device 304 to a first device 302 in accordance with an implementation of the disclosure. The first device 302 may be a receiver device. The second device 304 may be a sender device. At a step 306, a connect message is sent from the first device 302 to the second device 304 to establish a connection with the second device 304. The connect message includes a set of retransmission scheme parameters. At a step 308, the set of retransmission scheme parameters selected by the second device 304 is sent to the first device 302. At a step 310, an acknowledgement message is sent to the second device 304 to establish the connection by the first device 302. Optionally, the acknowledgement message is piggybacked on a first data packet sent by the first device 302 or even be eliminated. At a step 312, the one or more data packets are communicated to the first device 302 by the second device 304.

FIG. 4 is an exemplary interaction diagram that illustrates a method of communicating one or more data packets with a connect message from a first device 402 to a second device 404 in accordance with an implementation of the disclosure. At a step 406, the connect message is sent to the second device 404 and then the one or more data packets are communicated to the second device 404 immediately by the first device 402 at a step 408. At a step 410, (i) an acknowledgement message is sent to the first device 402 by the second device 404 if the second device 404 accepts the set of retransmission scheme parameters or (ii) a negative acknowledgement message is sent to the first device 402 if the second device 404 rejects the set of retransmission scheme parameters.

Optionally, the first device 402 starts sending the one or more data packet to the second device 404 without waiting for the acknowledgement message of the second device 404. If the one or more data packets are received from the first device 402 before the acknowledgement message of the second device 404, the second device 404 may decide to drop the one or more data packets. Optionally, all the data packets sent by the first device 402 (as a sender device) are considered lost, and may have to be transmitted again once the connection is established.

FIG. 5 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a first device 502 to a second device 504 using one or more set of retransmission scheme parameters in accordance with an implementation of the disclosure. At a step 506, a first set of retransmission scheme parameters associated with the first device 502 is sent to the second device 504 and then the one or more data packets are communicated to the second device 504 immediately by the first device 502 at a step 508. At a step 510, a negative acknowledgement message is sent to the first device 502 if the second device 504 unable to match the first set of retransmission scheme parameters received from the first device 502 with a set of retransmission scheme parameters that corresponds to the second device 504. Optionally, the second device 504 adds the retransmission scheme parameters associated with the second device 504 in the negative acknowledgement message to receive the one or more data packets from the first device 502. At a step 512, a second set of retransmission scheme parameters is sent to the second device 504 and then the one or more data packets are communicated to the second device 504 immediately by the first device 502. Optionally, the second set of retransmission scheme parameters includes the retransmission scheme parameters associated with the second device 504. At a step 514, the one or more data packets are sent to the second device 504 from the first device 502.

FIG. 6 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a first device 602 to a second device 604 using a two set of retransmission scheme parameters in accordance with an implementation of the disclosure. At a step 606, a first set of retransmission scheme parameters is sent to the second device 604 and then the one or more data packets are communicated to the second device 604 immediately by the first device 602 at a step 608. Optionally, the first set of retransmission scheme parameters may associate with a go-back-N scheme, GBN or a selective repeat scheme, SR. At a step 610, a second set of retransmission scheme parameters is sent to the first device 602 by the second device 604. Optionally, the second set of retransmission scheme parameters may associate with the go-back-N scheme, GBN or the selective repeat scheme, SR. At a step 612, an acknowledgement message is sent to the second device 604 by the first device 602 and then the one or more data packets are communicated to the second device 604 immediately by the first device 602 at a step 614.

FIG. 7 is an exemplary interaction diagram that illustrates a method of establishing a one-way connection to communicate one or more data packets from a second device 704 to a first device 702 in accordance with an implementation of the disclosure. At a step 706, a set of retransmission scheme parameters is sent to the second device 704 by the first device 702. Optionally, the second device 704 selects a set of retransmission scheme parameters that associates with a go-back-N scheme, GBN or a selective repeat scheme, SR to communicate the one or more data packets to the first device 702. At a step 708, the set of retransmission scheme parameters that is selected by the second device 704 is sent to the first device 702. Optionally, if the second device 704 decides to use a lower set of parameters, the second device 704 informs the first device 702 using its own connect message. At a step 710, the first device 702 is switched to using a lower set of parameters (e.g. from the selective repeat scheme, SR to the go-back-N scheme, GBN), and an acknowledgement message is sent to the second device 704 by the first device 702 to receive the one or more data packets from the second device 704. At a step 712, the one or more data packets are sent to the first device 702 by the second device 704

FIG. 8 is an exemplary interaction diagram that illustrates a method of establishing a two-way connection to communicate one or more data packets between a first device 802 and a second device 804 in accordance with an implementation of the disclosure. Optionally, the two-way connection is established, for which both the first device 802 and the second device 804 is a sender device and a receiver device and vice-versa. At a step 806, a set of retransmission scheme parameters is offered by the first device 802 to the second device 804. At a step 808, the set of retransmission scheme parameters is accepted by the second device 804 to communicate the one or more data packets. At a step 810, an acknowledgement message is sent to the second device 804 to establish the connection by the first device 802. Optionally, the acknowledgement message is piggybacked on a first data packet sent by the first device 802 or even be eliminated. At a step 812, the one or more data packets are communicated between the first device 802 and the second device 804.

Optionally, the first device 802 offers a two set of retransmission scheme parameters for each connection for a transmission and a reception. Optionally, the second device 804 decides to accept or reject the two set of retransmission scheme parameters. Optionally, both the connections use the selective repeat scheme, SR, with a same or different receiving window for the transmission and the reception. Optionally, both the connections use the go-back-N scheme, GBN for the transmission and the reception. Optionally, one of the connections use selective repeat scheme, SR, and the other connection uses the go-back-N scheme, GBN for the transmission and the reception vice versa.

FIG. 9 is an exemplary interaction diagram that illustrates a method of communicating one or more data packets using a controller 906 in accordance with an implementation of the disclosure. At a step 908, a set of retransmission scheme parameters is offered to the controller 906 by the first device 902. At a step 910, a set of retransmission scheme parameters is offered to the controller 906 by the second device 904. At a step 912, the set of retransmission scheme parameters selected by the controller 906 to communicate the one or more data packets is communicated to the first device 902. At a step 914, the set of retransmission scheme parameters selected by the controller 906 to communicate the one or more data packets is communicated to the second device 904. At a step 916, a connection-ready acknowledgement is sent from the first device 902 to the controller 906 to establish the connection. At a step 918, the connection-ready acknowledgement is sent from the second device 904 to establish the connection. At a step 920, a start data acknowledgement is sent to the first device 902 to communicate the one or more data packets by the controller 906. At a step 922, the start data acknowledgement is sent to the second device 904 to communicate the one or more data packets by the controller 906. At a step 924, to the first device 902 and the second device 904 are enabled to communicate the one or more data packets by the controller 906.

Optionally, a minimum set of retransmission parameters is decided for both the first device 902 and the second device 904 by the controller 906 to exchange the one or more data packets without handshake with each other. FIG. 10 is an exemplary bitmap 1002 of a receiver in accordance with an implementation of the disclosure. The bitmap 1002 includes a packet number 1004 and a status 1006 Optionally, a first device and a second device change a set of retransmission parameters when communicating one or more packets. Optionally, the set of retransmission parameters is upgraded for converting the connection from a go-back-N scheme, GBN, to a selective repeat, SR, scheme. Optionally, the set of retransmission parameters is downgraded for converting the connection from the selective repeat scheme, SR, to the go-back-N scheme or from the selective repeat scheme, SR, with a receiving window to the selective repeat scheme, SR, with a smaller receiving window.

Optionally, for a half-duplex connection, a receiving device prepares resources before sending an agreement for set 2 when the set of retransmission scheme parameters is upgraded from a set 1 to a set 2 (i.e. set 2 > set 1), and the receiving device starts working according to rules of the upgraded connection to communicate the one or more packets in the half-duplex connection.

The first device may perform based on the rules of the upgraded connection when the first device is informed that the second device agrees to upgrade the set of retransmission scheme parameters from set 1 to set 2.

Optionally, for the half-duplex connection, the set of retransmission scheme parameters is downgraded from the set 1 to the set 2, (set 2 < set 1), for converting the connection from the selective repeat scheme, SR to the go-back-N scheme, GBN or from the selective repeat scheme, SR with the receiving window to the selective repeat scheme, SR with the smaller receiving window.

Optionally, the second device drops the bitmap 1002 and immediately switches to the go-back- N scheme, GBN, when there are no gaps in the bitmap 1002 at the second device side. The second device may remember a sequence number of next expected data packet when the second device is switched to the go-back-N scheme.

Optionally, the first device resends the one or more data packets that are already accepted and delivered when there are gaps in the bitmap 1002 For example, the first device sends N packets starting from 0 (for example N=10) as a GBN sender. Each received data packet that was already accepted is dropped, and the second device sends an acknowledgement (ACK) for all the data packets received in a sequence, thereby preventing the duplication of the data packet. For example, the data packet 0 and data packet 3 are received for the first time and may be delivered or placed in a memory, and the second device may drop other data packets, to avoid duplication.

Optionally, the above-mentioned process continues until there is no gap in the bitmap 1002. Only at this time, the bitmap 1002 may be dropped. Optionally, the bitmap 1002 is dropped and the second device performs as a regular go-back-N scheme, GBN, and expects to receive a data packet number 10 when there is no gap in the bitmap 1002. Optionally, the second device informs the first device that the second device waits for packet number 0 when the second device uses the go-back-N scheme, GBN.

The first device may switch to perform in the go-back-N scheme, GBN, and starts communicating the data packet from a sequence number of a first missing data packet, i.e. the data packer 0 in the bitmap 1002 when the first device receives a confirmation from the second device for a new set of retransmission scheme parameters.

Optionally, the first device or the second device switches the connection from the selective repeat scheme, SR, with a given receiver window N to a selective repeat scheme, SR, with a shorter receiver window (M<N) when the second device uses a long window N. Optionally, the second device uses a long window N until all the first N-M data packets are successfully received. Optionally, the second device uses a long window N until all the first N-M data packets are successfully received. Optionally, the second device uses a long window N if the data packet 0 or last M data packets are missed.

FIG. 11 is a flow diagram that illustrates a computer-implemented method for communicating one or more data packets in accordance with an implementation of the disclosure. At a step 1102, a connect message is sent, from a first device to a second device, to establish a connection with the second device. The message includes a first set of one or more retransmission scheme parameters. At a step 1104, an acknowledgement message including a second set of retransmission scheme parameters is received by the first device from the second device. At a step 1106, the connection is established with the second device using a retransmission scheme based on a lowest parameter set. A set of retransmission scheme parameters indicating a go- back-N scheme, GBN, is lower than a set of retransmission scheme parameters indicating a selective repeat scheme, SR.

The method provides an option to the first device and the second device to decide whether to use the go-back-N scheme or the selective-repeat scheme for the connection. The connection may be established to communicate the one or more data packets between the first device to the second device or the second device to the first device. The first device and the second device may negotiate for the set of retransmission scheme parameters for each connection in a full- duplex communication independently. The method allows two nodes (e.g. the first device and the second device) of a reliable transport connection to change a type or parameters of the connection when the connection is already active. The method enables the first device and the second device to use at least one of the go-back-N scheme, GBN, or the selective repeat scheme, SR, fully at both sides of the connection. The method compromises between cost and value of various transport protocols, for each connection dynamically, based on the resources available at both the first device and the second device and their network status. The method further improves performance of a data center, by utilizing the available resources most efficiently.

Optionally, a set of retransmission scheme parameters indicating a smaller receiver window for a selective repeat scheme is lower than a set of retransmission scheme parameters indicating a larger receiver window for a selective repeat scheme. Optionally, the first device is a sending device, and establishing the connection comprises sending a further acknowledgement message and one or more data packets. Optionally, one or more initial data packets are transmitted with the connect message.

Optionally, the initial data packets are transmitted using the go-back-N scheme, GBN and establishing connection comprises determining whether to upgrade the retransmission scheme from the go-back-N scheme, GBN to the selective repeat scheme, SR. Optionally, the first device is a receiving device, and establishing the connection comprises sending a further acknowledgement message.

Optionally, if the lower set of retransmission scheme parameters indicates the go-back-N scheme, GBN, a sending device is configured to begin operating according to the go-back-N scheme, GBN, and the receiving device is configured to drop any packets that have already been successfully delivered.

In an implementation, a computer-readable medium configured to store instructions which, when executed by a processor, cause the processor to perform the above methods.

Optionally, the selective repeat scheme, SR, is better than the go-back-N scheme, GBN, when a packet loss rate (p) is large and when a bandwidth-delay product (b) is large. Optionally, a maximum throughput of the selective repeat scheme, SR, is 1-p and a maximum throughput of the go-back-N scheme, The value of b for a new connection may be determined

as a Bandwidth Delay Product (BDP) of a Network Interface Card (NIC) which is divided by a number N of connections. Optionally, the selective repeat scheme, SR, is used for new connections when p/N is below a threshold, and to use go-back-N scheme, GBN for new connections when p/N is greater the threshold.

In addition, while at least one of these components are implemented at least partially as an electronic hardware component, and therefore constitutes a machine, the other components may be implemented in software that when included in an execution environment constitutes a machine, hardware, or a combination of software and hardware.

Although the disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. A computer-implemented method for communicating one or more data packets, the method comprising: sending, from a first device (104, 202, 302, 402, 502, 602) to a second device (106, 204, 304, 404, 504, 604, 704, 804, 904), a connect message to establish a connection with the second device (106, 204, 304, 404, 504, 604, 704, 804, 904), the message including a first set of one or more retransmission scheme parameters; receiving, by the first device (104, 202, 302, 402, 502, 602, 702, 802, 902) from the second device (106, 204, 304, 404, 504, 604, 704, 804, 904), an acknowledgement message including a second set of retransmission scheme parameters; and establishing the connection with the second device (106, 204, 304, 404, 504, 604, 704, 804, 904) using a retransmission scheme based on a lowest parameter set; wherein a set of retransmission scheme parameters indicating a go-back-N scheme, GBN, is lower than a set of retransmission scheme parameters indicating a selective repeat scheme, SR.

2. The method of claim 1, wherein a set of retransmission scheme parameters indicating a smaller receiver window for a selective repeat scheme is lower than a set of retransmission scheme parameters indicating a larger receiver window for a selective repeat scheme.

3. The method of claim 1 or claim 2, wherein the first device (104, 202, 302, 402, 502, 602, 702, 802, 902) is a sending device, and establishing the connection comprises sending a further acknowledgement message and one or more data packets.

4. The method of claim 3, wherein one or more initial data packets are transmitted with the connect message.

5. The method of claim 4, wherein the initial data packets are transmitted using GBN and establishing connection comprises determining whether to upgrade the retransmission scheme from GBN to SR.

6. The method of claim 1 or claim 2, wherein the first device (104, 202, 302, 402, 502, 602, 702, 802, 902) is a receiving device, and establishing the connection comprises sending a further acknowledgement message.

7. The method of claim 1 or 2, wherein the invitation is for a duplex connection and the first set of retransmission scheme parameters includes transmission parameters and reception parameters, and wherein the connection is established using a first retransmission scheme and a second retransmission scheme.

8. The method of any preceding claim, wherein the connection is already established and the invitation includes a request to change the agreed set of retransmission scheme parameters.

9. The method of claim 8, wherein the devices agree on a higher set of retransmission scheme parameters, and the connection is upgraded to a corresponding retransmission scheme when the acknowledgment message is received.

10. The method of claim 8, wherein the devices agree on a lower set of retransmission scheme parameters, and a receiving device continues working with a larger window size corresponding to the higher set of retransmission scheme parameters until the number of missing packets is lower than a smaller window size corresponding to the agreed lower set of retransmission scheme parameters, wherein a set of retransmission parameters indicating GBN corresponds to a window size of 1.

11. The method of claim 10, wherein if the lower set of retransmission scheme parameters indicates GBN, a sending device is configured to begin operating according to GBN, and the receiving device is configured to drop any packets that have already been successfully delivered.

12. A computer-readable medium configured to store instructions which, when executed by a processor, cause the processor to execute the method of any preceding claim.

13. A system (102) comprising at least a first device (104, 202, 302, 402, 502, 602, 702, 802, 902) and a second device (106, 204, 304, 404, 504, 604, 704, 804, 904), wherein the system (102) is configured to execute the method of any one of claims 1 to 11.