JPH0614002A - Test control system for transmitter - Google Patents

Abstract

PURPOSE:To execute simultaneously a notice representing a test state and a loopback test by using independent data for a test state signal informed to a destination transmitter and for test data looped back in the transmitter. CONSTITUTION:Plural overhead information insert sections OH-INS are provided onto an output line 1 and plural overhead information extract sections OH- DROP are provided onto an input line 2. Then after the final stage of the insert section INS, a pattern signal generating section 3 generating a test state signal P-AIS and a data path changeover means 4 to loop back test data to the input line 2. The means 4 uses a line switching instruction to feed back the test data from the output line 1 to the input line 2 and the signal P-AIS generated by the generating section 3 is sent to the opposite transmitter through the output line 1 to inform it that the transmitter at the sender side is being tested. Thus, the communication of the sender side testing state and the loopback test using test data are implemented simultaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loopback circuit for testing a device in a high speed transmission line interface such as optical communication.

[0002]

2. Description of the Related Art With the demand for high-speed communication, optical synchronous networks (SONET: Synchronous Optical Network)
k) and digital synchronous hierarchy (SDH: Synchronous
Transmission formats such as Digital Hierachy have been studied.

In the SONET-compliant transmission device, the section termination device (ST
E: Section Terminating Equipment), line termination equipment (LTE: L
ine Terminating Equipment) and path termination equipment (PTE: P
ath Terminating Equipment) works.

The section terminating equipment (STE) is provided with section overhead information (SOH: Section O) in the SONET frame.
verHead), the line terminator (PTE) processes line overhead information (LOH: Line OverHead) in addition to the section overhead information (SOH), and the path terminator (PTE) processes the section. Overhead information (SOH)
In addition to the line overhead information (LOH), the path overhead information (POH: PathOverHead) is processed.

A digital synchronous hierarchy (SD
The overhead information similar to the above is also included in the SDH frame in H), and the same processing as that of the SONET frame is performed.

The overhead information in these SONET frames and SDH frames is used for the purpose of maintenance of the communication network, and these overhead information (SOH, L
Data to be originally transmitted is stored in a portion excluding (OH, POH) to form a payload portion (Payload).

By the way, in this kind of interface device, in order to test the normality of the transmission path, it is general that the device has a loopback circuit. This is to confirm the state of the device by returning the transmitted data as received data inside the device and comparing the transmitted data with the received data. By thus holding the folding circuit inside the device, it is intended to identify whether the failure location is inside or outside the device when a failure occurs, and to contribute to the realization of quick failure recovery.

For this purpose, the loopback circuit is preferably provided on the data input / output side (transmission path side) in the device as much as possible, and during the test using this loopback circuit, the counter transmission device 5a is opposed to the opposite transmission device 5a. It was necessary to notify that the device was under test by some means.

In this regard, FIG. 5 shows an example of a folding circuit used in a path terminating device (PTE) in the prior art. In the figure, E / O is a photoelectric conversion unit on the output side, O / E is a photoelectric conversion unit on the input side, POH-INS, LOH-INS and SOH-INS are path overhead information insertion unit, respectively.
The line overhead information insertion part and the section overhead information insertion part are shown. In addition, POH-DROP, LOH
-DROP and SOH-DROP respectively indicate a path overhead information extractor, a line overhead information extractor and a section overhead information extractor.

Further, SEL is a selector and has a function of forcibly returning the data in the transmission device 1 in the device by a path switching command (LOOP). On the other hand, the other side transmission device 5
a is notified that the test is in progress, the path under test signal (PA
This is done by sending IS: Path Alarm Indication Signal). And this path test signal (P-AIS) is
All bits of the payload section (Payload) of the SONET frame are set to "
1 ". That is, when the SONET frame in which" 1 "is stored in all bits of the payload section (Payload) arrives at the partner transmission device 5a, the transmission device on the opposite transmission side It can be recognized that 5 is undergoing a turnback test.

[0011]

However, in the configuration of the loopback circuit in FIG. 5, since the data output as the in-path test signal (P-AIS) is looped back as it is and returned to each overhead information extraction section on the input side. , Its payload part
There is a problem that data in which "1" is registered in all bits of (Payload) is returned, and virtually any test data cannot be stored in the payload section (Payload). Therefore, there is a problem that the folding back test lacks flexibility.

In view of such a point, as shown in FIG. 6, a selector (SEL) functioning as a folding circuit is provided at the front stage of the section overhead information processing unit (SOH-INS, SOH-DROP).
A circuit configuration has been proposed which is arranged (as viewed from the output side) so that the signal under path test (P-AIS) can be output after the data is folded back.

However, in order to output the in-path test signal (P-AIS), it is necessary to recognize the frame pulse (FP-P) stored in the payload section (Payload), which is originally the path overhead. It is possible only in the information insertion part (POH-INS), and in order to do this in the section overhead information insertion part (SOH-INS) in the subsequent stage, the frame pulse (FP-P) of the payload part (Payload) is set in the subsequent section. The overhead information insertion section (SOH-INS) must be further extended and transmitted, which not only complicates the circuit configuration, but also makes it impossible to realize a closed circuit configuration for each layer, so that the location of occurrence of a failure is There was a maintenance problem such as difficulty in classification.

The present invention has been made by paying attention to such a point, and an object thereof is that the transmission device on the transmission side is under test with respect to the transmission device on the other side with a simple circuit configuration. It is an object of the present invention to provide a technique capable of performing notification and performing a loopback test in an apparatus using desired test data.

[0015]

According to the present invention, a plurality of overhead information insertion units (OH-INS) for inserting the overhead information (OH) for each layer into a frame are provided on the output path 1, and these overhead information are also provided. A plurality of overhead information extraction units (SOH-DROP) for extracting (OH) from the frame are provided on the input path 2, and testing is performed after the final stage of the overhead information insertion section (OH-INS) on the output path 1. The pattern signal generator 3 for generating the signal (P-AIS) and the data path switching means 4 for returning the test data to the input path 2 side are provided.

[0016]

According to the present invention, the data path switching means 4 is provided.
The test data from the output path 1 is fed back to the input path 2 by a path switching command (LOOP) from outside, and the in-test signal (P-AIS) generated by the pattern signal generating section 3 is sent to the output path. 1 to the transmission device on the other side to notify that the transmission device on the transmission side is under test.

As described above, since the test data looped back inside the device and the in-test signal (P-AIS) sent to the partner transmission device are independent, any value can be registered in the test data. Can increase the flexibility of the loopback test,
In addition, it is possible to reliably notify the transmission device of the other party that the transmission device of the transmission side is under test.

[0018]

FIG. 2 shows an embodiment of the present invention. The transmission equipment shown in the figure is a path termination equipment (PTE), and has section overhead information (SOH) and line overhead information (LO).
H) and the path overhead information (POH).

In the figure, E / O and O / E are photoelectric conversion units, each having a function of converting an electric signal into an optical signal and an optical signal into an electric signal. Further, a data loopback processing unit 6 surrounded by a broken line in FIG. 2 is provided between each overhead information processing unit and the photoelectric conversion unit. The data loopback processing unit 6 will be described in detail later.

On the output path 1, a path overhead information insertion section (POH-INS), as an overhead information processing section,
A line overhead information insertion unit (LOH-INS) and a section overhead information insertion unit (SOH-INS) are provided respectively. Also, on the input path 2, a section overhead information extracting section is also provided as an overhead information processing section.
(SOH-DROP), line overhead information extractor (LHO-DRO)
P) and a path overhead information extraction unit (POH-DROP) are provided.

The functions of these overhead information processing units will be briefly described. First, the data (Payload) output from a transmission terminal (not shown) together with the payload frame pulse (FP-P) are first stored in the path overhead information insertion unit. Path overhead information (POH) in (POH-INS)
Is added, and then the line overhead information insertion part (LOH-
After the line overhead information (LOH) is added in (INS), the section overhead information (SOH) is input to the section overhead information insertion unit (SOH-INS) together with the SONET frame pulse generated based on the payload frame pulse. Is added. In a normal communication state, after various overhead information (POH, LOH, SOH) is added to the data (Payload) as described above, the data converted into an optical signal in the photoelectric conversion unit (E / O) The signal is output to the partner transmission device 5a.

On the other hand, the data signal received from the partner transmission device 5a is converted into an electric signal by the photoelectric conversion unit (O / E) on the input path 2 side, and then the section overhead information extraction unit (SOH-DROP). ) Section overhead information
(SOH) is extracted, then line overhead information (LOH-DROP) extracts line overhead information (LOH), and path overhead information extraction (POH-DROP)
Path overhead information (POH) is extracted in DROP) and data (Payload) and payload frame pulse (FP−
Only P) is input to the terminal device (not shown).

Next, the data loopback processing unit 6, which is a feature of this embodiment, will be described. The data loopback processing unit 6
One pattern signal generator 3 and two selectors 4a, 4
b, and the selectors 4a and 4b function as the data path switching means 4.

FIG. 3 shows a detailed configuration of the pattern signal generator 3. As shown in the figure, the pattern signal generator 3 is configured to detect a plurality of ROs in which signal patterns are registered.
M (Read Only Memory) is connected in parallel, and this ROM
A counter (CNT: Counter) and a frequency dividing circuit 7 are provided on the input side of. The output of the frequency dividing circuit 7 is the flip-flop element (FF) provided in the subsequent stage of each ROM.
Input to the clock (CLK) of. The outputs from these flip-flop elements (FF) are multiplexers (MUX: Mul:
It is multiplexed by a tip lexer) and output to the first selector 4a.

In the ROM, a signal pattern for one frame of SONET in which all bits of the PAYLOAD part are "1", which is a signal under path test (P-AIS), is registered. By the way, ROM
If the reading speed of the ROM is sufficiently high, it is not necessary to provide multiple ROMs and a single ROM is sufficient.
Since the transmission speed of the T transmission line is much faster than the read speed of the ROM, multiple ROMs are used to match the output speed of the path test signal (P-AIS) with the speed of the SONET transmission line. -ing

That is, the upper bits, the middle bits, and the lower bits of the signal pattern generated by a plurality of ROMs are shared and loaded, and this is loaded by the multiplexer (M
UX), the path under test signal (P-AIS) suitable for the transmission speed of the SONET transmission line is generated.

The operation of the data loopback processing unit 6 will be briefly described. First, the counter (CNT) synchronizes on the basis of the SONET frame pulse (FP-S) received from the section overhead information insertion unit (SOH-INS). , Each ROM
While counting the read sharing bits of, the pattern of the path test signal (P-AIS) is read from each ROM in synchronization with the SONET frame pulse (FP-S). The signal pattern read here is once latched and shaped by the flip-flop element (FF) synchronized with the clock of the transmission path, and then multiplexed by the multiplexer (MUX), and then to the first selector 4a. Is output. Here, the first selector 4a uses the data from the section overhead information insertion unit (SOH-INS) and the path test signal from the data loopback processing unit 6.
(P-AIS) is selectively transmitted to the outside. In the normal state, the data side from the section overhead information insertion unit (SOH-INS) is selected as an input. However, when performing a loopback test, the signal under path test from the multiplexer (MUX)
(P-AIS) is selectively input, and this is notified to the other side as an optical signal through the photoelectric conversion unit (E / O), whereby the other side transmission device 5a is being tested by our device. You can recognize that.

The second selector 4b provided on the input path 2 side
Is a section overhead information insertion unit of the output path 1.
Data output from (SOH-INS) and the other party's transmission device 5a
It has a function of selectively guiding the data from the input path 2 to the input path 2. In a normal state, the photoelectric conversion section (O / E), that is, the data from the partner transmission device 5a is selected as an input. ing.

In the present apparatus, when the loopback test in the apparatus is started, the path switching instruction (LOOP) is notified to the first selector 4a and the second selector 4b. As a result, the first selector 4a is switched so as to select and output the output from the pattern signal generator 3 as an input and the second selector 4b as the input to select and output the data from the section overhead information inserter (SOH-INS). .

As a result, the data that has passed through the overhead information insertion units (POH-INS, LOH-INS, SOH-INS) on the output path 1 side is passed through the second selector 4b to the overhead information extraction section (SOH) on the input path 2 side. -Drop, LOH-DROP, POH-DROP) side.

At this time, the path test in-progress signal (P-AIS) from the pattern signal generator 3 is sent to the opposite transmission device 5a facing the other side through the first selector 4a.
The pattern signal generator 3 described with reference to FIG. 3 may not be provided for each transmission line interface of each transmission device 5, but may be shared by a plurality of transmission line interfaces as shown in FIG. .

As described above, in the present embodiment, the test data used for the loopback test in the apparatus and the path test in-progress signal (P-AIS) for notifying the other party may be independent and independent data. it can. Therefore, any test data can be registered in the PAYLOAD section as the return data for the return test, and the flexibility of the return test can be enhanced.

Further, according to the present embodiment, since the return of the test data is performed just before the exit of the device, the range of the normality confirmation in the device can be widened, and the fault location can be identified by the test. Are better.

In the embodiment, as an example of the transmission device 5,
Although the path terminating device (PTE) has been described, it may be a line terminating device (LTE) or a section terminating device (STE) depending on the layer. For line terminator (LTE), section overhead information (SOH) and line overhead information
In order to process (LOH), a section overhead information processing unit (SOH-INS, SOH-DROP) and a line overhead information processing unit (LOH-INS, LOH-DROP) are provided.

In the case of the section terminating equipment (STE), the section overhead information processing unit (SOH-INS, SO) for processing the section overhead information (SOH).
H-DROP). For these end devices,
Although the configuration of each overhead information processing unit is different, the pattern signal generation unit 3 and the data path switching unit 4 can be applied similarly.

[0036]

According to the present invention, with a simple circuit configuration, the path test signal notified to the transmission device on the other side and the return data used in the device can be made into independent data. Therefore, it is possible to simultaneously realize the notification to the partner transmission device that the test is in progress and an arbitrary loopback test in the device using the test data.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a block diagram showing a folding circuit of a transmission device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing an internal configuration of a folding circuit according to an embodiment.

FIG. 4 is a block diagram showing a modification of the internal configuration of the folding circuit according to the embodiment.

FIG. 5 is a block diagram showing a folding circuit of a transmission device in the related art.

FIG. 6 is a block diagram showing a folding circuit of a transmission device in the related art.

[Explanation of symbols]

 1 ... Output path 2 ... Input path 3 ... Pattern signal generation section 4 ... Data path switching means 4a ... First selector 4b ... Second selector 5 ... Transmission device 5a ... Opponent transmission device 6 ...・ Data loopback processing unit 7 ・ ・ Dividing circuit POH-INS ・ ・ Path overhead information insertion unit LOH-INS ・ ・ Line overhead information insertion unit SOH-INS ・ ・ Section overhead information insertion unit POH-DROP ・ ・ Path overhead information extraction Section LOH-DROP .. line overhead information extraction section SOH-DROP .. section overhead information extraction section E / O, O / E .. photoelectric conversion section FP-P .. payload frame pulse FP-S .. SONET frame Pulse LOOP ··· Path switching instruction P-AIS ··· Signal under test ROM · · Storage means MUX · · Multiplexing means

Claims (3)

[Claims] 1. A plurality of overhead information insertion units (OH-INS) provided on an output path (1) for inserting overhead information (OH) for each layer into a frame, and a layer provided on an input path (2). A plurality of overhead information extraction units (SOH-DROP) for extracting the overhead information (OH) for each frame from the frame, and overhead information insertion units (OH-IN) on the output path (1).
A pattern signal generator (3) which is provided after the last stage of S) and generates a signal under test (P-AIS), and a data path switching means for returning the test data on the output path (1) to the input path 2 side. (4), the data path switching means (4) feeds back the test data from the output path (1) to the input path (2) by a path switching command (LOOP) from the outside, and the pattern The signal under test (P-AIS) generated by the signal generator (3) is sent to the partner transmission device (5a) through the output path (1), and the transmission device (5) on the transmission side is under test. A test control method for a transmission device characterized by notifying that 2. The data path switching means (4) is provided after the pattern signal generating section (3) on the output path (1), and the in-test signal (P) is output from the pattern signal generating section (3).
-AIS) and a first path switching means (4a) for selecting and outputting the transmission data signal from the overhead information insertion section (OH-INS) to the outside, and the above-mentioned on the input path (2) Overhead information extractor (SOH
-DROP), which is provided in the preceding stage, selects the data signal from the outside and the test data from the output path (1) and inputs it to the overhead information extracting section (SOH-DROP). 4. The test control method for a transmission device according to claim 1, further comprising: 3. The pattern signal generating section (3) registers data for at least one frame to generate a signal under test (P-AIS), and two or more storage means arranged in parallel with each other. (ROM) and multiplexing means (MUX) connected to the output side of the two or more storage means (ROM) and for multiplexing output signals from each storage means (ROM)
The test control system for a transmission apparatus according to claim 1, further comprising: