KR102078529B1 - Time Synchronization Method in Precision Time Protocol Network and Computer Program Therefore - Google Patents

Abstract

The present embodiment solves the problem of an unbalanced master-slave structure that may cause an imbalance problem such as high communication load and high bandwidth consumption in a plurality of boundary clocks, and enables a fast recovery mechanism in case of master clock failure. A time synchronization method in a precision visual protocol network and a computer program therefor.

Description

Time Synchronization Method in Precision Time Protocol Network and Computer Program Therefore}

This embodiment relates to a time synchronization method for providing a balanced master-slave structure and a fast recovery mechanism in a Precision Time Protocol (PTP), and a computer program therefor.

The contents described in this section merely provide background information on the present embodiment and do not constitute a prior art.

Precision Time Protocol (PTP) is an Institute of Electrical and Electronics Engineers (IEEE) 1588 standard time transfer protocol that enables accurate synchronization between networks.

For time synchronization of a PTP network device, a conventional BMC (Best Master Clock (BMC)) algorithm, which is constructed as a master-slave structure of a PTP network device, is used. However, because the BMC algorithm builds a master-slave structure in which each master clock has a large number of slave clocks and an uneven number of slaves, the master clock and slave clocks when the master clock and the slave clock exchange PTP messages. There is a limitation in that communication overload occurs.

In addition, the BMC algorithm does not provide a mechanism to recover the master-slave structure in a timely manner when the communication link between the master clock and the slave clock fails. For example, the BMC algorithm has a problem in that it takes time to perform the BMC algorithm to reselect a new master clock when a master clock fails.

This embodiment solves the problem of an unbalanced master-slave structure that can cause unbalanced problems such as high communication load and high bandwidth consumption at a plurality of boundary clocks, and the problem of master clock selection or master clock and slave clocks. It is an object of the present invention to provide a time synchronization method in a precise visual protocol network and a computer program therefor to enable a fast recovery mechanism in the event of a link failure between them.

According to the present embodiment, in a time synchronization method of a network device, each boundary clock of the network device may communicate with the grand master clock from other boundary clocks, and the number of slaves information (Number) Receiving boundary clock data information including Slaves) and clock identification information; Performing comparison between boundary clock data information received by the boundary clocks from the other boundary clocks; And determining, by each of the boundary clocks, the role of the other boundary clocks as a master clock or a slave clock according to a comparison result between the boundary clock data information.

Further, according to another aspect of the present embodiment, a time synchronization program is combined with hardware of a network device such that each boundary clock of the network device includes a communication distance with a grand master clock, slave count information, and clock identification information. Receiving clock data information from different boundary clocks, respectively; Performing comparison between boundary clock data information received by the boundary clocks from the other boundary clocks; And a time synchronization program stored in a computer-readable recording medium for executing a process of determining the role of the other boundary clocks as a master clock or a slave clock according to the comparison result of the boundary clock data information. to provide.

As described above, the present embodiment solves the problem of an unbalanced master-slave structure that may cause an imbalance problem such as high communication load and high bandwidth consumption in a plurality of boundary clocks in the time synchronization process of the precision time protocol network. However, there is an effect that a fast recovery mechanism can be achieved in the event of a master clock failure or a link failure between a master block and a slave clock.

1 is a block diagram showing a PTP network device according to the present embodiment.
2 is a block diagram of a master-slave structure of a PTP network device according to a conventional time synchronization method.
3 is a flowchart illustrating a time synchronization method of a PTP network device according to the present embodiment.
4 is an exemplary diagram illustrating boundary clock data information according to the present embodiment.
5 is a block diagram of a master-slave structure of a PTP network apparatus according to the time synchronization method according to the present embodiment.
6 is a view for explaining a connection recovery method between a master clock and a slave clock according to the time synchronization method according to the present embodiment.
7A to 7C are diagrams for describing an effect of the time synchronization method according to the present embodiment.

Hereinafter, the present embodiments will be described in detail with reference to exemplary drawings. In describing the present embodiments, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the accompanying drawings are intended to facilitate understanding of the embodiments disclosed herein, but are not limited to the technical spirit disclosed herein by the accompanying drawings, all changes included in the spirit and scope of the present invention. It should be understood to include equivalents and substitutes.

In the present embodiment, the term 'comprising' means that there is a component, a feature, a step, or a combination thereof described in the specification, and excludes in advance the possibility of the existence of one or a plurality of components or other features, steps, or a combination thereof. It should be understood that it does not.

Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a PTP network device according to the present embodiment.

As shown in FIG. 1, the PTP network apparatus 100 according to the present embodiment may include a grand master clock 120, an ordinary clock 140, and a boundary clock 160. It includes.

The grand master clock 120 refers to the highest clock that is a reference for time synchronization in the PTP protocol of the PTP network device 100.

The grand master clock 120 receives a GPS signal or an optical signal for a time and transmits the received signal to a lower network. In the present embodiment, the grand master clock 120 may serve to transmit boundary clock data information of another boundary clock to each boundary clock of the PTP network apparatus 100. In the present exemplary embodiment, the boundary clock data information may include a communication distance (eg, communication hop number) between the grand master clock and the boundary clock, the number of slave clocks, identification information of the boundary clock, port information, and the like.

The general clock 140 has one Ethernet port and serves as a grand master clock or slave clock in a network device of a master-slave structure. When the normal clock 140 serves as a slave clock, the normal clock 140 synchronizes time with a master clock connected to the port of the normal clock 140.

The boundary clock 160 serves as a master clock or a slave clock in a network device of a master-slave structure.

In this embodiment, the boundary clock 160 is implemented to have a balanced master-slave structure with other boundary clocks according to an improved time synchronization method (BSHSM: Balnaced Synchronization Hiererchy with Spare Masters). By preliminary provision of a preliminary master clock for each clock, a fast recovery mechanism can be achieved in the event of a master clock failure.

To this end, the boundary clock 160 according to the present embodiment receives boundary clock data information corresponding to another boundary clock, and configures and reserves the above master-slave structure by comparing the received boundary clock data information. A setting operation such as a master clock is performed.

Meanwhile, a detailed method of constructing a balanced master-slave structure and implementing a fast recovery mechanism according to the improved time synchronization method of the boundary clock 160 according to the present embodiment will be described in more detail with reference to FIGS. 3 to 6. Explain.

2 is a block diagram of a master-slave structure of a PTP network device according to a conventional time synchronization method.

The master-slave structure of FIG. 2 is a result of applying the conventional time synchronization method to the PTP network apparatus 100 including one grand master clock and 25 boundary clocks. Here, the conventional time synchronization method uses a Best Master Clock (BMC) algorithm.

2, in the case of the master-slave structure of the PTP network apparatus 100 according to the conventional time synchronization method, it is confirmed that some master clocks in the master-slave structure have more slave clocks than other master clocks. Can be. For example, a boundary clock having a unique number of 13 has five slave clocks, while a boundary clock having a unique number of eight has a slave clock of eight.

In other words, as the number of slave slaves of the master clock in the master-slave structure is not uniform, there is a problem that a high communication overload may occur when transmitting and receiving data related to time synchronization for only some boundary clocks.

In addition, according to the conventional time synchronization method, there is a problem that a fast recovery of the connection communication load between one or more slave clocks of the respective boundary clocks and the corresponding master clock is not possible due to a communication overload phenomenon. do. That is, in the conventional case, when a communication failure between the slave clock and the master clock occurs, it takes a lot of time as a new time synchronization method is applied to reselect the master clock and the hierarchical structure must also be set in this regard.

Accordingly, the present invention proposes an improved time synchronization method for solving the problem caused by the imbalance of the master-slave structure according to the conventional time synchronization method, and at the same time enabling a fast recovery mechanism.

3 is a flowchart illustrating a time synchronization method of a PTP network device according to the present embodiment.

Each boundary clock of the PTP network apparatus 100 according to the present exemplary embodiment includes a boundary clock including a communication distance between the grand master clock and the boundary clock, the number of slaves, and clock identification information (ex: unique number) from other boundary clocks. The data information is received (S302). In operation S302, each boundary clock may receive the boundary clock data information transmitted in the form of a broadcast message from another boundary clock.

Meanwhile, in the present embodiment, the boundary clock data information received by each boundary clock from another boundary clock further includes slave count information compared to the existing one, and a detailed form thereof may be confirmed through FIG. 4. In this case, the number of slaves may preferably include two datasets, that is, CurrentDS and ParentDS. CurrentDS means slave number information of the current boundary clock, and ParentDS means slave number information of the master clock of the corresponding clock. Each piece of information included in the boundary clock data information may be continuously updated according to a result of the time synchronization method according to the present embodiment.

Each boundary clock compares the communication distance with the grand master clock with respect to other boundary clocks based on the clock data information received in step S302 (S304). In step S304, each boundary clock selects, as the master clock, the boundary clock having the smallest communication distance with the grand master clock, among other boundary clocks, based on the comparison result.

Each boundary clock compares the number of slaves connected to the corresponding boundary clocks between the other boundary clocks when the communication distance with the grand master clock is the same for the other boundary clocks according to the comparison result of step S304 (S306). In step S306, each boundary clock selects a boundary clock having the minimum number of slaves among the other boundary clocks as the master clock based on the comparison result.

Each boundary clock compares the boundary clock unique number of the boundary clock between different boundary clocks when the number of slaves is the same with respect to the other boundary clocks according to the comparison result of step S306 (S308). In step S308, each boundary clock determines the boundary clock having the smaller clock identification information as the master clock according to the comparison result.

In FIG. 3, each process is described as being sequentially executed, but is not necessarily limited thereto. In other words, since the process described in FIG. 3 may be applied by changing or executing one or more processes in parallel, FIG. 3 is not limited to the time series order.

Meanwhile, the time synchronization method described in FIG. 3 is recorded on a recording medium (CD-ROM, RAM, ROM, memory card, hard disk, magneto-optical disk, storage device, etc.) implemented as a program and readable using software of a computer. Can be.

5 is a block diagram of a master-slave structure of a PTP network apparatus according to the time synchronization method according to the present embodiment.

Referring to FIG. 5, it can be seen that the number of slave clocks corresponding to each master clock of the master-slave structure according to the present embodiment is smaller than the number of slave clocks corresponding to the master clock of the conventional master-slave structure. .

As shown in Figs. 1 and 3, in the present embodiment, the slave clock corresponding to the boundary clock is different from the conventional time synchronization method on the boundary clock data information that determines the role as the master or slave clock for the boundary clock. The count information further includes. That is, each boundary clock receives boundary clock data information from other boundary clocks, and compares them according to the flow chart of the time synchronization method illustrated in FIG. 3 to select a master clock and a slave clock.

When each boundary clock selects a master clock, it transmits a master selection acknowledgment message to the master clock to indicate that it is a master clock corresponding to its boundary clock.

Each master clock that has sent a master selection confirmation message to the new master clock receives a master acknowledge message from the new master clock. Each boundary clock also sends a master release message to the previous master to indicate that the previous master clock is not the current master clock.

Therefore, as shown in FIG. 5, unlike the conventional master-slave structure, the master-slave structure according to the embodiment of the present invention has each master clock having a small number of slave clocks. This result can reduce communication overload caused by each boundary clock transmitting and receiving boundary clock data information.

The role selection history of the boundary clock as the master or slave clock is updated on the boundary clock data information of each boundary clock, and then used as a reference when newly selecting the role of the boundary clock.

6 is a view for explaining a connection recovery method between a master clock and a slave clock according to the time synchronization method according to the present embodiment.

FIG. 6A is a diagram illustrating a master-slave structure having a preliminary master clock constructed according to the time synchronization method according to the present embodiment.

As shown in FIG. 6A, in the time synchronization method according to the present embodiment, the slave clock selects an adjacent boundary clock except the master clock corresponding thereto as a preliminary master clock.

 In more detail, the at least one slave clock receives its boundary clock data information and clock data information of an adjacent boundary clock except the corresponding master clock. Thereafter, the at least one slave clock compares clock data information of adjacent boundary clocks.

As a result of the comparison, the one or more slave clocks select one of the adjacent boundary clocks as the preliminary master clock. Here, one of the boundary clocks means a boundary clock having a communication distance with the grand master clock, the number of slaves and the clock identification information smaller than the other adjacent boundary clocks.

Meanwhile, the method of selecting the preliminary master clock based on information included in at least one slave clock based on the boundary clock data information is the same as or similar to the method of determining the role of the boundary clock based on the boundary clock data information. The description is omitted.

FIG. 6B is a diagram illustrating a connection recovery process using a master-slave structure having a preliminary master clock constructed according to the time synchronization method according to the present embodiment.

Referring to FIG. 6B, when one or more slave clocks fail to connect to their corresponding master clocks, the one or more slave clocks may use adjacent boundary clocks except their corresponding master clocks as the spare master clocks. Select. For example, if the connection between the slave clock having the unique number 11 and the master clock having the unique number 6 fails, the slave clock having the unique number 11 is the new master clock and the preset unique number 7 as the preliminary master clock. Select the boundary clock with burn.

7A to 7C are diagrams for describing an effect of the time synchronization method according to the present embodiment.

7A is a graph comparing the number of slave clocks of each master clock of the PTP network apparatus 100 constructed by the time synchronization method and the conventional time synchronization method according to the present embodiment. On the other hand, the horizontal axis of Fig. 7A represents the clock unique number of each boundary clock, and the vertical axis represents the number of slave clocks of each master clock.

As shown in Fig. 7A, in the case of the master-slave structure constructed by the time synchronization method according to the present embodiment, each master clock has fewer slaves than the master-slave structure constructed by the conventional time synchronization method. I have a clock. For example, the master clocks having unique numbers 7, 13, and 19 constructed by the conventional time synchronization method have five slave clocks, respectively. Each master clock has one slave clock.

That is, the master slave structure constructed by the time synchronization method has a smaller number of slaves than the master slave structure constructed by the conventional time synchronization method, and each master clock has an equal slave clock. it means.

7B and 7C are graphs showing the number of slaves of each master clock as the number of boundary clocks of the PTP network apparatus 100 constructed by the time synchronization method and the conventional time synchronization method according to the present embodiment increases. Meanwhile, the horizontal axis of FIG. 7B is the number of boundary clocks, and the vertical axis is a graph showing an average value of the number of slaves of each master clock in the master-slave structure constructed by the conventional time synchronization method and the time synchronization method of the present invention. The horizontal axis of FIG. 7C represents the number of boundary clocks, and the vertical axis represents the standard deviation of the number of slaves of each master clock in the master-slave structure constructed by the conventional time synchronization method and the time synchronization method of the present invention.

As shown in the graphs of FIGS. 7B and 7C, as the number of boundary clocks increases, an average value for the number of slaves of each master clock constructed by the time synchronization method according to the present embodiment is equal, but It can be seen that the standard deviation is 0.5 times less than the standard deviation of the number of slaves of each master clock constructed by the conventional time synchronization method.

This result means that each master clock constructed by the time synchronization method according to the present embodiment has a uniform number of slave clocks than each master clock constructed by the conventional time synchronization method. Therefore, as described with reference to FIGS. 7A to 7C, it can be seen that the time synchronization method according to the present embodiment solves the communication overload problem of each boundary clock of the conventional time synchronization method.

The above description is merely illustrative of the technical idea of the present embodiment, and those skilled in the art to which the present embodiment belongs may make various modifications and changes without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of the present embodiment but to explain, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present embodiment.

100: PTP network device 120: grand master clock
140: normal clock 160: boundary clock

Claims (10)

In the time synchronization method of the network device,
Each boundary clock of the network device includes boundary clock data information including a communication distance from another boundary clock to a grand master clock, number of slaves, and clock identification information. Receiving each;
Performing comparison between boundary clock data information received by the boundary clocks from the other boundary clocks; And
Each of the boundary clocks determines a role of the other boundary clocks as a master clock or a slave clock according to a comparison result between the boundary clock data information, and has a smaller number of slaves according to the comparison result when utilizing the slave number information. Determining the Perimeter Clock as the Master Clock
Time synchronization method comprising a. The method of claim 1,
The determining process,
And each boundary clock compares a communication distance between the other boundary clocks with the grand master clock, and determines a boundary clock having a shorter communication distance as a master clock according to a comparison result. The method of claim 2,
The determining process,
And comparing the slave number information between the other boundary clocks when the comparison result of the communication distances is the same, and determining a boundary clock having a smaller number of slaves as a master clock according to the comparison result. The method of claim 3, wherein
The determining process,
When the comparison result of the slave number information is the same, comparing the clock identification information between the other boundary clocks, and determining a boundary clock having smaller clock identification information as a master clock according to the comparison result. . The method of claim 1,
If it is recognized that the connection between the one or more master clocks and the slave clocks corresponding to the one or more master clocks has failed, the slave clock may further include reselecting a preset preliminary master clock as a new master clock. Synchronization method. The method of claim 5,
The step of selecting the preliminary master clock further, wherein the process of selecting the preliminary master clock,
Receiving, by the slave clock, boundary clock data information including a communication distance with the grand master clock, slave number information, and clock identification information from adjacent boundary clocks other than the master clock corresponding to the slave clock; And
Selecting the preliminary master clock by performing comparison between boundary clock data information received from the adjacent boundary clocks by the slave clock;
Time synchronization method comprising a. The method of claim 6,
And updating the preliminary preliminary preliminary master clock for each of the boundary clocks according to a comparison result between the boundary clock data information received by the respective boundary clocks from the other boundary clocks. Way. The time synchronization program is combined with the hardware of the network device,
Receiving, by each boundary clock of the network device, boundary clock data information including a communication distance with a grand master clock, slave number information, and clock identification information from other boundary clocks, respectively;
Performing comparison between boundary clock data information received by the boundary clocks from the other boundary clocks; And
Each of the boundary clocks determines a role of the other boundary clocks as a master clock or a slave clock according to a comparison result between the boundary clock data information, and has a smaller number of slaves according to the comparison result when utilizing the slave number information. Determining the Perimeter Clock as the Master Clock
A time synchronization program stored on a computer readable recording medium for executing the program. The method of claim 8,
The determining process,
Wherein each of the boundary clocks compares some or all of the communication distance with the grand master clock, slave number information, and clock identification information between the other boundary clocks, and determines the roles of the other boundary clocks according to the comparison result. A time synchronization program stored on a computer-readable recording medium. The method of claim 8,
If it is recognized that the connection between the at least one master clock and the slave clock corresponding to the at least one master clock has failed, the slave clock may further include reselecting a preset preliminary master clock as a new master clock. A time synchronization program stored on a readable medium.

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