CN105610727B

CN105610727B - A kind of network data transmission method and device

Info

Publication number: CN105610727B
Application number: CN201510752868.1A
Authority: CN
Inventors: 杨宏宇; 秦萌
Original assignee: Raisecom Technology Co Ltd
Current assignee: Raisecom Technology Co Ltd
Priority date: 2015-11-06
Filing date: 2015-11-06
Publication date: 2019-02-12
Anticipated expiration: 2035-11-06
Also published as: CN105610727A

Abstract

The invention discloses a kind of network data transmission method and devices, applied to end-to-end asynchronous transmission network, it include: to hold the actual operation parameters to the network link at packet receiving end to belong to preset low-load state when giving out a contract for a project, and the data volume that packet receiving end receives in predetermined duration of giving out a contract for a project is when being less than the data volume that end of giving out a contract for a project is sent, and is given out a contract for a project the business transmission rate at end according to the adjustment of the first preset strategy；After the business transmission rate at end of giving out a contract for a project is adjusted to business minimum transmission rate, when the data volume that packet receiving end receives in predetermined duration of giving out a contract for a project is still less than the data volume that end of giving out a contract for a project is sent, it is synchronous that clock is carried out in the TCP message that transmission carries clock quality class information on network link of the end to packet receiving end of giving out a contract for a project.Network data transmission method and device provided by the invention, for reducing the packet loss in asynchronous network data transmission procedure.

Description

Network data transmission method and device

Technical Field

The present invention relates to the field of communications, and in particular, to a method and an apparatus for transmitting network data.

Background

In ethernet, conventional asynchronous data transmission takes place in the form of sending and receiving data packets. Ideally, the number of data packets received by the receiving end is equal to the number of data packets sent by the sending end. Moreover, because the sending rate, the receiving rate and the flow of the messages among the nodes in the Ethernet all have the burstiness, all the devices in the Ethernet adopt a cache mechanism to smooth the burstiness generated when the messages among different nodes are interacted. Specifically, each device sets a buffer space of a fixed size in advance. Taking a sliding window and a buffer mechanism in a Transmission Control Protocol (TCP)/Internet Protocol (IP) standard as an example for explanation, a packet sending end writes a message to be sent into a sending buffer, as shown in fig. 1, at this time, the sending buffer is used to temporarily store: the message data that the sending end is ready to send and the data that the sending end has sent but the receiving end has not confirmed that the receiving end has correctly received, wherein, the message data that has confirmed to receive will be deleted from the sending buffer memory, therefore, the sending buffer memory and the back porch of the sending window are coincident. The packet receiving end reads the received message byte information from the receiving cache, as shown in fig. 2, the receiving cache is used to temporarily store: data packets that arrive in order but have not yet been acknowledged by the receiving end as correctly received and data packets that do not arrive in order.

However, in an actual network, due to physical line failure, equipment failure, virus attack, network congestion, routing information error, and the like, the ideal state of data transmission usually does not occur. The packet receiving end cannot normally receive all data sent by the packet sending end, that is, the entire network system loses packets in the data transmission process, so that the information received by the packet receiving end is lost, and the normal communication of the service is affected. The above situation is more seriously affected in services with higher requirements on network performance, such as video communication, and therefore, how to reduce the packet loss in data transmission in the ethernet network is a problem that needs to be solved urgently.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a method and an apparatus for transmitting network data, which are used to reduce packet loss during asynchronous network data transmission.

In order to achieve the above technical object, the present invention provides a network data transmission method applied to an end-to-end asynchronous transmission network, including: when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset low-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time, adjusting the service sending rate of the packet sending end according to a first preset strategy; and after the service sending rate of the packet sending end is adjusted to the service minimum sending rate, when the data volume received by the packet receiving end is still smaller than the data volume sent by the packet sending end within the preset packet sending time, transmitting a TCP message carrying clock quality grade information on a network link of the packet sending end and the packet receiving end to carry out clock synchronization.

Further, the method further comprises: when the actual operation parameters of the network link from the sending end to the receiving end belong to a preset high-load state, and the data volume received by the receiving end is smaller than the data volume sent by the sending end within the preset sending Time, transmitting a TCP message carrying a Precision Time Protocol (PTP) field on the network link from the sending end to the receiving end for clock synchronization.

Further, the transmitting a TCP packet carrying a PTP field on a network link between the packet sending end and the packet receiving end to perform clock synchronization includes:

determining the master-slave attribute of the clock through negotiation between every two connected network nodes on a network link of a packet sending end and a packet receiving end;

the master clock side sends an Announce message carrying master clock information to the slave clock side;

the master clock side sends a Sync message to the slave clock side, wherein the Sync message carries a sending time stamp t1 of the Sync message;

the slave clock side records an arrival time stamp t2 of a Sync message and sends a Delay _ Req message to the master clock side, wherein the Delay _ Req message carries a sending time stamp t3 of the Delay _ Req message;

the master clock side sends a Delay _ Resp message to the slave clock side, wherein the Delay _ Resp message carries a receiving time stamp t4 of the master clock side to the Delay _ Req message;

the slave clock side determines the double between the master clock side and the slave clock side according to the time stamps t1, t2, t3 and t4The average time delay difference and the time difference between the master clock and the slave clock are calculated, and the adjustment is carried out according to the two-way average time delay difference and the time differenceRectifying the slave clock to synchronize with the master clock, wherein the two-way average delay difference isWhen saidWith a difference of

Further, the adjusting the service sending rate of the packet sending end according to the first preset policy includes:

determining the optimal service sending rate of a packet sending end as follows:

wherein, T is the period duration of data transmission packet loss measurement period, M is the maximum bandwidth of a network link from a packet sending end to a packet receiving end, and V_maxMaximum transmission rate for traffic, and V_maxM/8, △ f is the frequency offset generated end-to-end by the network,the buffer value is the sum of the buffer values of all the intermediate devices between the packet sending end and the packet receiving end;

after the service sending rate of the packet sending end is adjusted to the optimal service sending rate, if the data volume received by the packet receiving end is equal to the data volume sent by the packet sending end within the preset packet sending time, the service sending rate of the packet sending end is adjusted according to a second preset strategy;

after the service sending rate of the packet sending end is adjusted to the optimal service sending rate, if the data volume received by the packet receiving end is still less than the data volume sent by the packet sending end within the preset packet sending duration, the service packet sending rate of the packet sending end is adjusted to the minimum service sending rate, wherein the minimum service sending rate V is the minimum service sending rate_minM is the network required bandwidth of the basic service, and m is m/8.

Further, the adjusting the service sending rate of the packet sending end according to the second preset policy includes:

according to V_i＝(V_max+V_i-1) Adjusting the service sending rate of a packet sending end, wherein i is an integer greater than or equal to 1, and V₀For the optimal sending rate of the service, when the sending rate of the service at the packet sending end is V_iIf the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending duration, the packet sending end adjusts the data volumeThe service sending rate of the whole sending packet end is V_i-1(ii) a Or,

according to V_i＝V_i-1+A_iAdjusting the service sending rate of a packet sending end, wherein i is an integer greater than or equal to 1, A_iIs a preset value, V₀Optimal sending rate for said service, and V_i≤V_maxWhen the service transmission rate of the packet transmitting end is V_iIf the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending duration, the service sending rate of the packet sending end is adjusted to be V_i-1。

Further, the transmitting a TCP packet carrying clock quality level information on a network link from the packet sending end to the packet receiving end for clock synchronization includes:

a network node on a network link of a packet sending end to a packet receiving end acquires the clock reference source level of an opposite end node according to a received TCP message;

and the network node compares the level of the local clock reference source with the level of the clock reference source of the opposite node, and takes the clock reference source of the opposite node as the current local clock reference source when the level of the local clock reference source is lower than the level of the clock reference source of the opposite node.

Further, the clock reference source level from high to low comprises: the reference clock, transit office clock, local office clock, synchronization device timing source, synchronization quality unknown and not applied for synchronization.

The invention also provides a network data transmission device, which is applied to the network node of the end-to-end asynchronous transmission network and comprises the following components: the rate adjusting module is used for adjusting the service sending rate of the packet sending end according to a first preset strategy when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset low load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time length; and the first synchronization module is used for transmitting the TCP message carrying the clock quality grade information to perform clock synchronization when the data volume received by the packet receiving end is still less than the data volume sent by the packet sending end within the preset packet sending time length after the rate adjustment module adjusts the service sending rate of the packet sending end to be the service minimum sending rate.

Further, the apparatus further comprises: and the second synchronization module is used for transmitting the TCP message carrying the PTP field to perform clock synchronization when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset high-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending time.

Further, the second synchronization module is configured to transmit a TCP packet carrying a PTP field for clock synchronization, and includes:

when the network node is used as a master clock side, the network node is used for sending an Announce message carrying master time information to a slave clock side; sending a Sync message to a slave clock side, wherein the Sync message carries a sending time stamp t1 of the Sync message; after receiving a Delay _ Req message sent by a slave clock side, sending a Delay _ Resp message to the slave clock side, wherein the Delay _ Resp message carries a receiving timestamp t4 of the master clock side to the Delay _ Req message;

when the network node is used as a slave clock side, the network node is used for sequentially receiving an Announce message carrying master clock informationAnd a Sync message carrying a message sending timestamp t 1; recording arrival time stamp t2 of Sync message and sending carrying messageSending a Delay _ Req message of a timestamp t3 to a master clock side; receiving Delay _ Req message carried by master clock sideDelay _ Resp message of timestamp t 4; determining between a master clock side and a slave clock side from the timestamps t1, t2, t3, and t4According to the two-way average delay difference and the time difference between the master clock and the slave clockAdjusting the slave clock to synchronize with the master clock by a difference, wherein the two-way average delay difference isThe time difference is

Further, the rate adjusting module is configured to adjust a service sending rate of the packet sending end according to a first preset policy, and includes:

Further, the rate adjusting module is configured to adjust a service sending rate of the packet sending end according to a second preset policy, and includes:

according to V_i＝(V_max+V_i-1) Adjusting the service sending rate of a packet sending end, wherein i is an integer greater than or equal to 1, and V₀To the industry ofThe service optimal sending rate is V when the service sending rate of the packet sending end is V_iIf the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending duration, the service sending rate of the packet sending end is adjusted to be V_i-1(ii) a Or,

Further, the first synchronization module is configured to transmit a TCP packet carrying clock quality level information for clock synchronization, and includes: acquiring the clock reference source grade of the opposite end node according to the received TCP message; and comparing the level of the local clock reference source with the level of the clock reference source of the opposite node, and taking the clock reference source of the opposite node as the current local clock reference source when the level of the local clock reference source is lower than the level of the clock reference source of the opposite node.

According to the invention, when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset low load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending time, the service sending rate of the packet sending end is adjusted according to a first preset strategy; and after the service sending rate of the packet sending end is adjusted to the service minimum sending rate, when the data volume received by the packet receiving end is still smaller than the data volume sent by the packet sending end within the preset packet sending time, transmitting a TCP message carrying clock quality grade information on a network link of the packet sending end and the packet receiving end to carry out clock synchronization. Therefore, when the end-to-end asynchronous transmission network is in a low load state, the service sending rate of a packet sending end is reduced, and the utilization rate of the current link of the network is reduced, so that the residual available cache and value of the intermediate node of the network are increased, the time of no packet loss in the network is increased, and the occurrence probability of the packet loss of the network is reduced; when the network service can not meet the requirement due to the reduction of the service sending rate of a packet sending end, the TCP/IP protocol is combined with a clock quality level coding technology, so that clock quality level information is borne in a TCP/IP protocol message to be transmitted, and the asynchronous transmission Ethernet system becomes a synchronous transmission Ethernet system by synchronizing other clocks through a high-quality trackable primary reference clock signal, so that the time without packet loss is greatly increased, and the generation probability of network packet loss is reduced.

Further, when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset high load state, and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end within the preset packet sending time, the TCP message carrying the PTP field is transmitted on the network link from the packet sending end to the packet receiving end to perform clock synchronization. Therefore, when the end-to-end asynchronous transmission network is in a high-load state, the most accurate clock in the distributed network is kept synchronous with other clocks through a PTP (precision time protocol) synchronization technology, high-precision frequency is provided, and high-precision frequency and time synchronization is realized on the premise that the precision is met (the uplink and downlink time delays are kept consistent).

Drawings

Fig. 1 is a schematic diagram of a transmission buffer of a packet sending end in the prior art;

FIG. 2 is a diagram illustrating a receiving buffer of a packet receiving end in the prior art;

FIG. 3 is a schematic diagram of an application scenario of the present invention;

fig. 4 is a flowchart of a network data transmission method according to an embodiment of the present invention;

FIG. 5 is a TCP/IP packet format diagram carrying a Synchronization Control (SC) field in an embodiment of the present invention;

FIG. 6 is a diagram of a TCP/IP packet format carrying PTP packet fields in an embodiment of the present invention;

fig. 7 is a schematic diagram of a network data transmission apparatus according to an embodiment of the present invention.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, and it should be understood that the embodiments described below are only for illustrating and explaining the present invention and are not intended to limit the present invention.

The network data transmission method provided by the embodiment of the invention is applied to an end-to-end asynchronous transmission network, as shown in fig. 3. In the end-to-end asynchronous transmission Ethernet, when the message service is transmitted and received between two network nodes, namely one network node is a packet transmitting end, the other network node is a packet receiving end, and the intermediate network node transmits the message. The full-load fixed packet sending rate of the packet sending end is, for example, V, the packet sending end sends an ethernet packet with a fixed frame length, if the packet sending duration is T, the total packet sending quantity Q of the packet sending end is V × T, and the total packet receiving quantity Q' of the packet receiving end is. When the number Q' of the packets received by the packet receiving end within the packet sending time T is less than the number Q of the packets sent by the packet sending end, there is a packet loss in the ethernet network. The Ethernet tester feeds back the data receiving condition of the packet receiving end to the packet sending end.

For an end-to-end asynchronous transmission network, the size of a sending buffer or a receiving buffer is a preset fixed value, and the sending buffer or the receiving buffer is not changed normally in the network running state, but the data message volume is also a fixed value, so that the sending rate of the Ethernet data message directly influences the time from empty to full buffer, namely, the time of not losing packets.

Fig. 4 is a flowchart of a network data transmission method according to an embodiment of the present invention. As shown in fig. 4, the network data transmission method provided in this embodiment includes the following steps:

step 401: and when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset low-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time, adjusting the service sending rate of the packet sending end according to a first preset strategy.

Here, the preset low load state is, for example, that the actual utilization rate of the network link from the packet sending end to the packet receiving end is less than the maximum utilization rate of the network link, and the actual load of the network link from the packet sending end to the packet receiving end is less than or equal to half of the maximum load of the network link.

The network nodes on the network link from the packet sending end to the packet receiving end include, for example, a network node as the packet sending end, a network node as the packet receiving end, and an intermediate node. In this way, the packet sending end can directly adjust the service sending rate according to the first preset strategy. Or, a network node independent of the packet sending end, a network node independent of the packet receiving end and a management node except the intermediate node are arranged in the end-to-end asynchronous transmission network, the management node determines the adjusted service sending rate of the packet sending end according to a first preset strategy, and indicates the adjusted service sending rate of the packet sending end to the network node independent of the packet sending end. However, the present invention is not limited thereto.

wherein, T is the period duration of data transmission packet loss measurement period, M is the maximum bandwidth of a network link from a packet sending end to a packet receiving end, and V_maxMaximum transmission rate for traffic, and V_max△ f is network end-to-endThe frequency offset that is generated is,the buffer value is the sum of the buffer values of all the intermediate devices between the packet sending end and the packet receiving end;

according to V_i＝(V_max+V_i-1) Adjusting the service sending rate of a packet sending end, wherein i is an integer greater than or equal to 1, and V₀For the optimal sending rate of the service, when the sending rate of the service at the packet sending end is V_iIf the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending duration, the service sending rate of the packet sending end is adjusted to be V_i-1(ii) a Or,

Step 402: and after the service sending rate of the packet sending end is adjusted to the service minimum sending rate, when the data volume received by the packet receiving end is still smaller than the data volume sent by the packet sending end within the preset packet sending time, transmitting a TCP message carrying clock quality grade information on a network link of the packet sending end and the packet receiving end to carry out clock synchronization.

Wherein the clock reference source level from high to low comprises: reference Clock (PRC), transit office clock (TNC), local office clock (LNC), Synchronous Equipment Timing Source (SETS), UNKNOWN quality of synchronization (UNKNOWN), and do not apply synchronization (DNU).

Step 403: and when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset high-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time, transmitting a TCP message carrying a PTP field on the network link from the packet sending end to the packet receiving end for clock synchronization.

Here, the preset high load state is, for example, that the actual utilization rate of the network link from the packet sending end to the packet receiving end is equal to the maximum utilization rate of the network link, or that the actual load of the network link from the packet sending end to the packet receiving end is greater than half of the maximum load of the network link.

the slave clock side determines the double between the master clock side and the slave clock side according to the time stamps t1, t2, t3 and t4The average time delay difference and the time difference between the master clock and the slave clock are calculated, and the adjustment is carried out according to the two-way average time delay difference and the time differenceThe slave clock is synchronized with the master clock, wherein the bidirectional average time delay difference isWhen saidWith a difference of

The following specifically describes embodiments of the present invention.

First, in order to clearly illustrate the network data transmission method provided by the embodiment of the present invention, the following description is first made:

in an end-to-end Ethernet network which does not work initially, the device cache values of the intermediate node devices 1 to n are respectively b_kWhere k is 1, …, n, n is an integer greater than 1, and the unit of the device buffer value is megabit (Mb); thus, the available buffer value B in the end-to-end network is equal to the sum of the device buffer values of the intermediate node devices 1-n,

namely, it isWhen the end-to-end ethernet network is operational,except the used cache part occupied by each intermediate node sliding window, the sum of the remaining available cache values of the network intermediate nodes is the sum, wherein U' is the actual utilization rate of the Ethernet network link, and U is the maximum benefit of the Ethernet network linkThe rate, U' ═ V × 8/M, where M is the total bandwidth (unit: Mb/s) of the current network link, and V is the total traffic of the current network packet sending endTraffic flow transmission rate (unit: Bps);

the maximum load C of a traffic flow is N × t, where N is a single traffic bandwidth, and the unit is: mb; when t is a network linkDelay, unit: milliseconds (ms); when the network runs n service flows, the maximum load of the network link is satisfied as follows: c_max-M x t, wherein,m is the total bandwidth of the current network link, and t is the network link time delay; when the number of the operation service flows in the network is n, the network link is realThe load isWherein N is_kFor the kth serviceThe service bandwidth of the stream, t is the network link delay;

as the current load of the network link in the end-to-end ethernet network will change constantly, the network may be in a low load state or a high load state; specifically, when the actual utilization U' of the network link is less than the maximum utilization U of the network link, and the actual load of the network link is less than or equal to half of the maximum load of the network link, i.e.,at this time, the network is in a low load state; otherwise, the actual utilization rate U' of the network link is equal to that of the network linkThe maximum utilization U, or, the actual load of the network link is greater than half the maximum load of the network link, i.e.,at this time, the network is in a high load state;

in addition, according to different service requirements of the network, in order to ensure important basic service bandwidth resources, the required bandwidth m (m) based on the basic service network<M), defining the minimum sending rate V of the service meeting the current basic service bandwidth_minM/8, unit: MB/s.

Specifically, when the end-to-end network is in a low load state and packet loss occurs, the optimal service sending rate V of the packet sending end is re-determined₀Comprises the following steps:

wherein, T is a data transmission packet loss measurement period duration, unit: second(s); m is the maximum bandwidth of the system design of the current known network link, unit: mb; v_maxSending a maximum rate, V, for traffic when the system is designed_maxThe unit is Mb/s, △ f is the frequency offset generated end to end by the current network, the unit is Hertz (Hz), the network equipment usually uses the same crystal oscillator, the frequency offset of the crystal oscillator is known, because the network is in a low load state, the network overtime retransmission is not easy to occur, the transmission time delay generated on the link is small and can be ignored, thereby the hardware frequency offset can be directly utilized;is the sum of the buffer values of all the intermediate devices of the end-to-end network, wherein the intermediate device buffer values are known.

Herein, when the service transmission rate of the packet transmitting end is adjusted to the optimal service transmission rate V₀(V_min<V₀<V_max) After that, the network service packet loss still occurs,then adjust the network traffic transmission rate to V_minAnd checking the network service sending rate as V_minIf so, judging whether packet loss exists in the current network service; when the service transmission rate is adjusted to V_minAnd then, if no network service packet loss occurs, determining to adjust the current network service sending rate to V_minAt this time, not only the service bandwidth of the current network basic service is satisfied, but also the network service does not lose packets;

when the service sending rate of the packet sending end is adjusted to be the optimal service sending rate V₀(V_min<V₀<V_max) Then, no network service packet loss occurs, and when the network service sending rate is adjusted for the first time, the network service sending rate is set as V₁＝(V_max+V₀) V, check adopted₁Whether the network service has packet loss or not when the data message is sent; if the network service has packet loss, V is set₀Determining a current network traffic transmission rate, V₀That is, sending the optimal rate for the service; if the network service has no packet loss, continuing to adjust the network service sending rate, and when the network service sending rate is adjusted for the second time, setting the network service sending rate as V₂＝(V_max+V₁) And/2, repeating the steps until the network service is lost when the network service sending rate is adjusted for the nth time, and adjusting the network service sending rate V obtained by the adjustment for the nth-1 (n is more than or equal to 1) time_n-1＝(V_max+V_n-2) Therefore, when the network is in a low load state, the current link utilization rate U 'of the Ethernet network is reduced by reducing the service sending rate, so that the sum △ B' of the remaining available cache values of the network intermediate nodes is increased, and the time without packet loss in the network is prolonged, namely the occurrence probability of network packet loss is reduced.

However, the present invention is not limited to the specific adjustment method. In other embodiments, when the service sending rate of the packet sending end is adjusted to the optimal service sending rate V₀(V_min<V₀<V_max) Then, no network service packet loss occurs, and can be according to V_i＝V_i-1+A_iAnd adjusting the current service sending rate. Specifically, i is an integer of 1 or more, A_iIs a preset value, V₀Optimal sending rate for traffic, and V_i≤V_max. In other words, the transmission rate V is optimized from the traffic₀Towards V_maxThe adjustment is performed step by step, the step value Ai of each adjustment can be set according to actual needs, the adjustment is stopped until the network generates packet loss, and the service sending rate of the previous time of sending the packet loss is used as the current service sending rate.

When the network service transmission rate is adjusted to V_minAnd when the network still loses packets, the network service transmission rate is continuously reduced, and the current network service requirement cannot be met. Therefore, the time without packet loss is increased by adding the transmission synchronization information in the interactive message, so that the network packet loss is reduced. For the change of the TCP message structure, the option and the padding field are used to carry the Synchronization Control (SC) field of the time quality level, as shown in fig. 5, the SC field occupies 4 bits of length (bit 0-bit 3) in the option and the padding field.

Wherein the quality level of the synchronous clock can be described by different bit encodings in the SC field. For example, in connection with the description and delivery of information in a synchronous network, the SC field bit encoding may be defined as follows, as in table 1: the SC (b0-b3) Value (Value) is encoded in binary format, but may be encoded in 16-ary format or in other formats, as long as it can distinguish different clock sources.

TABLE 1 SC field bit encoding

When the network equipment is powered on for the first time, the default clock quality level of the clock reference source is UNKNOWN (UNKNOWN).

The clock reference source level of SC field coding has the following sequence: reference Clock (PRC, Primary Reference Clock) > Transit office Clock (TNC, Transit Node Clock) > Local office Clock (LNC, Local Node Clock) > Synchronous device Timing Source (SETS), Synchronous quality agnostic (UNKNOWN) > Do not apply synchronization (DNU, Do not use for synchronization). If the level of the reference source is DNU and the SC field participates in control, the path of reference source is not selected during protection switching.

Next, taking any two network nodes on the network link from the packet sending end to the packet receiving end as an example, a process of performing clock synchronization through a TCP packet carrying an SC field is described.

Step S101: the method comprises the steps that TCP connection is established between two network nodes, and because an SC field is carried in a TCP message, in the process of finishing TCP handshake (typically three-way handshake), the clock reference source grade of a current network opposite-end node can be obtained through the transmitted SC field;

step S102: the current network node compares the local clock reference source grade with the clock reference source grade of the opposite node, and if the clock reference source grade of the opposite node is higher than the local clock reference source grade, the current network node takes the clock reference source of the opposite node as the current local clock reference source; and if the clock reference source grade of the opposite end node is lower than the local clock reference source grade, the current network node informs the opposite end node, and the local clock reference source of the current network node is used as the clock reference source of the current opposite end node.

In practical application, when a network node serving as a packet sending end adopts a minimum service sending rate and network packet loss still exists, the network node serving as the packet sending end starts to send a TCP message carrying an SC field to a downstream receiving node for clock synchronization; or, an independent management node is set in the end-to-end network, and when the current network adopts the minimum service sending rate and network packet loss still exists, the management node indicates the network node serving as the packet sending end, the network node serving as the packet receiving end and the intermediate node to send the TCP message carrying the SC field to perform clock synchronization.

Therefore, the clock reference source of the whole network node can be set as the highest-level clock reference source in the current network in a network point-by-point tracking mode, and the clocks of the whole network are synchronized, so that the network data transmission delay is reduced, and the packet loss among the network nodes is effectively reduced.

Therefore, when the network is in low load, the current network service sending rate is reduced, namely the available cache value can be increased, the time without packet loss is increased, the generation of network packet loss in a preset time is reduced, and when the network service cannot meet the requirement due to the reduction of the service sending rate, the clock quality level coding field is borne in the TCP/IP protocol message for transmission, namely: clock quality grade coding SC fields are added in the TCP/IP protocol message headers, and the clock synchronization of each network node is kept through message interaction, so that the network packet loss is reduced.

However, when the end-to-end network is in a high load state, if the method of adjusting the buffer sum value is still used, the occurrence of the timeout retransmission time in the network is easily caused, thereby causing the occurrence of the network packet loss time. At this time, it is necessary to consider reducing the delay t in the actual networkThe increase of △ C caused by the increase reduces the actual network load, so that the end-to-end network is always in a low load state, and further, no packet loss of the ethernet network is ensured within a fixed time.

Therefore, the structure of the synchronization message between the nodes is changed, the PTP message is encapsulated in the TCP/IP message, and the option and the padding field in the TCP message structure are occupied, as shown in fig. 6. The PTP message field comprises: PTP message header, PTP message body and PTP extension field are selectable.

The PTP message header is common to all PTP messages, occupies 32 bytes (Octets), and has a specific format shown in table 2.

TABLE 2 PTP message header structure

As shown in table 2, the format of the PTP header is described as follows:

(1) the messageId field occupies 1 byte, and defines the current PTP message type, such as Sync, Delay _ Req, Delay _ Resp, Announce, PDelay _ Req, and PDelay _ Resp;

(2) the version PTP field occupies 1 byte and defines the current PTP message protocol version, for example, version PTP is 1 corresponding to IEEE1588v1, and version PTP is 2 corresponding to IEEE1588v 2;

(3) the messageLength field occupies 2 bytes, defines the total length of the transmitted PTP message field and comprises selectable fields of a PTP message header, a message body and a message extension field;

(4) the domain number field occupies 1 byte and defines the time domain to which the PTP message belongs; when the Clock type is an Ordinary Clock (OC) or a Boundary Clock (BC), a Clock domain to which the message sending device belongs currently is described; when the Clock type is a Transparent Clock (TC), a Clock domain to which the initial packet sending device belongs is described;

(5) the flag field occupies 2 bytes and is defined as a flag field of various display states of the PTP message;

(6) the correction field occupies 8 bytes and defines the correction value of the time information carried in the PTP message to the retention time at the nanosecond level when the time information passes through the TC clock;

(7) the Reserved field occupies 3 bytes and is a Reserved field;

(8) the sourceportId field occupies 2 bytes and defines the source port Identification (ID, Identification) for sending the PTP message;

(9) the sourcePortIdentify field occupies 8 bytes and defines the address information of a clock chip source port for sending the PTP message;

(10) the sequence Id field occupies 2 bytes, and each clock sending period is defined to correspond to a unique number identifier;

(11) the control field occupies 1 byte, and particularly refers to the field of the message type described by the IEEE1588v1 version;

(12) the logmessage interval field occupies 1 byte, and defines the message transmission interval after the negotiation is successfully displayed.

The PTP message mainly comprises the following types: the specific message type definitions of Announce, Sync, Delay _ Req, Follow _ Up, Delay _ Resp, PDelay _ Req, and PDelay _ Resp are shown in table 3.

TABLE 3 PTP message type definition

Next, taking any two network nodes on the network link from the packet sending end to the packet receiving end as an example, a process of performing clock synchronization through a TCP message carrying a PTP field is described.

After establishing a TCP connection between a sending end node and a receiving end node, typically performing handshake three times, sending a TCP packet carrying a PTP field, establishing a clock synchronization connection, and performing clock synchronization. In the End-to-End (E2E, End to End) mode, the specific steps of the above process are as follows:

step S201: automatically negotiating the clock master-slave attribute of a port between two connected network nodes, wherein the master clock side is a sending end node, and the slave clock side is a receiving end node;

step S202: the method comprises the steps that a master clock side sends an Announce message to a slave clock side, and the clock source quality level of a master clock of the slave clock side is informed through clock information carried by a grandmaster priority1, a grandmaster clock accuracy, a grandmaster clock quality, a grandmaster priority 2 and a time resource field in the Announce message; wherein, the structure of the Announce message is shown in Table 4;

table 4 Announce message structure

As shown in table 4, the format of the Announce packet is described as follows:

(1) the originTimestamp field takes 10 bytes and defines a timestamp;

(2) the origincurrentutoffset field takes 2 bytes and defines the leap second Time difference between Universal Time Coordinated (UTC) and International Atomic Time (TAI) Time scales;

(3) the grandmaster priority1 field occupies 1 byte and defines the priority1 of a master clock (grandmaster) defined by a user;

(4) the grandmaster clock quality field occupies 1 byte and defines the grandmaster clock quality level;

(5) the grandmaster clock accuracy field occupies 3 bytes and defines the specific description information of the grandmaster clock quality level;

(6) the grant master priority 2 field occupies 1 byte and defines the user-defined grant master priority 2;

(7) reserved field takes 1 byte, reserved field;

(8) the grandmaster clock identity field occupies 8 bytes and defines the grandmaster clock ID information;

(9) the localstepromoved field occupies 2 bytes and defines the clock path hop count between the grandmaster and the slave (slave) device;

(10) the time resource field occupies 1 byte and defines the type of a clock source;

step S203: the method comprises the steps that a master clock side sends a Sync message, and a precise timestamp t1 of the Sync message sent by a master clock side device is sent to a slave clock side through an originTimestamp field in the Sync message; wherein, the structure of the Sync message is shown in table 5;

table 5 Sync message structure

As shown in table 5, the originTimestamp field takes 10 bytes, defining a timestamp;

step S204: the main clock side then sends a Follow _ Up message, and notifies an actual sending timestamp t1 of the previous Sync message through a prediseOriginTimestamp field, wherein the Follow _ Up message is only valid for two step, and one step has no Follow _ Up message;

wherein, the following is shown in following table 6;

table 6 following the following table

As shown in table 6, the preciseOriginTimestamp field takes 10 bytes, defining a timestamp;

step S205: recording an arrival time stamp t2 of the Sync message from a corresponding slave clock side, and adjusting a local clock; then the slave clock side sends Delay _ Req message at the timestamp t3, and informs the master clock side of the timestamp t3 through the carried preiseOriginitinstarch field;

wherein, the Delay _ req message structure is consistent with the Sync message structure; therefore, the description is omitted herein;

step S206: recording a timestamp t4 of the received Delay _ Req message by the master clock side, and sending a response message Delay _ Resp message; wherein, the Delay _ Resp message structure is shown in table 7;

table 7 Delay _ Resp message structure

As shown in table 7, the receiveTimestamp field occupies 10 bytes and is defined as a reception timestamp for responding to the Delay _ Req packet; the requestsourceportidentity field occupies 8 bytes and is defined as the grant master clock ID information responding to the Delay _ Req message; the field of requestingSourcePort Id occupies 2 bytes and is defined as the port ID information of the sending equipment responding to the Delay _ Req message;

step S207: the slave clock side determines one of the master clock side and the slave clock side according to the time stamps t1, t2, t3 and t4The time difference between the master clock and the slave clock and the time difference between the master clock and the slave clock are averaged in two directions, and the time difference is calculated according to the average time difference in two directions and the timeAdjusting the slave clock to synchronize with the master clock by a difference, wherein the two-way average delay difference isWhat is needed isThe time difference is

In practical application, when a network node serving as a packet sending end learns that a current network is in a high-load state and a packet loss exists in the network, the network node serving as the packet sending end transmits a TCP message carrying a PTP field to a downstream receiving node, so that a clock of the downstream receiving node is synchronized with a clock of the network node serving as the packet sending end, and then clock synchronization between subsequent network nodes is sequentially performed, and finally clocks of the network node serving as the packet sending end, the network node serving as the packet receiving end and an intermediate node between end to end are all synchronized. Or, an independent management node is arranged in the end-to-end network, when the current network is in a high load state and packet loss exists in the network, the management node indicates the network node serving as the packet sending end to transmit a TCP message carrying a PTP field to the downstream receiving node, so that the clock of the downstream receiving node is synchronized with the clock of the network node serving as the packet sending end, further clock synchronization among subsequent network nodes is sequentially performed, and finally the clocks of the network node serving as the packet sending end, the network node serving as the packet receiving end and the intermediate node between the end and the end are all synchronized.

In this manner, by employing PTP synchronization techniques, the most accurate clock within the distributed network can be kept synchronized with other clocks when the network is in a high load state.

Fig. 7 is a schematic diagram of a network data transmission apparatus according to an embodiment of the present invention. As shown in fig. 7, the network data transmission apparatus provided in this embodiment is applied to a network node of an end-to-end asynchronous transmission network, and includes: the rate adjusting module is used for adjusting the service sending rate of the packet sending end according to a first preset strategy when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset low load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time length; and the first synchronization module is used for transmitting the TCP message carrying the clock quality grade information to perform clock synchronization when the data volume received by the packet receiving end is still less than the data volume sent by the packet sending end within the preset packet sending time length after the rate adjustment module adjusts the service sending rate of the packet sending end to be the service minimum sending rate.

Further, the above apparatus further comprises: and the second synchronization module is used for transmitting the TCP message carrying the PTP field to perform clock synchronization when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset high-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending time.

when the network node is used as a slave clock side, the network node is used for sequentially receiving an Announce message carrying master clock informationAnd a Sync message carrying a message sending timestamp t 1; recording arrival time stamp t2 of Sync message and sending carrying messageSending a Delay _ Req message of a timestamp t3 to a master clock side; receiving Delay _ Req message carried by master clock sideDelay _ Resp message of timestamp t 4; determining between a master clock side and a slave clock side from the timestamps t1, t2, t3, and t4According to the two-way average delay difference and the time difference between the master clock and the slave clockAdjusting the slave clock to synchronize with the master clock, wherein the bi-directional average delay difference isWhat is needed isThe time difference is

determining the end of a hair packetThe optimal service sending rate is as follows:

after the service sending rate of the packet sending end is adjusted to the optimal service sending rate, if the data volume received by the packet receiving end is equal to the data volume sent by the packet sending end within the preset packet sending time length, the service sending rate of the packet sending end is adjusted according to a second preset strategy;

Wherein the clock reference source level from high to low comprises: the reference clock, transit office clock, local office clock, synchronization device timing source, synchronization quality unknown and not applied for synchronization.

Specifically, the network data transmission apparatus provided in this embodiment is distributed on network nodes of an end-to-end asynchronous transmission network. Network nodes of an end-to-end asynchronous transfer network include, for example: the network node is used as a packet sending end, the network node is used as a packet receiving end and the intermediate node. The rate adjustment module is distributed on a network node as a packet sending end, and the first synchronization module and the second synchronization module are distributed on the network node as the packet sending end, the network node as a packet receiving end and an intermediate node. Alternatively, the network nodes of the end-to-end asynchronous transfer network comprise, for example: the network node is used as a packet sending end, the network node is used as a packet receiving end, the intermediate node and the management node. The rate adjustment module is distributed on the management node, for example, and the first synchronization module and the second synchronization module are distributed on the network node as the packet sending end, the network node as the packet receiving end, and the intermediate node, for example.

In practical applications, the rate adjustment module is, for example, a component such as a processor, and the first synchronization module and the second synchronization module are, for example, a communication component such as a transmitter or a receiver. However, the present invention is not limited thereto. The functions of the above-described modules may also be implemented, for example, by a processor executing programs/instructions stored in a memory.

In addition, the specific processing procedure of the above device is the same as that of the above method, and therefore, the detailed description thereof is omitted.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. The present invention is not limited to the above-described embodiments, which are described in the specification and illustrated only for illustrating the principle of the present invention, but various changes and modifications may be made within the scope of the present invention as claimed without departing from the spirit and scope of the present invention.

Claims

1. A network data transmission method is applied to an end-to-end asynchronous transmission network, and is characterized by comprising the following steps:

when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset low-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time, adjusting the service sending rate of the packet sending end according to a first preset strategy;

and after the service sending rate of the packet sending end is adjusted to the service minimum sending rate, when the data volume received by the packet receiving end is still smaller than the data volume sent by the packet sending end within the preset packet sending time, transmitting a Transmission Control Protocol (TCP) message carrying clock quality grade information on a network link of the packet sending end and the packet receiving end to carry out clock synchronization.

2. The method of claim 1, further comprising: and when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset high-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time, transmitting a TCP message carrying a Precision Time Protocol (PTP) field on the network link from the packet sending end to the packet receiving end for clock synchronization.

3. The method of claim 2, wherein the transmitting the TCP message carrying the PTP field for clock synchronization over the network link from the sender to the receiver comprises:

the slave clock side determines a bidirectional average time delay difference between the master clock side and the slave clock side and a time difference between the master clock side and the slave clock side according to the time stamps t1, t2, t3 and t4, and adjusts the slave clock to be synchronous with the master clock according to the bidirectional average time delay difference and the time difference, wherein the bidirectional average time delay difference isThe time difference is

4. The method of claim 1, wherein the adjusting the service sending rate of the packet sender according to the first preset policy comprises:

5. The method as claimed in claim 4, wherein said adjusting the service sending rate of the packet sender according to the second preset policy comprises:

6. The method of claim 1, wherein the transmitting the TCP packet carrying the clock quality level information over the network link from the sender to the receiver for clock synchronization comprises:

7. The method of claim 6, wherein the clock reference source level from high to low comprises: a reference clock PRC, a transit office clock TNC, a local office clock LNC, a synchronization device timing source SETS, an UNKNOWN synchronization quality and no synchronization DNU application.

8. A network data transmission apparatus applied to a network node of an end-to-end asynchronous transmission network, comprising:

the rate adjusting module is used for adjusting the service sending rate of the packet sending end according to a first preset strategy when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset low load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in a preset packet sending time length;

and the first synchronization module is used for transmitting the TCP message carrying the clock quality grade information to perform clock synchronization when the data volume received by the packet receiving end is still less than the data volume sent by the packet sending end within the preset packet sending time length after the rate adjustment module adjusts the service sending rate of the packet sending end to be the service minimum sending rate.

9. The apparatus of claim 8, further comprising: and the second synchronization module is used for transmitting the TCP message carrying the PTP field to perform clock synchronization when the actual operation parameters of the network link from the packet sending end to the packet receiving end belong to a preset high-load state and the data volume received by the packet receiving end is less than the data volume sent by the packet sending end in the preset packet sending time.

10. The apparatus of claim 9, wherein the second synchronization module, configured to transmit a TCP packet carrying a PTP field for clock synchronization, comprises:

when the network node is used as a master clock side, the network node is used for sending an Announce message carrying master clock information to a slave clock side; sending a Sync message to a slave clock side, wherein the Sync message carries a sending time stamp t1 of the Sync message; after receiving a Delay _ Req message sent by a slave clock side, sending a Delay _ Resp message to the slave clock side, wherein the Delay _ Resp message carries a receiving timestamp t4 of the master clock side to the Delay _ Req message;

when the network node is used as a slave clock side, the network node is used for sequentially receiving an Announce message carrying master clock information and carrying the Announce messageSending a Sync message with a timestamp t 1; recording an arrival time stamp t2 of the Sync message, and sending a Delay _ Req message carrying a message sending time stamp t3 to a master clock side; receiving a Delay _ Resp message carrying a receiving time stamp t4 of a Delay _ Req message from a master clock side; according to the timestamps t1, t2, t3 and t4, determining a bidirectional average delay difference between the master clock side and the slave clock side and a time difference between the master clock side and the slave clock side, and adjusting the slave clock to be synchronous with the master clock according to the bidirectional average delay difference and the time difference, wherein the bidirectional average delay difference isThe time difference is

11. The apparatus of claim 8, wherein the rate adjustment module is configured to adjust a service sending rate of a packet sending end according to a first preset policy, and comprises:

12. The apparatus of claim 11, wherein the rate adjustment module is configured to adjust a service sending rate of a packet sending end according to a second preset policy, and the rate adjustment module comprises:

13. The apparatus of claim 8, wherein the first synchronization module, configured to transmit a TCP packet carrying clock quality level information for clock synchronization, comprises: acquiring the clock reference source grade of the opposite end node according to the received TCP message; and comparing the level of the local clock reference source with the level of the clock reference source of the opposite node, and taking the clock reference source of the opposite node as the current local clock reference source when the level of the local clock reference source is lower than the level of the clock reference source of the opposite node.

14. The apparatus of claim 13, wherein the clock reference source level from high to low comprises: a reference clock PRC, a transit office clock TNC, a local office clock LNC, a synchronization device timing source SETS, an UNKNOWN synchronization quality and no synchronization DNU application.