JP6483367B2 - Transmission apparatus and delay measurement method - Google Patents

Description

  The present invention relates to a transmission apparatus and a delay measurement method, and more particularly, to a transmission apparatus and a delay for measuring a delay of a transmission line with a transmission apparatus to be measured using information for delay measurement set in a frame header. It relates to a measurement method.

  In a transmission system for transmitting data, a transmission delay between transmission apparatuses is measured from various viewpoints. For example, the measured transmission delay between transmission apparatuses is used as an index for confirming the reliability of data transmission in the transmission path. Patent Documents 1 to 4 disclose an invention for measuring a transmission delay between such transmission apparatuses.

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

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

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

  The transmission side optical transmission apparatus continues to transmit frames having DM bit = 1 at regular intervals, and the reception side optical transmission apparatus loops back the frame received from the transmission side. That is, the measurement unit measures the time from the start of transmission of a frame having DM bit = 1 to the time when a predetermined number of frames having DM bit = 1 that have been looped back are continuously received to determine the delay time. taking measurement. Then, the delay measurement is repeatedly performed a plurality of times, and the delay determination unit determines the delay time based on a 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 the actual traffic situation in a packet network.

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

  The invention disclosed in Patent Document 3 relates to a technique for setting a transmission path for 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 route is automatically adjusted based on the measured transmission delay time. Can do. In this technique, a transmission apparatus that has received a transmission time measurement command transmits a test signal including time information at the time of transmission to a transmission apparatus that is a transmission destination of a path. The transmission apparatus that has received the test signal detects the transmission delay time from the difference between the reception time and the transmission time, and transmits it to the network management apparatus.

  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 with the mobile terminal, and the mobile terminal is connected to the mobile terminal according to the communication quality. The present invention relates to a technology for performing connection control.

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

JP 2013-153367 A JP 2002-044125 A JP 2005-151186 A JP 2010-220011

  Transmission delay measurement has several problems as described below.

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

  (2) In the 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. Edges may not be transferred correctly. Therefore, there is a problem that the delay measurement value is smaller or larger than the normal measurement value, and an erroneous delay value is notified.

  (3) When a transmission apparatus on the transmission side and a transmission apparatus on the reception side face each other through a network in which a plurality of transmission apparatuses exist, path switching may be performed due to a failure in the network. Therefore, there is a problem that the delay measurement values between the transmission device on the transmission side and the transmission device on the reception side vary greatly.

  The invention disclosed in Patent Document 1 solves the above problem (1) by performing delay measurement using loopback. The invention disclosed in Patent Document 1 compares delay values after performing delay measurement a plurality of times, and determines that the delay measurement result is valid when the delay measurement result is smaller than a threshold defined as an error. Resolve issues.

  However, the invention disclosed in Patent Document 1 does not consider the problem (3). In other words, the invention disclosed in Patent Document 1 is a case where opposing transmission apparatuses are connected via a network, route switching in the network is not performed, and there is only variation in delay within a certain range. It is effective in the environment. However, when the number of relay devices increases due to a detour route due to a failure in the network, the delay measurement result fluctuates more than the variation in measurement values defined as errors before and after the route switch. 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 from an incoming edge router and removing the time stamp from the outgoing edge router. Therefore, in the measurement of the propagation delay time, it is necessary to perform time synchronization between the incoming edge router and the outgoing edge router, and the problem (1) is not solved.

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

  In the invention disclosed in Patent Literature 3, the transmission apparatus on the transmission side transmits a test signal including time information at the time of transmission to the transmission apparatus on the transmission destination of the path, and the time received by the transmission apparatus that has received the test signal. The transmission delay time is detected from the difference between the transmission time and the transmission time. Therefore, it is necessary to perform time synchronization between the transmission apparatus on the transmission side and the transmission apparatus on the transmission destination of the route, and the problem (1) is not solved.

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

  The present invention provides a transmission apparatus capable of obtaining a new determination reference value based on a delay measurement result and re-evaluating the delay measurement result when a route in a network to be subjected to delay measurement is changed to a different route. It is another object of the present invention to provide a delay measurement method.

  In order to achieve the above object, a transmission apparatus according to one aspect of the present invention outputs a loopback information extracted from a reception frame received from a counterpart apparatus, disassembles the reception frame, and outputs the received data as reception data. A frame termination unit, constructing transmission data as a transmission frame, and generating the transmission frame subjected to a loopback process for inserting the loopback information output by the reception frame termination unit at a predetermined position of the transmission frame. At the time of delay measurement for measuring a signal delay between the transmission frame generation means for transmitting to the opposite device and the opposite device, the transmission frame generation means is stopped from executing the loopback process, and Measurement control for outputting control information for instructing insertion of a change point edge at a predetermined position where the loopback information is inserted. And the delay measurement from the reception of the change point edge insertion start information output from the transmission frame generation unit to the detection of the change point edge insertion in the loopback information output from the reception frame termination unit. Delay measurement means for outputting the measurement value as a measurement value, wherein the measurement control means determines normality of the measurement value output by the delay measurement means based on a first determination reference value stored in advance, and When an abnormality of the measured value that is outside the range defined by the determination criterion value of 1 is identified, an inquiry is made to the network management means that manages the connected network as to whether or not the route to the opposite device has been changed. The normality of the measurement value is determined again based on the second determination reference value acquired based on the result.

  In addition, the delay measurement method according to another aspect of the present invention is configured to receive from the opposite device at a predetermined position of a transmission frame constructed based on transmission data at the time of delay measurement for measuring a signal delay with the opposite device. The measurement control means causes the transmission frame generation means to stop executing the loopback processing for inserting the loopback information extracted from the received frame and to insert the change point edge at a predetermined position where the loopback information of the transmission frame is inserted. Instructing and pulling in the loopback information to the delay measuring means, and receiving a change point edge insertion start information output from the transmission frame generating means until detecting the insertion of the change point edge in the loopback information. Based on a first determination reference value that is output as the measurement value of the delay measurement and stored in advance, the normality of the measurement value is determined in the measurement control method. If the measurement control means identifies an abnormality in the measurement value that is outside the range defined by the first determination reference value, the opposite device is connected to the network management means that manages the connected network. An inquiry is made as to whether or not the route has been changed, and the measurement control means again determines the normality of the measurement value based on a second determination reference value acquired based on the inquiry result.

  According to the present invention, when a route in a network to be subjected to delay measurement 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 | summary of a delay measurement. It is a time chart explaining the outline | summary of a delay measurement. It is a time chart explaining measurement abnormality of delay measurement. It is a time chart explaining another measurement abnormality of delay measurement. It is a time chart explaining the case where route switching occurs in delay measurement. It is a block diagram which shows the structure of the transmission apparatus of 1st Embodiment. It is a flowchart which shows operation | movement of the delay measuring 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 synchronous frame. It is a figure explaining the loopback by PM & TCM. It is a figure which shows the change of the transmission path | route in a network. It is a figure which shows the example of the content of route information DB. It is a flowchart which shows operation | movement of the delay measuring method of 2nd Embodiment. It is a flowchart which shows operation | movement of the delay measuring method of 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described with reference to the drawings.

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

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

  The form for implementing this invention is a system which measures a delay using the information for delay measurement accommodated in the header area | region of this frame, when data is transferred by the synchronous transfer system using a frame.

  FIG. 1A shows a state in which loopback information set in a header area of a frame transferred between transmission apparatuses is transmitted / received at a normal time. In this manner, a signal that does not change as loopback information is normally returned to the opposite device while 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 is to measure the delay value of a transfer signal between opposing transmission apparatuses, and the transmission apparatus (transmission side) 1 transmits the signal transmitted to the transmission path by being turned back by the opposing transmission apparatus (reception side) 2. Measure the time to receive from the road.

  Therefore, the transmission apparatus 1 on the transmission side stops the loopback of the own apparatus, 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 apparatus 2 on the reception side, a frame in which the loopback information in which the change point edge is set is replaced as it is is generated and transmitted to the transmission apparatus 1 on the transmission side. In other words, the change point edge set in the loopback information by the transmission apparatus 1 on the transmission side is returned as it is by the transmission apparatus 2 on the reception side and received by the transmission apparatus 1 on the transmission side.

  Therefore, the transmission apparatus 1 on the transmission side uses the time difference from the transmission of the frame in which the change point edge is set in the loopback information to the reception of the frame in which the change point edge is set in the loopback information as the delay time. .

  Thus, since the signal used for delay measurement uses the loopback information in the header area of the frame transferred between the transmission apparatuses, the delay measurement can be performed without affecting the user data transfer. In addition, since the control at the time of delay measurement only needs to stop the loopback by the own apparatus, the control for the loopback to the opposite transmission apparatus is not required.

  The change point edge is “1” when the normal setting value of the predetermined area is “0”, and “0” when the normal setting value is “1”. The point where the set value “0/1” is reversed.

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

In the following cases, the measurement result is determined to be abnormal.
• The measurement signal does not return 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 path error has occurred.

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

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

  FIG. 2 shows a case where a delay measurement start trigger is given and a change point edge is set to a frame and transmitted to the transmission line at time T0 after a predetermined waiting time elapses. T1 shows a state received from the transmission line.

  That is, the operation for delay measurement is started in the transmission apparatus by “1. Measurement start trigger” in the figure. In “2. Change point edge transmission” in the figure, after a predetermined waiting time has elapsed, the change point edge is set in the frame and 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 opposite transmission apparatus (reception side) 2 in FIG. 1 is set is received from the transmission line at time T1.

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

  On the other hand, with respect to the measured delay value, a certain measurement allowable error is defined in consideration of processing variations in the transmission apparatus and delay variations in the transmission path. Then, the normality of the delay 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 the reception measurement time of the change point edge varies between time t0 and time t1. If the reception measurement time of the change point edge is within the measurement allowable error range at time ta and time tb, the measurement result is determined to be normal.

FIG. 3 shows an example of the following measurement abnormality.
• The measurement signal does not return within the maximum measurable delay time.
• Multiple triggers occur within the maximum measurable delay time.
• The measurement result is out of the allowable delay error range.

  In FIG. 3, “2. Change point edge transmission” and “3. Change point edge reception” in the figure are shown as a reference for a normal measurement example in FIG. 2. 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 maximum delay time that can be measured is timed out and the change point edge does not return within the maximum delay time that can be measured. The

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

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

  “7. Fault alarm occurrence” in FIG. 4 indicates a state in which a transmission path fault or a counter device fault alarm is notified. While such a failure alarm is occurring, 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 indicates that the transmission apparatus (transmission side) 1 is caused by the occurrence of a failure in the network existing between the transmission apparatus (transmission side) 1 and the transmission apparatus (reception side) 2. And the measurement result when the path between the transmission device (reception side) 2 has changed. In this case, the measurement result is determined as a normal delay value although it is clearly out of the measurement allowable error range. Details will be described later.

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

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

  The embodiments are examples, and the disclosed apparatus and system are not limited to the configurations of the following embodiments.

  The transmission apparatus 10 according to the first embodiment includes a reception frame termination unit 11, a transmission frame generation unit 12, a delay measurement unit 13, and a measurement control unit 14.

  In addition, although the structure of an opposing apparatus is not illustrated, it shall have the same structure as FIG. That is, the transmission frame transmitted by the transmission apparatus 10 is received as a reception frame by the opposite apparatus, and the transmission frame transmitted by the opposite apparatus is received by the transmission apparatus 10 as a reception frame.

  The reception frame termination unit 11 has a function of terminating the reception frame received from the opposite apparatus. The reception frame termination unit 11 outputs 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 it to the opposite device. The transmission frame generation unit 12 generates a transmission frame that has been subjected to loopback processing for inserting the loopback information output by the reception frame termination unit 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 respect to the opposite device. The measurement control unit 14 provides control information for instructing the transmission frame generation unit 12 to stop executing the loopback process and insert a change point edge at a predetermined position where the loopback information of the transmission frame is inserted at the time of delay measurement. Output.

  The delay measurement unit 13 has a function of performing delay measurement. The delay measurement 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 insertion of the change point edge in the loopback information output by the reception frame termination means. Output as measured value.

  The measurement control unit 14 also has a function of determining the normality of the measurement value output from the delay measurement unit 13 based on a first determination reference value stored in advance. When the measurement control unit 14 identifies an abnormality in the measurement value that is outside the range defined by the first determination reference value, the network management unit that manages the connected network has changed the path to the opposite device. Inquire. Then, the measurement control unit 14 again determines the normality of the measurement value based on the second determination reference value acquired based on the inquiry result.

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

  FIG. 7 is a flowchart showing the operation of the delay measurement method according to 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 loopback processing for the transmission frame generation means, and the change point edge at a predetermined position where the loopback information of the transmission frame is inserted Is inserted (S101). The loopback process is a process of inserting 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 unit instructs the transmission frame generation unit to insert a change point edge that becomes a measurement start trigger.

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

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

  When the abnormality of the measurement value outside the range defined by the first determination reference value is identified, the measurement control unit determines whether or not the route to the opposite device is changed with respect to the network management unit that manages the connected network. An inquiry is made (S105).

  Based on the second determination reference value acquired based on the inquiry result, the measurement control means determines again the normality of the measurement value (S106).

  As described above, in the present embodiment, a path for delay measurement is formed without performing any processing in the opposite device simply by stopping the loopback processing on the device side that performs the delay measurement at the time of delay measurement. The

  In addition, when a path change with the opposite device is performed in the network, an abnormality in the measured value that falls 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 unit is inquired of whether or not the route to the opposite device has been changed, and the normality of the measurement value is determined based on the second determination reference value acquired based on the inquiry result. Determine again.

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

<Second Embodiment>
A second embodiment will be described.

  FIG. 8 is a block diagram illustrating a configuration of the transmission apparatus according to the second embodiment.

  The transmission apparatus 20 according to 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 a configuration related to frame transmission / reception. .

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

  The configuration corresponding to the transmission frame generation unit 12 of the first embodiment includes 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.

  The transmission frame generation unit 22 constructs 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 termination unit 21 at a position indicated by the control information of the transmission frame. Further, when the control information has a content for instructing to stop the loopback, the loopback processing is stopped.

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

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

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

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

  That is, the loopback information extracted from the received frame is output to the loopback execution unit 23 and the change point edge detection unit 26. When delay measurement is not performed, this loopback information is looped back by the loopback execution unit 23. Since no delay measurement is performed, no processing is performed on 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 in response to the measurement start trigger output from the delay measurement start trigger generation unit 25, and stops the delay measurement in response to the measurement stop trigger output from the change point edge detection unit 26. Then, the counter value from the delay measurement start to the delay measurement stop is output as a delay measurement result (measurement value).

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

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

  The path information database 29 is a delay that takes into account the transmission path related to the transmission apparatus and the information of the transmission apparatus (relay apparatus) connected to each transmission path, the delay value of each transmission path and each transmission apparatus, and the variation of the delay. Error information is stored.

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

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

  When the measurement control unit 28 identifies an abnormality in the measurement value that is outside the range defined by the determination reference value, the measurement control unit 28 inquires of the network management device whether the transmission path to the opposite device has been changed. If route switching has occurred as a result of the inquiry, the transmission device, delay value, and delay error information relating to 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 measurement value is determined again based on the new determination reference value.

The information stored in the route information database 29 is updated with information about a new route acquired from the network management device.
Thereafter, the G.I. 709 / Y. Description will be made using an example using an OTUk (Optical channel transport unit-k) (k = 1, 2, 3, 4) frame defined in the 1331 recommendation “Interfaces for the Optical Transport Network (OTN)”. ITU-T is an abbreviation for “International Telecommunication Union-Telecom standardization”.

  In the following description, the reference numbers given to the transmission devices are different depending on the drawings for the convenience of explanation, and any transmission device is the transmission device 20 of the second embodiment described with reference to FIG. It is.

FIG. 9 is a diagram illustrating 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 (not shown).

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

  In this embodiment, delay measurement is performed using PM & TCM arranged in Column # 3 and Row # 2 of the OTUk header. PM & TCM has a 1-byte configuration as shown in FIG. 9, and the first to sixth bits are used as DMt1 to DMt6, respectively. The seventh bit is used as DMp, and the eighth bit is unused. DM is an abbreviation for “Delay Measurement”. The use of 7 bits of DMt1 to DMt6 and DMp of PM & TCM will be described with reference to FIG.

FIG. 10 is a diagram for explaining loopback by PM & TCM.
Here, a transmission path in which the transmission apparatuses 1 to 5 are connected in series by a transmission path is assumed.

  This transmission path may be partially divided and managed. FIG. 10 illustrates a section between A1 and A2 between the transmission apparatus 1 and the transmission apparatus 5, a section between B1 and B2 between the transmission apparatus 2 and the transmission apparatus 3, and between the transmission apparatus 3 and the transmission apparatus 4. An example is shown in which three C1-C2 sections are managed.

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

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

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

  That is, a frame in which loopback information is set in the DMp bit in the section A1-A2, loopback information is set in the DMt1 bit in the section B1-B2, and loopback information is set in the DMt2 bit in the section C1-C2. Is transferred. In the transmission path, it is possible to loop back in seven types of sections at the same time.

  How to manage the network is determined at the time of network construction, and depending on this management form, the section to be looped back is determined. Then, a setting is made so that loopback is not performed except for any two points defined by any bit of DMt1 to DMt6 and DMp.

In this embodiment, a change point edge is set to any one of the 7 bits DMt1 to DMt6 and DMp to perform delay measurement.
The transmission device may be directly connected to the opposite device via one transmission path, but is often connected via a network. When connected via a network, a large number of transmission apparatuses intervene as relay apparatuses, and transmission paths may be switched due to a transmission path failure or a device failure.

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

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

  On the other hand, FIG. 2 shows a transmission path when a transmission path failure occurs in the network and the path is switched to a detour path. Also in this case, as indicated by the bold line, the transmission device 5-2, the transmission devices 5-3 to 5-6, and the transmission device 5-8 are provided between the transmission device 5-1 and the transmission device 5-9. Intervenes.

  As described above, the transmission delay value differs between the case where no transmission path failure occurs and the case where a transmission path failure occurs because the number of transmission apparatuses and the routes are different. If the number of transmission devices to be relayed increases, the delay also increases, and in the detour path at the time of transmission line failure, if the comparison is made based on the determination reference value in a state where no transmission line failure has occurred, the determination reference value is It will be judged as out of the prescribed range.

  However, the network management apparatus that manages the network grasps the change in the transmission path in the network, and provides information on whether or not the transmission path is changed and information on the relay apparatus after the path change in response to an inquiry from the transmission apparatus.

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

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

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

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

  In FIG. 12, two types of transmission paths are registered between the transmission apparatus 1 and the transmission apparatus 5. A first transmission path from the transmission apparatus 1 to the transmission apparatus 5 via the transmission apparatuses 2 to 4 and a second transmission path that directly connects the transmission apparatus 1 and the transmission apparatus 5 are registered. Since the second transmission path is registered and updated later than the first transmission path, the second transmission path is treated as an effective path at the present time.

  How the transmission apparatus 20 operates will be described with reference to a block configuration diagram illustrating an outline of delay measurement in FIG. 1 and a block configuration diagram of the transmission apparatus 20 of the second embodiment in FIG. 8. It is assumed that the opposite device having the same configuration as that of the transmission device 20 is connected via the network as described with reference to FIG.

  First, in the state where the delay is not measured, as shown in FIG. 1A, both the transmission apparatus (transmission-side transmission apparatus 1) and the opposite transmission apparatus (reception-side transmission apparatus 2) perform loopback. It is in a state.

  That is, the loopback information extracted by the reception frame termination unit 21 of the transmission apparatus 20 in FIG. 8 is input to the loopback execution unit 23. On the other hand, 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 apparatus 20 and the opposite apparatus are managed by the PM shown in FIG.

  In the measurement control unit 28, PM & TCM measurement conditions that are basic information on which bits in the PM & TCM byte area are to be looped back based on the network configuration are registered. In this case, since the management is based on the PM shown in FIG. 10, the DMp bit in the PM & TCM byte area is used.

  The reception frame termination unit 21 extracts 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 loops back only DMp bits in the PM & TCM byte area of the OTU frame input from the transmission frame generation unit 22 by specifying the loopback position of the control information output from the measurement control unit 28. Let That is, the loopback execution unit 23 performs control to insert the DMp bit of the loopback information extracted by the reception frame termination 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. When the delay measurement is not performed, the trigger insertion signal of the control information output from the measurement control unit 28 is OFF, and the input from the loopback execution unit 23 is selected. Output to the transmission line.

  As described above, in a 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 position corresponding to the DMp bit of the loopback information, and the OTU frame is Is output.

  A similar process is executed in the opposite apparatus that has received the OTU frame output in this way, and both transmission apparatuses are looped back at the DMp bit position in PM & TCM.

  Next, an operation when starting delay measurement will be described. In the following description, the flowchart of FIG. 13 showing the operation of the delay measurement method of the second embodiment will be described as appropriate.

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

  The PM & TCM measurement condition registration in the measurement control unit 28 described above is one of the preparation settings. Furthermore, there are a transmission path 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 measurement value.

  The maximum measurable value of the transmission line delay timer delay is used as a time used for time-out determination when the transition point edge does not return, and as a waiting time until a measurement start trigger is actually output after trigger insertion described later.

  Here, the first criterion value uses the expected delay value and the allowable delay error of the transmission path to be measured. The delay value of each transmission apparatus registered in the path information database 29 and its allowable error are added to the transmission apparatus related to the transmission path to be measured to obtain the expected delay value and the allowable delay error.

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

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

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

  The loopback is stopped (step S202 in FIG. 13) when the measurement control unit 28 sends control information for loopback stop to the loopback execution unit 23. Receiving the loopback stop control information, the loopback execution unit 23 stops selecting the DMp bit of the loopback information extracted from the reception frame termination unit 21. Therefore, the OTU frame generated by the transmission frame generation unit 22 is input to the frame transmission unit 24.

  After the loopback stop control is performed, a measurement start trigger is given after a waiting time of a predetermined time based on the above-described maximum value that can be measured by the transmission line delay timer delay (step S203 in FIG. 13). This control is performed by sending a trigger insertion signal to the delay measurement start trigger generation unit 25 after a waiting time of a predetermined time after the measurement control unit 28 performs the loopback stop control, and delay measurement start trigger based on the trigger insertion signal. The generation unit 25 outputs a measurement start trigger.

  The delay measurement operation will be described.

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

  The measurement start trigger depends on the logic at the time of delay measurement start. If it is “0”, it is the transition point edge from “0 to 1”, and if it is “1”, it is the transition point edge from “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 to start counting by the delay measurement counter 27. In addition, the timeout counter also starts counting the maximum value that can be measured for the transmission line delay timer delay by the measurement start trigger.

  Therefore, the presence or absence of timeout of the timeout counter that has 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. Change point edge does not return (timeout)” described with reference to FIG.

  The OTU frame in which the transition start edge of the measurement start trigger is inserted transfers the transmission path to the opposite apparatus, and returns to the transmission apparatus that has started the measurement by transferring the transmission path again by the loopback of only the PM & TCM byte in the opposite apparatus. come.

  The OTU frame inserted with the change start edge of the measurement start trigger returned to the transmission device 20 is terminated at the reception frame termination unit 21 to be synchronized with the frame, and the measurement control unit 28 determines the head 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 termination unit 21 based on the set network configuration information (PM & TCM measurement conditions).

  The reception frame termination unit 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 the DMp bit.

  The loopback information (DMp bit) extracted from the reception frame termination unit 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 in FIG. 13: none, step S205), 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).

  Note that, due to the measurement stop trigger, the above-described timeout counter also stops counting the maximum value that can be measured by the transmission line delay timer delay.

  The operation for determining the normality of the delay 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 as the delay measurement value by the delay measurement counter 27 and the expected delay value that is the first determination reference value of the transmission path to be measured set in the preparation setting in step S201 in FIG. Compare with the allowable delay error.

  At this time, the measurement control unit 28 also confirms whether there is a failure in the transmission path or the device. For example, if there is a failure in the opposite device or the directly connected transmission path, the reception frame termination unit 21 detects the failure and outputs a failure alarm. Moreover, you may refer to the failure alarm reported from a network management apparatus.

  If no failure alarm occurs and the measured value is within the allowable delay error range based on the expected delay value, the measured value is determined to be normal, and the measured value is output as a measurement determination result (step in FIG. 13). S207: Normal, step S212).

  If a failure has occurred, any measurement value is regarded as abnormal, and the measurement abnormality is output as a measurement determination result (step S207: abnormality 1, step S213 in FIG. 13). This corresponds to “7. Fault alarm generation” described with reference to FIG.

  Also, in the case of “5. Change edge frequent occurrence (edge detection abnormality)” described with reference to FIG. 3, a measurement abnormality is output as a measurement determination result (step S207 in FIG. 13: abnormality 1, step S213). .

  On the other hand, if the measured value is out of the allowable delay error range based on the expected delay value, it corresponds to “6. Out of allowable error range” described with reference to FIG. 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 allowable delay error range 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).

  In this case, it is assumed that the route information at the start of operation is registered as 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 path information database 29, the network control apparatus is inquired about its validity. (Step S208 in FIG. 13). Based on the inquiry from 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, returns a device related to the switched path and reference data related to the transmission path. .

  The presence / absence of a route change based on the result of the inquiry is determined (step S209 in FIG. 13).

  As a result of the inquiry, if the transmission path to be measured has not been switched (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. The determination result is output (step S213 in FIG. 13).

  On the other hand, as a result of the inquiry, if the transmission path to be measured is switched (step S209 in FIG. 13: present), 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 path based on the information related to the switched path and the transmission path information returned from the network management apparatus. (Step S210 in FIG. 13).

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

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

  The measurement control unit 28 also updates and registers in the route information database 29 if there is information on the device and transmission route related to the route after switching in the response of the network management device.

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

  Furthermore, when a path change is made in the transmission path to be measured in the network, when the measurement control unit determines the normality of the measurement value based on the first determination reference value stored in advance, the reference It may identify anomalies in measured values that are out of range.

  In such a case, the measurement control unit inquires of the network management device whether there is a path change in the transmission path to be measured, and based on the second determination reference value acquired based on the inquiry result, Determine normality again.

  By providing such a configuration, when a route in the network to be subjected to delay measurement is changed to a different route, a new determination 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 apparatus of the third embodiment has the same configuration as the transmission apparatus 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 flowchart illustrating a delay measurement method according to the third embodiment.

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

  This is because delay measurement is performed by detecting a change point edge via a transmission line, and when a noise enters the transmission line, an unexpected change point edge appears and a result different from the actual delay value is obtained. The 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 the normality of the measurement is determined from the frequency and occurrence tendency of the measurement abnormality after the predetermined number of measurements are completed. To evaluate.

  For example, in a plurality of delay measurements, if the occurrence state of an abnormality in which the measurement value is outside the range of the first determination reference value is random, it is determined as a measurement abnormality. If all the measurement results are out of the range of the first determination reference value, it is suspected that the path has been switched and the first determination reference value being 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 delay measurement based on the second determination reference value is executed again. Furthermore, 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 path switching has occurred during the measurement. Also 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.

  A delay measurement method according to the third embodiment will be described with reference to FIG. For operations similar to the delay measurement method of the second embodiment described with reference to FIG. 13, refer to the steps described with reference to FIG. 13 as appropriate.

  First, preparation for the measurement control unit 28 is performed prior to delay measurement (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 number of implementations is also defined.

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

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

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

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

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

  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 a first determination reference value that is an allowable delay error.

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

  If no failure alarm is generated and each measured value is within the allowable delay error range centered on the expected delay value, the measured value is determined to be normal, and the measured value is output as a measurement determination result (FIG. 14). Step S307: normal, step S312).

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

  In addition, in a plurality of delay measurements, the abnormality 1 is also determined as the abnormality 1 when the occurrence state of the abnormality in which the measurement value is out of the range of the first determination reference value is random.

  However, when all the measurement results are out of the range of the first determination reference value, or when only the measurement results performed after a certain time are out of the range of the first determination reference value, the path is switched. Suspected of occurring. Therefore, in such a case, abnormality 2 is output to perform control for inquiring the network management apparatus (step S307: abnormality 2 in FIG. 14).

  When abnormality 2 is output, the operations after step S308 in FIG. 14 are executed. The operation after step S308 in FIG. 14 is the same as the operation after step S208 in FIG.

  Also in the present embodiment, when the occurrence of a route change is assumed in the transmission route, the network management device is inquired about whether or not the route change has been changed, and based on the second determination reference value acquired based on the inquiry result. Determine the normality of the measured value again.

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

<Modification of Embodiment>
A modification of the above-described embodiment will be described.

  The first modification example defines the determination reference value as an allowable maximum error in a plurality of measurement results in the third embodiment. In this case, the normality of the measurement is determined based on 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 allowable maximum error that is the determination reference value. That is, instead of comparing each measured value within the allowable delay error range based on the expected delay value, the difference between the maximum and minimum measured values is within the allowable maximum error range, which is the criterion value. Compare what is in.

  And, when the difference between the maximum value and the minimum value of the measurement results carried out a plurality of times does not fall within the range of the first criterion value, the measurement result giving the maximum value or the minimum value is generated randomly Is determined to be a measurement abnormality. However, when it 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 path switching occurred during the measurement. Also 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.

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

  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 in the route information database 29 is 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 used for determination are calculated at the start of measurement, set as the first determination reference value in the measurement control unit 28, and output from the delay measurement counter 27. The measured value was evaluated based on the set first criterion value. In the process in the case of path switching, an inquiry is made to the network management apparatus, the second determination reference value is acquired from the answer, and update registration of the path information database 29 is performed with the information of the answer contents.

  The second modification is configured such that when a failure occurs in the network and the transmission path changes, the network management apparatus rewrites the contents of the path information database 29 of each transmission apparatus in the network.

  Therefore, in the case of the second modification, the measurement control unit 28 refers to the route information database 29 installed in its own device without making an inquiry to the network management device when it is suspected that the route switching has occurred. That's fine. Then, the measurement control unit 28 generates a second determination reference value from the registration information in the route information database 29 and re-determines the measurement value. Furthermore, the measurement control unit 28 updates and sets the generated second determination reference value as the first determination reference value used in the next measurement.

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

  A modification of the configuration of the transmission apparatus 20 according to the second embodiment will be described.

  As described above, since the delay measurement is performed by detecting the change point edge through 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 modification of the configuration of the transmission apparatus 20 according to 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 a change point edge. Then, a signal that changes within a certain pulse width is determined to be noise, and control is performed so that the signal is not accepted.

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

  As described in each of the above embodiments and modifications, in this embodiment, by stopping the loopback on the device side that performs the delay measurement, no processing is performed in the opposite device, and the delay measurement is performed. A path for is formed.

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

  By providing such a configuration, when a route in the network to be subjected to delay measurement is changed to a different route, a new determination 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 apparatus 11 Received frame termination unit 12 Transmitted frame generation unit 13 Delay measurement unit 14 Measurement control unit 21 Received frame termination unit 22 Transmitted frame generation unit 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 Path information database

Claims (10)

Output the loopback information extracted from the received frame received from the opposite device, receive frame termination means for disassembling the received frame and outputting as received data;
The transmission data is constructed as a transmission frame, and the transmission frame that has been subjected to the loopback processing for inserting the loopback information output by the reception frame termination unit at a predetermined position of the transmission frame is generated and transmitted to the opposite device Transmission frame generating means for performing,
At the time of delay measurement for measuring a signal delay with respect to the opposite device, the transmission frame generation unit is stopped at the execution of the loopback process, and a change point at a predetermined position where the loopback information of the transmission frame is inserted. Measurement control means for outputting control information for instructing insertion of an edge;
The time from the reception of the change point edge insertion start information output by the transmission frame generation means until the detection of the insertion of the change point edge in the loopback information output by the reception frame termination means is a measured value of the delay measurement. Delay measuring means for outputting as
The measurement control unit determines normality of the measurement value output from the delay measurement unit based on a first determination reference value stored in advance, and the measurement value is out of a range defined by the first determination reference value. If the abnormality is identified, the network management means for managing the connected network is inquired about whether or not the route to the opposite device has been changed, and based on the second determination reference value obtained based on the inquiry result And determining the normality of the measured value again. A transmission device connected to the transmission path for each transmission path and a path information database in which delay information of each transmission apparatus is registered as path information,
The measurement control means calculates an expected delay value and an allowable delay error of a transmission path to be measured as the first determination reference value based on the path information in the path information database, and a path to the opposite device Based on the route information after the route change obtained based on the inquiry about whether or not there is a change, a delay expected value and an allowable delay error of the transmission route after the route change to be measured are calculated as the second determination reference value. The transmission apparatus according to claim 1, wherein contents of the route information database are updated. The measurement control means performs the delay measurement a plurality of times, and determines that each measurement value is normal when all the measurement values are within a range defined by the first determination reference value, and the measurement value is the first determination value. When a measurement abnormality occurs outside the range defined by the reference value, the normality of the measurement is evaluated from the frequency of occurrence of the measurement abnormality , the occurrence status, and the time zone of the occurrence , and the measurement abnormality has a predetermined frequency of occurrence , In the case of the occurrence status and the time zone of occurrence , an inquiry is made to the network management means as to whether or not the route to the opposite device has been changed, and the second determination reference value after the route change obtained based on the inquiry The transmission apparatus according to claim 2, wherein the normality of the measurement value is determined again based on the measurement value. A transmission device connected to the transmission path for each transmission path and a path information database in which delay information of each transmission apparatus is registered as path information,
The measurement control means calculates an allowable maximum delay error of a transmission path to be measured as the first determination reference value based on the path information in the path information database, and performs the delay measurement a plurality of times. It was determined to be normal when the difference between the maximum value and the minimum value of the measured values is within the range of the allowable maximum delay error, when the measurement abnormality occurs, the occurrence frequency of the measurement abnormality, the occurrence and development The measurement normality is evaluated from the time zone , and if the measurement abnormality is at a predetermined frequency , occurrence status, and time zone of occurrence , an inquiry is made to the network management means as to whether or not the route to the opposite device has been changed. And based on the route information after the route change acquired based on the inquiry, the allowable maximum delay error of the transmission route after the route change to be measured is calculated as the second determination reference value, Transmission apparatus according to claim 1, characterized in that updating the contents of the serial path information database. The route information database acquires network update information from the network management means, and the measurement control means inquires of the route information database whether the route to the opposite device has been changed or not. The transmission apparatus according to any one of claims 2 to 4. The transmission apparatus according to any one of claims 1 to 5, wherein the delay measuring unit includes a pulse width determination circuit that eliminates, as noise, a signal that changes within a predetermined pulse width. Loopback processing for inserting loopback information extracted from a received frame received from the opposite device into a predetermined position of a transmission frame constructed based on transmission data at the time of delay measurement for measuring a signal delay with the opposite device And the measurement control means instructs the transmission frame generation means to insert the change point edge at a predetermined position where the loopback information of the transmission frame is inserted,
The loopback information is drawn into the delay measurement means, and 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 is measured as the delay. Output as the measured value of
The measurement control means determines normality of the measurement value based on a first determination reference value stored in advance,
When the measurement control unit identifies an abnormality in the measurement value that is outside the range defined by the first determination reference value, the network management unit that manages the connected network is connected to the opposite device. Queries whether there is a change,
A delay measurement method, wherein the measurement control means determines again the normality of the measurement value based on a second determination reference value acquired based on the inquiry result. For each transmission path, based on the path information in the path information database in which the delay information of the transmission apparatus connected to the transmission path and each transmission apparatus is registered as path information, the expected delay value and the allowable value of the transmission path to be measured Calculating a delay error as the first determination reference value;
Based on the route information after the route change obtained based on the inquiry about whether or not the route to the opposite device has been changed, the delay expected value and the allowable delay error of the transmission route after the route change to be measured are calculated based on the second information. Calculate as a criterion value,
The delay measurement method according to claim 7, wherein the content of the route information database is updated based on the route information after the route change. The delay measurement is performed a plurality of times, and it is determined that the measurement values of each time are all normal within the range defined by the first determination reference value,
When a measurement abnormality occurs outside the range defined by the first criterion value, the measurement normality is evaluated from the occurrence frequency , occurrence state, and time zone of the measurement abnormality,
When the measurement abnormality has a predetermined occurrence frequency , occurrence state, and occurrence time zone , the network management unit is inquired about whether or not the route to the opposite device has been changed, and the route change obtained based on the inquiry The delay measurement method according to claim 8, wherein the normality of the measurement value is determined again based on the later second determination reference value. For each transmission path, based on the path information in the path information database in which the delay information of the transmission apparatus connected to the transmission path and each transmission apparatus is registered as path information, the allowable maximum delay error of the transmission path to be measured is calculated. Calculating as the first criterion value,
When the delay measurement is performed a plurality of times and the difference between the maximum value and the minimum value of the measurement value is within the range of the allowable maximum delay error, it is determined as normal,
If a measurement abnormality occurs, evaluate the normality of the measurement from the frequency of occurrence, state of occurrence , and time of occurrence of the measurement abnormality,
When the measurement abnormality has a predetermined occurrence frequency , occurrence state, and occurrence time zone , the network management unit is inquired about whether or not the route to the opposite device has been changed, and the route change obtained based on the inquiry Based on the later path information, the allowable maximum delay error of the transmission path after the path change to be measured is calculated as the second determination reference value,
The delay measurement method according to claim 7, wherein the content of the route information database is updated based on the route information after the route change.

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