Fiber inspection device and fiber inspection method

Abstract

A fiber inspection device 1 comprises: a switch control unit 12 that establishes a pathway by controlling the connection states inside of respective switches; and a pathway calculation unit 14 that, on the basis of the fiber wiring state assumed for a test terminal for controlling a test terminal 50 for measuring a received light power of a test light that has passed through an inspection path, calculates a pathway by which the test light passes through the switches and fiber to reach the test terminal 50. The test light is inputted to the inspection path and received by the test terminal 50. If, with one uplink and one downlink for connecting between leaf switches and spine switches being taken to be a fiber to be inspected, the received light power does not satisfy a threshold value, then the fiber inspection device 1 classifies the uplink and the downlink under an unspecified-state fiber. For respective unspecified-state fibers, the fiber inspection device 1 classifies the state of the unspecified-state fiber on the basis of the received light power, as the fiber to be inspected.

Description

Fiber inspection device and fiber inspection method

[0001] The present disclosure relates to a fiber inspection device and a fiber inspection method.

[0002] In recent years, there has been an increase in the number of cases where optical switches are introduced into switch fabrics in data centers to accommodate traffic generated within the data centers with low power consumption and low cost. By arranging optical switches according to a topology called a CLOS network or a TF-CLOS network, a non-blocking fiber switching network can be constructed.

[0003] K. Chen et.al, “DAC: Generic and automatic address configuration for data center networks,” in IEEE / ACM Transactions on Networking, vol. 20, no. 1, pp.84-99, 2011C. Jian, et.al, “MTR: Fault tolerant routing in Clos data center network with miswiring links,” in 2014 IEEE 20th International Workshop on Local & Metropolitan Area Networks (LANMAN), pp. 1-6, 2014X. Ma, et al. "Error tolerant address configuration for data center networks with malfunctioning devices." in IEEE 32nd International Conference on Distributed Computing Systems, 2012.

[0004] 70% of problems that occur in data centers are caused by human error, with incorrect wiring accounting for a large proportion of these. When expanding a fiber switching network, manual rewiring is required, making it prone to human error. Furthermore, there is a risk of damaging the fiber during the wiring work. Therefore, an efficient method for inspecting the fiber wiring and quality is required.

[0005] In a conventional Ethernet Switching Network (ESN), electrical processing is possible at intermediate switches, so faulty wiring can be detected by utilizing protocols such as Link Layer Discovery Protocol (LLDP) and ICMP, or existing technologies (Non-Patent Documents 1-3). However, optical switches process signals directly from light without converting them to electricity, so conventional mechanisms and technologies cannot be directly applied.

[0006] One possible method is to build a fiber switching network using optical switches equipped with power meters and send test signals to each fiber to easily identify faulty wiring locations. However, introducing optical switches equipped with power meters is not desirable because it increases costs, insertion loss, and power consumption.

[0007] One possible method is to connect a test terminal between two optical switches, send a test signal from one optical switch, and receive the test signal from the other optical switch via only one fiber to be tested, thereby testing each fiber connecting two optical switches one by one. However, when testing a fiber connecting two other optical switches, manual reconnection of the test terminal is required, which makes it impossible to avoid human error. Furthermore, testing each fiber one by one takes a very long time. When testing two or more fibers at once, it may not be possible to determine the condition of each fiber.

[0008] The present disclosure has been made in view of the above, and aims to automatically and correctly inspect the status of all fibers in a fiber switching network.

[0009] a test terminal control unit that controls a test terminal that measures the received optical power of test light that has passed through the route; a route calculation unit that calculates the route along which the test light passes through the switches and fibers to reach the test terminal based on an assumed fiber wiring situation; and an inspection unit that inputs the test light into the route, measures the received optical power of the test light received by the test terminal, and classifies the state of the fiber on the route based on the received optical power. The fiber inspection device of one aspect of the present disclosure is a fiber inspection device that inspects the state of a fiber connecting between a first switch group and a second switch group, and includes: a switch control unit that controls the internal connection state of each switch to establish a route; a test terminal control unit that controls a test terminal that measures the received optical power of test light that has passed through the route; a route calculation unit that calculates the route along which the test light passes through the switches and fibers to reach the test terminal based on an assumed fiber wiring situation; and an inspection unit that inputs the test light into the route, measures the received optical power of the test light received by the test terminal, and classifies the state of the fiber on the route based on the received optical power. The fiber inspection device establishes the route including one uplink and one downlink that connect between a switch of the first switch group and a switch of the second switch group as fibers to be inspected, measures the received optical power, and classifies the uplink and the downlink as fibers with an unspecified state if the received optical power is less than a threshold value, and establishes the route including only one fiber with an unspecified state as a fiber to be inspected for each of the fibers with an unspecified state, measures the received optical power, and classifies the state of the fiber with an unspecified state based on the received optical power.

[0010] According to the present disclosure, the condition of fibers in a fiber switching network can be inspected correctly and efficiently.

[0011] FIG. 1 is a diagram illustrating an example of the configuration of a fiber inspection device. FIG. 2 is a diagram illustrating an example of a fiber switching network. FIG. 3 is a flowchart illustrating an example of the processing flow of the fiber inspection device. FIG. 4 is a flowchart illustrating an example of the processing flow for inspecting a fiber between a leaf switch and a spine switch. FIG. 5 is a flowchart illustrating an example of the processing flow for inspecting a fiber whose status is unknown. FIG. 6 is a diagram illustrating an example of fiber inspection. FIG. 7 is a diagram illustrating an example of fiber inspection. FIG. 8 is a diagram illustrating an example of fiber inspection. FIG. 9 is a diagram illustrating an example of fiber inspection. FIG. 10 is a diagram illustrating an example of fiber inspection. FIG. 11 is a diagram illustrating an example of fiber inspection. FIG. 12 is a diagram illustrating an example of fiber inspection. FIG. 13 is a diagram illustrating an example of fiber inspection. FIG. 14 is a diagram illustrating an example of fiber inspection. FIG. 15 is a diagram illustrating the relationship between the time required to install a test terminal and the inspection time. FIG. 16 is a diagram illustrating the relationship between the number of quality-degraded fibers and miswired fibers and the inspection time. FIG. 17 is a diagram illustrating an example of the hardware configuration of a fiber inspection device.

[0012] The fiber switching network configuration (topology) to be inspected by the fiber inspection device of this embodiment is TF-CLOS, and the fibers connecting k leaf switches I = {1,...,k} and m spine switches J = {k+1,...,k+m} are inspected. The set of all switches is represented as S = I∪J. Leaf switches provide connections between end devices and the network within the data center. Spine switches connect to all leaf switches and forward traffic within the data center. Fibers that transmit data from leaf switches to spine switches are called uplinks, and fibers that transmit data from spine switches to leaf switches are called downlinks. The set of fibers connecting leaf switches and spine switches is represented as E, and each fiber is represented as e∈E. The fiber to be inspected is e∈E.

[0013] The physical wiring between switches that the operator envisions (wants to build) is called the envisioned topology. The envisioned topology describes the connection information between the ports of each optical switch. The operator builds a network based on the envisioned topology. The fiber inspection device inspects the envisioned topology for any wiring errors or abnormalities in the quality of each fiber.

[0014] It is assumed that all optical switches are normal, that there is no miswiring between the same optical switches or between optical switches in the same layer, and that there is no miswiring between Tx ports or Rx ports.

[0015] In general network construction work, only a small portion of the fibers have abnormalities in wiring or loss, and most fibers are correctly wired and have normal loss. We assume that more than half of the fibers to be inspected are correctly wired and have normal loss.

[0016] [Configuration of Fiber Inspection Device] An example of the configuration of a fiber inspection device 1 of this embodiment will be described with reference to Fig. 1. The fiber inspection device 1 shown in Fig. 1 includes a test terminal control unit 11, a switch control unit 12, an inspection unit 13, a path calculation unit 14, a path loss calculation unit 15, a topology information storage unit 16, and a retention unit 17.

[0017] The test terminal control unit 11 controls the test terminals connected to the fiber switching network. An example of the fiber switching network and the test terminals will be described later.

[0018] The switch control unit 12 controls the internal connection state of each optical switch included in the fiber switching network to establish a test path. The test path is a path along which input test light passes through the fiber switching network and is received by the test terminal. The switch control unit 12 controls the optical switches so that ports not on the test path are not connected to any other port.

[0019] The inspection unit 13 measures the received optical power of the test light received by the test terminal when the test light is input to the inspection path, and classifies the state of the fiber on the inspection path based on the received optical power. Specifically, the inspection unit 13 measures the received optical power of the inspection path including one uplink and one downlink for the fiber connecting the leaf switch and the spine switch, and classifies the uplink and downlink whose received optical power does not meet the standard as an unspecified fiber. Then, for each unspecified fiber, the inspection unit 13 measures the received optical power of the inspection path including only one unspecified fiber, and classifies the state of the unspecified fiber based on the received optical power. During the inspection, each fiber is classified as a good fiber, a healthy fiber, a degraded fiber, or a miswired fiber. Miswired fibers also include broken fibers.

[0020] The inspection unit 13 classifies the state of the fiber between each spine switch and each leaf switch to which the test terminal is connected in procedure 1, and classifies the state of the fiber between each spine switch and each leaf switch to which the test terminal is not connected in procedure 2. In procedure 2, an inspection path that passes through the fiber classified as normal in procedure 1 is used.

[0021] After the inspection, the inspection unit 13 outputs information on the quality-degraded fibers and the mis-wired fibers.

[0022] The route calculation unit 14 calculates a test path along which test light from the test terminal passes through the fiber switching network and returns to the test terminal, based on an assumed topology provided by an operator.

[0023] The path loss calculation unit 15 calculates the loss of the fiber on the test path based on the input power of the test light, the received power of the test light after passing through the test path, and the insertion loss of each optical switch.

[0024] The topology information storage unit 16 stores the assumed physical wiring status given by the operator.

[0025] The storage unit 17 stores information about each optical switch included in the fiber switching network, such as the time required for control required for switching and the maximum and minimum values ​​of insertion loss.

[0026] FIG. 2 is a diagram illustrating an example of a fiber switching network to be inspected.

[0027] The fiber switching network shown in Figure 2 includes leaf switches I1, I2, and I3 and spine switches J4 and J5. The number of uplinks / downlinks connecting the leaf switches and spine switches is v. In other words, the number of fibers is 2v. Hereinafter, when optical switches are not distinguished individually, they will be referred to as leaf switches and spine switches. When leaf switches and spine switches are not distinguished, they will simply be referred to as optical switches.

[0028] The test terminal 50 is connected to a transmit / receive port of a leaf switch. In the example of FIG. 2, the test terminal 50 is connected to leaf switch I1. The test terminal 50 inputs test light into a test path established in the fiber switching network, receives the test light that has passed through the test path, and measures the received optical power of the test light. The test terminal 50 only needs to be able to send and receive optical signals. The test terminal 50 may be connected to any leaf switch. If a spine switch has a free port, the test terminal 50 may be attached to the spine switch. A terminal other than the test terminal 50 may input test light into the test path. The test terminal 50 does not need to be reconnected until all fibers to be tested have been tested.

[0029] [Operation of Fiber Inspection Apparatus] An example of the processing flow of the fiber inspection apparatus 1 will be described with reference to the flowchart of FIG.

[0030] In step S1 (procedure 1), the fiber inspection device 1 inspects the fibers connecting the leaf switch connected to the test terminal and each spine switch. First, the fiber inspection device 1 limits the number of fibers included in the inspection path to a total of two, one uplink and one downlink, and sequentially inspects each pair of uplink and downlink connecting the leaf switch and spine switch. An uplink and downlink pair whose received optical power at the test terminal does not satisfy a threshold is classified as an unspecified fiber. Next, the fiber inspection device 1 establishes an inspection path including only one unspecified fiber and inspects the status of each unspecified fiber one by one. In the example fiber switching network of FIG. 2, in procedure 1, the fiber connecting the leaf switch I connected to the test terminal 50 and the spine switches J and J is inspected.

[0031] In step S2 (procedure 2), the fiber inspection device 1 establishes an inspection path using fibers that were found to be free in procedure 1, and inspects the fibers connecting each leaf switch to which a test terminal is not connected and each spine switch. In procedure 2, as in procedure 1, the fiber inspection device 1 first limits the fibers to be inspected included in the inspection path to two fibers: one uplink and one downlink between the leaf switch to be inspected and the spine switch, and sequentially inspects each pair of uplink and downlink connecting the leaf switch to be inspected and the spine switch. An uplink and downlink pair whose received optical power at the test terminal does not satisfy the threshold is classified as an unspecified fiber. Next, the fiber inspection device 1 establishes an inspection path including only one unspecified fiber, and inspects the status of each unspecified fiber one by one. In the example fiber switching network of FIG. 2, procedure 2 inspects the fibers connecting between leaf switch I2 and spine switches J4 and J5, and between leaf switch I3 and spine switches J4 and J5.

[0032] Consider creating an arbitrary test path on an assumed topology. If the number of test uplinks and test downlinks on the test path is a maximum of one each, paths other than the test path considered on the assumed topology will not be created due to faulty wiring or other reasons. In other words, a path is generated according to the assumed topology. Conversely, considering the possibility of faulty wiring, if the number of test uplinks and test downlinks is greater than one, the fiber condition cannot be uniquely identified. Therefore, it is necessary to estimate the fiber condition using only test paths that contain a maximum of one test uplink and one test downlink. Since the test paths generated in steps 1 and 2 above satisfy the above, if the received optical power at the test terminal is as expected, it can be guaranteed that there are no faulty wiring in any of the fibers on the test path and that there are no quality issues.

[0033] 4 and 5, an example of the inspection process of the fiber between the leaf switch and the spine switch by the fiber inspection device 1 will be described. The processes in FIGS. 4 and 5 are performed when inspecting the fiber between the leaf switch and the spine switch in each of steps 1 and 2. In the following, the description will be made assuming that the fiber connecting the leaf switch i and the spine switch j is to be inspected.

[0034] In the process of FIG. 4, the fiber inspection device 1 determines a set E of uplinks from the leaf switch i to the spine switch j. ij and a set E of downlinks from spine switch j to leaf switch i. ji and input the uplink / downlink pair (e, e′∈E ij , E ji ) is examined one by one. For example, in step 1, the set E of fibers connecting the leaf switch 1 to which the test terminal is connected and each spine switch j∈{k+1,...,k+m} is examined. 1j , E j1 In step 2, a set of fibers E connecting each leaf switch i∈{2,...,k} and each spine switch j∈{k+1,...,k+m} is input. ij , E jiEnter.

[0035] In step S41, the fiber inspection device 1 controls each optical switch to establish an inspection path including the fibers e and e' to be inspected. In procedure 1, the inspection path does not include any fibers other than the fibers e and e' to be inspected. In procedure 2, the inspection path passes through the leaf switch 1 to which the test terminal is connected, and includes the fibers classified as good fibers in procedure 1 and the fibers e and e' to be inspected. The test terminal inputs test light into the inspection path, receives the test light that has passed through the inspection path, and measures the received optical power P of the test light.

[0036] In step S42, the fiber inspection device 1 determines whether the fiber loss on the inspection path is negligibly small based on the received light power P. If the loss of the test light passing through the inspection path is approximately the sum of the losses of all the optical switches on the inspection path, the fiber inspection device 1 determines that the fiber loss on the inspection path is negligibly small.

[0037] If the transmission power of the test light is P0, the received light power P can be expressed by the following equation.

[0038]

[0039] Here, S q is the set of switches on the inspection path q, L s is the insertion loss of the optical switch s, E q is the set of fibers on the inspection path q, and L(e) is the loss of fiber e.

[0040] When testing a test path q, if the received optical power P does not include any fiber loss, the loss of all fibers on the test path q is approximately the loss L0 of a typical fiber. For single-mode fiber, the loss of a typical fiber is 0.2 dB / km at a wavelength of 1550 nm and 0.3 dB / km at 1310 nm. Within a central office or data center, the fiber length is several hundred meters, so the loss L0 of a typical fiber is so small that it can be ignored.

[0041]

[0042] If the loss of the fiber on the inspection path is negligibly small, the fiber inspection device 1 classifies the fibers e and e' as good fibers in step S43.

[0043] If the loss of the fiber on the inspection path cannot be ignored, in step S44, the fiber inspection device 1 determines, based on the received light power P, whether the loss of the fiber on the inspection path is within the allowable loss.

[0044] When testing test path q, if the total loss of all fibers on test path q is L, the received optical power P at the test terminal can be expressed by the following equation: In this case, the loss L(e) of each fiber on test path q will not exceed L.

[0045]

[0046] The minimum optical power required for an endpoint to communicate is P min For example, if the endpoint in the network is a DR4 transceiver, then P min =-5.9dB. min Signals with a strength lower than -5.9 dB cannot be received correctly and communication is not possible. min To receive a signal with a strength of this magnitude, each fiber on the inspection path q must have an allowable loss L ok The loss should not be greater than

[0047]

[0048] When the inspection path q is tested, the received light power P is expressed by the following formula: ok If this is the case, the loss of all fibers on the test path q is the allowable loss L ok The following is the result.

[0049]

[0050] If the loss of the fiber on the test path is within the allowable loss, that is, P ≥ P ok In this case, in step S45, the fiber inspection device 1 classifies the fibers e and e' as sound fibers.

[0051] P<P okIn this case, in step S46, the fiber inspection device 1 classifies the fibers e and e' as fibers whose status is not specified.

[0052] The above process is executed for each pair of uplink / downlink connecting leaf switch i and spine switch j.

[0053] 4 is completed, all fibers connecting leaf switch i and spine switch j are classified as good fibers, healthy fibers, or fibers with an unspecified status. After the processing of FIG. 4, the fiber inspection device 1 proceeds to the processing of FIG. 5.

[0054] In the process of FIG. 5, the fiber inspection device 1 identifies the state of each of the fibers that are classified as state-unspecified fibers among the fibers connecting the leaf switch i and the spine switch j.

[0055] In step S51, the fiber inspection device 1 selects a fiber e' classified as a good fiber from among the fibers in the opposite direction to the fiber e to be inspected. For example, if the fiber e is an uplink, the fiber inspection device 1 selects a downlink fiber e' classified as a good fiber, and if the fiber e is a downlink, the fiber inspection device 1 selects an uplink fiber e' classified as a good fiber.

[0056] In step S52, the fiber inspection device 1 controls each optical switch to establish an inspection path including fibers e and e'. The inspection path includes one fiber e whose status is unknown and one or more normal fibers. The testing terminal inputs test light into the inspection path, receives the test light that has passed through the inspection path, and measures the received optical power P of the test light.

[0057] In step S53, the fiber inspection device 1 determines whether the loss of the fiber on the inspection path is within the allowable loss based on the received light power P.

[0058] P ≥ P ok In this case, in step S54, the fiber inspection device 1 classifies the fiber e as a sound fiber.

[0059] P<P okIn this case, in step S55, the fiber inspection device 1 determines whether or not the test light has been received. ε Then, P<P ε In this case, the test terminal cannot receive the test light.

[0060] P ≥ P ε In this case, in step S56, the fiber inspection device 1 classifies the fiber e as a quality-degraded fiber.

[0061] P<P ε In this case, in step S57, the fiber inspection device 1 classifies the fiber e as a miswired fiber.

[0062] The above process is executed for each fiber whose state is not specified.

[0063] After the process of FIG. 5 is completed, all fibers connecting leaf switch i and spine switch j are classified as either good fibers, healthy fibers, degraded fibers, or miswired fibers.

[0064] [Example] An example of fiber inspection using the fiber inspection device 1 will be described with reference to Figs.

[0065] Figure 6 shows the fiber switching network to be tested. The fiber switching network shown in the figure includes leaf switches I1 and I2 and spine switches J3 and J4. Leaf switch I1 is connected to spine switch J3 by four fibers e1-e4. Leaf switch I1 is connected to spine switch J4 by two fibers e5 and e6. Leaf switch I2 is connected to spine switch J3 by two fibers e7 and e8. Leaf switch I2 is connected to spine switch J4 by four fibers e9-e12. A test terminal 50 is attached to leaf switch I1.

[0066] Assume that fiber e4 connecting leaf switch I1 and spine switch J3 is a deteriorated fiber.

[0067] In step 1, the fiber inspection device 1 inspects fibers e1-e4 connecting the leaf switch I1 and the spine switch J3, and fibers e5 and e6 connecting the leaf switch I1 and the spine switch J4. After inspecting fibers e1-e6 for each uplink-downlink pair, the fiber inspection device 1 inspects each of fibers e3 and e4 classified as status-unspecified fibers.

[0068] 7, the fiber inspection device 1 inspects fibers e1 and e2, which are a pair of uplink and downlink fibers connecting the leaf switch I1 and the spine switch J3. Because both fibers e1 and e2 are normal, the test terminal 50 can receive test light with sufficient strength. The fiber inspection device 1 classifies fibers e1 and e2 as good fibers.

[0069] Next, as shown in Figure 8, the fiber inspection device 1 inspects another uplink-downlink pair, fibers e3 and e4, connecting leaf switch I1 and spine switch J3. Because fiber e4 is degraded, the test terminal 50 receives test light with a lower intensity than expected. At this point, it is not possible to distinguish whether fiber e3 or fiber e4 is degraded. The fiber inspection device 1 classifies fibers e3 and e4 as fibers with an unspecified status.

[0070] 9, the fiber inspection device 1 inspects fibers e5 and e6, which are a pair of uplink and downlink fibers connecting the leaf switch I1 and the spine switch J4. Because both fibers e5 and e6 are normal, the testing terminal 50 can receive test light with sufficient strength. The fiber inspection device 1 classifies fibers e5 and e6 as good fibers.

[0071] Next, the fiber inspection device 1 identifies the states of the fibers e3 and e4, which are fibers with an unspecified state. To identify the fibers with an unspecified state, the fibers e3 and e4 are inspected in combination with the normal fibers e1 and e2.

[0072] 10, the fiber inspection device 1 inspects the downlink fiber e3 paired with the uplink fiber e2. Since the fiber e3 is normal, the test terminal 50 can receive test light with sufficient intensity. The fiber inspection device 1 classifies the fiber e3 as a healthy fiber.

[0073] 11, the fiber inspection device 1 inspects the uplink fiber e4 paired with the downlink fiber e1. Because the fiber e4 is degraded, the test terminal 50 receives test light with a lower intensity than expected. Since the fiber e1 is known to be normal, the fiber inspection device 1 classifies the fiber e4 as a quality-degraded fiber.

[0074] This is the processing of step 1.

[0075] Next, in procedure 2, the fiber inspection device 1 inspects fibers e7 and e8 connecting the leaf switch I2 and the spine switch J3, and fibers e9-e12 connecting the leaf switch I2 and the spine switch J4. In procedure 2, fibers e1, e2, e5, and e6, which were found to be normal in procedure 1, are used to inspect fibers e7-e12 connecting the leaf switch I2 and the spine switches J3 and J4, respectively.

[0076] 12, the fiber inspection device 1 first establishes an inspection path via fibers e1 and e2, and inspects fibers e7 and e8, which are an uplink and downlink pair connecting leaf switch I2 and spine switch J3. Because both fibers e7 and e8 are normal, the testing terminal 50 can receive test light with sufficient strength. The fiber inspection device 1 classifies fibers e7 and e8 as good fibers.

[0077] 13, the fiber inspection device 1 establishes an inspection path via fibers e5 and e6 and inspects fibers e9 and e10, which are an uplink and downlink pair connecting leaf switch I2 and spine switch J4. Because both fibers e9 and e10 are normal, the testing terminal 50 can receive test light with sufficient strength. The fiber inspection device 1 classifies fibers e9 and e10 as good fibers.

[0078] 14, the fiber inspection device 1 establishes an inspection path via fibers e5 and e6 and inspects fibers e11 and e12, which are an uplink and downlink pair connecting leaf switch I2 and spine switch J4. Because both fibers e11 and e12 are normal, the testing terminal 50 can receive test light with sufficient strength. The fiber inspection device 1 classifies fibers e11 and e12 as good fibers.

[0079] In step 2, since no fibers with unspecified states were present, this is the end of the processing in step 2. If any fibers with unspecified states are present, they are inspected one by one in the same manner as in step 1.

[0080] The fiber inspection device 1 outputs the inspection result that the fiber e4 is a quality-degraded fiber and that there is no miswired fiber.

[0081] [Effects of the fiber inspection device] Experiments were conducted using actual equipment on a network consisting of three leaf switches, two spine switches, and 24 single-mode fibers. A Whitebox switch / CFP2ACO was used as the test terminal. The probe light was 193.5 THz coherent light with a transmission power of 0.0 dBm. The threshold for determining whether a fiber had deteriorated quality was set to the sum of the maximum losses of the switches passing through the inspection path. When deteriorated fiber and miswired fiber were intentionally added, it was confirmed that the abnormal fiber could be correctly identified.

[0082] The total testing time required for the existing method of connecting a test terminal between a leaf switch and a spine switch and testing each fiber one by one can be calculated as follows: The number of switch pairs, which combine k leaf switches and m spine switches, is km. Since each switch pair is connected by v uplinks / downlinks, the number of tests is 2 kmv. The time required to install the test terminal is calculated as T t , the time required for one inspection is T p Then, the total inspection time is 2 km (T t +vT p )

[0083] The total inspection time required for the method proposed in this embodiment can be calculated as follows. If the average number of inspections required to identify the state of the fiber whose state is not identified in the processing of Figures 4 and 5 is |U|, then the number of inspections for a switch pair is v + 2|U|. Since the number of switch pairs is km, the total number of inspections is km(v + 2|U|). Assuming that the number of quality-degraded fibers and miswired fibers is sufficiently small and |U|<<v, the number of inspections can be approximated as kmv. The time required to install the test terminal is T t , the time required for one inspection is T p Then, the total inspection time is T t +kmvT p This becomes:

[0084] We simulated a large-scale data center with the number of leaf switches k = 32, the number of spine switches m = 32, and the number of fibers v = 16, and we simulated the time required to complete the inspection using both the existing method and the proposed method.

[0085] FIG. 15 shows the time T required to attach the test terminal. t The horizontal axis shows the relationship between the time required for inspection and the time required for inspection. t The vertical axis shows the time required for inspection, and the existing method is shown as Baseline, and the proposed method is shown as Ours. t When the time required for the proposed method is 600 seconds, the time required for the conventional method is 387 hours, while the time required for the proposed method is 26 hours. This indicates that the proposed method can complete fiber inspection 14 times faster without manual intervention.

[0086] FIG. 16 shows the relationship between the number of quality-degraded fibers and mis-wired fibers and the inspection time. The horizontal axis represents the number of quality-degraded fibers and mis-wired fibers, and the vertical axis represents the inspection time. t = 60 seconds. The time required to install the test terminal was set to be short enough so that the existing method would not be at a disadvantage. It can be seen that the proposed method significantly improves the time required to complete the inspection, even when the number of quality-degraded fibers and miswired fibers increases.

[0087] As described above, the fiber inspection device 1 of this embodiment includes a switch control unit 12 that controls the internal connection state of each switch to establish a path; a test terminal control unit 11 that controls the test terminal 50 that measures the received optical power of test light that has passed through the inspection path; a route calculation unit 14 that calculates the path along which the test light will pass through the switch and fiber to reach the inspection terminal 50 based on an assumed fiber wiring situation; and an inspection unit 13 that inputs the test light into the inspection path, measures the received optical power of the test light received by the inspection terminal 50, and classifies the state of the fiber on the inspection path based on the received optical power. The fiber inspection device 1 establishes an inspection path including one uplink and one downlink connecting a leaf switch and a spine switch as fibers to be inspected, measures the received optical power, and classifies the uplink and downlink as fibers with an unspecified state if the received optical power does not meet a threshold. For each fiber with an unspecified state, the fiber inspection device 1 establishes an inspection path including only one fiber with an unspecified state as the fiber to be inspected, measures the received optical power, and classifies the state of the fiber with an unspecified state based on the received optical power. This enables accurate inspection of multiple fibers.

[0088] In the fiber inspection device 1 of this embodiment, in Procedure 1, the state of the fiber connecting the leaf switch to which the test terminal is connected and each spine switch is classified, and in Procedure 2, the state of the fiber connecting the leaf switch to which the test terminal is not connected and each spine switch is classified. In Procedure 2, an inspection path is established including the fiber classified as normal in Procedure 1. This eliminates the need to reconnect the test terminal 50, avoids human error in reconnecting the test terminal 50, and shortens the inspection time.

[0089] 17, a general-purpose computer system including a central processing unit (CPU) 901, a memory 902, a storage 903, a communication device 904, an input device 905, and an output device 906 can be used as the fiber inspection device 1 described above. In this computer system, the CPU 901 executes a predetermined program loaded onto the memory 902, thereby realizing the fiber inspection device 1. This program can be recorded on a computer-readable non-transitory recording medium such as a magnetic disk, an optical disk, or a semiconductor memory, or can be distributed via a network.

[0090] REFERENCE SIGNS LIST 1 fiber inspection device 11 test terminal control unit 12 switch control unit 13 inspection unit 14 route calculation unit 15 route loss calculation unit 16 topology information storage unit 17 retention unit 50 test terminal

Claims

1. A fiber inspection device for inspecting the condition of a fiber connecting a first switch group and a second switch group, comprising: a switch control unit that controls the internal connection state of each switch to establish a route; a test terminal control unit that controls a test terminal that measures the received power of test light that has passed through the route; a route calculation unit that calculates the route along which the test light passes through the switches and fibers to reach the test terminal based on an assumed fiber wiring situation; and an inspection unit that inputs test light to the route, measures the received power of the test light received by the test terminal, and classifies the condition of the fiber on the route based on the received power, wherein the fiber inspection device establishes the route including one uplink and one downlink connecting between a switch of a first switch group and a switch of a second switch group as fibers to be inspected, measures the received power, and if the received power does not meet a threshold, classifies the uplink and the downlink as fibers with an unspecified status, and establishes the route including only one of the unspecified fibers as fibers to be inspected for each of the unspecified status fibers, measures the received power, and classifies the condition of the unspecified fiber based on the received power.

2. A fiber inspection device as claimed in claim 1, comprising: a first step of classifying the state of the fiber connecting between a first switch of said first switch group to which said test terminal is connected and each switch of said second switch group; a second step of classifying the state of the fiber connecting between each switch of said first switch group other than said first switch and each switch of said second switch group; and in the second step of establishing said path including the fiber classified as normal in the first step.

3. A fiber inspection device according to claim 1, wherein the switch control unit does not connect a port of the switch that is not on the path.

4. A fiber inspection method using a fiber inspection device for inspecting the condition of a fiber connecting a first switch group and a second switch group, comprising the steps of: controlling the internal connection state of each switch to establish a route; controlling a test terminal for measuring the received power of test light that has passed through the route; calculating a route through which the test light passes through the switches and fibers to reach the test terminal based on an assumed fiber wiring situation; inputting test light into the route, measuring the received power of the test light received by the test terminal, and classifying the condition of the fiber on the route based on the received power; the fiber inspection method establishes the route including one uplink and one downlink connecting between a switch of the first switch group and a switch of the second switch group as fibers to be inspected, measures the received power, and if the received power does not meet a threshold, classifies the uplink and the downlink as status-unspecified fibers; and for each of the status-unspecified fibers, establishes the route including only one of the status-unspecified fibers as a fiber to be inspected, measures the received power, and classifies the condition of the status-unspecified fiber based on the received power.

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