Data transmission methods and devices, network devices and storage media

Abstract

Embodiments of the present disclosure provide a data transmission method and apparatus, a network device, and a storage medium. The method comprises the steps of: determining whether there is a packet to be transmitted at the transition time of a current time window by a first network device; and if there is no packet to be transmitted at the transition time of a current time window, the first network device transmits a pre-set identifier packet to a second network device, wherein the pre-set identifier packet has a window value of a time window, and the window value is for determining the transition time of a different time window of the first network device by the second network device. Through the present disclosure, the problem of being unable to detect the time window abnormality rate of an upstream device by a downstream device is solved, thereby achieving the effect of shortening the fault recovery time and improving communication efficiency.

Description

Technology Field

[0001] The present disclosure is based on Chinese patent application CN202110786820.8, filed on July 12, 2021, with the title of the invention "Data transmission method and apparatus, network device and storage medium," and also claims priority to the said patent application and incorporates all of the contents disclosed by reference into the present disclosure.

[0002] The present disclosure relates to the field of communication technology, specifically to a data transmission method and device, a network device and a storage medium. Background Technology

[0003] With the rapid development of internet technology, the transmission of information content over networks is transitioning from voice transactions to data transactions, and communication networks are transitioning from SDH technology networks oriented toward voice transactions to Ethernet technology networks oriented toward data packets. Related technologies introduce Time-Sensitive Networking (TSN) technology into the network and apply time gate queuing scheduling technology (i.e., CQF technology, cyclic queuing and forwarding) to TSN technology, receiving user packets within one time window and then transmitting all received user packets within the next time window.

[0004] After applying asynchronous CQF technology, the downstream device extracts the time window value of a packet to determine that the packet is being sent from the upstream device within that time window. Based on the packet's time window value, the downstream device can determine the time of the upstream device's time window transition through changes in the packet's window value. If there are few packets sent by the upstream device, or if there are no packets to send, the downstream device cannot accurately determine the time of the upstream device's time window transition. If a fault abnormality occurs in the upstream device and a hopping transition occurs in the upstream device's time window, and the downstream device cannot detect the upstream device's time window abnormality but still forwards packets according to the previous time window, the forwarding operation cannot satisfy the requirements of the new time window, resulting in a forwarding operation error, and in severe cases, a user transaction interruption.

[0005] Regarding the technical challenge where a failure abnormality occurs in the upstream device and the downstream device cannot detect the time window abnormality of the upstream device, an effective solution has not yet been presented.

[0006] Embodiments of the present disclosure provide a data transmission method, apparatus, network device, and storage medium for solving the problem of not being able to detect the time window abnormality rate of an upstream device at least in a downstream device.

[0007] According to one embodiment of the present disclosure, a data transmission method is provided comprising: a step in which a first network device determines whether there is a packet to be transmitted at the transition time of a current time window; and a step in which, if there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, wherein the pre-set identifier packet has a window value of the time window, and the window value is for determining the transition time of a different time window of the first network device at the second network device.

[0008] According to another embodiment of the present disclosure, if there is no packet to be transmitted at the transition time of the current time window, the second network device receives a pre-set identifier packet transmitted by the first network device and determines the transition time of the current time window of the first network device, wherein the pre-set identifier packet includes a window value of the current time window; and the second network device discards the pre-set identifier packet after receiving the window value of the current time window. A data transmission method is further provided.

[0009] According to another embodiment of the present disclosure, a data transmission device is provided comprising: a determination unit configured to determine whether there is a packet to be transmitted at the transition time of a current time window; and a transmission unit configured such that, if there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, wherein the pre-set identifier packet has a window value of the time window, and the window value is for determining the transition time of a different time window of the first network device at the second network device.

[0010] According to another embodiment of the present disclosure, when there is no packet to be transmitted at the transition time of the current time window, the second network device is configured to receive a pre-set identifier packet transmitted by the first network device and determine the transition time of the current time window of the first network device, wherein the pre-set identifier packet includes a window value of the current time window; and the second network device is configured to discard the pre-set identifier packet after receiving the window value of the current time window; thereby providing a data transmission device comprising: a determination unit; and a discard unit.

[0011] According to another embodiment of the present disclosure, a computer-readable storage medium is further provided, wherein the computer-readable storage medium is configured to perform a step in any one of the method embodiments of the above-described method when the computer program is executed.

[0012] According to another embodiment of the present disclosure, an electronic device comprising a memory and a processor is further provided, wherein the memory stores a computer program and the processor is configured to execute the computer program to perform a step in any one of the method embodiments described above.

[0013] By applying the steps of: determining whether there is a packet to be transmitted at the transition time of the current time window through an embodiment of the present disclosure; and if there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, wherein the pre-set identifier packet has a window value of the time window, and the window value is intended to allow the second network device to determine the transition time of a different time window of the first network device; thereby enabling the downstream device to accurately recognize the time window transition location of the upstream device based on a method of supplementing the transmission of a specific packet, and rapidly forwarding user transactions according to the new time window after the hopping transition at the downstream device, thereby shortening the fault recovery time and improving communication efficiency. Brief explanation of the drawing

[0014] FIG. 1 is a block diagram of the hardware structure of a mobile terminal of a data transmission method according to an embodiment of the present disclosure. FIG. 2 is a flowchart of a data transmission method according to an embodiment of the present disclosure. FIG. 3 is a flowchart of another data transmission method according to an embodiment of the present disclosure. FIG. 4 is an example diagram of the process of transmitting packets in an Ethernet network according to an embodiment of the present disclosure. FIG. 5 is an example diagram of the operation process of a CQF scheduling technology according to an embodiment of the present disclosure. FIG. 6 is an example diagram of a problem in which packets are delayed due to optical fiber delay time in a synchronized CQF technology according to an embodiment of the present disclosure. FIG. 7 is an example of a packet forwarding case in a synchronized CQF technology according to an embodiment of the present disclosure. FIG. 8 is an exemplary diagram of the operation process of an asynchronous CQF technology according to an embodiment of the present disclosure. FIG. 9 is an example diagram showing the occurrence of a problem in the asynchronous CQF technology according to an embodiment of the present disclosure. FIG. 10 is an example diagram of two time slice positions before and after the time window transition time according to an embodiment of the present disclosure. FIG. 11 is an exemplary diagram of the structure of a data transmission method according to an embodiment of the present disclosure. FIG. 12 is an exemplary diagram of an Ethernet packet format structure according to an embodiment of the present disclosure. FIG. 13 is an example diagram of the format structure of an Ethernet packet in the coding layer according to an embodiment of the present disclosure. FIG. 14 is an example diagram of a pause frame structure having a time window value according to an embodiment of the present disclosure. FIG. 15 is an exemplary diagram of another structure of a data transmission method according to an embodiment of the present disclosure. FIG. 16 is an exemplary diagram of another structure of a data transmission method according to an embodiment of the present disclosure. FIG. 17 is an example diagram of an application scene of a data transmission method according to an embodiment of the present disclosure. FIG. 18 is an example diagram of the structure of different window values ​​of a data transmission method according to an embodiment of the present disclosure. FIG. 19 is an exemplary diagram of the structure of a data transmission device according to an embodiment of the present disclosure. FIG. 20 is an exemplary structural diagram of another data transmission device according to an embodiment of the present disclosure. Specific details for implementing the invention

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings and examples.

[0016] It should be noted that terms such as "first," "second," etc. in the specification, claims, and drawings of this disclosure are intended to distinguish similar objects and are not used to describe a specific order or sequence.

[0017] The method embodiments provided in the embodiments of the present application may be executed on a mobile terminal, a computer terminal, or a similar computing device. As an example of execution on a mobile terminal, FIG. 1 is a block diagram of the hardware structure of a mobile terminal for a data transmission method according to an embodiment of the present disclosure. As shown in FIG. 1, the mobile terminal may include one or a plurality of processors (102, the processor (102) may include, but is not limited to, a processing device such as a microprocessor (MCU) or a programmable logic device (FPGA)) and a memory (104) for data storage, and the mobile terminal may further include a transmission device (106) and an input / output device (108) for communication functions. It will be understood by those skilled in the art that the structure shown in FIG. 1 is merely an example and does not limit the structure of the mobile terminal. For example, the mobile terminal may include more or fewer components than shown in FIG. 1, or may have a different configuration than shown in FIG. 1.

[0018] Memory (104) may be used to store computer programs, such as software programs and modules of application software, such as computer programs corresponding to the data transmission method in the present disclosure embodiment, for example, and the processor (102) may execute the computer programs stored in memory (104) to perform various functional applications and data processing, that is, to realize the method. Memory (104) may include high-speed random access memory and may further include one or more non-volatile memory such as magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some embodiments, memory (104) may further include memory installed remotely from the processor (102), and such remote memory may be connected to a mobile terminal via a network. Examples of the network include, but are not limited to, the Internet, intranet, local area network, mobile network, and combinations thereof.

[0019] The transmission device (106) is intended to transmit and receive data through a network. Specific embodiments of the network may include a wireless network provided by a communication provider of a mobile terminal. In one embodiment, the transmission device (106) includes a network adapter (Network Interface Controller, abbreviated as NIC), which can communicate with the Internet by being connected to other network devices through a base station. In one embodiment, the transmission device (106) may be a radio frequency (Radio Frequency, abbreviated as RF) module, which is intended to communicate with the Internet in a wireless manner.

[0020] FIG. 2 is a flowchart of a data transmission method according to an embodiment of the present disclosure. As shown in FIG. 2, the flow includes the following steps S202 and S204.

[0021] In step S202, the first network device determines whether there is a packet to be sent at the transition time of the current time window.

[0022] In step S204, if there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device. The pre-set identifier packet has a window value of the time window, and the window value is intended to allow the second network device to determine the transition time of the different time windows of the first network device.

[0023] In step S202, when actually applied, the first network device may include, but is not limited to, an upstream device in the network packet transmission process, and the second network device may include, but is not limited to, a downstream device in the network packet transmission process. The first network device may transmit a data packet to the second network device.

[0024] In step S204, when actually implemented, time synchronization is not required between the upstream device and the downstream device, and the time window transition time of the upstream device may not be the same as that of the downstream device; it is sufficient to synchronize the clock speeds between the upstream and downstream devices and ensure that the time window transition speeds between the upstream and downstream devices are the same. When the upstream device sends a packet, the packet possesses the sending time window value of the upstream device, and when the downstream device receives a packet, the time window value of the packet is extracted to determine that the packet is being sent within that time window of the upstream device. In the data packet transmission process, user packets are received within one time window, and then all received user packets are sent within the next time window. All packets within a single time window are transmitted and received within the same time window, and when packets within the same time window are transmitted from any node in the network, they are always maintained within the same time window.

[0025] By applying the steps of: determining whether there is a packet to be transmitted at the transition time of the current time window through the present disclosure; and if there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, wherein the pre-set identifier packet has a window value of the time window, and the window value is intended to allow the second network device to determine the transition time of a different time window of the first network device, the downstream device accurately recognizes the time window transition location of the upstream device based on a method of supplementing the transmission of a specific packet, and rapidly forwards user transactions according to the new time window after the hopping transition in the downstream device, thereby realizing a reduction in fault recovery time and an improvement in communication efficiency.

[0026] In one embodiment, in step S202, the step of determining whether there is a packet to be sent at the transition time of the current time window by the first network device includes the following steps.

[0027] The first network device determines whether there is a packet to be transmitted within a time slice prior to the transition time of the current time window; or the first network device determines whether there is a packet to be transmitted within a time slice after the transition time of the current time window, and the time slice is intended to indicate the time at which an Ethernet packet is transmitted.

[0028] In one embodiment, when there is no packet to be sent at the transition time of the current time window, the step of the first network device sending a pre-set identifier packet to the second network device includes the following steps.

[0029] If there are no packets to be transmitted within the time slice prior to the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device; or,

[0030] If there are no packets to be transmitted within the time slice after the transition time of the current time window mentioned above, the first network device transmits a pre-set identifier packet to the second network device.

[0031] In one embodiment, the preset identifier packet includes a type tag field, and when there is no packet to be sent at the transition time of the current time window, the step of the first network device sending the preset identifier packet to the second network device includes the following steps.

[0032] If there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, and the second network device determines the type of the pre-set identifier packet according to the type tag field, extracts the window value of the current time window, and discards the pre-set identifier packet.

[0033] In one embodiment, the data transmission method further comprises the step of, when the sending port of the packet to be sent is a time window of various types and there is no packet to be sent at the transition time of the current time window of each type time window, the first network device sending a pre-set identifier packet including the type tag to the second network device so that the second network device determines the transition time of the time window of the plurality of type packets according to the type tag, wherein the type tag is for tokenizing different window types.

[0034] In one embodiment, the preset identifier packet includes at least one of a pause packet for controlling data traffic, a packet of VLAN tags, a packet including a packet destination address and a source address, and a code block flow sequence.

[0035] FIG. 3 is a flowchart of another data transmission method according to an embodiment of the present disclosure. As illustrated in FIG. 3, the flow includes the following steps S302 and S304.

[0036] In step S302, if there is no packet to be transmitted at the transition time of the current time window, the second network device receives a pre-set identifier packet transmitted by the first network device and determines the transition time of the current time window of the first network device, and the pre-set identifier packet includes the window value of the current time window.

[0037] In step S304, the second network device receives the window value of the current time window and then discards the pre-set identifier packet.

[0038] In one embodiment, in step S302, if there is no packet to be transmitted at the transition time of the current time window, the step of the second network device receiving a pre-set identifier packet transmitted by the first network device includes the following steps.

[0039] If there is no packet to be transmitted within the time slice prior to the transition time of the current time window mentioned above, the second network device receives the preset identifier packet transmitted by the first network device; or,

[0040] If there is no packet to be transmitted within the time slice after the transition time of the current time window mentioned above, the second network device receives the preset identifier packet transmitted by the first network device.

[0041] In one embodiment, the preset identifier packet includes a type tag field, and when there is no packet to be transmitted at the transition time of the current time window, the step of the second network device receiving a preset identifier packet transmitted by the first network device includes the following steps.

[0042] If there is no packet to be transmitted at the transition time of the current time window, the second network device determines the type of the pre-set identifier packet according to the received type tag field; extracts the window value of the current time window, and discards the pre-set identifier packet.

[0043] In one embodiment, the data transmission method further comprises the steps of: the sending port of the packet to be sent includes various types of time windows, and when there is no packet to be sent at the transition time of each corresponding type of time window, the second network device receives a plurality of time window type packets sent by the first network device, and the plurality of time window type packets include different types of tags; and determining the transition time of the time windows of the plurality of type packets according to the types of tags.

[0044] Through an embodiment of the present disclosure, when there is no packet to be transmitted at the transition time of the current time window, the second network device receives a pre-set identifier packet transmitted by the first network device and determines the transition time of the current time window of the first network device, wherein the pre-set identifier packet includes a window value of the current time window; and the second network device discards the pre-set identifier packet after receiving the window value of the current time window; by applying this, the downstream device accurately recognizes the time window transition location of the upstream device based on a method of supplementing and transmitting a specific packet, and the downstream device rapidly forwards user transactions according to the new time window after the hopping transition, thereby shortening the fault recovery time and improving communication efficiency.

[0045] With the rapid advancement of Internet technology, the transmission of information content over networks is shifting from voice transactions to data transactions, and communication networks are transitioning from SDH technology networks oriented toward voice transactions to Ethernet technology networks oriented toward data packets. The length of a typical Ethernet packet is not a single fixed value (ranging from 64 bytes to 9,600 bytes), and during transmission, packets of various lengths are mixed within the packet flow. Since these packets mutually influence each other during processing, the actual processing time becomes uncertain when handling user packets internally, leading to uncertainty in packet processing latency. For example, when packets from multiple different ports are aggregated into a single output port, a phenomenon occurs where a long packet with low priority blocks a short packet with high priority. For instance, if a long packet with low priority is being output and a received short packet with high priority must also be output, to prevent packet interruption during the transmission of the low-priority packet, the short packet with high priority must have a high transmission priority but can only be sent externally after the transmission of the long packet with low priority is completed. Since the length of low-priority packets is random, the waiting time of high-priority packets is uncertain, and since the waiting time of high-priority packets is uncertain, the delay jitter is large. Since low-priority packets can be long, the waiting time of the corresponding high-priority packets is long, and when comparing the waiting time with the actual sending time required for a short high-priority packet (the sending time of a short packet is short), the waiting time is much larger than the actual sending time, and the result is that the main cause of the time high-priority packets are delayed inside the device is the waiting time due to blocking, and the actual processing time is short.When packets are transmitted through many devices on a network, uncertain delays and jitters appear at each station, and the delays and jitters of multiple stations overlap and accumulate, and the total transmission delay time and jitter of the packets accumulate to become very large, thus affecting the transmission quality of the packets.

[0046] Current improvement technology involves introducing Time-Sensitive Networking (TSN) technology into the network and applying Time Gate Queuing scheduling technology (i.e., CQF technology, cyclic queuing and forwarding) to the TSN technology. After receiving user packets within one time window, all received user packets are transmitted within the next time window. All packets within one time window are transmitted and received within the same time window. When packets within the same time window are transmitted from any node in the network, they are always maintained within the same time window. The total transmission time of a packet in the network is n*T, where n is the number of network nodes passed through and T is the size of the time window. A packet may vary within one time window but does not exceed the time window, and the jitter value resulting from packet variation is less than T. This ensures reliable transmission of the packet over the network. CQF technology requires time synchronization between upstream and downstream devices, and since the transmission time window and reception time window are switched simultaneously when the time of the upstream and downstream devices is synchronized, the technology is suitable only for local area networks where the distance between the upstream and downstream devices is short and the optical fiber latency between devices can be ignored. In urban area networks and wide area networks, the distance between devices is long and the packet latency in the optical fiber is long; therefore, even if the upstream and downstream devices switch their time windows simultaneously, when a packet transmitted from the transmission end of the upstream device passes through the optical fiber and is sent to the reception end of the downstream device, the packet actually reaches the receiving port of the downstream device after a predetermined time delay, so the arrival time of the packet and the time window switching time of the downstream receiving device do not coincide.To address issues caused by optical fiber latency, an asynchronous CQF method is proposed. This approach eliminates the need for time synchronization between upstream and downstream devices; the time window transition times of the upstream and downstream devices may not be identical, requiring only the synchronization of clock speeds between the devices and the same time window transition speed between them. When an upstream device transmits a packet, the packet possesses the transmission time window value of the upstream device. When a downstream device receives a packet, the time window value of the packet is extracted to determine that the packet was transmitted within that time window of the upstream device. Asynchronous CQF technology resolves the problem of unavoidable optical fiber latency in urban area networks and wide-area networks by avoiding optical fiber transmission time between upstream and downstream devices.

[0047] After applying asynchronous CQF technology, the downstream device extracts the time window value of a packet to determine that the packet is being sent from the upstream device within that time window. Based on the packet's time window value, the downstream device can determine the time of the upstream device's time window transition through changes in the packet's window value. If there are few packets sent by the upstream device, or if there are no packets to send, the downstream device cannot accurately determine the time of the upstream device's time window transition. If a fault abnormality occurs in the upstream device and a hopping transition occurs in the upstream device's time window, and the downstream device cannot detect the upstream device's time window abnormality but still forwards packets according to the previous time window, the forwarding operation cannot satisfy the requirements of the new time window, resulting in a forwarding operation error, and in severe cases, a user transaction interruption.

[0048] To solve the above technical problem, the data transmission method provided by an embodiment of the present disclosure, based on the above embodiment, further comprises steps S1, S2, and S3 as follows.

[0049] In step S1, the sender of the upstream device determines whether there is a user packet to be sent at the time window transition time.

[0050] In step S2, if the sender of the upstream device does not have a user packet to send at the time window transition time, it sends a supplementary packet with a specially defined time window value.

[0051] In step S3, the receiver of the downstream device extracts the time window value of the packet and determines the transition time of the time window value of the upstream device, considering it as reference information for subsequent decisions and judgments.

[0052] In one embodiment, step S1 of the data transmission method further includes steps S11, S12, S13, and S14 as follows.

[0053] In step S11, the sender of the upstream device determines whether there is a user packet to be sent at the time window transition time, and the determination method is divided into whether there is a user packet to be sent within a time slice prior to the time window transition time and whether there is a user packet to be sent within a time slice after the time window transition time.

[0054] In step S12, the size range of the time slice may be the transmission time of the minimum packet defined by Ethernet standards, or the actual transmission time of the packet to be specially defined.

[0055] In step S13, the time slice prior to the time window transition time indicates a sending location that can supplement and send one packet prior to the time window transition time.

[0056] In step S14, the time slice after the time window transition time indicates a sending location that can supplement and send one packet after the time window transition time.

[0057] In one embodiment, step S2 of the data transmission method further includes the following steps S21, S22, S23, S24, and S25.

[0058] In step S21, the supplemental dispatch for the specially defined packet may be one of the following modes: Mode 1, Mode 2, and Mode 3.

[0059] Mode 1 checks both time slices before and after the transition time.

[0060] Mode 2 checks only the time slice prior to the transition time.

[0061] Mode 3 checks only the time slice after the transition time.

[0062] In step S22, in a mode that checks both the previous and subsequent two time slices, the time slice before the time window transition time and the time slice after the time window transition time are checked simultaneously, and if there are no user packets to be transmitted within either time slice, a specially defined packet is transmitted in that time slice.

[0063] In step S23, in a mode that checks only the time slice prior to the time window transition time, the time slice prior to the deviation time window transition time is checked, and if there is no user packet to be transmitted within the said time slice, a specially defined packet is transmitted as a supplement within the said time slice.

[0064] In step S24, in a mode that checks only the time slice after the time window transition time, the time slice after the time window transition time is checked, and if there is no user packet to be transmitted within the time slice, a specially defined packet within the time slice is transmitted as a supplement.

[0065] In step S25, the specially defined packet has special flag information, and the time window value information of the specially defined packet can be identified and extracted by a downstream device.

[0066] In one embodiment, step S3 of the data transmission method further includes steps S31, S32, S33, S34, and S35 as follows.

[0067] In step S31, when a user packet is received at the receiver of a downstream device, the time window value of the user packet is extracted; when a specially defined packet is received at the receiver of a downstream device, the time window value of the specially defined packet is extracted, and the specially defined packet is discarded.

[0068] In step S32, when a mode is applied to check both the previous and subsequent packet transmission time slices, if a change occurs in the time window value extracted from two adjacent packets (including user packets and specially defined packets), the boundary position of the previous and subsequent packets is the transition time position of the transmission time window of the upstream device.

[0069] In step S33, in a mode that checks only the packet sending time slice prior to the switching time, the end position of the specially defined packet is the switching time position of the upstream device's sending time window, and the time window value of the specially defined packet is the sending time window value of the upstream device prior to the switching time.

[0070] In step S34, in a mode that checks only the packet sending time slice after the switching time, the starting position of the specially defined packet is the switching time position of the upstream device's sending time window, and the time window value of the specially defined packet is the sending time window value of the upstream device after the switching time.

[0071] In step S35, the time window transition position of the upstream device is obtained, and whether the transition position corresponds to the expected situation is considered as the basis for determining and judging whether the outgoing time window transition position of the upstream device is abnormal.

[0072] Based on the above embodiment, in one or more embodiments, the data transmission method further includes the following steps. As illustrated in FIG. 4, when a packet is transmitted through many devices on a network, uncertain delay and jitter appear at each station, and the delay and jitter of multiple stations overlap and accumulate, and the total transmission delay time and jitter of the packet accumulate and become very large, thus affecting the transmission quality of the packet. The current improvement technology introduces Time-Sensitive Networking (TSN) technology into the network and, as shown in Fig. 5, applies time gate queuing scheduling technology (i.e., CQF technology, cyclic queuing and forwarding) to the TSN technology. After receiving user packets within one time window, all received user packets are transmitted within the next time window, and all packets within one time window are transmitted and received within the same time window. When packets within the same time window are transmitted from any node in the network, they are always maintained within the same time window. The total transmission time of a packet in the network is n*T, where n is the number of network nodes passed through and T is the size of the time window. Although a packet may vary within one time window, it does not exceed the time window, and the jitter value caused by the variation of the packet is less than T. In this way, reliable transmission of the packet is realized on the network. Since CQF technology requires time synchronization between upstream and downstream devices and switches the transmission and reception time windows simultaneously when the times of the upstream and downstream devices are synchronized, the technology is suitable only for local area networks where the distance between the upstream and downstream devices is short and the optical fiber latency between the devices can be ignored.In urban area networks and wide area networks, the distance between devices is long and the packet delay time in the optical fiber is long. Even if the upstream and downstream devices switch time windows simultaneously, when a packet transmitted from the transmitting end of the upstream device passes through the optical fiber and is transmitted to the receiving end of the downstream device, the packet actually reaches the receiving port of the downstream device after a predetermined time delay. Therefore, as shown in FIG. 6, the time difference Δ in FIG. 6 does not coincide with the arrival time of the packet and the time window switching time of the downstream receiving device. To solve the problem caused by optical fiber delay, an asynchronous CQF method is proposed. Time synchronization between the upstream device and the downstream device is not required, and the time window switching time of the upstream device and the time window switching time of the downstream device may not be the same. It is sufficient to simply synchronize the clock speed between the upstream device and the downstream device and have the same time window switching speed between the upstream device and the downstream device. When an upstream device transmits a packet, the packet possesses the transmission time window value of the upstream device; conversely, when a downstream device receives a packet, the time window value of the packet is extracted to determine that the packet is transmitted within that time window of the upstream device. Asynchronous CQF technology eliminates the need for time synchronization between upstream and downstream devices and avoids the need to switch their time windows at the same time. By avoiding optical fiber transmission time between the upstream and downstream devices, it resolves the problem where optical fiber latency cannot be ignored in metropolitan area networks (AMMs) and wide-area networks (WVAs).As illustrated in FIG. 7, after applying the asynchronous CQF technology, the downstream device extracts only the time window value of the user packet, and the time window value is the time window position where the packet is transmitted from the sender of the upstream device. The same time window value indicates that such packets are transmitted within the same time window, and different time window values ​​within the packet indicate that such packets are not within the same time. The downstream device must forward packets with the same time window value within the same time window. There are multiple values ​​for the time window value, and in FIG. 7, the time window values ​​are 1 to 8. The sender of the device determines that the window value for all packets transmitted in time window 1 is 1, the window value for all packets transmitted in time window 2 is 2, and by inference in order, the window value for all packets transmitted in time window 8 is 8. The next time window value starts again from 1, and the time window values ​​appear in a cyclical manner in order. Optical fiber latency can be large, for example, it can be larger than a single time window size, such as when optical fiber latency is 2.7 times the single time window size. When an upstream device transmits a packet, the packet has the transmission time window value of the upstream device, and when a downstream device receives a packet, the time window value of the packet is extracted to determine that the packet is transmitted within that time window of the upstream device, thereby determining the transmission location of such a packet at the transmission end of the upstream device. As shown in FIG. 8, the time position of the upstream device's time window transition can be determined through the change location of the time window value of the packet.Asynchronous CQF technology does not require time synchronization between upstream and downstream devices and does not require switching the time windows of upstream and downstream devices at the same time, thereby preventing problems caused by optical fiber transmission time between upstream and downstream devices. This makes it suitable for application scenarios in metropolitan area networks and wide-area networks where optical fiber latency cannot be ignored.

[0073] In asynchronous CQF technology, the downstream device extracts the time window value of a packet to determine that the packet is being transmitted within the upstream device's time window. Based on this time window value, the device can determine the time window transition time of the upstream device through changes in the packet's time window value. Under normal circumstances, the time window transition time of the upstream device's transmitting port is periodic and regular, always maintaining a stable and unchanging state, and the window value of the packet extracted by the downstream device also changes periodically according to fixed rules. However, if an abnormality occurs in the upstream device, such as a reset, reboot, or optical fiber switching, the transition time position of the upstream device's transmitting time window and the magnitude of the packet's time window value change abruptly. Consequently, the downstream device detects these abnormal changes, resets the delay parameters of the packet received by the downstream device, and subsequently updates the transmission time window position of the corresponding packet at the downstream device. Therefore, it is crucial for the downstream device to detect the upstream device's transmission time window transition position in real time and to determine whether the packet's time window value is abnormal. In a scenario where user packets are bearered in large quantities, the downstream device continuously receives user packets, extracts the time window value from the user packets, and determines the time position of the upstream device's time window transition through the time window value from the user packets, thereby easily determining whether the upstream device's time window transition position and the time window value of the user packets are abnormal.

[0074] If user packets carried over the network are sparse or there are no user packets to be sent within a short period of time, as illustrated in FIG. 9, the downstream device cannot accurately determine the time window transition time of the upstream device. If a fault abnormality occurs in the upstream device and a hopping transition occurs in the upstream device's time window, and the downstream device cannot detect the upstream device's time window abnormality but still forwards packets according to the previous time window, the forwarding operation cannot satisfy the requirements of the new time window, resulting in a forwarding operation error, and in severe cases, a user transaction interruption occurs.

[0075] In order to solve the above problem and to easily monitor in real time whether the transmission time window of an upstream device is abnormal, the present patent replaces empty user packets with specially defined packets through a method of supplementing transmission with specially defined packets, thereby enabling the downstream device to accurately know the time window transition position of the upstream device, so as to quickly and accurately determine whether the time window transition time of the upstream device is abnormal, and if it is detected that a hopping conversion has occurred at the upstream transmission time, the downstream device quickly forwards user transactions according to the new time window after the hopping conversion, thereby shortening the fault recovery time. The specific implementation is as follows. The transmission end of the upstream device determines whether there is a user packet to be transmitted within the two time slices before and after the transmission time window transition time position, as shown in FIG. 10. If there is no packet to be transmitted within the time slice, a specially defined packet is transmitted within the time slice to replace the user packet and to be transmitted to the downstream device, as illustrated in FIG. 11, the packet with the added thick black arrow in FIG. 11 is the specially defined packet. The specially defined packet is a user-defined packet agreed upon by the upstream and downstream devices, and the packet has a specially defined flag and also has a time window value in which the packet is located. The time slice is greater than or equal to the time required to transmit the specially defined packet, thereby ensuring that the specially defined packet can be transmitted within the time slice.By supplementing the transmission with a specially defined packet, the transmission end ensures that even if there are no user packets to be delivered to the link, there is a single packet sent to the downstream device both before and after the time window transition point, and the packets before and after the time window transition point have different time window values. The downstream device can accurately determine the time window transition point of the upstream device through the time window values ​​it possesses. The receiver of the downstream device detects the specially defined packet, directly extracts the window value information contained in the packet, uses it to determine the time window transition point of the upstream device, and finally discards the specially defined packet. The specially defined packet is intended solely to bear the time window value information, and loses its significance once the bearing of the time window value information is completed.

[0076] A specially defined packet is a user-defined packet having specific flag features agreed upon between an upstream device and a downstream device. The downstream device detects the specific flag features of the packet, determines that the packet is a specially defined packet, extracts the time window value, and then discards the packet. A specially defined packet may be an Ethernet packet having specific flag features, and general Ethernet has information regarding specific flag features and time window values. As illustrated in FIG. 12, FIG. 12 is a general Ethernet packet structure, and in a general Ethernet packet, the type domain may have user-defined specific flag features. For example, a feature value of the type domain being 0xffff is considered a specific flag feature. Specific specific flag features may take various other forms. For example, in a general Ethernet packet, a packet in which the destination address domain value is a special destination address value (e.g., 0xff-ff-ff-ff-ff-ff) is considered a specially defined packet.

[0077] A specially defined packet may be a standard Ethernet packet format, or it may be a specific bitstream sequence in which a standard Ethernet packet appears as a bitstream sequence at the PCS layer of the physical layer. For example, when a standard Ethernet packet is transmitted from a physical port, it is first 64 / 66 coded and then transmitted in the form of a 66-bit block flow. As illustrated in FIG. 13, the code block sequence of standard Ethernet after 64 / 66 coding consists of an S block + multiple D blocks + T blocks, where the S block is the start block of the packet, the D blocks are the data blocks, and the T blocks are the end blocks. In the standard Ethernet definition, the content of the S block consists of 66 bits, and the structure is "0b10" + "0x78" + 7 "0x55". The "0b10" + "0x78" field is generally used to identify that it is an S block, and the following seven "0x55" can be modified appropriately during the application process, and the content of some of the seven "0x55" fields can be modified with specially defined flags. For example, six "0x55" + "0xAA" are considered as a specially defined packet with specially defined flags (some D blocks have window values). In actual applications, the "0x78" field is modified to a field not used in other Ethernet standards and is considered as a specially defined flag. Since the shortest packet length defined by Ethernet standards is 64 bytes, the number of D blocks in the code block flow sequence after a standard Ethernet packet is coded is at least 4, and any D blocks fewer than 4 are illegal packet blocks. The receiving end discards the code block sequence after receiving it, and thus the code block flow sequence S+n*D (where n is any one of 0, 1, 2, or 3)+T can be considered as a specially defined packet.For example, an S+T code block flow sequence, or an S+D+T code block flow sequence, or an S+D+D+T code block flow sequence, or an S+D+D+D+T code block flow sequence are considered as specially defined packets, and a D block or a T block has a time window value. At the receiving end, after detecting this type of code block flow sequence, the specially defined packet can be identified through the number of D blocks, the time window value of the D block or the T block is extracted, and then the code block sequence is discarded.

[0078] In actual applications, in addition to considering a general Ethernet packet with a specially defined flag or a specific code block sequence as a specially defined packet, new functions can be extended in Ethernet protocol packets to realize the purpose of having a time window value. For example, in an Ethernet physical interface, a pause frame is applied to notify the counterparty device to stop sending packets, thereby limiting the sending rate of user transactions. Upon receiving the pause frame, the receiver initiates a flow control operation and then discards the pause frame packet. The pause frame format is as illustrated in FIG. 14, where the destination address domain in the pause frame is a fixed value (0x01-80-C2-00-00-01), the type value is 0x8808, and the operation code is 0x0001. The operation parameter is the length of time during which the PAUSE sender requests the counterparty to stop sending data frames; the time scale unit is the time used to transmit 512 bits of data at the current transmission rate; and the time actually stopped by the receiver is the product of the operation parameter field content and the time used to transmit 512 bits of data at the current transmission rate. In the application process, the operation parameter generally takes 0xFFFF, and the pause time takes the maximum value. In the application process, the operation parameter can be taken as 0x0000 and considered as a specially defined flag (a pause frame with the operation parameter taken as 0x0000 indicates that no flow control is performed during flow control), and generally, a pause packet with the operation parameter taken as 0x0000 can be considered as a specially defined packet (it may be a different operation value). As shown in FIG. 14, the field reserved in the pause packet has a time window value. After receiving a pause packet with an operation code of 0x0000 at the receiver, the time window value of the reserved field is extracted.

[0079] As illustrated in FIG. 15, by combining the embodiment as illustrated in FIG. 11, detection is performed in both of the two time slices before and after the transmission time window transition time position of the upstream device; however, in actual application, detection may be performed in only one of the time slices and a specially defined packet may be supplemented. In FIG. 15, detection is performed only in the time slice after the detection time window transition time and a specially defined packet is supplemented. When the upstream device and the downstream device negotiate to perform detection only in the time slice after the detection time window transition time and supplementally send a specially defined packet, the upstream device performs detection only in the time slice after the detection time window transition time and supplementally sends a specially defined packet, and when the downstream device receives the specially defined packet, it determines that the start position time of the packet is the transition position of the time window and the time window value of the packet is the time period value after the transition. In actual application, detection may be performed only in the time slice before the detection time window transition time and a specially defined packet may be supplemented. As illustrated in FIG. 16, when negotiations are made to proceed with detection only in the time slice prior to the detection time window transition time in the upstream device and to supplementally transmit a specially defined packet, the upstream device proceeds with detection only in the time slice prior to the detection time window transition time and supplementally transmits the specially defined packet, and when the downstream device receives the specially defined packet, it determines that the end position time of the packet is the transition position of the time window and that the time window value of the packet is the time period value prior to the transition.

[0080] In the above embodiment, both the sending port and the receiving port operate according to the physical port, and a single physical port has only one time window value. In actual operation, a single physical port may have multiple user flows, and each user flow has a separate, independent, different time window value. As illustrated in FIG. 17, there are multiple different user transaction flows on the same physical link (the same pair of physical sending and receiving ports), and the different user transaction flows have different sending time periods and sending time window transition times. As illustrated in FIG. 18, when different user transaction flows exist on the same physical port, the time window of the sending end operates periodically according to the time window of each user flow, and if there is no such user transaction flow before and / or after the time window transition time of a single independent user transaction flow, a specially defined packet belonging to that user transaction flow is sent as a supplement. The specially defined packet has a special label belonging to that user transaction flow, so the sending end can identify which user transaction flow the specially defined packet belongs to. There are various different methods for specific implementation. For example, different user flows are identified through VLAN labels, and user transactions of the same user flow and specially defined packets of that user transaction flow have the same VLAN label value. At the receiving physical port, processing is performed separately according to the different user transaction flows. In the case of the same user flow, specially defined packets are extracted from that user transaction flow, and a time window value is obtained from the extracted packets to obtain the time window transition time of the upstream port of that user flow.

[0081] The patent application scenario presented in the above embodiment is an asynchronous CQF operation scenario. In actual applications, the embodiment of the invention may be applied to an 802.1Qch operation scenario in a TSN protocol suite, i.e., CQF (synchronized with CQF). In 802.1Qch protocol operation, time synchronization between upstream and downstream devices (or devices on the network) is required, but after applying this patent, time synchronization between devices may not be required, and the packet only needs to have a sending time window value. If there are no user packets to be sent within the time slice before and after a change in the sending time window occurs, a specially defined packet having the time window value is sent to the downstream device as a supplement.

[0082] In the embodiments provided by the present disclosure, the definition of a specially defined packet may be an extension of new functions from a general user packet, and may have specific flag features to realize the purpose of having a time window value. The specially defined packet may be of various other forms, and the position of the time window value may also be diverse, and is not limited in the present disclosure.

[0083] By applying the steps of: determining whether there is a packet to be transmitted at the transition time of the current time window through an embodiment of the present disclosure; and if there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, wherein the pre-set identifier packet has a window value of the time window, and the window value is intended to allow the second network device to determine the transition time of a different time window of the first network device; thereby enabling the downstream device to accurately recognize the time window transition location of the upstream device based on a method of supplementing the transmission of a specific packet, and rapidly forwarding user transactions according to the new time window after the hopping transition at the downstream device, thereby shortening the fault recovery time and improving communication efficiency.

[0084] Through the description of the above embodiments, those skilled in the art will clearly understand that the method according to the above embodiments can be realized through software and a necessary general-purpose hardware platform, and of course, can also be realized by hardware, but in many cases, the former is a more preferred embodiment. Based on this understanding, the essence of the means of solution of the present disclosure or the part contributing to the prior art may be implemented in the form of a software product, said computer software product is stored on a storage medium (e.g., ROM / RAM, magnetic disk, optical disk) and includes several instructions that enable a terminal device (which may be a mobile phone, computer, server or network device, etc.) to perform the method according to each embodiment of the present disclosure.

[0085] In this embodiment, a data transmission device is further provided. The device is intended to realize the above embodiment and preferred embodiment, and descriptions of previously described parts are omitted. For example, terms such as "module" used below may realize a combination of software and / or hardware with a predetermined function. While the device described in the following embodiment is preferably realized in software, it is also possible to realize it in hardware or a combination of software and hardware.

[0086] FIG. 19 is a structural block diagram of a data transmission device according to an embodiment of the present disclosure. As shown in FIG. 19, the device includes a judgment unit (1902) and a transmission unit (1904).

[0087] The judgment unit (1902) is configured to determine whether there is a packet to be sent at the transition time of the current time window.

[0088] The transmitting unit (1904) is configured such that when there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, the pre-set identifier packet has a window value of the time window, and the window value is for determining the transition time of different time windows of the first network device at the second network device.

[0089] In embodiments of the present disclosure, the first network device may include, but is not limited to, an upstream device in the network packet transmission process, and the second network device may include, but is not limited to, a downstream device in the network packet transmission process. The first network device may transmit a data packet to the second network device.

[0090] In the embodiments of the present disclosure, time synchronization is not required between the upstream device and the downstream device, and the time window transition time of the upstream device and the time window transition time of the downstream device may not be the same; it is sufficient to synchronize the clock speed between the upstream device and the downstream device and have the same time window transition speed between the upstream device and the downstream device. When the upstream device transmits a packet, the packet has the transmission time window value of the upstream device, and when the downstream device receives a packet, the time window value of the packet is extracted to determine that the packet is transmitted within that time window of the upstream device. In the data packet transmission process, user packets are received within one time window, and then all received user packets are transmitted within the next time window. All packets within one time window are transmitted and received within the same time window, and when packets within the same time window are transmitted from any node in the network, they are always maintained within the same time window.

[0091] By applying the steps of: determining whether there is a packet to be transmitted at the transition time of the current time window through the present disclosure; and if there is no packet to be transmitted at the transition time of the current time window, the first network device transmits a pre-set identifier packet to the second network device, wherein the pre-set identifier packet has a window value of the time window, and the window value is intended to allow the second network device to determine the transition time of a different time window of the first network device, the downstream device accurately recognizes the time window transition location of the upstream device based on a method of supplementing the transmission of a specific packet, and rapidly forwards user transactions according to the new time window after the hopping transition in the downstream device, thereby realizing a reduction in fault recovery time and an improvement in communication efficiency.

[0092] FIG. 20 is a structural block diagram of another data transmission device according to an embodiment of the present disclosure. As shown in FIG. 20, the device includes a determination unit (2002) and a disposal unit (2004).

[0093] The determination unit (2002) is configured such that, when there is no packet to be transmitted at the transition time of the current time window, the second network device receives a pre-set identifier packet transmitted by the first network device and determines the transition time of the current time window of the first network device, and the pre-set identifier packet includes the window value of the current time window.

[0094] The discard unit (2004) is configured such that the second network device discards the preset identifier packet after receiving the window value of the current time window.

[0095] It must be explained that each of the above modules can be realized through software or hardware, and in the latter case, the modules can be realized by being located on the same processor or by each of the modules being located on different processors in any combination, but is not limited thereto.

[0096] Embodiments of the present disclosure further provide a computer-readable storage medium. A computer program is stored in the computer-readable storage medium, and the computer program is configured to perform a step in an embodiment of the method of any one of the above-described claims when executed.

[0097] In an exemplary embodiment, the computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as a USB memory, read-only memory (abbreviated as ROM), random access memory (abbreviated as RAM), a removable hard disk, a magnetic disk, or an optical disk.

[0098] Embodiments of the present disclosure further provide an electronic device. The electronic device includes a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to execute the computer program to perform a step in any one of the method embodiments of the above-described invention.

[0099] In an exemplary embodiment, the electronic device may further include a transmission device connected to the processor and an input / output device connected to the processor.

[0100] Specific examples in this embodiment may refer to the examples described in the above embodiments and exemplary embodiments, and this embodiment is omitted from description herein.

[0101] It is obvious that each module or each step of the above disclosure can be realized by a general-purpose computer device, and these can be concentrated in a single computer device or distributed in a network of multiple computer devices, and since they can be realized as program code executable on a computer device, they can be stored in a storage device and executed on a computer device. Furthermore, those skilled in the art should know that in some cases, the steps illustrated or described can be executed in a different order than herein, or they can be manufactured as separate integrated circuit modules, or multiple of these modules or steps can be manufactured as a single integrated circuit module. As such, the present disclosure is not limited to any specific combination of hardware and software.

[0102] The above is merely a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and the present disclosure may be modified and changed in various ways by those skilled in the art. Any modification, equivalent substitution, improvement, etc. made within the principles of the present disclosure shall be included within the scope of protection of the present disclosure.

Claims

Claim 1 A data transmission method comprising: a first network device determining whether there is a packet to be transmitted within a time slice prior to or after the transition time of the current time window, wherein the time slice is a continuous time of a pre-set length; and if there is no packet to be transmitted within the time slice prior to or after the transition time of the current time window, the first network device transmitting a pre-set identifier packet to a second network device, wherein the pre-set identifier packet has a window value of the time window, and the window value is for determining the transition time of a different time window of the first network device at the second network device. Claim 2 In claim 1, the step of the first network device transmitting a pre-set identifier packet to the second network device when there is no packet to be transmitted at the transition time of the current time window comprises: the first network device transmitting a pre-set identifier packet to the second network device when there is no packet to be transmitted within a time slice prior to the transition time of the current time window; or the first network device transmitting a pre-set identifier packet to the second network device when there is no packet to be transmitted within a time slice after the transition time of the current time window. Claim 3 A data transmission method comprising: in claim 1, the pre-set identifier packet includes a type tag field, and when there is no packet to be sent at the transition time of the current time window, the first network device sends the pre-set identifier packet to the second network device, wherein when there is no packet to be sent at the transition time of the current time window, the first network device sends the pre-set identifier packet to the second network device, and the second network device determines the type of the pre-set identifier packet according to the type tag field, extracts the window value of the current time window, and discards the pre-set identifier packet. Claim 4 A data transmission method according to claim 1, wherein the sending port of the packet to be sent is a time window of various types, and there is no packet to be sent at the transition time of the current time window of each type of time window, the first network device sends the pre-set identifier packet including a type tag to the second network device so that the second network device determines the transition time of the time window of multiple type packets according to the type tag, and the type tag is for tokenizing different window types. Claim 5 A data transmission method according to claim 1, wherein the pre-set identifier packet comprises at least one of a pause packet for controlling data traffic, a packet of VLAN tags, a packet including a packet destination address and a destination address, and a code block flow sequence. Claim 6 A data transmission method comprising: a step in which, if there is no packet to be transmitted within a time slice prior to or after the transition time of the current time window, the second network device receives a pre-set identifier packet transmitted by the first network device and determines the transition time of the current time window of the first network device, wherein the pre-set identifier packet includes a window value of the current time window and the time slice is a continuous time of a pre-set length; and a step in which, after receiving the window value of the current time window, the second network device discards the pre-set identifier packet. Claim 7 In claim 6, the above-mentioned pre-set identifier packet includes a type tag field, and when there is no packet to be transmitted at the transition time of the current time window, the step of the second network device receiving the pre-set identifier packet transmitted by the first network device comprises: a step of determining the type of the pre-set identifier packet according to the received type tag field when there is no packet to be transmitted at the transition time of the current time window; and a step of extracting the window value of the current time window and discarding the pre-set identifier packet. Claim 8 A data transmission method according to claim 6, further comprising: a step in which, if the sending port of the packet to be sent includes various types of time windows and each corresponding type of time window has no packet to be sent at the transition time of its respective current time window, the second network device receives a plurality of time window type packets sent by the first network device, and the plurality of time window type packets include tags of different types; and a step of determining the transition time of the time windows of the plurality of type packets according to the tags of the types. Claim 9 A data transmission device comprising: a determination unit configured to determine whether there is a packet to be transmitted within a time slice prior to or after the transition time of a current time window, wherein the time slice is a continuous time of a preset length; and a transmission unit configured such that, if there is no packet to be transmitted within the time slice prior to or after the transition time of the current time window, the first network device transmits a preset identifier packet to a second network device, wherein the preset identifier packet has a window value of the time window, and the window value is for determining the transition time of a different time window of the first network device at the second network device. Claim 10 A data transmission device comprising: a determination unit in which, when there is no packet to be transmitted within a time slice prior to or after the transition time of the current time window, the second network device receives a pre-set identifier packet transmitted by the first network device and determines the transition time of the current time window of the first network device, wherein the pre-set identifier packet includes a window value of the current time window and the time slice is a continuous time of a pre-set length; and a discarding unit in which the second network device is configured to discard the pre-set identifier packet after receiving the window value of the current time window. Claim 11 A network device comprising: a determining unit configured to determine whether there is a packet to be transmitted within a time slice prior to or after the transition time of a current time window, wherein the time slice is a continuous time of a preset length; and a transmitting unit configured such that, if there is no packet to be transmitted within the time slice prior to or after the transition time of the current time window, the first network device transmits a preset identifier packet to a second network device, wherein the preset identifier packet has a window value of the time window, and the window value is for determining the transition time of a different time window of the first network device at the second network device. Claim 12 A network device comprising: a determination unit in which, if there is no packet to be transmitted within a time slice prior to or after the transition time of the current time window, the second network device receives a pre-set identifier packet transmitted by the first network device and determines the transition time of the current time window of the first network device, wherein the pre-set identifier packet includes a window value of the current time window and the time slice is a continuous time of a pre-set length; and a discard unit in which the second network device is configured to discard the pre-set identifier packet after receiving the window value of the current time window. Claim 13 A computer-readable storage medium in which a computer program is stored, wherein the computer-readable storage medium is configured to perform a method according to any one of claims 1 to 5 and claims 6 to 8 when the computer program is executed. Claim 14 delete Claim 15 delete

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