JP2005151186A - System for setting transmission route of virtual concatenation signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically adjust the delay time of virtual concatenation signal among a plurality of routes regarding a system for setting the transmission route of the virtual concatenation signal among transmitters. <P>SOLUTION: A network management device includes: a database for storing a measurement result of a transmission time relative to each path among the respective transmitters constituting a network and the idle state of a line, etc., among the transmitters; and a path setting processing part. When only a plurality of low-speed paths, connecting the indicated transmitters, via the same route cannot be used, the path setting processing part selects the path of the idle lines of a plurality of different routes. When a difference between the transmission times of the shortest first route and the long second route in the selected path is within a predetermined time, an indication for generating delay corresponding to the difference of the transmission times, by cross-connection, is given to the respective transmitters of the first route. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transmission path setting method for a virtual concatenation signal in an optical transmission network.

  In the optical transmission network, transmission path paths having various transmission speeds are formed and transmitted synchronously by a technique of SDH (Synchronous Digital Hieralchy) or SONET (Synchronous Optical Network). In such an optical transmission network, when a high-speed signal is transmitted through a low-speed transmission path, a method of transmitting in parallel using a plurality of paths is adopted, but the transmission delay differs depending on the path. If the delay is large, transmission of high-speed signals becomes difficult.

  In an optical transmission network such as an SDH / SONET network, a concatenation signal is a signal that flows on a path between transmission apparatuses (also referred to as NE (Network Element)) that constitute an optical network. Virtual concatenation divides a concatenation signal into a plurality of signals in order to transfer a high-speed signal in an SDH / SONET network using a communication network that can transfer only a lower-speed path (cross-connect) than the signal. A technology that transmits each divided signal as multiple virtual concatenation signals that are slower than the original signal, transfers them using a relatively slow path network, and restores and reproduces the original concatenation signals on the receiving side. It is.

  FIG. 13 shows an example of transmission of a virtual concatenation signal. In the figure, reference numerals 80 to 83 denote transmission apparatuses (NE). In this example, the transmission device 80 is a transmission source, the transmission device 82 is a transmission destination, a high-speed signal AU44C (about 600 Mbps) is input to the transmission device 80, and the signal generation unit 80a divides the signal into four low-speed signals AU4. Of the four divided signals, three signals pass through the low-speed paths (also referred to as paths) a, b, and c, reach the transmission device 82 of the transmission destination through the transmission device 81, and the remaining signals. Reaches the transmission device 82 through the transmission device 83 through d, which is a low-speed path. In the transmission device 83, the restoration unit 82a restores the original signal AU44C after adjusting the time difference for the signals that have passed through the four paths.

  As described above, in the virtual concatenation signal, a plurality of paths connecting the two NEs may not be the same route, but it is necessary to suppress them within a certain transmission delay time range between the paths of each route. It becomes. When planning and setting this virtual concatenation path, either calculate the transmission delay for each route on the desk, or actually set the virtual concatenation path from the network management system. It is necessary to confirm whether data can be restored normally. If there is a problem with data reconstruction, it is necessary to repeat the same procedure again and study the network design.

  ITU-T Recommendation G. 803 stipulates that when a virtual concatenation signal arrives through different paths, the arrival time difference due to the path difference between the signals can be absorbed within one frame (125 μs) time. As a technology that enables transmission of the virtual concatenation signal, a frame identifier is assigned to the transmitter node to absorb the time difference, and the receiver node absorbs the time difference by matching the timing of the identifier. Is known (see Patent Document 1).

In addition, as a technique for providing a device for measuring a network delay time for each packet attribute such as an application type in a network, a test packet transmitting means for transmitting a test packet in which a specific packet attribute is set is transmitted over the network. When the test packet is received, it is determined whether the test packet is transmitted by the own device or another device, and if it is determined by the other device, it is returned to the transmission source device. When it is determined that the packet reception means and the test packet reception means are transmitted by the own device, the time elapsed between the transmission and reception of the test packet is measured by the delay time measurement means. A technique for measuring the network delay time is also proposed (see Patent Document 2).
JP 2001-53705 A JP 2000-209205 A

  As described above, the conventionally known method of calculating the delay time for each path route of virtual concatenation in advance on the desk requires complicated calculations including various calculation elements, which is difficult for the operator or maintenance personnel. It was a heavy burden, and a similar burden occurred every time a route was reconstructed. In addition, a method for confirming whether data can be restored normally by setting a virtual concatenation path from the network control device and performing data transmission and reception is a test that requires labor and maintenance personnel to obtain results from the setting. There was a problem that it took time.

  Next, in the method shown in Patent Document 1, when the arrival time difference exceeds one frame time, an identifier is assigned to each frame in order to absorb the time difference. The receiving side needs to detect the identifier of each frame and perform processing, which requires complicated processing, and is not a technique for efficiently performing virtual concatenation path setting including delay within one frame. . Further, in the case of the above-mentioned Patent Document 2, it is a technique for measuring a transmission delay time to each transmission device of a test packet corresponding to a packet attribute such as a packet type, and the route setting of virtual concatenation is efficiently performed. It does not solve the problem of doing.

  An object of the present invention is to provide a transmission path setting method for a virtual concatenation signal that can automatically adjust delay times between a plurality of paths of the virtual concatenation signal.

  FIG. 1 is a diagram showing a principle configuration of the present invention. In the figure, 1 is a network management device (NMS) for managing a transmission device network composed of a number of transmission devices (NE) 2A to 2D, 2 is a transmission device (NE) network, and 2A to 2D are individual transmission devices (NE: Network Element), ad are transmission paths between SDH / SONET transmission devices 2A and 2B, between transmission devices 2A and 2C, between transmission devices 2C and 2D, between transmission devices 2D and 2B, and 3 is a network management device 1 and a transmission apparatus network. In the network management apparatus 1, 10 is a path-specific transmission time measuring unit, 11 is a path setting processing unit, 11a is an inter-path time difference detecting unit, 11b is a path setting request unit that generates a path-specific path setting request including a delay, and 11c. Is a cross-connect setting requesting unit, 11d is a commanding unit, 12 is a database storing transmission times by route obtained by measurement, presence / absence of a line in each transmission device (NE), free capacity, and the like, 13 is a communication unit , 14 are input / output units.

  When the administrator of the network management device 1 transmits high-speed data from one transmission device of the transmission device network 2 to another transmission device, for example, from the transmission device 2A to the transmission device 2B via an optical transmission line (SDH / SONET). , Because the bandwidth of the path of the path passing through the transmission path a directly connected from the transmission apparatus 2A to the transmission apparatus 2B is narrow and insufficient for high-speed data transmission, the transmission path b, the transmission apparatus 2C, the transmission path c, It is necessary to use the transmission device 2D and the route through the transmission line d in parallel. Therefore, in order to measure the transmission time of each of the two routes, route information (source transmission device, relay transmission device, destination transmission device) is specified to the transmission time measurement unit 10 for each route. When a measurement instruction is given from the input / output unit 14, the path-specific transmission time measurement unit 10 generates a transmission time measurement command (including path information) for the transmission apparatus that is the transmission source of each path. This command is sent from the communication unit 13 via the network 3 to the transmission apparatus 2A serving as a transmission source. When the transmission apparatus 2A receives the command, the transmission apparatus 2A generates a test signal toward the transmission apparatus on the path transmission destination. This test signal includes time information at the time of transmission of the test signal. When the transmission apparatus 2B of the transmission destination receives this test signal, the transmission time is calculated from the difference between the received time and the transmission time in the test signal. (Transmission delay time) is detected, and the transmission time is transmitted to the network management apparatus 1 via the network 3. In this example, two transmission times (transmission delay times) obtained from test signals that have passed through two paths are transmitted from the transmission apparatus 2B to the network management apparatus 1, and the network management apparatus 1 transmits them to the transmission time measurement unit for each path. When received at 10, it is stored in the database 12.

  When the transmission time for each route is obtained and stored in the database 12, an instruction to set the path of the virtual concatenation including the route of the transmission device and the necessary transmission amount (bandwidth) is generated from the input / output unit 14. The setting processing unit 11 is driven. The path setting processing unit 11 first outputs a path setting request based on the route to the path setting request unit 11b when the transmission capacity instructed by the inter-path time difference detecting unit 11a is sufficient for a single route and has a sufficient capacity. If there is insufficient capacity in one route, if there are empty paths of a plurality of routes, the transmission times stored in the database 12 for these routes are identified, and the shortest transmission time (p) Difference (qp) between the route (referred to as the first route) and the route (referred to as the second route) between the longest transmission time (referred to as q) and supplied to the path setting request unit 11b. . The path setting request unit 11b determines whether the value of the transmission time difference is within the permissible range in the system. If it is within the permissible range, a path of a virtual concatenation signal by a plurality of paths is formed and exceeds the permissible range. Is notified to the path setting request unit 11b, and the path setting request unit 11b gives the transmission time difference (qp) to each transmission device (NE) 2 of the route with the shortest transmission time r (r is the shortest transmission time). Requests setting of a path that generates a delay by time (qp) / r divided by the number of transmission devices existing on the path), and requests setting of a path that does not generate a delay for other paths. . Upon receiving this path setting request, the cross-connect setting request unit 11c transmits a cross-connect (mechanism for outputting the input optical signal to another optical fiber) including a path that generates the requested delay with respect to the shortest path. A request is generated that instructs each transmission device to form. When this cross-connect request is supplied to the commanding unit 11d, a cross-connect control command for each transmission apparatus is generated. When this command is supplied to each of the transmission apparatuses 2A to 2D via the network 3, a path (cross connect) for virtual concatenation is formed in each transmission apparatus. After this, even if the virtual concatenation signal is transmitted from the source transmission device to the destination transmission device through the network divided path, the difference in delay time between the divided paths is absorbed and almost the same time. Received by the destination transmission device.

  According to the present invention, the network management apparatus can automatically adjust the path path of the virtual concatenation for the SDH / SONET optical transmission network without being aware of the transmission delay time, and can perform network planning and setting. Become. In addition, effective use of the bandwidth (line), which is an advantage of virtual concatenation, can be realized.

  FIG. 2 shows an example of a system configuration for network management. In the figure, reference numerals 1-1 to 1-3 denote network management apparatuses (displayed by NMS: Network Management System), which correspond to 1 in FIG. 2A to 2D, 2E to 2H, 2I to 2L, and 2M to 2O are transmission devices (corresponding to the transmission devices 2A,..., 2D in FIG. 1), and each group of 2A to 2D,. This is a ring network composed of transmission devices, and 2M to 2O are networks in which three transmission devices are connected in series, and each of the networks 2A to 2O is managed by network management devices 1-1 to 1-3. Reference numerals 3-1 to 3-3 denote digital communication networks, and reference numeral 4 denotes communication between the plurality of NMSs and the transmission apparatuses 2A to 2H via the networks 3-1 to 3-3, transmission apparatuses 2I to 2L, and transmission apparatuses 2M. Represents a LAN that communicates with ˜2O.

  Network management devices (NMS) 1-1 to 1-3 are paths for executing data transmission between the transmission devices to the individual transmission device networks 2A to 2D,..., 2I to 2L, 2M to 2O. Control settings and cross-connect settings.

  In the present invention, it is necessary to previously store transmission time measurement data in an individual network, and therefore transmission time measurement control is performed. After this measurement is performed, the measurement result is stored in the database, and when the virtual concatenation signal is transmitted under the same conditions, it is not necessary to measure again by reusing the measurement data.

  FIG. 3 is a configuration diagram of a network that is an object of transmission time measurement. This example is a ring-type network, and corresponds to a network configuration example by the transmission apparatuses 2A to 2D in the system configuration shown in FIG. In FIG. 3, NE represents a transmission device, and constitutes a network in which 12 transmission devices NE # A to NE # L are connected to a ring. In the network configuration of FIG. 3, as a route from NE # A to NE # C, a route (1) NE # A, NE # B, NE # C, NE # A, NE # L, NE # K,. , NE # C is a detour route (2), and the transmission time of both routes is measured.

  FIG. 4 shows a transmission time measurement sequence, which is a sequence executed on two routes (1) and (2) between NE # A and NE # C in the network shown in FIG.

  First, a transmission time measurement instruction command is output from the NMS (network management apparatus 1 in FIG. 1) to NE (transmission apparatus) #A (a in FIG. 4).

  FIG. 5 is an explanatory diagram of commands and test signals used in transmission time measurement, and the transmission time measurement instruction command format is shown in FIG. As shown in FIG. 5, the command includes a command name, parameters, and a route NE list. The transmission time measurement command for the route (2) is shown in FIG. It becomes the contents shown in.

  When NE # A receives the transmission time measurement instruction command for route (1) from NMS, NE # A contains NE # B in the route NE list. And a test signal in a transmission time measurement test signal format including the transmission time is transmitted to NE # B (b in FIG. 4) and a response to NMS (confirmation of transmission time measurement instruction command reception) is transmitted. Return (c in FIG. 4). E. of FIG. Indicates a specific example of the content of a transmission time measurement result collection command. When NE # B receives the test signal for transmission time measurement and confirms that it is not the end of the route NE list of route (1), it transmits the test signal to the next NE # C (d in FIG. 4).

  When NE # C receives the test signal for transmission time measurement, it is known that NE # C is the last in the route NE list of route (1), and the test signal for transmission time measurement is included in the reception time (x) and the test signal. The transmission time (xy) is calculated from the difference in transmission time (y), and is held together with the route NE lithos of the route (1).

  Next, when NE # C receives a transmission time measurement / collection command having the format shown in F of FIG. 5 from NMS (e in FIG. 4), the corresponding transmission time is sent to NMS from the parameter (path NE list) of the command. Return (f in FIG. 4). G of FIG. 5 shows an example of parameters, a route NE list, and transmission time in the command of route (1).

  Thereafter, when a transmission time measurement instruction command is sent from the NMS to NE # A for path (2) (g in FIG. 4), a test signal for transmission time measurement is transmitted from NE # A to NE # L (FIG. 4). 4 h), test signals are transmitted in order from NE # L to NE # K,... And transmitted until NE # C is reached, and the transmission time is calculated and held in NE # C. Is received (i in FIG. 4), the held transmission time is returned to the NMS (j in FIG. 4).

  In the network configuration example in FIG. 3, there are only two virtual concatenation signal paths (1) and (2). However, depending on the network configuration of the transmission equipment (NE), there may be three or more paths. The route with the short transmission time is set as the first route, and the other route is set as the second route.

  6 and 7 are explanatory diagrams (No. 1) and (No. 2) of paths of virtual concatenation. In this figure, only some transmission apparatuses 2A to 2C in the network shown in FIGS. 1 and 2 are shown.

  FIG. 6 shows one virtual concatenation path (cross) on a route (route (1) of the network in FIG. 3) set up between the transmission devices NE # A, NE # B, NE # C. (Connect) is shown by a bold line, and route (2) is omitted. In this example, TU12 (2 Mbps speed) is used as one path. FIG. 7 shows the path configuration of the TU 12 shown in FIG. 6 in each of the transmission apparatuses NE # A, NE # B, and NE # C. In the transmission apparatus NE # A, one end point among a number of TUs 12 constituting AU4 (138 Mbps) in an STM-16 (2.4 Gbps) slot by cross-connecting from a port of “TU12 # 1” that is a path starting point. Is connected to the side port “TU12 # 1”, enters the transmission device NE # B through the optical fiber link, passes through the same path (cross-connect), passes through the optical fiber, and transmits to the next transmission device NE # C. Enter. Transmission device NE # C connects to the port of TU12 # 1 at the path end point through the cross-connect.

  A flowchart up to the determination of such a virtual concatenation path is shown in FIG. In this case, a virtual concatenation path of AU4-6V (AU4 is divided into 6) is set between NE # A to NE # C, which is executed in the network management apparatus (NMS).

  First, NE # A and NE # C, which are the start and end points of the path, are selected (S1 in FIG. 8), and it is determined whether the NE is directly or indirectly linked (whether the path can be set) ( (S2). This determination is made by confirming the link connection status on the database 12 in the NMS. If it is determined that the link connection is not established, the process is terminated. If the link connection is established, whether or not there is a free line capacity capable of setting the necessary paths (six lines) in the database 12 of FIG. To determine (S3 in FIG. 8). If there is free line capacity on the same path, it is defined as the first route (S4 in FIG. 8), and the path setting for that route is executed (S5).

  If the required number of free lines does not exist on the same route, it is determined whether there is another connectable route (other path) (S6 in FIG. 8). Determines whether there is an available line capacity that can set the required number of paths in the next route (S7). If there is no free line capacity, the number of times of processing is recorded (S8 in FIG. 8), and the process returns to step S6 to proceed to processing for another connectable path and repeat the same processing as described above. If it is determined in step S7 that there is an empty line capacity, it is defined as the nth route (S9), and the paths are set one by one for all routes (all available routes from the first route to the nth route). (S10).

  After setting the path, it is determined whether the transmission delay time between the paths (the result of measuring the transmission delay time stored in the database 12 in FIG. 1) is within the allowable range on the system (S11 in FIG. 8). The remaining path setting (a temporary path is set in S10 of FIG. 8) is executed (S12), and the process ends. If the transmission delay time is not within the permissible range in the system in step S11, the transmission delay time is set ((qp) / r) to the transmission device (NE) on the first path (FIG. 8). S13), it is determined whether the transmission delay time between the paths is within the permissible range in the system (S14 in FIG. 8). If it is not within the range, the process is terminated, and if it is within the range, the remaining paths are set (S15). .

  FIG. 9 shows the configuration of the network management apparatus and the flow of path setting control. In the figure, 1 is a network management device, 1a is a screen control unit, 1b is a processing control unit, 1c is a DB (database) control unit, and 1d is a command creation unit. Reference numeral 12 denotes a network configuration of NEs (transmission apparatuses) to be managed similar to reference numeral 12 in FIG. 1, transmission time (measurement results) of paths (by band) between the transmission apparatuses, presence / absence of lines in each NE, and free space A database (DB) in which capacity and the like are stored, 13a is a communication driver (corresponding to the communication unit 13 in FIG. 1), 14a and 14b correspond to the input / output unit 14 in FIG. 1, 14a is an input unit, and 14b is An output (display) unit. Reference numeral 2 denotes a transmission apparatus network, and the LAN and the networks 3-1 to 3-3 shown in FIG.

  When the operator requests six paths in the network as shown in FIG. 3, the transmission time difference (q−p) between the transmission time (p) of the first route and the transmission time (q) of the second route. ) Does not exceed the allowable range, the process proceeds to the path setting process, but if it exceeds, the network management apparatus applies to each of a plurality (r) of transmission apparatuses (NE) constituting the first route. (Qp) / r to set a path delay process, and a path that generates a delay time is formed by a switch of the cross-connect so that the transmission delay time of the second path is almost the same. Adjust the delay time.

  9 will be described with reference to FIG. 10 for the control for causing each transmission apparatus to execute path setting including this delay time. FIG. 10 is a configuration example of information used in the path setting process.

  The screen control unit 1a of the NMS 1 instructs the processing control unit 1b to make a path setting request (a) in response to the path setting request from the input unit 14a. Information on this path setting request (a) is shown in FIG. Shown in This information is information in the case where it is requested to set the path of the two routes of the route (1) and the route (2) in the transmission device network configuration shown in FIG. “Delay time” (time to delay the transmission of route (1)) is set, “NE name” (transmission device name) for each route, and “start point” (input port) of the cross-connect in the transmission device And “end point” (output port) are set for each NE on the route. For example, in the route (1) example, the delay time is (qp) / r, and the port of the start point “1-1-1” and the end point “8-1-1” is connected as a path to the transmission device NE # A. Request that the start point "1-2-1" and the end point "8-1-4" be connected, and the start point "1-3-1" and the end point "8-1-7" be connected. doing. For the path (2), the delay time is set to 0 (based on the transmission time of the path (2)), and each of the transmission devices NE # A, NE # L, NE # K,. FIG. The path setting information as shown in FIG.

  Upon receiving this path setting request (a), the processing control unit 1b creates a cross-connect setting request (b) from the path setting information and outputs it to the command creating unit 1d. The cross-connect setting request information is shown in Fig. 7B. This information is shown in FIG. The information for the transmission device NE # A is shown corresponding to the path setting request information shown in FIG. 5 and the three sets of cross-connect setting requests corresponding to the route (1) are set as “start point”, “end point”, and “delay time”. “(Q−p) / r” is specified. For route (2), three sets of information are designated, and the “delay time” is “0”.

  When the command creation unit 1d receives the cross-connect setting request (b), it creates a cross-connect setting command (c) for the instructed NE (transmission device) from the cross-connect setting information and outputs it to the communication driver 13a. To do. C. of FIG. Shows the cross-connect setting command format. This example represents a cross-connect setting command corresponding to one path including the delay time of the route (1) in NE # A. Cross-connect setting command). These commands are sent from the communication driver 13a to the transmission device name (NE name) included in the network command.

  When a cross-connect setting response (d) corresponding to the cross-connect setting command is returned from the network, it is received by the processing control unit 1b via the communication driver 13a and the command creation unit 1d, and the processing control unit 1b receives the cross-connect information. A DB registration request (e) is sent to the database control unit 1c. An example of cross-connect information DB registration request information is shown in FIG. Shown in This example is cross-connect information from NE # A. The DB control unit 1c registers the cross-connect information DB registration request information in the DB (database) 12, and sends a cross-connect information DB response (f) to the processing control unit 1b.

  The processing control unit 1b repeats the cross-connect setting request (b) and the cross-connect information DB registration request (e) for the number of path setting request information (a). A. of FIG. In the example of the path setting request information, the process for 12 times is performed, and after the repetition, the path setting response (g) is returned to the screen control unit 1a.

  Upon receiving the path setting response (g), the screen control unit 1a ends the path setting end message on the screen.

  FIG. 11 shows a configuration example of the transmission apparatus (NE). In the figure, 2 is a transmission device, 20 is a communication driver for communicating with a network management device via a network, 21 is a processing control unit, 22 is a cross-connect control unit, 23 is a cross-connect, and 24 is a loopback control unit. . When the communication driver unit 20 receives the command (command) from the network management device 1 shown in FIG. 9 above, the transmission device (NE) 2 performs processing control corresponding to the command in the processing control unit 21. When a control command for the cross-connect 23 is received, the control contents are supplied to the cross-connect control unit 22 and the input port signal is switched to be output to the designated output port according to the contents. In addition, when connected to a delay port for generating a delay in the cross-connect (described with reference to FIG. 12 described later), the loop-back control unit 24 is connected to the cross-connect control unit 22 in order to provide a loop-back path for the delay port. Control.

  FIG. 12 shows the state of the cross connection when the delay is set. In the figure, reference numeral 23 denotes a cross-connect switch (mechanism for outputting an input optical signal to another optical fiber) provided in the transmission apparatus. In this example, the optical signal of the input port 1-1-1 is output to the output port. The function that outputs to 8-1-1 is realized. The route indicated by the dotted line in (1) is a route that is directly output from the input port to the output port without delay, and (2) is the specified one. In order to generate a delay time, the optical signal of the input port 1-1-n is a path that generates a delay of a delay time that designates the four delay ports (dummy ports) a, b, c, and d in order. is there. In this case, assuming that the delay time when one delay port is connected is s, a delay time of 4 s is generated by passing through four. B. of FIG. In the case of the cross connection of the start point 1-1-1 and the end point 8-1-1 of NE # A, (qp) / rs delay ports are used. In this delay port, loopback processing (formation of a return path) is performed.

It is a figure which shows the principle structure of this invention. It is a figure which shows the structural example of a network management system. It is a block diagram of the network used as the object of transmission time measurement. It is a figure which shows a transmission time measurement sequence. It is explanatory drawing of the command and test signal which are used by transmission time measurement. It is explanatory drawing (the 1) of the path | pass of virtual concatenation. It is explanatory drawing (the 2) of the path | pass of virtual concatenation. It is a figure which shows the flowchart of virtual concatenation path | pass determination. It is a figure which shows the structure of a network management apparatus, and the flow of path setting control. It is a figure which shows the structural example of the information used by the process of a path | pass setting. It is a figure which shows the structural example of a transmission apparatus. It is a figure which shows the state of the cross connection at the time of a delay setting. It is an example of transmission of a virtual concatenation signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Network management apparatus 10 Route-specific transmission time measurement part 11 Path setting process part 11a Inter-path time difference detection part 11b Path setting request part 11c Cross-connect setting request part 11d Command conversion part 12 Database 13 Communication part 14 Input / output part 2 Transmission apparatus network 2A-2D transmission equipment (NE)
3 network

Claims (3)

In a transmission path setting method for a virtual concatenation signal between a plurality of transmission apparatuses constituting an SDH / SONET network managed by a network management apparatus,
The network management device is started by a database that stores information such as transmission time measurement results for each path between multiple transmission devices that make up the network and the line availability between transmission devices, and path setting instructions. Path setting processing unit
The path setting processing unit selects a plurality of free line paths via different paths when a plurality of low speed paths via the same path connecting between the designated transmission apparatuses cannot be used. A first route having the shortest transmission time and a second route having a longer transmission time than the other first routes are determined from the database, and the first route and the second route are determined. If the difference in the transmission time of the path is within a preset time, the entire path is instructed to generate a delay corresponding to the difference in the transmission time in the cross-connect to each transmission device of the first path. A virtual concatenation signal transmission path setting method characterized by adjusting the transmission time. In claim 1,
The network management device obtains a difference (qp) between the transmission time (p) of the first route and the transmission time (q) of the second route, and the number of transmission devices on the first route. A virtual concatenation signal transmission path setting method in which the value divided by (r) is instructed to generate a delay time in the cross-connect of each transmission device of the first path. In claim 1,
The network management device is provided with a route-specific transmission time measurement unit,
The route-specific transmission time measurement unit generates a route-specific transmission time measurement instruction including information on the transmission device of the transmission route for the designated transmission device,
The transmission device that has received the instruction transmits a test signal including the transmission time to the next transmission device on the path, and the next transmission device receives the test signal. When the test signal is transmitted to the device and the test signal is received by the final transmission device on the path, the transmission time is detected and held from the reception time and the transmission time in the test signal,
The transmission time measurement unit by path transmits a transmission time measurement result collection instruction to the last transmission device on the transmission path after generating the transmission time measurement instruction, and the last transmission device transmits the transmission time measurement result. A transmission path setting method for a virtual concatenation signal, in which a transmission time that has been held is responded when a collection instruction is received.

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