JP6783881B2 - Transmission equipment and delay measurement method - Google Patents

Description

The present invention relates to a transmission device and a delay measurement method, and in particular, a transmission device and a delay for measuring a delay of a transmission line to and from a transmission device to be measured by using information for delay measurement set in a frame header. Regarding the measurement method.

In a transmission system that transmits data, the transmission delay between transmission devices is measured from various points of view. For example, the measured transmission delay between transmission devices is used as an index for confirming the reliability of data transmission in the transmission path. The inventions for measuring the transmission delay between such transmission devices are disclosed in Patent Documents 1 to 4.

The invention disclosed in Patent Document 1 relates to a technique for measuring a transmission delay without performing time synchronization between a transmitting device and a receiving device in an optical transmission system that transfers data in frame units.

According to Patent Document 1, the optical transmission device determines a delay time based on a measurement unit that measures the time from when a frame is transmitted to an opposite device to when a corresponding looped frame is received, and a measurement result. It is equipped with a delay determination unit. The delay determination unit determines the delay time based on a plurality of measurement results obtained by the remaining delay measurements obtained by removing at least the first delay measurement from the plurality of delay measurements.

In this technique, the DM (Delay Measurement) bit of the PM (Path Monitoring) & TCM (Tandem Connection Monitoring) field in the frame according to the OTN (Optical Transport Network) standard is used for the delay measurement.

The optical transmission device on the transmitting side continues to transmit frames having a DM bit = 1 at regular intervals, and the optical transmission device on the receiving side loops back the frames received from the transmitting side. That is, the measuring unit measures the time from the start of transmitting the frame having the DM bit = 1 to the time when a predetermined number of frames having the loopback DM bit = 1 are continuously received to determine the delay time. taking measurement. Then, this delay measurement is repeated a plurality of times, and the delay determination unit determines the delay time based on the plurality of measurement results obtained by the remaining delay measurements excluding the first delay measurement.

The invention disclosed in Patent Document 2 relates to a technique for performing route selection reflecting an actual traffic situation in a packet network.

According to Patent Document 2, the actual round trip delay or propagation delay time of each route is measured without preferentially selecting the route with a small number of router hops, and the route for transmitting the packet is selected according to the measurement result. To do. In this technique, in order to measure the round trip delay or the propagation delay time, a time stamp is added to the IP (Internet Protocol) packet, and the time difference between the time stamp addition time and the time stamp removal time is obtained.

The invention disclosed in Patent Document 3 relates to a technique for setting a transmission path of a virtual concatenation signal in an optical transmission network.

According to Patent Document 3, when a concatenation signal is divided into a plurality of low-speed signals and transferred using a low-speed path network, the delay time for each path path is automatically adjusted based on the measured transmission delay time. Can be done. In this technique, the transmission device that has received the transmission time measurement command transmits a test signal including time information at the time of transmission to the transmission device at the transmission destination of the route. The transmission device that has received the test signal detects the transmission delay time from the difference between the reception time and the transmission time, and transmits the test signal to the network management device.

In the invention disclosed in Patent Document 4, a communication control device connected to a mobile terminal via a communication network measures the communication quality of the communication network between the mobile terminal and the mobile terminal according to the communication quality. It relates to a technology for performing connection control.

According to Patent Document 4, the communication control device transmits a test packet to the mobile terminal in response to receiving the registration request from the mobile terminal, and communicates with the mobile terminal based on the round-trip delay time. It is judged whether or not the communication quality of the network is normal. Specifically, the round-trip delay time is measured by transmitting an ICMP (Internet Control Message Protocol) echo request to the mobile terminal and receiving the ICMP echo reply returned from the mobile terminal.

Japanese Unexamined Patent Publication No. 2013-1533367 Japanese Unexamined Patent Publication No. 2002-044125 Japanese Unexamined Patent Publication No. 2005-151186 Japanese Unexamined Patent Publication No. 2010-22011

The transmission delay measurement has some problems as described below.

(1) In the method of determining the time on the transmitting side and the time on the receiving side using a time stamp and measuring the delay, it is necessary to synchronize the time in the network. Therefore, there is a problem that the system configuration becomes complicated.

(2) In delay measurement using loopback, when a transmission line error occurs, the change point edge of the signal transmitted for delay measurement disappears or the change point edge is erroneously generated, resulting in a change point. Edges may not be transferred correctly. Therefore, there is a problem that the delayed measured value becomes smaller or larger than the regular measured value, and an erroneous delayed value is notified.

(3) When the transmission device on the transmitting side and the transmission device on the receiving side face each other via a network in which a plurality of transmission devices exist, route switching may be performed due to a failure in the network. Therefore, there is a problem that the delay measurement value between the transmission device on the transmitting side and the transmission device on the receiving side greatly varies.

The invention disclosed in Patent Document 1 solves the above problem (1) by performing delay measurement using a loopback. Further, the invention disclosed in Patent Document 1 is described in (2) above by comparing the delay values after performing the delay measurement a plurality of times and determining that the delay measurement result is valid when the delay value is smaller than the threshold value defined as the error. The problem is also solved.

However, the invention disclosed in Patent Document 1 does not consider the problem (3) above. That is, in the invention disclosed in Patent Document 1, when the opposing transmission devices are connected via the network, the route is not switched in the network, and the delay varies only within a certain range. It is effective in the environment. However, when the number of relay devices increases by passing through a detour route due to a failure in the network, the delay measurement result fluctuates more than the variation of the measured value defined as an error before and after the route switching. It may end up. In such a case, the invention disclosed in Patent Document 1 always determines that the delay measurement result is abnormal.

In the invention disclosed in Patent Document 2, the propagation delay time is measured by taking out an IP packet with a time stamp transmitted by the incoming edge router by the outgoing edge router and removing the time stamp. Therefore, in the measurement of the propagation delay time, it is necessary to synchronize the time between the edge router on the entry side and the edge router on the exit side, and the above problem (1) cannot be solved.

The invention disclosed in Patent Document 2 also discloses the measurement of round trip delay. In the measurement of the round trip delay, the IP packet with the time stamp transmitted by the incoming edge router is looped back by the outgoing edge router and received by the incoming edge router. Therefore, in the measurement of the round trip delay, it is not necessary to synchronize the time between the incoming edge router and the outgoing edge router. However, the measurement of the round trip delay is intended only to be used as an index for preferentially selecting a route, and does not determine whether the route is normal or abnormal. Therefore, no consideration has been given to solving the above problem (3).

In the invention disclosed in Patent Document 3, the transmission device on the transmitting side transmits a test signal including time information at the time of transmission to the transmission device of the transmission destination of the route, and the transmission device receiving the test signal receives the test signal. The transmission delay time is detected from the difference between the time of transmission and the time of transmission. Therefore, it is necessary to synchronize the time between the transmission device on the transmission side and the transmission device at the transmission destination of the route, and the above problem (1) cannot be solved.

The invention disclosed in Patent Document 4 uses an echo request and an echo reply to measure the round-trip delay time in the communication network between the communication control device and the mobile terminal. The invention disclosed in Patent Document 4 is applied in an environment in which the route is not switched in the network between the communication control device and the mobile terminal and the delay varies only within a certain range. Therefore, no consideration has been given to solving the above problem (3).

The present invention is a transmission device capable of obtaining a new determination reference value based on the delay measurement result and re-evaluating the delay measurement result when the route in the network to be the delay measurement target is changed to a different route. And to provide a delay measurement method.

In order to realize the above object, the transmission device according to one embodiment of the present invention outputs the loopback information extracted from the reception frame received from the opposite device, disassembles the reception frame, and outputs it as reception data. A transmission frame is generated by constructing a frame termination means and transmission data as a transmission frame and executing a loopback process for inserting the loopback information output by the reception frame termination means at a predetermined position of the transmission frame. At the time of delay measurement for measuring the signal delay between the transmission frame generation means to be transmitted to the opposite device and the opposite device, the execution of the loopback process is stopped for the transmission frame generation means, and the transmission frame is From the reception of the measurement control means that outputs the control information instructing the insertion of the change point edge to the predetermined position into which the loopback information is inserted and the change point edge insertion start information output by the transmission frame generation means, the end of the received frame. The loopback information output by the means includes a delay measuring means that outputs the time until the insertion of the change point edge is detected as a measurement value of the delay measurement, and the measurement control means stores in advance the first. If the normality of the measured value output by the delay measuring means is judged based on the judgment reference value of, and an abnormality of the measured value outside the range specified by the first judgment reference value is identified, the connection is established. The network management means that manages the network is inquired about whether or not the route to the opposite device has been changed, and the normality of the measured value is determined again based on the second determination reference value acquired based on the inquiry result. It is characterized by that.

Further, the delay measurement method according to another aspect of the present invention receives from the opposite device at a predetermined position of a transmission frame constructed based on the transmission data at the time of delay measurement for measuring the signal delay with the opposite device. The measurement control means sets the transmission frame generation means to stop the execution of the loopback process for inserting the loopback information extracted from the received frame and to insert the change point edge at a predetermined position to insert the loopback information of the transmission frame. The time from the reception of the change point edge insertion start information output by the transmission frame generation means to the detection of the insertion of the change point edge in the loopback information by instructing and drawing the loopback information into the delay measuring means. The measurement control means determines the normality of the measured value based on the first determination reference value that is output as the measurement value of the delay measurement and is stored in advance, and is out of the range specified by the first determination reference value. When the measurement control means identifies an abnormality in the measured value, the network management means that manages the connected network is inquired about whether or not the route to the opposite device has been changed, and the result is obtained based on the inquiry result. The measurement control means redetermines the normality of the measured value based on the second determination reference value.

According to the present invention, when the route in the network to be the delay measurement target is changed to a different route, a new determination reference value can be obtained based on the delay measurement result, and the delay measurement result can be evaluated again.

It is a block block diagram explaining the outline of the delay measurement. It is a time chart explaining the outline of delay measurement. It is a time chart explaining the measurement abnormality of the delay measurement. It is a time chart explaining another measurement abnormality of a delay measurement. It is a time chart explaining the case where the route switching occurs in the delay measurement. It is a block diagram which shows the structure of the transmission apparatus of 1st Embodiment. It is a flow figure which shows the operation of the delay measurement method of 1st Embodiment. It is a block diagram which shows the structure of the transmission apparatus of 2nd Embodiment. It is a figure which shows the structure of the header part of a synchronization frame. It is a figure explaining the loopback by PM & TCM. It is a figure which shows the change of the transmission path in a network. It is a figure which shows the content example of the route information DB. It is a flow figure which shows the operation of the delay measurement method of 2nd Embodiment. It is a flow figure which shows the operation of the delay measurement method of 3rd Embodiment.

A mode for carrying out the present invention will be described with reference to the drawings.

<Overview>
First, in the embodiment for carrying out the present invention, an outline of the premise of delay measurement will be described with reference to FIGS. 1 to 5.

FIG. 1 is a block configuration diagram illustrating an outline of delay measurement.

A mode for carrying out the present invention is a method in which data is transferred by a synchronous transfer method using a frame, and the delay is measured using information for delay measurement stored in the header area of the frame.

FIG. 1A shows how the loopback information set in the header area of the frame to be transferred between the transmission devices is transmitted and received at normal times. In this way, normally, a signal that does not change as loopback information is returned to the opposite device while maintaining the state of being received by each device.

On the other hand, FIG. 1B shows a state of loopback at the time of delay measurement.

The delay measurement measures the delay value of the transfer signal between the opposing transmission devices, and the transmission device (transmission side) 1 folds back the signal transmitted to the transmission line at the opposite transmission device (reception side) 2 for transmission. Measure the time from the road to reception.

Therefore, the transmission device 1 on the transmission side stops the loopback of its own device, sets the change point edge as the information for delay measurement in the loopback information, and transmits the frame. Since the loopback is maintained in the transmission device 2 on the receiving side, a frame in which the loopback information in which the change point edge is set is directly replaced is generated and transmitted to the transmission device 1 on the transmitting side. That is, the change point edge set in the loopback information by the transmission device 1 on the transmission side is folded back as it is by the transmission device 2 on the reception side and received by the transmission device 1 on the transmission side.

Therefore, the transmission device 1 on the transmitting side sets the delay time by the time difference between transmitting the frame in which the change point edge is set in the loopback information and receiving the frame in which the change point edge is set in the loopback information. ..

As described above, since the signal used for the delay measurement uses the loopback information of the header area of the frame transferred between the transmission devices, the delay measurement can be performed without affecting the user data transfer. Further, since the control at the time of delay measurement only needs to stop the loopback by the own device, the control for the loopback for the opposite transmission device is not required.

The change point edge is "1" when the normal setting value of the predetermined area is "0", and is "0" when the normal setting value is "1". In addition, it refers to a place where the set value "0/1" is reversed.

Further, when the measurement result of the delay measurement is evaluated and the measurement result is determined to be abnormal, the measurement result is discarded and the delay measurement abnormality is output.

The measurement result is determined to be abnormal in the following cases.
-The measurement signal does not come back within the maximum measurable delay time.
-Multiple triggers occur within the maximum measurable delay time.
-The measurement result is out of the allowable delay time of the expected delay value.
-A transmission line error has occurred.

2 to 5 are time charts for explaining the outline of the delay measurement described above, and show examples of cases where the delay measurement is normally performed and examples of various measurement abnormalities.

FIG. 2 is a time chart showing an example of delay measurement of the transmission device (transmitting side) 1 in FIG. 1 when the delay measurement is normally performed.

In FIG. 2, a start trigger for delay measurement is given, a change point edge is set as a frame at time T0 after a predetermined waiting time has elapsed, and the frame is transmitted to the transmission line, and the frame with the change point edge is timed. The state of reception from the transmission line is shown in T1.

That is, the operation for delay measurement is started inside the transmission device by "1. Measurement start trigger" in the figure. In "2. Change point edge transmission" in the figure, the change point edge is set in the frame after a predetermined waiting time has elapsed, and the change point edge is transmitted to the transmission line at time T0. Then, in "3. Change point edge reception" in the figure, a frame in which the change point edge looped back by the transmission device (reception side) 2 in FIG. 1 is set is received from the transmission line at time T1.

Therefore, the time difference between the time T0 and the time T1 in FIG. 2 is measured as a delay value.

On the other hand, for the measured delay value, a certain measurement tolerance is defined in consideration of the variation in processing in the transmission device and the variation in delay in the transmission line. Then, the normality of the delayed measurement value is determined based on the measurement tolerance.

In FIG. 2, the expected delay value and the reception time T1 are shown as the same time, and an example is shown in which the reception measurement time of the change point edge varies between the time t0 and the time t1. Then, if the reception measurement time of the change point edge is within the range of the measurement tolerance of the time ta and the time tb, it is shown that the measurement result is determined to be normal.

FIG. 3 shows an example of the following measurement abnormality.
-The measurement signal does not come back within the maximum measurable delay time.
-Multiple triggers occur within the maximum measurable delay time.
-The measurement result is out of the margin of error.

In FIG. 3, “2. Change point edge transmission” and “3. Change point edge reception” in the figure are shown with reference to the normal measurement example in FIG. This also applies to FIGS. 4 and 5 below.

“4. Change point edge does not return” in FIG. 3 indicates a state in which the change point edge does not return within the maximum measurable delay time after timing out the maximum measurable delay time, and is determined to be a measurement abnormality. To.

“5. Frequent change point edges” in FIG. 3 indicates a state in which a plurality of change point edges occur within the maximum measurable delay time and edge detection is abnormal. In particular, the time until the first change point edge detection is identified as a delay value, and it is determined that the measurement abnormality is based on the situation where the change point edge frequently occurs in this way. For example, it is assumed that an error occurs in the transmission line and the bits in the predetermined area corresponding to the measurement signal of the transfer frame are rewritten.

“6. Out of tolerance range” in FIG. 3 indicates a state in which the change point edge is out of the measurement tolerance range with respect to the expected measurement result. Both (1) and (2) in the figure are determined to be erroneous delay values.

“7. Failure alarm occurrence” in FIG. 4 indicates a state in which an alarm for a transmission line failure or an opposite device failure is notified. While such a failure alarm is generated, it is regarded as a delay measurement impossible time, and even if a normal delay value is measured, it is determined as a measurement abnormality.

“8. Route switching” in FIG. 5 refers to the transmission device (transmission side) 1 due to the occurrence of a failure or the like in the network existing between the transmission device (transmission side) 1 and the transmission device (reception side) 2. The measurement result when the route between and the transmission device (reception side) 2 is changed is shown. In this case, although it is clearly out of the measurement tolerance range, the measurement result is judged as a normal delay value. Details will be described later.

<First Embodiment>
The first embodiment of the present invention will be described on the premise of the outline of the delay measurement described above.

FIG. 6 is a block diagram showing a configuration of a transmission device according to the first embodiment of the present invention.

It should be noted that the embodiments are exemplary, and the disclosed devices and systems are not limited to the configurations of the following embodiments.

The transmission device 10 of the first embodiment has a configuration including a reception frame termination means 11, a transmission frame generation means 12, a delay measurement means 13, and a measurement control means 14.

Although the configuration of the opposite device is not shown, it is assumed that the device has the same configuration as that of FIG. That is, the transmission frame transmitted by the transmission device 10 is received as a reception frame in the opposite device, and the transmission frame transmitted by the opposite device is received as a reception frame in the transmission device 10.

The reception frame terminating means 11 has a function of terminating a reception frame received from the opposite device. The reception frame terminating means 11 outputs the loopback information extracted from the reception frame, disassembles the reception frame, and outputs it as reception data.

The transmission frame generation means 12 has a function of constructing transmission data as a transmission frame and transmitting the transmission data to the opposite device. The transmission frame generation means 12 generates a transmission frame that has been subjected to a loopback process for inserting the loopback information output by the reception frame termination means 11 at a predetermined position of the transmission frame.

The measurement control means 14 has a function of executing control related to delay measurement for measuring a signal delay with the opposite device. At the time of delay measurement, the measurement control means 14 instructs the transmission frame generation means 12 to stop the execution of the loopback process and insert the change point edge at a predetermined position for inserting the loopback information of the transmission frame. Output.

The delay measuring means 13 has a function of executing the delay measurement. The delay measuring means 13 measures the time from the reception of the change point edge insertion start information output by the transmission frame generation means 12 to the detection of the change point edge insertion in the loopback information output by the reception frame end means. Output as a measured value.

Further, the measurement control means 14 also has a function of determining the normality of the measured value output by the delay measuring means 13 based on the first determination reference value stored in advance. When the measurement control means 14 identifies an abnormality in the measured value that is outside the range specified by the first determination reference value, whether or not the route to the opposite device is changed with respect to the network management means that manages the connected network. Inquire. Then, the measurement control means 14 redetermines the normality of the measured value based on the second determination reference value acquired based on the inquiry result.

Next, the operation of the delay measurement method of the first embodiment will be described.

FIG. 7 is a flow chart showing the operation of the delay measurement method of the first embodiment.

At the time of delay measurement for measuring the signal delay with the opposite device, the measurement control means stops the execution of the loopback process for the transmission frame generation means and the change point edge at a predetermined position to insert the loopback information of the transmission frame. Is instructed to be inserted (S101). The loopback process is a process of inserting the loopback information extracted from the received frame received from the opposite device at a predetermined position of the transmission frame constructed based on the transmission data. In the process of step S101, the measurement control means instructs the transmission frame generation means to insert the change point edge that triggers the measurement start.

When the execution of the loopback process is stopped, the loopback information is drawn into the delay measuring means. Then, the delay measuring means outputs the time from the reception of the changing point edge insertion start information (S102) output by the transmission frame generating means to the detection of the insertion of the changing point edge in the loopback information as the measured value of the delay measurement. (S103).

The measurement control means determines the normality of the measured value based on the first determination reference value stored in advance (S104).

When an abnormality in the measured value outside the range specified by the first determination reference value is identified, the measurement control means determines whether or not the route to the opposite device has been changed with respect to the network management means that manages the connected network. Inquire (S105).

The measurement control means redetermines the normality of the measured value based on the second determination reference value acquired based on the inquiry result (S106).

As described above, in the present embodiment, the loopback process is simply stopped on the device side that performs the delay measurement at the time of the delay measurement, and the path for the delay measurement is formed without performing any process on the opposite device. To.

Further, when the route is changed between the device and the opposite device in the network, an abnormality of the measured value outside the range defined by the first determination reference value may be identified.

Even in such a case, in the present embodiment, the network management means is inquired about whether or not the route to the opposite device has been changed, and the normality of the measured value is determined based on the second determination reference value acquired based on the inquiry result. Judge again.

By providing such a configuration, in the present embodiment, when the route in the network to be the delay measurement target is changed to a different route, a new determination reference value is obtained based on the delay measurement result, and the delay measurement is performed. The results can be evaluated again.

<Second embodiment>
A second embodiment will be described.

FIG. 8 is a block diagram showing the configuration of the transmission device of the second embodiment.

The transmission device 20 of the second embodiment includes a reception frame termination unit 21, a transmission frame generation unit 22, a loopback execution unit 23, a frame transmission unit 24, and a delay measurement start trigger generation unit 25 as configurations for transmitting and receiving frames. ..

The reception frame termination unit 21 corresponds to the reception frame termination means 11 of the first embodiment. The reception frame termination unit 21 terminates the reception frame received from the opposite device, outputs the loopback information extracted from the reception frame, disassembles the reception frame, and outputs it as reception data. The reception frame terminal 21 also has a function of detecting a transmission line failure, and outputs a failure alarm when a transmission line failure is detected.

Then, as a configuration corresponding to the transmission frame generation means 12 of the first embodiment, the transmission frame generation unit 22, the loopback execution unit 23, the frame transmission unit 24, and the delay measurement start trigger generation unit 25 are included.

The transmission frame generation unit 22 constructs the transmission data as a transmission frame.

The loopback execution unit 23 receives the loopback control information and inserts the loopback information output by the reception frame end unit 21 at a position specified by the control information in the transmission frame. If the control information indicates that the loopback should be stopped, the loopback processing is stopped.

The delay measurement start trigger generation unit 25 receives the control information of the trigger insertion, and outputs the measurement start trigger that sets the change point edge in the transmission frame after a predetermined timing.

The frame transmission unit 24 receives the control information of trigger insertion and the measurement start trigger output by the delay measurement start trigger generation unit 25, and the change point edge at the position where the loopback information of the transmission frame instructed by the control information is inserted. Is set and output to the transmission line.

As a configuration corresponding to the delay measuring means 13 of the first embodiment, a change point edge detecting unit 26 and a delay measuring counter 27 are provided.

The change point edge detection unit 26 determines whether or not the loopback information output by the reception frame end unit 21 includes the change point edge, and outputs a measurement stop trigger when the change point edge is included. ..

That is, the loopback information extracted from the reception frame is output to the loopback execution unit 23 and the change point edge detection unit 26. When the delay measurement is not performed, this loopback information is looped back by the loopback execution unit 23. Further, since the delay measurement is not performed, nothing is processed for the loopback information input to the change point edge detection unit 26. When the delay measurement is started, the change point edge detection unit 26 performs the above processing.

The delay measurement counter 27 starts the delay measurement by receiving the measurement start trigger output by the delay measurement start trigger generation unit 25, and stops the delay measurement by receiving the measurement stop trigger output by the change point edge detection unit 26. Then, the counter value from the start of the delay measurement to the stop of the delay measurement is output as the delay measurement result (measured value).

A measurement control unit 28 and a route information database (DB) 29 are provided as a configuration corresponding to the measurement control means 14 of the first embodiment.

The measurement control unit 28 identifies the frame position based on the synchronization information output from the reception frame end unit 21, outputs loopback control information and trigger insertion control information, and executes control related to delay measurement.

The route information database 29 is a delay considering the information of the transmission path related to the transmission device and the transmission device (relay device) connected to each transmission path, the delay value of each transmission path and each transmission device, and the variation of the delay. Stores error information.

The measurement control unit 28 calculates a determination reference value based on the delay value and delay error information stored in the route information database 29, and the normality of the measurement value output by the delay measurement counter 27 based on the determination reference value. To judge.

The measurement control unit 28 is connected to a network management device (not shown), controls the device, monitors the presence or absence of an alarm, and notifies the delay measurement result.

When the measurement control unit 28 identifies an abnormality in the measured value that is out of the range specified by the determination reference value, the measurement control unit 28 inquires the network management device whether or not the transmission path to the opposite device is changed. When the route switching occurs as a result of the inquiry, the transmission device, the delay value, and the delay error information regarding the new route are acquired from the network management device. Then, a new determination reference value is calculated based on the acquired information on the new route, and the normality of the measured value is determined again based on the new determination reference value.

The information stored in the route information database 29 is updated with the information regarding the new route acquired from the network management device.
After that, ITU-T's G.M. 709 / Y. An example using an OTUk (Optical channel transport unit-k) (k = 1,2,3,4) frame specified in the 1331 Recommendation "Interfaces for the Optical Transport Network (OTN)" will be described. ITU-T is an abbreviation for "International Telecommunication Union-Telecom standardization".

Further, as the reference numbers assigned to the transmission devices in the following description, different numbers are used depending on the drawings for convenience of explanation, but all the transmission devices have the transmission device 20 of the second embodiment described with reference to FIG. Is.

FIG. 9 is a diagram showing the structure of the header portion of the synchronization frame.
The figure shows a 4 × 16 byte OTUk header (k = 1,2,3,4), and a payload for storing user data is arranged after Column # 17, which is not shown.

Note that k = 1,2,3,4 means the difference in the specified bit rates (2.67 Gb / s, 10.71 Gb / s, 43.02 Gb / s, 111.81 Gb / s). Hereinafter, it is simply referred to as an OTUk header.

In the present embodiment, the delay measurement is performed using PM & TCM arranged in Column # 3 and Row # 2 of the OTUk header. As shown in FIG. 9, the PM & TCM has a 1-byte structure, and the 1st to 6th bits are used as DMt1 to DMt6, respectively. The 7th bit is used as DMp and the 8th bit is unused. DM is an abbreviation for "Delay Measurement". The usage of the 7 bits of DMt1 to DMt6 and DMp of PM & TCM will be described with reference to FIG.

FIG. 10 is a diagram illustrating loopback by PM & TCM.
Here, it is assumed that the transmission devices 1 to 5 are connected in series on the transmission line.

This transmission path may be partially divided and managed. FIG. 10 shows a section of A1-A2 between the transmission device 1 and the transmission device 5, a section of B1-B2 between the transmission device 2 and the transmission device 3, and between the transmission device 3 and the transmission device 4. An example of managing three sections of a certain C1-C2 is shown.

When looping back each section, any of 7 bits of DMt1 to DMt6 and DMp is used.

DMp is used when looping back between the transmission devices at the farthest end of the transmission path. For DMt1 to DMt6, the correspondence between each bit and the section to be looped back is determined in advance at the time of network construction, and each bit is used based on the condition.

In FIG. 10, DMt1 is used for the loopback in the section of B1-B2 between the transmission device 2 and the transmission device 3, and the loop in the section of C1-C2 between the transmission device 3 and the transmission device 4 is used. An example of using DMt2 is shown on the back.

That is, in the A1-A2 section, the loopback information is set in the DMp bit, in the B1-B2 section, the loopback information is set in the DMt1 bit, and in the C1-C2 section, the loopback information is set in the DMt2 bit. Is transferred. Loopback is possible in up to 7 types of sections at the same time in the transmission path.

How to manage the network is decided at the time of network construction, and depending on this management form, where to set the loopback section is decided. Then, the loopback is not performed except for any two points defined by any bit of DMt1 to DMt6 and DMp.

In the present embodiment, the delay measurement is performed by setting the change point edge to any of the 7 bits of DMt1 to DMt6 and DMp.
The transmission device may be directly connected to the opposite device via one transmission line, but is often connected to the other device via a network. When connected via a network, a large number of transmission devices intervene as relay devices, and the transmission path may be switched due to a transmission line failure or device failure.

FIG. 11 is a diagram showing changes in transmission paths in the network.

FIG. 11 (1) shows a transmission path when there is no failure in the network. In this case, a transmission device 5-2, a transmission device 5-7, and a transmission device 5-8 are interposed between the transmission device 5-1 and the transmission device 5-9, as indicated by a thick line.

On the other hand, FIG. (2) shows a transmission path when a transmission line failure occurs in the network and the route is switched to a detour route. In this case as well, as shown by the thick line, the transmission device 5-2, the transmission device 5-3 to the transmission device 5-6, and the transmission device 5-8 are connected between the transmission device 5-1 and the transmission device 5-9. Intervenes.

As described above, the transmission delay value is different because the number of relaying devices and the route are different depending on whether the transmission line failure has occurred or the transmission line failure has occurred. As the number of relaying transmission devices increases, the delay also increases, and when comparing the detour route at the time of transmission line failure based on the judgment reference value in the state where no transmission line failure has occurred, the judgment reference value is It will be judged as out of the specified range.

However, the network management device that manages the network keeps track of changes in the transmission path in the network, and provides information on whether or not the transmission path has been changed and the relay device after the route change in response to an inquiry from the transmission device.

FIG. 12 is a diagram showing an example of the contents of the route information database 29.

Information (route information) of a transmission path related to the transmission device, a transmission device related to the transmission path, a delay value and delay error information of the transmission device, and the like are stored.

In FIG. 12, with respect to the transmission device included in the transmission path to which the transmission device is involved, the delay value and the maximum allowable error of each device are registered together with the time acquired from the network management device and registered.

Further, in the lower part of FIG. 12, information about the transmission device included in the transmission path related to the transmission device is registered together with the time when the maximum allowable error in the path is acquired from the network management device and the registration is updated. The maximum allowable error in the path is calculated from the delay value of each device and the maximum allowable error thereof, and is defined by adding a margin to the delay value and the maximum allowable error.

In FIG. 12, two types of transmission paths are registered between the transmission device 1 and the transmission device 5. A first transmission path from the transmission device 1 to the transmission device 5 via the transmission device 2 to 4 and a second transmission path that directly connects the transmission device 1 and the transmission device 5 are registered. Since the registration and update of the second transmission path is performed later than that of the first transmission path, the second transmission path is currently treated as an effective path.

How the transmission device 20 operates will be described with reference to the block configuration diagram illustrating the outline of the delay measurement of FIG. 1 and the block configuration diagram of the transmission device 20 of the second embodiment of FIG. It is assumed that the opposite device having the same configuration as the transmission device 20 is connected via the network as described with reference to FIG.

First, in the state where the delay measurement is not performed, as shown in FIG. 1A, the loopback occurs in both the transmission device (transmission device 1 on the transmission side) and the opposite transmission device (transmission device 2 on the reception side). It is in a state.

That is, the loopback information taken out by the reception frame terminal 21 of the transmission device 20 of FIG. 8 is input to the loopback execution unit 23. On the other hand, the transmission data is constructed as an OTU frame in the transmission frame generation unit 22 and input to the loopback execution unit 23. Here, it is assumed that the transmission device 20 and the opposite device are managed by the PM shown in FIG.

The measurement control unit 28 registers PM & TCM measurement conditions that serve as basic information as to which bit in the PM & TCM byte region is to be looped back, judging from the network configuration. In this case, since the management is performed by PM shown in FIG. 10, the DMp bit in the PM & TCM byte area is used.

The reception frame terminal 21 takes out the DMp bit in the PM & TCM byte area based on the loopback position information output by the measurement control unit 28 according to the PM & TCM measurement conditions, and outputs it as loopback information.

The loopback execution unit 23 functions as a selector, and by specifying the loopback position of the control information output by the measurement control unit 28, loopbacks only the DMp bits in the PM & TCM byte area of the OTU frame input from the transmission frame generation unit 22. Let me. That is, the loopback execution unit 23 controls to insert the DMp bit of the loopback information taken out by the reception frame end unit 21 into the DMp bit position in the PM & TCM byte area of the OTU frame and output it.

The frame transmission unit 24 functions as a selector, and the trigger insertion signal of the control information output by the measurement control unit 28 is OFF when the delay measurement is not performed, and the input from the loopback execution unit 23 is selected. Output to the transmission line.

In this way, in the state where the delay measurement is not performed, the DMp bit of the loopback information is inserted into the OTU frame generated by the transmission frame generation unit 22 at the corresponding position in the loopback execution unit 23, and the OTU frame is inserted. It is output.

The same process is executed in the opposite device that has received the OTU frame output in this way, and loopback is performed at the DMp bit position in the PM & TCM in both transmission devices.

Next, the operation when starting the delay measurement will be described. In the following description, a flow chart showing the operation of the delay measurement method of the second embodiment of FIG. 13 will also be appropriately referred to.

First, the preparation setting is performed prior to the delay measurement (step S201 in FIG. 13).

Registration of PM & TCM measurement conditions in the measurement control unit 28 described above is also one of the preparation settings. Further, there is a transmission line delay timer delay measurable maximum value setting for determining the normality of measurement and a first determination reference value setting for determining the normality of the measured value.

The maximum value of the transmission line delay timer delay measurable is used as the time used for determining the timeout when the change point edge does not return and the waiting time from the trigger insertion described later to the actual output of the measurement start trigger.

As the first determination reference value, the expected delay value and the allowable delay error of the transmission path to be measured are used here. The delay value and the tolerance of each transmission device registered in the route information database 29 are added to the transmission devices related to the transmission path to be measured to obtain the expected delay value and the tolerance.

The above information is set in the measurement control unit 28.

First, when starting the delay measurement, it is necessary to stop the loopback in the transmission device 1 on the transmitting side shown in FIG.

Then, the change point edge is inserted after waiting for a certain period of time for the unnecessary signal before the loopback stop to disappear from the transmission path. This waiting time is the maximum measurable value of the transmission line delay timer delay described above. The maximum value of the transmission line delay timer delay measurable is determined based on, for example, the maximum value of the delay measurable in the transmission path. The maximum value that can be measured for delay is determined based on the delay value of each transmission line and each transmission device that constitutes the transmission path.

The loopback stop (step S202 in FIG. 13) is executed by the measurement control unit 28 sending the loopback stop control information to the loopback execution unit 23. The loopback execution unit 23 that has received the control information for stopping the loopback stops selecting the DMp bit of the loopback information extracted from the reception frame end unit 21. Therefore, the OTU frame generated by the transmission frame generation unit 22 is input to the frame transmission unit 24.

After controlling the loopback stop, a measurement start trigger is given after a waiting time for a certain period of time due to the above-mentioned transmission line delay timer delay measurable maximum value (step S203 in FIG. 13). In this control, a trigger insertion signal is sent to the delay measurement start trigger generation unit 25 after a waiting time of a certain period of time after the measurement control unit 28 controls the loopback stop, and the delay measurement start trigger is performed based on the trigger insertion signal. The generation unit 25 outputs a measurement start trigger.

The operation of delay measurement will be described.

The frame transmission unit 24 inputs an OTU frame output by the loopback execution unit 23 and a measurement start trigger output by the delay measurement start trigger generation unit 25, respectively. Then, the OTU frame in which the measurement start trigger is inserted at the corresponding PM & TCM bit position (DMp bit) is output to the transmission line by the trigger insertion signal input from the measurement control unit 28.

The measurement start trigger depends on the logic at the start of the delayed measurement. If it is "0", it is the change point edge of "0 to 1", and if it is "1", it is the change point edge of "1 to 0". Each is defined.

This measurement start trigger is also input to the delay measurement counter 27 at the same time and is used for control for starting counting at the delay measurement counter 27. In addition, the timeout counter also starts counting the maximum value of the transmission line delay timer delay measurable by the measurement start trigger.

Therefore, the presence or absence of a timeout of the timeout counter that started counting by the measurement start trigger is monitored (step S204 in FIG. 13). If the change point edge cannot be detected even if the timeout counter times out, a measurement timeout occurs and a measurement abnormality is output (step S204: Yes, step S213 in FIG. 13). This corresponds to "4. The change point edge does not return (timeout)" explained with reference to FIG.

The OTU frame into which the change point edge of the measurement start trigger is inserted transfers the transmission path to reach the opposite device, and the opposite device transfers the transmission path again by loopback of only PM & TCM bytes and returns to the transmission device that started the measurement. come.

The OTU frame into which the change point edge of the measurement start trigger returned to the transmission device 20 is inserted is terminated at the reception frame end portion 21 to achieve frame synchronization, and the measurement control unit 28 determines the beginning of the frame based on the synchronization information. Frame position information is generated. The measurement control unit 28 outputs loopback position information to the reception frame end unit 21 based on the set network configuration information (PM & TCM measurement conditions).

The reception frame end portion 21 extracts the DMp bit in the PM & TCM byte area based on the loopback position information and outputs it as loopback information. A change point edge is set in this DMp bit.

The loopback information (DMp bit) extracted from the reception frame terminal 21 is input to the change point edge detection unit 26.

When the change point edge detection unit 26 detects the change point edge in the loopback information (step S204: none, step S205 in FIG. 13), the change point edge detection unit 26 outputs a measurement stop trigger to the delay measurement counter 27.

The delay measurement counter 27 that has received the measurement stop trigger stops the count started by the measurement start trigger. The delay measurement counter 27 outputs this count value as a delay measurement value to the measurement control unit 28 (step S206 in FIG. 13).

The measurement stop trigger also stops the above-mentioned timeout counter from counting the maximum value of the transmission line delay timer that can be measured.

The operation of determining the normality of the delayed measurement value measured as described above will be described. This determination operation is executed by the measurement control unit 28 (step S207 in FIG. 13).

The measurement control unit 28 uses the measurement value output by the delay measurement counter 27 as the delay measurement value as the delay expected value which is the first determination reference value of the transmission path to be measured set in the preparation setting in step S201 of FIG. Compare with allowable delay error.

At this time, the measurement control unit 28 also confirms whether or not there is a failure in the transmission line or the device. For example, if there is a failure in the opposite device or the directly connected transmission line, it is detected by the receiving frame terminal 21 and a failure alarm is output. You may also refer to the failure alarm reported by the network management device.

If there is no failure alarm and the measured value is within the allowable delay error based on the expected delay value, the measured value is judged to be normal, and the measured value is output as the measurement judgment result (step of FIG. 13). S207: Normal, step S212).

When a failure occurs, any measured value is regarded as an abnormality, and the measurement abnormality is output as a measurement determination result (step S207: abnormality 1, step S213 in FIG. 13). This corresponds to "7. Failure alarm occurrence" described with reference to FIG.

Further, in the case of "5. Frequent change point edges (edge detection abnormality)" described with reference to FIG. 3, the measurement abnormality is output as the measurement determination result (step S207: abnormality 1, step S213 in FIG. 13). ..

On the other hand, when the measured value is out of the allowable delay error range based on the expected delay value, it corresponds to "6. Out of the allowable error range" explained with reference to FIG. 3, and the measurement abnormality is the measurement judgment. It should be output as a result. However, there may be a case of "8. Route switching" described with reference to FIG. Therefore, when the measured value is out of the range of the allowable delay error based on the expected delay value, the measurement control unit 28 confirms the validity of the first determination reference value used for the determination (FIG. 13). Step S207: Abnormality 2).

Here, it is assumed that the route information at the start of operation is registered in the content of the route information database 29, and the registered content is updated under the control of the measurement control unit 28.

Since the measurement control unit 28 calculates the first determination reference value for the transmission path to be measured based on the content of the reference data registered in the route information database 29, inquires the network management device about its validity. (Step S208 in FIG. 13). Based on the inquiry of the measurement control unit 28, the network management device returns whether or not the transmission path to be measured is switched, and if there is a switch, the device related to the switched path and the reference data regarding the transmission path. ..

Whether or not the route is changed is determined based on the result of the inquiry (step S209 in FIG. 13).

As a result of the inquiry, if there is no switching in the transmission path to be measured (step S209 in FIG. 13: none), it is determined that the first determination reference value used for the measurement is appropriate, and the measurement abnormality is measured. It is output as a determination result (step S213 in FIG. 13).

On the other hand, as a result of the inquiry, if there is a switch in the transmission path to be measured (step S209 in FIG. 13: Yes), it is determined that the first determination reference value used for the measurement should be updated. In this case, the measurement control unit 28 calculates a second determination reference value to be used for the switched route based on the information of the device related to the switched route and the transmission route returned from the network management device. (Step S210 in FIG. 13).

The measurement control unit 28 redetermines the measured value output by the delay measurement counter 27 as the delay measurement value using the second determination reference value (step S211 in FIG. 13).

As a result of this re-judgment, if it is within the allowable delay error based on the expected delay value which is the second judgment reference value, the measured value is judged to be normal, and the measured value is output as the measurement judgment result. (Step S211 in FIG. 13: Normal, Step S212). On the other hand, if the result of the re-judgment is outside the range of the permissible delay error based on the expected delay value, the measurement abnormality is output as the measurement determination result (step S211: abnormality, step S213 in FIG. 13).

Further, if the answer of the network management device includes information on the device and the transmission route related to the route after switching, the measurement control unit 28 updates and registers the information in the route information database 29.

As described above, in the present embodiment, at the time of delay measurement, the measurement control unit instructs the loopback execution unit to stop the execution of the loopback. With the loopback stop in the loopback execution unit, the loopback information extracted from the received frame is input to the change point edge detection unit. That is, the loopback is stopped on the device side that performs the delay measurement without performing any processing on the opposite device, so that a path for the delay measurement is formed.

Further, when the route is changed in the transmission path to be measured in the network, when the normality of the measured value is judged based on the first judgment reference value stored in advance by the measurement control unit, the reference is obtained. May identify abnormalities in measurements that are out of range.

In such a case, the measurement control unit inquires the network management device whether or not there is a route change in the transmission path to be measured, and the measurement value is measured based on the second determination reference value acquired based on the inquiry result. Determine normality again.

By providing such a configuration, when the route in the network to be the delay measurement target is changed to a different route, a new judgment reference value is obtained based on the delay measurement result, and the delay measurement result is evaluated again. be able to.

<Third embodiment>
A third embodiment will be described.

The configuration of the transmission device of the third embodiment has the same configuration as that of the transmission device 20 of the second embodiment described with reference to FIG. Then, the measurement control unit 28 executes the delay measurement method shown in FIG. FIG. 14 is a flow chart showing the delay measurement method of the third embodiment.

In the third embodiment, the measurement control unit 28 performs the delay measurement a plurality of times, and when all the measured values are determined to be normal based on the first determination reference value, it is determined to be normal. In this case, for example, a value that is an average value or an intermediate value of the measured values at each time is used as the measurement result.

This is because the delay is measured by detecting the change point edge via the transmission line, so that an unexpected change point edge appears when noise enters the transmission line, and a result different from the actual delay value is obtained. A third embodiment aims to improve the accuracy of measurement by confirming the normality of the measurement results of all times.

Further, in the third embodiment, even if a measurement abnormality occurs during the measurement, the measurement is continuously performed a predetermined number of times, and after the measurement is completed a predetermined number of times, the measurement normality is determined from the frequency and tendency of the measurement abnormality. To evaluate.

For example, in a plurality of delay measurements, if the occurrence of an abnormality in which the measured value is out of the range of the first determination reference value is random, it is determined as a measurement abnormality. Further, when the measurement results of all the times are out of the range of the first determination reference value, it is suspected that the route is switched and the first determination reference value used is not appropriate. In this case, an inquiry is made to the network management device, the second determination reference value after the route change is acquired, and the delay measurement based on the second determination reference value is executed again. Further, when only the measurement result performed after a certain time is out of the range of the first determination reference value, it is suspected that the route switching has occurred in the middle of the measurement. Also in this case, the network management device is inquired, the second determination reference value after the route change is acquired, and the delay measurement based on the second determination reference value is executed again.

The delay measurement method of the third embodiment will be described with reference to FIG. For the operation similar to the delay measurement method of the second embodiment described with reference to FIG. 13, the step described with reference to FIG. 13 is also referred to as appropriate.

First, prior to the delay measurement, the preparation setting for the measurement control unit 28 is performed (step S301 in FIG. 14).

Here, in addition to the preparation in step S201 of FIG. 13 (PM & TCM measurement condition registration, transmission line delay timer delay measurable maximum value setting, delay expected value and allowable delay error setting for each transmission path to be measured), delay measurement The maximum value of the number of times of implementation is also specified.

Then, the initial value 1 is set in the counter of the number of times the delay measurement is performed, and the delay measurement is performed (steps S302 and S303 in FIG. 14).

Here, the operation of performing the delay measurement in step S303 of FIG. 14 corresponds to the operation of steps 202 to S206 of FIG.

The measurement result output by the delay measurement counter 27 as the delay measurement value by the above operation is recorded in a memory or the like (not shown) (step S304 in FIG. 14).

If the number of times the delay measurement is performed is confirmed and the maximum number is not reached, the delay measurement number counter is added by 1 and the delay measurement is performed again (step S305: No, step S306 in FIG. 14). Step S303).

When the number of times the delay measurement is performed reaches the maximum number, the result of the delay measurement performed so far is evaluated (step S305: Yes, step S307 in FIG. 14).

The measurement control unit 28 compares the result of each delay measurement with the expected delay value of the transmission path to be measured and the first determination reference value which is the allowable delay error.

At this time, the measurement control unit 28 also confirms the presence or absence of a failure alarm of the transmission line or the device during the time zone in which the delay measurement is performed.

If there is no failure alarm and the measured value at each time is within the allowable delay error centered on the expected delay value, the measured value is judged to be normal, and the measured value is output as the measurement judgment result (FIG. 14). Step S307: Normal, Step S312).

When a failure alarm is generated, any measured value is regarded as an abnormality, and the measurement abnormality is output as a measurement determination result (step S307: abnormality 1, step S313 in FIG. 14).

Further, in a plurality of delay measurements, if the occurrence of an abnormality in which the measured value is out of the range of the first determination reference value is random, it is determined as the above abnormality 1.

However, if the measurement results of all times are out of the range of the first judgment reference value, or if only the measurement results performed after a certain time are out of the range of the first judgment reference value, the route is switched. Suspected of occurring. Therefore, in such a case, the abnormality 2 is output in order to control the network management device to make an inquiry (step S307 of FIG. 14: abnormality 2).

When the abnormality 2 is output, the operations after step S308 in FIG. 14 are executed. Since the operations after step S308 in FIG. 14 are the same as the operations after step S208 in FIG. 13, the description thereof will be omitted.

Also in this embodiment, when a route change is expected to occur in the transmission path, the network management device is inquired about whether or not the route change has been changed, and based on the second determination reference value obtained based on the inquiry result. To determine the normality of the measured value again.

By providing such a configuration, when the route in the network to be the delay measurement target is changed to a different route, a new judgment reference value is obtained based on the delay measurement result, and the delay measurement result is evaluated again. be able to.

<Modified example of the embodiment>
A modified example of the above-described embodiment will be described.

In the first modification, the determination reference value is defined as the maximum allowable error in a plurality of measurement results in the third embodiment. In this case, the normality of the measurement is judged by whether or not the difference between the maximum value and the minimum value of the measurement results performed a plurality of times is within the range of the maximum allowable error which is the judgment reference value. That is, instead of comparing whether each measured value is within the range of the allowable delay error based on the expected delay value, the difference between the maximum value and the minimum value of the measured value is within the range of the allowable maximum error which is the judgment reference value. Compare if it is in.

Then, when the difference between the maximum value and the minimum value of the measurement results performed multiple times is not within the range of the first judgment reference value, the measurement result giving the maximum value or the minimum value is randomly generated. Is determined to be a measurement abnormality. However, if the measurement result is out of the range of the first determination reference value only due to the measurement result performed after a certain time, it is suspected that the route switching has occurred in the middle of the measurement. Also in this case, the network management device is inquired, the second determination reference value after the route change is acquired, and the delay measurement based on the second determination reference value is executed again.

Such a first modification can be realized by changing the definition of the reference value data in the route information database 29 and as a function of the measurement control unit 28.

The second modification is a configuration in which the way of holding the determination reference value is changed.

In the delay measurement method of the second embodiment, the registered information of the route information database 29 was used as the first determination reference value stored in advance. That is, the expected delay value and the allowable delay error value of the transmission path to be measured used for the determination are calculated at the start of measurement, set in the measurement control unit 28 as the first determination reference value, and output from the delay measurement counter 27. The measured value to be measured was evaluated based on the set first determination reference value. Then, in the process in the case of route switching, the network management device is inquired, the second determination reference value is acquired from the answer, and the route information database 29 is updated and registered with the information of the answer contents.

The second modification has a configuration in which the network management device rewrites the contents of the route information database 29 of each transmission device in the network when a failure occurs in the network and the transmission path changes.

Therefore, in the case of the second modification, when it is suspected that the route switching has occurred, the measurement control unit 28 refers to the route information database 29 installed in the own device without inquiring to the network management device. Just do it. Then, the measurement control unit 28 generates a second determination reference value from the registered information in the route information database 29 and re-determines the measured value. Further, the measurement control unit 28 updates and sets the generated second determination reference value as the first determination reference value to be used in the next measurement.

The second modification can be applied in common to the second embodiment and the third embodiment.

In addition, a modified example of the configuration of the transmission device 20 of the second embodiment will be described.

As described above, since the delay is measured by detecting the change point edge via the transmission line, an unexpected change point edge appears when noise enters the transmission line, and a result different from the actual delay value is obtained. In the modified example of the configuration of the transmission device 20 of the second embodiment, a pulse width determination circuit is provided in front of the change point edge detection unit 26 so that this noise is not detected as the change point edge. Then, a signal that changes within a certain pulse width is determined to be noise, and the signal is controlled so as not to be accepted.

The pulse width is the interval at which the change point edge appears. Since the change point edge is set to the OTU frame and transferred, the transfer cycle is in frame units. Therefore, the change point edges that appear at intervals shorter than the frame unit of the currently used OTU frame are determined to be noise.

As described in each of the above embodiments and modifications, in the present embodiment, by stopping the loopback on the device side that performs the delay measurement, the opposite device does not perform any processing, and the delay measurement is performed. A route for is formed.

Further, when the route is changed in the transmission path to be measured in the network, the network management device is inquired about whether or not the route change has been changed without immediately outputting an abnormality. Then, the normality of the measured value is determined again based on the new determination reference value acquired based on the inquiry result.

By providing such a configuration, when the route in the network to be the delay measurement target is changed to a different route, a new judgment reference value is obtained based on the delay measurement result, and the delay measurement result is evaluated again. be able to.

1, 2, 3, 4, 5 Transmission device 5-1, 5-2, 5-3, 5-4, 5-5 Transmission device 5-6, 5-7, 5-8, 5-9 Transmission device 10 , 20 Transmission device 11 Receive frame termination means 12 Transmission frame generation means 13 Delay measurement means 14 Measurement control means 21 Receive frame termination 22 Transmission frame generator 23 Loopback execution unit 24 Frame transmission unit 25 Delay measurement start trigger generation unit 26 Change Point edge detection unit 27 Delay measurement counter 28 Measurement control unit 29 Route information database

Claims (2)

A reception frame termination means that outputs loopback information extracted from a reception frame received from the opposite device, disassembles the reception frame, and outputs it as reception data.
The transmission frame is constructed as a transmission frame, and the transmission frame is generated by executing the loopback process of inserting the loopback information output by the reception frame termination means at a predetermined position of the transmission frame and transmitted to the opposite device. Transmission frame generation means and
At the time of delay measurement for measuring the signal delay with the opposite device, the execution of the loopback process is stopped for the transmission frame generation means, and the change point is set at a predetermined position into which the loopback information of the transmission frame is inserted. A measurement control means that outputs control information that instructs the insertion of an edge,
The time from the reception of the change point edge insertion start information output by the transmission frame generation means to the detection of the change point edge insertion in the loopback information output by the reception frame end means is the measured value of the delay measurement. Equipped with a delay measuring means to output as
The measurement control unit, a result of determining the normality of the measurement values to be output by the delay measuring means based on the first determination reference value, to identify anomalies before Symbol measurements, and route to the counter device If change of Ru organic determines normality of the measurement value based on the second determination reference value again
Den feeding apparatus. Loopback processing that inserts loopback information extracted from the received frame received from the opposite device at a predetermined position of the transmission frame constructed based on the transmission data at the time of delay measurement for measuring the signal delay with the opposite device. The measurement control means instructs the transmission frame generation means to stop the execution of the data and insert the change point edge at a predetermined position to insert the loopback information of the transmission frame.
The delay measurement is the time from the reception of the change point edge insertion start information output by the transmission frame generation means to the detection of the insertion of the change point edge in the loopback information by drawing the loopback information into the delay measuring means. Output as a measured value of
As a result of the measurement control means determining the normality of the measured value based on the first determination reference value,
If prior Symbol abnormal measurements to identify said measurement controller, and change the route to the counter device Ru Yu,
The measurement control means redetermines the normality of the measured value based on the second determination reference value.
Delay measurement method.

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