WO2001028144A1

WO2001028144A1 - Synchronizing device and synchronizing system

Info

Publication number: WO2001028144A1
Application number: PCT/JP1999/005715
Authority: WO
Inventors: Yasuo Fujii
Original assignee: Fujitsu Limited
Priority date: 1999-10-15
Filing date: 1999-10-15
Publication date: 2001-04-19

Abstract

A synchronizing device capable of preventing generation of a synchronous loop between SDH transmission devices including an SONET and of being synchronized with one reference clock in any case, and a system for the synchronizing device. This device comprises synchronizing means, line input/output means for inputting/outputting synchronizing signals on a line, external output means for outputting the synchronizing signal inputted to the line input/output means to the outside, external input means to which an external synchronizing signal is inputted, and opposition input means to which a synchronizing signal of an opposed device is inputted. The synchronizing means outputs the external synchronizing signal of the external input means to the line through the line input/output means when the quality of the external synchronizing signal of the external input means is identical to that of the input synchronizing signal of the line input/output means and to that of the synchronizing signal of the opposition input means.

Description

Description Synchronizer and Synchronous System Technical Field

The present invention relates to a synchronization device, and in particular, to a transmission device capable of configuring various synchronization networks by preventing the occurrence of a synchronization loop between SDH (Synchronous Digital Hierarchy) transmission devices including SONET (Synchronous Optica 1 Network). The present invention relates to a device synchronization device and its system.

Background art

In recent years, SDH transmission has become widespread with the digitization, diversification, and high speed of information. In SDH transmission, signals are transmitted and received while synchronizing with each other between transmission devices. The transmission device detects an external clock signal input from a clock device inside the office or a synchronization signal in a timing signal distributed from another transmission device by a transmission line, and detects those clock signals. By comparing the clock source qualities with each other, the highest quality clock source is selected and synchronized. As a result, the entire transmission network is synchronized with the reference timing.

The SDH transmission equipment uses STM (Synchronous Transfer Mode) —frame synchronization signals (A1 and A2 bytes in the section overhead) from the n-line or external signals from the clock equipment. It operates in synchronization with the timing and distributes it to other devices via the STM-n line. Synchronizers are very important for SDH devices. Normally, multiple synchronizing signals are input to the synchronizer, and the synchronizer is used as an operating synchronization source. When an error occurs, a redundant configuration is used to switch to another source. When selecting a source, the STM-n line is a 4-bit information called SS MB (Synchronization Management Half Byte) added to the external signal itself. Use to compare the quality of the input clock sources and select the highest quality source to use. The SDH has five qualities specified by the International Telecommunication Union (ITU-T), and the following qualities are specified in order of higher quality.

P R CZ S S U-A / S S U-BZ S E C ZD N U

Figures 1 and 2 show an example of the synchronization sequence.

In the example of Fig. 1, the external input (Ε Χ Τ) 23 and the STM-η line (LINE a) 21 are set as the source of the device 11, and the source of the other device 12 is set as the source. STM-n line (LINE b) 25 is set. In this case, the device 11 receives the external clock of the quality PRC by the clock device 10 from the external input 23, and receives the timing information of the quality SSU-A from the line 21. I do. Based on these quality comparisons, the device 11 synchronizes with the higher-quality PRC side, and sends a SYNC message to the STM-n lines 22 and 24 with the synchronization quality of its own device as PRC. As a result, the opposing device 12 is synchronized with the quality PRC.

FIG. 2 shows a case in which the clock device 10 in FIG. 1 has failed and the clock quality from the external input 23 has dropped to SSU-B. In this case, the device 11 synchronizes with the clock quality SSU—A side from the STM—n line 21, and the SSU—to the opposing device 12 via the STM—n line 24. Send the SYNC message changed to A. As a result, the synchronization quality of the device 12 also deteriorates to SSU-A. It should be noted in the examples of Figs. 1 and 2 that a device synchronized to the quality of a certain STM-n line input has the lowest quality DNU (Do Not Use) at the output side of the same line. This is the point of sending SYNC messages marked with (apparatus 12 in FIG. 1 and apparatuses 11 and 12 in FIG. 2). This avoids the occurrence of a timing group in which the device itself resynchronizes with the synchronization quality sent by the device itself.

Figures 3 and 4 show the operating principle of such a conventional timing group prevention measure.

Figure 3 operates as follows. In other words, “The device that synchronizes with the receiving STM-n line sends DNU to the synchronized STM-n line.” (Hereafter, this is referred to as “timing group prevention method 1”.) ). In this example, the STM-n lines 21 and 25 are set as the source of the device 11, and the STM-n lines 24 and 27 are set as the source of the device 12. ing. Therefore, the device 11 having the quality SSU-A synchronizes with the quality PRC from the STM-n line 21 and sends the DNU to the output line 22 thereof. Also, the device 12 synchronizes with the quality PRC of the STM-n line 24 and sends out DNU to the output line 25 thereof.

On the other hand, Fig. 4 shows an example of the case in Fig. 3 in which synchronization is performed only by a simple comparison of synchronization quality without performing the above-mentioned preventive measure 1 of the timing group. In this case, the device 11 synchronized with the quality PRC in FIG. 3 also sends the PRC to the STM-n line 22. Similarly, device 1 2 sends a PRC to STM-n line 25. Next, as shown in Fig. 4, if the quality of the STM-n line 21 input to the device 11 degrades to DNU, the quality of the STM-η line 25 is PRC. Still, device 11 continues to send PRC to STM-n line 24. As a result, even though there is no actual PRC quality signal source, A PRC loop occurs between units 11 and 12. Thus, when the highest quality PRC loop occurs, there is no way to stop it. Figure 5 shows another time-group prevention measure. In other words, "a device that temporarily outputs the timing signal of the STM_n line to the EXTOUT line, which is synchronized with the timing signal from the EXT IN line and outputs the EXT IN signal. If the quality of the STM-n line is equal to the quality of the STM-n line, the DNU is sent to that STM-n line. "(Hereinafter, this is referred to as" timing group prevention measure 2 ").

In the example of FIG. 5, the PRC-quality timing signal given to the device 12 from the STM-n line 24 is output to the EXTOUT line 28 once, and the signal at the output destination is reproduced. The same PRC quality timing signal whose waveform has been shaped by the device (SCU) 13 is input to the EXT IN line 29 of the device 12. Device 12 compares the quality of the STM-n line 24 and the EXT IN line 29 and, in this case, the same quality PRC, the EXT IN line according to the priority level (EXT> LINE b). Synchronize with the PRC quality from pin 29 and send the DNU to the output of the STM-n line 24.

In the above timing group prevention measure No. 2, although the device 12 is not directly synchronized with the STM-n line 24, the STM-n is indirectly connected via the signal reproducing device 13. In order to synchronize with line 24, the DNU is sent to the output side of the STM-n line 24 in the same way as the timing group prevention measure 1 described above, so that the timing shown in FIG. Prevent the occurrence of mining loops.

However, in some specific cases, the occurrence of the timing group cannot be avoided in some specific cases even if the conventional timing group prevention measures 1 and 2 described above are used. Below, about the example This will be described with reference to FIGS.

FIG. 6 shows an example of a transmission network in which a clock source is made redundant by two clock devices 10 and 16 for supplying a clock of PRC quality. Here, the device 11 is synchronized with the EXT line 23 or the STM-n line 25, and if both have the same quality, the EXT line 23 side has priority. Similarly, device 15 synchronizes to EXT line 35 or STM-n line 34. However, if the EXT line 35 and the STM-n line 34 have the same quality, the STM-n line 34 side has priority.

Also, the device 12 is synchronized with the EXTIN line 29 or the STM-n line 24 and outputs the synchronization timing of the STM-n line 24 to the EXTOUT line 28. . If the EXTIN line 29 and the STMn line 24 have the same quality, the EXTIN line 29 has priority. Similarly, the device 14 synchronizes with the EXTIN line 31 or the STM-n line 33, and gives priority to the EXTIN line 31. The signal reproducing device 13 receives the timing from the EXTOUT lines 28 and 32 from the devices 12 and 14, selects the high-quality side, performs waveform shaping, and performs the waveform shaping. Output to EXTIN lines 29 and 31 of 12 and 14. If both are of the same quality, the line 28 side has priority.

In this example, both of the two clock devices 10 and 16 supply a clock of PRC quality, and the device 11 side gives priority to the EXT line 23 while the other device In order to give priority to the STM-n line 34 on the 15 side, the devices 12 and 14 are based on the timing group prevention measure 2 described above, and the device 15 is based on the timing group prevention measure. Synchronize with the PRC quality of the clock device 10 side by 1. Therefore, the entire network is synchronized with the PRC quality of the clock device 10. FIG. 7 shows a case where a failure has occurred in the clock device 10 in this state, and the quality of the clock device 10 has been degraded to DNU. At this point, since the two inputs become DNU at the same time, the device 11 transits to the holdover which is in the free-running state, and sends SEC, which is the synchronization quality, to the STM-n line 24. I do. Since the SEC has only one higher quality than the DNU, it reaches the STM-n line 34 of the device 15 without changing the synchronization destination based on the previous PRC quality.

As a result, as shown in FIG. 8, the side of the higher-quality clock device 16 is selected by the device 15, and the device 14 receives the PRC quality from the STM-n line 33. Synchronize with Group Prevention Measure No.2, Device 1 and 2 also synchronize with PRC, and finally Device 11 synchronizes with Time Group Prevention Measure No.1 with PRC quality of STM-n line 25 . Thus, the entire network is synchronized with the PRC quality of the clock device 16.

Up to now, the existing evening group preventive measures No. 1 and No. 2 have been functioning effectively, but the problem is that the clock device 10, which once failed, as shown in Figure 9 below. This is the case when it is restored. When the clock device 10 recovers, the device 11 outputs a PRC to the STM_n line 24 in synchronization with its PRC quality. As a result, the devices 12 and 14 are both synchronized with the clock device 10 PRC in the timing group prevention measure 2. However, as is evident from FIGS. 8 and 9, even at this point, the quality of the STM-n line 34 remains DNU. Therefore, device 15 still synchronizes with the PRC quality of clock device 16 and within the network devices 11, 12, and 12 that synchronize with clock device 10. The device 14 and the device 15 synchronized with the clock device 16 coexist. This is a major problem in SDH networks where it is necessary to synchronize the entire network to one reference clock. It was a title.

The cause of this problem is that, in the example of FIG. 9, the signal source of the EXT IN line 31 supplied from the signal reproducing device 13 to the device 14 is the signal from the EX TOUT line 28 of the device 12. The point is that the device 14 itself could not determine whether the signal was from the EXTOUT line 32 of the device 14. As a result, the device 14 cannot detect a change such that the quality of the EXT OUT line 28 becomes equal to the quality of the existing EXT IN line 31, and the STM-n Line 34 continued sending DNU. Disclosure of the invention

In view of the above problems, it is an object of the present invention to provide a new normal Z-slave setting for a device accommodating the EX TOUT and EXTIN lines, and to provide an existing or new spare Z monitor port for the slave device. If the existing synchronization quality of the slave device is equal to the synchronization quality of the normal device, the synchronization device that solves the above problem by not executing loop prevention measure 2 is used. It is to provide a synchronization system.

This provides an SDH network that synchronizes the entire network with a single reference clock.

According to the present invention, a synchronization processing unit, a line input / output unit for inputting / outputting a synchronization signal on a line, an external output unit for externally outputting a synchronization signal input to the line input / output unit, An external input unit to which an external synchronization signal is input; and an opposite input unit to which a synchronization signal of an opposite device is input, wherein the synchronization processing unit is configured to control the quality of the external synchronization signal of the external input unit and the license. If the quality of the input synchronization signal of the input / output means is equal and the quality of the synchronization signal of the opposite input means is equal, the line A synchronizer is provided for outputting an external synchronization signal of the external input means onto the line via an input / output means.

The synchronization processing means, when the quality of the external synchronization signal of the external input means and the quality of the input synchronization signal of the line input / output means are equal and different from the quality of the synchronization signal of the opposite input means, A synchronization signal of synchronization quality DNU is output onto the line via a line input / output unit. According to the present invention, the synchronization processing unit is set to switch between normal / slave, The set device is provided with opposed output means for outputting a synchronizing signal to be applied thereto, instead of the opposed input means of the device (corresponding to a slave device). BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing an example (1) of a synchronization sequence.

FIG. 2 is a diagram showing an example (2) of the synchronization sequence.

Figure 3 is a diagram showing the operating principle (1) of the conventional timing group prevention measure No. 1.

Figure 4 is a diagram showing the operation principle (2) of the conventional timing group prevention measure No. 1.

FIG. 5 is a diagram showing the operation principle of the conventional timing group prevention measure 2.

Figure 6 is a diagram showing an example (1) of a conventional transmission network operation with a redundant clock source.

Figure 7 shows an example (2) of a conventional transmission network operation with a redundant clock source.

Fig. 8 is a diagram showing an example (3) of a conventional transmission network operation with a redundant clock source. Fig. 9 is a diagram showing an example (4) of a conventional transmission network operation in which a clock source is made redundant.

FIG. 10 is a diagram showing an example (1) of a transmission network operation in which a clock source according to the present invention is made redundant.

FIG. 11 is a diagram showing an example (2) of a transmission network operation in which a clock source according to the present invention is made redundant.

FIG. 12 is a diagram showing an example (3) of a transmission network operation in which a clock source according to the present invention is made redundant.

FIG. 13 is a diagram showing an example (4) of a transmission network operation according to the present invention in which a clock source is made redundant.

Fig. 14 is an example (5) of a transmission network operation in which a clock source is redundant according to the present invention (5), and is a diagram showing an operation result of the timing group prevention measure 3 of the present invention. is there.

FIG. 15 is a diagram illustrating an example of the SDH transmission device.

FIG. 16 is a diagram showing an outline of a processing process of the control processing unit. FIG. 17 is a diagram showing an example of a main processing routine of the SYNC processing process.

FIG. 18 is a diagram showing an example of the SYNC table.

FIG. 19 is a diagram illustrating an example of the synchronization source determination step process. FIG. 20 is a diagram illustrating an example of the EXTOUT-P determination step process.

Figure 21 shows an example of the EXTOUT-S confirmation step process.

Figure 22 shows an example of the step processing of loop prevention measure # 1. FIG. 23 is a diagram showing an example of the step processing of loop prevention measures 2 and 3. BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 10 to 14 show an example of the basic operation of the synchronizer according to the present invention and a system using the synchronizer. Figs. 10 to 13 correspond to the conventional operations of Figs. 6 to 9 described above, respectively. Therefore, the same portions are denoted by the same reference symbols, and will not be described repeatedly below.

In FIG. 10, the EXTOUT and EXTIN lines 28 and 29 and the devices 12 and 14 containing the 31 and 32 lines are used as the modes when they synchronize with the EXTIN. A circle and a slave are provided (MO DE = NO RMA LZ SLAVE). In this example, device 12 is set to normal and device 14 is set to slave. Furthermore, by using the input / output ports of the STM-n line which is prepared in advance for the existing equipment as a spare Z monitor (these may be newly installed), the normal equipment Connect a new monitor line 41 between the output port of 1 2 and the input port of the slave device 14. The normal device 12 outputs the timing information of the STM-n line 24 to the monitor line 41. Therefore, the normal device 12 has an existing EXTOUT port, an EXTOUT primary port (EXTOUT-P) and a spare EXTOUT secondary port (EXTOUT-S), and the slave device 14 has an existing EXTOUT port. It has an existing EXTIN port, an EXTIN primary port (EXTIN-P) and a spare EXTIN secondary port (EXTIN-S).

The input to the EXTIN-P port of the slave device 14 is from the signal reproducing device 13 and to the EXTIN-S port is to the signal reproducing device 13 E The XTOUT signal of the normal device 12 is input. Further, the slave device 14 adds the following processing to the conventional timing group prevention measure 2. In other words, "If the quality from £ chome 1 ^^-3 is the same as the quality from EXTIN-P, do not perform loop prevention measure 2" (hereinafter referred to as "timing group prevention measure 3"). ). As a result, the slave device 14 sends the EXTIN-P clock information to the STM-n line 34, and the device 15 synchronizes with it. In the example of FIG. 10, the slave device 14 does not become a target of the loop prevention measure No. 2, and thus operates exactly the same as the conventional example of FIG.

Next, in FIG. 11, as in the case of FIG. 7, a failure occurs in the clock device 10 and its quality is degraded to DNU. As a result, the device 11 that has transited to the holdover sends the synchronization quality SEC to the STM_n line 24. The operation here is exactly the same as in Fig. 7. Also, in FIG. 12 below, the entire network is synchronized with the PRC quality of the higher-quality clock device 16 in exactly the same manner as in FIG.

In the following FIG. 13, the clock device 10 recovers from the failure as in FIG. 9 described above. In this case, regarding the slave device 14, the DNU continues to be provided from the device 14 to the device 15 by the timing group prevention measure 2 regardless of whether or not the clock device 10 is restored. In the present invention, the quality of the monitor line 41 of the EXTIN-S of the slave device 14 becomes PRC, which coincides with the quality PRC of the EXTIN-P line 31. Therefore, the timing group prevention measure 3 is applied. You. Therefore, as shown in FIG. 14, the slave device 14 stops sending DNU to the STM-n line 34, and instead, the PRC-quality clock from the EXTIN-P line 31 is stopped. Data to the STM-n line 34. As a result, equipment 15 is a measure to prevent The clock is synchronized with the PRC of the clock device 10 by the 1st. As a result, the entire network is resynchronized with the PRC quality of the clock device 16.

Next, an embodiment of an SDH transmission apparatus having the above-described configuration of the present invention will be described with reference to FIGS.

FIG. 15 shows an example of an SDH transmission device 51 including one or a plurality of shelves and a unit mounted in the shelves.

In FIG. 15, the control processing unit 52 receives a command from a transmission monitoring device (not shown), and controls the main signal unit 53 and the clock processing unit 54 in its own device according to the command. It also monitors the status of each unit and notifies the transmission monitoring device of fault information. The main signal unit 53 performs the transmission device's original functions such as transmission, reception, multiplexing, demultiplexing, cross-connect, and switching of the transmission main signal.

The clock processing unit 54 executes the synchronization processing of the transmission device. STM—A timing signal from the n-line or an external EXT signal is input to this clock processing unit 54, and SDH transmission synchronized with one of the selected timing signals is performed there. Device 51 Generates its own timing. The generated timing is distributed to each unit 52, 53 inside the device, and the entire device is synchronized.

As described above, the SDH transmission device 51 originally has a redundant configuration. In the context of the present invention, when a normal device is used, an EXTERNAL-OUT-PRIMA is used to output a synchronization signal. Two output ports are available: RY (EXTOUT—P) and EXTERNAL—〇UT—SEC 0 NDARY (EXTOUT-S). Each can output signals from different sources, and clock processing of 2 Mbits or 2 MHz signals synchronized with the timing of the STM-n line Unit 4 output.

On the other hand, in the case of a slave device, two input ports called EXTERNAL-IN-PRIMARY (EXTI-P) and EXTERNAL-IN-SECONDARY (EXTIN-S) are used to input the synchronization signal. Available. During synchronization, the EXTIN-P / S signal is monitored independently, and a high-quality signal is used as the timing source. For the synchronization signal, a 2 Mbit or 2 MHz signal from a signal reproduction device (SCU) is used.

Figure 16 shows an overview of the processing process of the control processing unit 52.

O o

2 3 2 C processing, X.25 communication, and LAN communication processing processes 61 1, 62, and 63 are respectively performed by a personal computer (PC), bucket device, or bucket network for remote login. Performs interface processing with the network and hub devices in the campus network. The user management process 64 performs authentication processing for the user who logs in. The TL1 processing process 65 processes messages and commands input through the respective interfaces, thereby setting the normal Z slave setting in the present invention to the SYNC processing process 6. Notify 6.

The details of the SYNC processing process 66 will be described in detail with reference to FIGS. 17 to 23 below. In this example, the change detection process 69 is used as another processing flow. The content of detection of a change in synchronization quality or an abnormality in the processing unit 54 is notified. The SYNC processing process 66 requests the alarm processing process 68 to perform the alarm processing based on the notification. The alarm processing process 68 performs an alarm process based on the notification content, and passes the process content to the report communication process 67. The report communication process 67 transforms it into a predetermined form. By converting and adjusting the format, the report is compiled into a report, and the contents of the report are reported to a predetermined administrator or the like via the interfaces 61 to 63.

FIG. 17 shows an example of the main processing routine in the SYNC processing process 66. FIGS. 18 to 23 show an example of a detailed processing flow executed in each processing routine in the main processing routine. When the SYNC processing process 66 receives a command from each of the interfaces 61 to 63 or a synchronization status change notification from the change detection process 69 (S101), it determines which one it is. (S102), in the case of command reception, the table contents are updated in the setting change table creation step (S103), and in the case of change notification, the LIN EZ EXTERNAL change step (S102) In 104), the contents of change in the synchronization state of the STM-n line or EXT line are determined.

FIG. 18 shows an example of the SYNC table created in the step (S103) of creating the setting change table. In this table, the normal Z slave status setting, the number of registered synchronization sources, and the current setting value (each current quality value) are given by a command from an operator or the like who has logged in remotely. , EXTOUT-P registration number and current setting value (each current quality value), EXTOUT-S registration and current setting value (each current quality value) are written in the corresponding data areas. The priority order is determined according to the registration order of each registered number.

Next, in the synchronization source determination step (S105) of FIG. 17, as shown in FIG. 19, the variable M is set to the minimum synchronization quality DNU as an initial value, and the variable MS is set to the value of FIG. Set the start source identification value of the synchronization source registration data area of (S201). Then, the processes in steps S202 to S207 are repeated by the number of synchronization source registrations in FIG. This In the case of the normal setting, the contents of the variables M and MS are updated to those of a higher quality source. At the end of the processing, the synchronization quality (M) of the device and the corresponding synchronization source (MS) are selected ( S205 and 206). Then, the data of the current apparatus synchronization source and its current quality value are updated with the value (S208).

Although the above processing contents are the same as the conventional processing, in the present invention, it is further determined whether the determination of the slave (S203) and the synchronization of EXTINS are performed. The former is determined by the SLAV EZNORMAL status data in FIG. 18 and the latter is determined by the result of the LINE / EXTERNAL change (S104) in FIG. As a result, the lowest DNU is given to the synchronization quality M in the case of SLAVE and EXTIN-S is YESS, so that the slave device is prohibited from synchronizing to EXTIN-S.

In the following EXTOUT-P determination step (S106 in Fig. 17) and EXTOUT-S determination step (S106 in Fig. 17), start as shown in Figs. 20 and 21. In each of the variables 0 PM and 0 SM, D NU is set as the initial value, and in the variables O PMS and O SMS, the EXT E RNA L OUT—P registration data area and EX T E The head source identification value of the RNA L OUT-S registration data area is set (S301, S401). Subsequent processing is almost the same as that in Fig. 18; the normal setting is the same as the conventional setting. However, in the case of slave setting, the highest priority source, which is the default value in EXTOUT-PZS Is set, and in either case, the output as the source of EXT IN-S is prohibited.

In the next loop prevention measure, step 1 (S108 in Fig. 17), as shown in Fig. 22, when synchronizing to LINE, DNU is set to that synchronization line quality (S50) 1 and 502)). Here, LINE It is determined whether or not the synchronization has been performed with the result of the LIN EZE XTE RNA L change step (S104). If synchronized with other than LINE, skip the processing of step S502 and do not perform the processing of loop prevention measure No. 1.

In the next loop prevention steps 2 and 3 (S109 in Fig. 17), first, as shown in Fig. 23, it is determined whether or not synchronization with EXTIN-P / S is performed. EXTE RNA LIN— If not synchronized with PZS, end this process (S109). That is, loop prevention measures 2 or 3 are not performed. Even if the slave is synchronized with EXT IN-P / S and the synchronization quality of EXT IN-S is the same as EXT IN-P, loop prevention measure 2 is not performed (S601) ~ 603). This means that loop prevention measure 3 itself was implemented.

All other steps are related to master setting and are the same as before. That is, the output of EXTOUT-P of the normal device determined in step S106 of FIG. 17 is from the STM-n line, and the quality of the STM-n line is the normal device's output. If it is the same as the synchronization quality (EXTIN-P quality), the DNU is transmitted to the STM-n line (S604 to 606). The output of EXTOUT-S of the normal device determined in step S107 of Fig. 17 is also from the STM-n line, and the quality of the STM-n line is the same as that of the normal device. If the synchronization quality (EXTIN-P quality) is the same, the DNU is sent to the STM-n line (S607-609).

Returning to FIG. 17, in step S110, the hardware for executing the contents of the determination in the above-described steps is set. For example, the synchronization source switching switch is set. Finally, the new status is notified to the administrator or the like via the report communication process (FIG. 16) or the like (S111). As described above, according to the present invention, a normal z-slave setting is provided in a synchronization device, and the slave device detects the synchronization quality of the normal device, so that it can be used simply in the event of a failure recovery which has conventionally been a problem. It is possible to provide a synchronization device and a synchronization system that enable re-synchronization to one clock, and as a result, achieve both loop prevention and synchronization with a single reference clock.

Claims

The scope of the claims

1. Synchronization processing means,

A line input / output means for inputting / outputting a synchronization signal on the line;

External output means for externally outputting a synchronization signal input to the line input / output means,

External input means for receiving an external synchronization signal,

Opposing input means to which a synchronizing signal of the opposing device is input, wherein the synchronization processing means is configured to determine the quality of the external synchronizing signal of the external input means and the quality of the input synchronizing signal of the line input / output means. If the quality of the synchronization signal is equal and the quality of the synchronization signal of the opposite input means is equal, an external synchronization signal of the external input means is output onto the line via the line input / output means. Synchronization device.

2. The synchronization processing means, when the quality of the external synchronization signal of the external input means and the quality of the input synchronization signal of the line input / output means are equal and different from the quality of the synchronization signal of the opposite input means. The apparatus according to claim 1, wherein a synchronization signal of synchronization quality DNU is output onto the line via the line input / output means.

3. Synchronization processing means for setting the normal Z slave, line input / output means for inputting / outputting a synchronization signal on the line,

Opposing output means for monitoring and outputting the synchronization signal input to the line input / output means to the opposing device;

External input means for receiving an external synchronization signal,

Opposing input means for receiving the monitor output of the opposing device, When the slave is set, when the slave is set, the quality of the external synchronization signal of the external input means is equal to the quality of the input synchronization signal of the line input / output means, and the quality of the synchronization signal of the opposite input means is the same. If they are equal, an external synchronization signal of the external input means is output onto the line via the line input / output means.

4. The synchronization processing means, when the slave is set, the quality of the external synchronization signal of the external input means is equal to the quality of the input synchronization signal of the line input / output means, and the synchronization signal of the opposite input means is 4. The apparatus according to claim 3, wherein when the quality is different, a synchronization signal of a synchronization quality DNU is output onto the line via the line input / output means.

5. Synchronous processing means,

Facing output means for outputting a synchronization signal input to the line input / output means to a facing slave device;

A normal synchronization device having an external input means to which an external synchronization signal is input; and

Synchronous processing means;

External input means for receiving an external synchronization signal,

Opposing input means for receiving a synchronizing signal of the opposing normal device; a slave synchronizing device having:

A higher-quality synchronization signal is reproduced from the synchronization signal output from the normal and slave synchronization device to the external input of each device. And a signal reproducing apparatus for providing the means, and a synchronous network comprising:

In the synchronization processing means of the slave synchronizer, the quality of the external synchronization signal of the external input means is equal to the quality of the input synchronization signal of the line input / output means, and is equal to the quality of the synchronization signal of the opposite input means. A synchronous network for outputting an external synchronization signal of the external input means to the line via the line input / output means.

6. The synchronization processing means of the slave synchronizer is such that the quality of the external synchronization signal of the external input means is equal to the quality of the input synchronization signal of the line input / output means, and is different from the quality of the synchronization signal of the opposite input means. 6. The apparatus according to claim 5, wherein in such a case, a synchronization signal of a synchronization quality DNU is output onto the line via the line input / output means.