JPH01109842A - Timing switching system for transmitter - Google Patents

Abstract

PURPOSE:To conduct efficient loopback test by storing information relating to a clock source of data transmission in a network so as to switch the synchronizing timing of data transmission based on the information. CONSTITUTION:A command signal from a MODEM 221 is synchronous with a clock source 223 and sent to a MODEM 251 via MODEMs 231, 241. In receiving the command signal sent from the MODEM 221, a main control section 321 reads clock source information stored in a clock information storage section 311 and changes the timing for the modulation implemented synchronously with a synchronizing signal 343 generated from an extracted clock signal 353 extracted by a demodulation section 351.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Field of Application Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems Action Example ■, Correspondence between the Example and Figure 1 Relationship ■, Structure of Example ■, Operation of Example (i) Clock source information for data transmission (11) Data loopback operation (iii) Timing change operation during data loopback (iv) Detailed operation in modem (iv-1) ) Data loopback from the line side 1v-2) Data loopback from the device side■, Summary of Examples ■2 Variations of the invention Effects of the invention [Summary] When performing a loopback test to check the network status Regarding the timing switching method of a transmission device, for the purpose of efficiently conducting loopback tests, a clock information storage means for storing information regarding the clock source of data transmission within the network, and a clock information storage means for storing information regarding the clock source of data transmission within the network, and a , a timing switching means for switching the synchronization timing of data transmission, and a loopback means for loopbacking the data during the loopback test in synchronization with the timing switched by the timing switching section.

[Industrial application field]

The present invention relates to a timing switching method for a transmission device, and particularly to a timing switching method for a transmission device when performing a loopback test to check the state of a network.

[Conventional technology]

In a network constructed using synchronous transmission devices, the timing of data transmission of each transmission device must be synchronized.

Therefore, it is necessary to satisfy the following two conditions.

■There is one clock source for data transmission on the data transmission path.
There are two.

Connect and set up each transmission device so that all the transmission devices on the path are synchronized with the clock source described in ■■.

FIG. 6 is an example of a network. For example, a host computer 611 and a data terminal equipment (hereinafter referred to as DTE) 661 may have modems 621, 631, 641, 65
It is assumed that the connection is made through 1. Data from host computer 611 is modulated by modem 621 and sent to modem 631, and further sent to DTE 661 via modems 641 and 651.

For example, in the data transmission path from the host computer 611 to the DTE 661 (data transmission path from the host computer 611), the clock source 6 in the modem 621
Data transmission is performed based on 23. Also, DTE66
1 to the host computer 611 (data receiving path to the host computer 611), data transmission is performed based on a clock source 653 within the modem 651.

By the way, when a fault occurs in a network, there is a loopback test as a method for detecting the location of the fault.

For example, in the network shown in FIG. 6, data is sent from modem 621 to modem 631, and modem 631
The data is looped back and sent back to the modem 621. modem 6
In step 21, since the data sent to the modem 631 is returned normally, it is confirmed that there is no abnormality in the line between the modem 621 and the modem 631 (or the operation within the modem 631). Similarly, by returning data from modem 621 to modem 641 or modem 651, abnormalities in the line can be detected.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned loopback test, inconveniences may occur depending on the position of the clock source on the transmission line.

For example, when returning data from modem 621 to modem 651, from modem 621 to modem 651
Data transmission to the modem 621 is performed in synchronization with a clock source 623 within the modem 621. However, data transmission from modem 651 to modem 621 is performed by clock source 6 in modem 651.
It is carried out in synchronization with 53. Therefore, two clock sources are present on the data transmission path (the data transmission path from modem 621 to modem 651 and the data transmission path from modem 651 to modem 621) during the loopback test. Furthermore, depending on the loopback test route, there may be no clock source at all.

In the above case (when there is a clock source other than one), the timing of data transmission is not synchronized, resulting in data dropout or duplication.

Therefore, in the loopback test, when there are two or more clock sources or one clock source disappears, it is necessary to take measures to change the clock source to one.

As means for changing the clock source to one, the following are mainly considered.

■During the loopback test, maintenance personnel change the settings of the transmission device (modem) for the loopback test. For example, the modem 651 is changed from transmitting data in synchronization with the clock source 653 to transmitting data in synchronization with a clock signal extracted from the received signal.

(2) Each transmission device is provided with information regarding a route during a loopback test within a limited range, and settings within the range are changed in the transmission device during the loopback test.

(2) Provide each transmission device with information regarding all transmission devices that make up the network, and change the settings in each transmission device according to this information during the return test.

However, in case (2), it takes time and effort for maintenance personnel, so the test cannot be carried out efficiently. In case (2), if the scale of the network becomes large, it becomes impossible to cope with the problem. In (2), since the information stored in each transmission device becomes large, a large memory etc. is required, and it becomes necessary to increase the processing capacity to process the information. Therefore,
None of these methods are practical, and a method that can efficiently perform folding tests has been desired.

The present invention was created in view of these points, and an object of the present invention is to provide a timing switching method for a transmission device that can efficiently perform loopback tests.

[Means for solving problems]

FIG. 1 is a principle block diagram of a timing switching system of a transmission device according to the present invention.

In the figure, clock information storage means 111 in a timing switching method of a transmission device when performing a loopback test to check the state of a network stores information regarding a clock source for data transmission within the network.

The timing switching means 121 switches the synchronization timing of data transmission based on the information stored in the clock information storage means 111.

The loopback means 131 loops back the data during the loopback test in synchronization with the timing switched by the timing switching section 121.

Therefore, overall, the synchronization timing is switched based on the information stored in the clock information storage means 111,
It is configured to wrap data.

[Operation] The clock information storage means 111 stores information regarding a clock source for data transmission within the network, and based on this information, the timing switching means 121 switches the synchronization timing of data transmission.

The loopback means 131 loops back data in synchronization with the timing switched by the timing switching section 121.

According to the present invention, by switching the synchronization timing according to the information stored in the clock information storage means 111, the loopback test can be performed efficiently.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows the configuration of a network to which the timing switching method of the transmission device of the present invention is applied. Further, FIG. 3 shows the detailed configuration of the modem used in the network of FIG. 2.

③ Correspondence between 11j and 1゛Here, the correspondence between the embodiment of the present invention and FIG. 1 will be shown.

The clock information storage section stage 111 includes the clock information storage section 3
It corresponds to 11.

The timing switching means 121 includes a main control section 321, a clock generation section 323. Modulation section 341. This corresponds to the demodulation section 351.

The folding means 131 includes a switching section 331. This corresponds to the switching section 333.

Examples of the present invention will be described below assuming that the correspondence relationship as described above exists.

-L-Real 1'' (Column 1) In FIG. 2, the network of the embodiment includes a host computer 211 that controls the entire network and processes data handled by the network, and four modems 221 and 231. 241, 251, and a DTE 261 that inputs and outputs data processed by the host computer 211.The DTE 261 is equipped with a display and a keyboard. can be displayed.

Data input from the DTE 261 is sent to the modem 251, which modulates the data and sends it to the modem 241. Modem 241 demodulates the modulated signal sent from modem 251 and sends the demodulated data to modem 231 via R3-232C or the like. Furthermore, the modem 231 performs modulation, the modem 221 performs demodulation,
Data is supplied from the modem 221 to the host computer 211.

The modem 221 also includes a clock source 223 for synchronizing data transmission from the host computer 211 to the DTE 261. The modem 251 is DTE26
A clock source 253 is provided for synchronizing data reception from 1 to the host computer 211.

FIG. 3 shows the detailed configuration of the modem 251. It is assumed that the three modems 221, 231, and 241 other than the modem 251 have the same configuration as the modem 251, and a description of the configuration will be omitted.

In the figure, the modem 251 includes a main control section 321 that controls the entire modem 251, a modulation section 341 that modulates digital data to obtain an analog signal for transmission, and a modulation section 341 that demodulates the analog signal to generate digital data. a demodulating section 351 for generating data, two switching sections 331 and 333 for returning data, a clock generating section 323 for generating a synchronized clock signal for each component of the modem 251 to operate, and a clock generating section 323 for generating a synchronized clock signal for each component of the modem 251 The clock information storage section 311 stores information regarding clock sources for data transmission existing inside and outside.

Here, when a clock source for data transmission exists in the modem 251, the operations of each component in the modem 251 are performed in synchronization with the clock signal generated by the clock generator 323, and the clock signal (or A modulation (data transmission) operation in the modulation section 341 is performed in accordance with a transmission clock signal obtained by dividing the frequency of the clock signal.

Furthermore, when a clock source for data transmission does not exist in the modem 251, operations in each component of the modem 251 (for example, control operations in the main control section 321) are performed in synchronization with the clock signal generated by the clock generation section 323. It will be done. At this time, the transmission (modulation) in the modulation section 341
The operation is synchronized with the data supplied from the DTE 261 to the modulating section 341 via the switching section 331, or based on the extracted clock signal 353 extracted from the signal supplied from the modem 241 to the demodulating section 351 via the switching section 333. It is done synchronously.

Data input to the modem 251 from the DTE 261 side is supplied to the modulation section 341 via the switching section 331. The modulated signal by the modulation section 341 is transmitted to the modem 241 side via the switching section 333.

The signal input to the modem 251 from the modem 241 side is
The signal is supplied to the demodulating section 351 via the switching section 333. The demodulated data from the demodulation section 351 is transferred to D via the switching section 331.
It is sent to the TE261 side.

Furthermore, the demodulation section 351 extracts a data transmission clock signal for synchronizing data transmission based on the signal supplied from the switching section 333, and extracts the extracted clock signal 353.
The data is supplied to the main control unit 321 as a signal.

The main control unit 321 also receives a clock signal generated by the clock generation unit 323 and a clock information storage unit 31.
Information regarding the clock source stored in the modem 1, instruction data sent from the DTE 261 side via the switching unit 331, and information on the clock source stored in the modem 2 via the switching unit 333 and the demodulating unit 351.
The instruction data sent from the 41 side is introduced.

Furthermore, the modulation unit 34 is connected from the main control unit 321 to the modulation unit 341.
Synchronization signal 343 for synchronizing the modulation operation in 1
However, switching instructions are input to the two switching units 331 and 333, respectively.

From now on, the side that outputs the modulated signal of each modem will be referred to as the "line side".
In the following explanation, the side that outputs the demodulated signal will be referred to as the "apparatus side."

-1-Considerations Control Operation Next, the operation of the embodiment of the timing switching method of the transmission apparatus of the present invention described above will be explained.

(i) Clock information storage section of each modem with clock source for data transmission (modem 251 in Figure 3)
In the clock information storage section 311), information regarding the clock source for data transmission in the network shown in FIG. 2 (clock source information) is stored.

The clock source information is information that focuses on a certain modem and indicates whether or not a clock source for data transmission exists on the device side of the modem, inside the modem, or on the line side of the modem.

“1” indicates that a clock source is present, and “1” indicates that there is no clock source.

0", the clock source information can be represented by 3-bit data. Therefore, the clock source information "x x x
” represents (presence or absence of a clock source on the device side), (presence or absence of a clock source inside the modem), or (presence or absence of a clock source on the line side).

In the network shown in FIG. 2, modem 221 and modem 251 have clock sources. Therefore, modem 25
The clock information storage unit 311 of 1 has “011°” as clock source information, the modem 241 (clock information storage unit) has “io i” as clock source information, and the modem 231 has “io i” as clock source information. 101°゛ is
"011'" is stored in the modem 221 as clock information.

At the bottom of each modem in FIG. 2, clock source information stored in the clock information storage section of each modem is shown.

Figure 4 explains data return during the return test.

The data return operations represented by "loop 1" to "loop 4" will be explained below (■ to ■).

``Loop I'': Indicates a data return operation in which data sent from the device is sent back to the device without being processed (modulation, demodulation) in the corresponding modem.

In the modem 251 shown in FIG.
The data sent from the modem 251 to the switching unit 331
The operation of manually transmitting data from the switching section 331 to the DTE 261 corresponds to "loop 1."

``Loop 2'': Indicates a data return operation in which data sent from the line side (modulated signal in the case of a modem) is processed in the corresponding modem and then sent back to the line side.

In the modem 251, the modem 241 to the modem 25
The signal sent to the switching unit 333° demodulating unit 351 (
The signal is input to the switching section 331 via the signal generator (which demodulates the signal). The switching unit 331 loops back the data and sends the data back to the modem 241 via the modulating unit 341 (which performs modulation) and the switching unit 333. The modulated signal is sent to the demodulator 3
51, and the switching unit 331 returns the demodulated signal,
The operation of modulating the signal in the modulation section 341 and sending back the modulated signal corresponds to "loop 2."

``Loop 3'': Indicates a data return operation in which a signal sent from the device side is processed in the corresponding modem and then sent back to the device side.

In contrast to "loop 2", the data sent from the DTE 261 is modulated by the modulation section 341, the switching section 333 returns the demodulated signal, and the demodulated data is sent to the demodulation section 351.
The operation of sending the data back to the TE 261 corresponds to "loop 3".

■"Loop 4" This shows a data loopback operation in which a signal sent from the Coro line is sent back to the line without being processed by the corresponding modem.

The signal sent from the modem 241 to the modem 251 is input to the switching unit 333, and the signal sent from the switching unit 333 to the modem 241
The operation of sending back a signal corresponds to "loop 4".

iii Data ゛ ShiH timing!・1st 5th
The figure shows the operation of changing the data transmission timing in a modem that performs data loopback, or the operation of instructing another modem to change the timing from the modem.

When data is looped back in "loop 1" or "loop 4", the transmission timing from the modulation section in the modem cannot be changed (because it does not go through the modulation section), so equipment (modem, DT
A data transmission timing change instruction from the E261 or host computer 211) is sent to the device, so that the data transmission timing is changed in the device.

The modem we are focusing on (modem that loops back data)
The timing change operation will be explained by associating the clock source information in the data with the data folding operation.

Note that combinations of clock sources other than those shown below (clock source information "OOO", ""110", "clock information storage means 111') are not normally possible due to the network system configuration, so their explanation will be omitted.

■Clock source information "001"': Since the clock source exists only on the line side, "Loop 1"
and timing changes regarding “loop 3”.

In the case of "loop 1", since there is no clock source for data transmission on the device side, there is no clock source on the data transmission path during the loopback test. Therefore,
The modem of interest sends a timing change instruction to the device side, and generates a clock source for data transmission in an adjacent device on the device side (the adjacent device is set to perform data transmission in synchronization with the clock signal generated by the clock generator) ).

In the case of "loop 3", a clock source for data transmission is generated within the modem of interest. For example, if the configuration of the modem of interest is the same as the modem 251, the main control unit 321
The modulating unit 3 transmits the synchronizing signal 343 for data transmission according to the clock signal supplied from the clock generating unit 323.
41, and the data transmission operation in the modulation section 341 is performed.

■Clock source information "010": Since a clock source exists only in the modem of interest, the timing is changed for "loop 1" and "loop 4."

In the case of "Loop 1" and "Loop 4", there is no clock source on the data transmission path, so the modem in question sends a timing change instruction to the adjacent device, and the adjacent device clocks the data transmission clock. generate a source.

■Clock source information “011”: There is a clock source on the line side and the target modem.
The timing is changed for "Loop 1" and "Loop 2".

In the case of "loop 1", since there is no clock source for data transmission on the device side, the modem of interest sends a timing change instruction to the device side, and causes the adjacent device to generate a clock source for data transmission.

In the case of "loop 2", since there are two clock sources on the data transmission path, the data transmission operation within the modem of interest is changed to synchronize with the other clock sources.

For example, assuming that the modem of interest has the same configuration as the modem 251, the main control section 321 generates a synchronization signal 3 according to the clock signal supplied from the normal clock generation section 323.
43 to the modulation section 341, and the modulation operation in synchronization with the synchronization signal 343 is performed. Change it to do so.

■Clock source information “100”: Since the clock source exists only on the device side, “Loop 2”
and timing changes regarding "loop 4".

In the case of "Loop 2" and "Loop 4", there is no clock source on the data transmission path in both cases, so the modem in question sends a timing change instruction to the adjacent device on the line side, and the adjacent device transmits the data. Generates a clock source for transmission.

■Clock source information ° “101”: Since clock sources exist on the device side and the line side, there is no need to change the timing for all loops from “loop 1” to “loop 4”.

In FIG. 5, r M -) 3 J represents a change in the timing generated by the clock source in the modem of interest or an adjacent device, and "S→M" represents the change in the timing of data transmission in the modem of interest using the clock source within the modem. ``-'' indicates that there is no timing change.

iv In the modem, Φ Next, a specific example of data loopback in the modem 251 will be described. The clock information storage unit 311 in the modem 251 stores “011” as clock source information.

1v-1 port, data from 1 First, consider the data looping operation in "loop 2". It is assumed that the data transmission source is the modem 221 (the same can be said when the data transmission source is the host computer 211 or the modem 231 or 241).

First, modem 221 sends an instruction signal for modem 251 to loop back data.

The instruction signal from modem 221 is synchronized with clock source 223 and sent to modem 251 via modems 231 and 241. Inside the modem 251, the instruction signal received via the switching section 333 is demodulated by the demodulation section 351, and the main control section 321 performs a timing change operation based on the demodulated data. In addition, from modem 221 to modem 251
The instruction signal sent to the modem 251 includes an instruction as to whether data loopback in the modem 251 is "loop 2" or "loop 4."

Upon receiving the instruction signal sent from modem 221,
The main control unit 321 reads the clock source information (“'011”) stored in the clock information storage unit 311. When receiving the data return instruction for “loop 2”, the main control unit 3
21 performs an operation corresponding to clock source information "011" and "loop 2".

As shown in ``(ji) Timing change operation during data return'' above, the modulation (transmission) operation that was performed in synchronization with the synchronization signal 343 created from the clock signal output from the clock generator 323 is now changed. The timing is changed to a modulation operation performed in synchronization with the synchronization signal 343 created from the extracted clock signal 353 extracted by the demodulator 351.

Thereafter, when a return test is performed and test data is sent from the modem 221 to the modem 251, the data is transferred to the switching unit 333. The signal is returned to the switching section 331 via the demodulating section 351, and further sent back to the modem 221 via the modulating section 341 and the switching section 333.

Furthermore, once the main control unit 321 receives the data return instruction for "loop 4", there is no need to change the timing.
Timing change in modem 251 or modem 2
The test data sent from the modem 221 may be returned without sending a timing change instruction from the modem 51 to other devices.

(iv-2), ゛ of the data from the '- side, then '
Let us consider the data looping operation in "Loop 1". It is assumed that the data transmission source is the DTE 261.

First, the DTE 261 sends an instruction signal to the modem 251 to loop back data. The instruction signal from the DTE 261 is sent to the modem 251 in synchronization with the clock source 253 within the modem 251. Inside the modem 251, based on the signal received via the switching unit 331,
A timing change operation is performed by the main control unit 321. Note that the instruction signal sent from the DTE 261 to the modem 251 indicates that the data return at the modem 251 is "
It includes an instruction as to whether it is "loop 1" or "loop 3."

Upon receiving the instruction signal, the main control section 321 reads out the clock source information stored in the clock information storage section 311. Upon receiving the data return instruction for "loop 1", the main control section 321 performs an operation corresponding to the clock source information "011'" and "loop 1".

As shown in '(iii) Timing change operation during data loopback'' above, if the data sent from the DTE 261 is looped back via the switching unit 331, there will be no clock source on the data transmission path. Therefore, the main control unit 321 sends an instruction to the DTE 261 via the switching unit 331 to generate a clock source for data transmission.

Upon receiving the instruction, the DTE 261 generates a clock source for data transmission based on a clock signal output from a clock generation section within the DTE 261.

Furthermore, once the main control unit 321 receives the data return instruction for "loop 3", there is no need to change the timing.
The data sent from the DTE 261 may be sent back via the switching unit 331.

Summary of n In this way, the clock information storage unit 311 stores data regarding the presence or absence of a clock source on the device side, the presence or absence of a clock source inside the modem, and the presence or absence of a clock source on the line side as clock source information related to data transmission. put. other modem,
When an instruction signal for loopback of data is sent from the host computer 211 or DTE 261 to the modem 251, the main control unit 321 uses the clock source information read from the clock information storage unit 311 and the loopback loop (“loop 1”). to "loop 4"), the timing of data transmission in modem 251 is changed, or a timing change instruction is sent to a device adjacent to modem 251 (modem 241 or DTE 261). The modem 241 or the DTE 261 changes the timing in response to a timing change instruction sent from the modem 251.

Therefore, by switching the timing of data transmission according to the clock source information stored in the clock information storage section 311, efficient loopback testing becomes possible.

In the embodiment of the present invention described above, a modem was considered as a transmission device constituting a network, but the same can be said of other transmission devices (such as a DSU). For example, when the two modems 251 and 241 are replaced with DSUs, the timing of the transmitter transmitting data from one DSU to another is changed.

Furthermore, in the embodiment, the case where the clock source exists in the modem 221 and the modem 251 was considered, but in other cases, it is sufficient to simply change the clock source information stored in the clock information storage section of each modem. .

Furthermore, in ``correspondence between examples and FIG. 1'',
Although the correspondence between the present invention and the embodiments has been described, those skilled in the art will easily assume that the present invention is not limited to this and that there are various modifications.

〔Effect of the invention〕

As described above, according to the present invention, the synchronization timing is switched in accordance with the information regarding the clock source for data transmission within the network stored in the clock information storage means, and the synchronization timing is switched in synchronization with the switched timing, during the return test. Since data can be folded back, it is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a principle block diagram of the timing switching method of the transmission device of the present invention, Fig. 2 is a configuration diagram of a network in an embodiment of the invention, and Fig. 3 is a modem to which the timing switching method of the transmission device of the present invention is applied. FIG. 4 is an explanatory diagram of data loopback in the loopback test of the embodiment, FIG. 5 is an explanatory diagram of timing changes in the modem of the embodiment, and FIG. 6 is an explanatory diagram of a clock source in data transmission. In the figure, 111 is a clock information storage means, 121 is a timing switching means, 131 is a return means, 211 is a host computer, 221.231, 241, 251 are modems, 223.2
53 is a clock source, 261 is a DTE. 311 is a clock information storage section, 321 is a main control section, 323 is a clock generation section, 331 and 333 are switching sections, 341 is a modulation section, 353 is a synchronization signal, 351 is a demodulation section, and 353 is an extracted clock signal. Main house s7; Simple R Nephew A 07 Kuro Figure 1 Table of contents @Lc6 宕≧Sun Moon Ri] Figure 4 Yusaki - Ri'° Figure 6

Claims (1)

[Scope of Claims] A timing switching method for a transmission device when performing a loopback test to check the state of a network, comprising: clock information storage means (111) for storing information regarding a clock source for data transmission within the network; a timing switching means (121) for switching the synchronization timing of data transmission based on the information stored in the clock information storage means (111); A timing switching system for a transmission device, characterized in that it is configured to include a return means (131) for returning data during a test.