Optical transmission system and optical path setting and congestion control method

Abstract

An optical transmission system comprising a connection device 1 and a control device 2, wherein: the connection device 1 comprises a certain number of measuring devices 12 for measuring the quality of a transmission line to a user terminal 3, a notification device 13 for notifying the user terminal of Busy information, and a switching device 11 for switching the connection destination of the user terminal 3 to any one of the measuring device 12, the notification device 13, and an optical transmission network; the control device 2 comprises a control unit 21 that controls the switching device 1; and the control unit 21 detects a connection request from the user terminal 3, connects, when a free measuring device 12 exists in the certain number of measuring devices 12, the user terminal 3 to the free measuring device 12, temporarily connects, when no free measuring device 12 exists in the certain number of measuring devices 12, the user terminal 3 to the notification device 13 and connects, when a free measuring device 12 becomes available in the measuring devices 12, the user terminal 3 to the free measuring device 12, and connects the user terminal 3 to the optical transmission network after the quality of the line transmission has been measured by the measuring device 12.

Description

[Technical Field]

[0001] The present invention relates to an optical transmission system and an optical path setting and congestion control method. [Background technology]

[0002] In recent years, the application and spread of digital coherent optical transmission technology has progressed rapidly. The application of digital technology to optical transmission equipment has not only realized increased transmission capacity and transmission distance, but also simplified and reduced the cost of system configurations, including transmission lines, through adaptive compensation technology for transmission line characteristics (Non-Patent Document 1). This has led to progress in the miniaturization and cost reduction of the transceivers themselves, making optical transmission equipment easily available to users other than carriers.

[0003] Furthermore, openness is advancing in the optical transmission field, making it possible to use open hardware and software. An example of hardware (transponder) is a white-box optical transmission device in which the hardware and software are separated. An example of software is an open NetworkOS that can be installed in white-box optical transmission equipment (Non-Patent Documents 2-4). By utilizing open hardware and software, users other than carriers can also prepare optical transmission equipment and build transmission networks for their own in-house services (Non-Patent Document 5).

[0004] With the simplification, cost reduction, and openness of optical transmission areas, it is conceivable that in the future users other than carriers (for example, service providers such as data center operators) will prepare their own optical transmission equipment and establish end-to-end λ connections (optical path connections) between user locations. In such cases, it is expected that carriers will need to accommodate the optical paths of users from outside the carrier network and establish λ connections in the optimal transmission mode (Non-Patent Documents 6 and 7). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] H. Nishizawa and 7 others, “Open whitebox architecture for smart integration of optical networking and data center technology”, Journal of Optical Communications and Networking, Vol.13, No.1, January 2021, A78-A87 [Non-patent document 2] “TAI (Transponder Abstraction Interface)”, Telecominfraproject / oopt-tai, [online], [retrieved June 28, 2022],<URL: https: / / github.com / Telecominfraproject / oopt-tai> [Non-patent document 3] “Goldstone”, Telecominfraproject / oopt-goldstone, [online], [retrieved June 28, 2022],<URL: https: / / github.com / Telecominfraproject / oopt-goldstone> [Non-patent document 4] V. Lopez and 5 others, “Enabling fully programmable transponder white boxes”, Journal of Optical Communications and Networking, Vol.12, No.2, February 2020, A214-p.A223 [Non-patent document 5] "Building a backbone network using white-box optical transmission equipment for our own products - Achieving both network stability and high customizability at low cost," MIXI, November 14, 2019, [online], [Retrieved June 28, 2022].<URL: https: / / mixi.co.jp / news / 2019 / 1114 / 2096 / > [Non-patent document 6] H. Nishizawa, 5 others, "Study on Open All-Photonic Network in IOWN Global Forum," NTT Technical Review, [online], [searched on June 28, 2022] <url: https: www.ntt-review.jp archive ntttechnical.php?contents="ntr202205fa2.html"> [Non-Patent Document 7] "Open All-Photonic Network Functional Architecture", IOWN GLOBAL FORUM, [online], [Retrieved June 28, 2022],<URL: https: / / iowngf.org / technology / #Open-All-Photonic-Network> Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional technology had the problem that when a carrier terminates and accommodates a connection request from a user terminal to a carrier network, there was no way to automatically set up an optical path effectively using limited resources (especially transmission quality measurement equipment).

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a technology that can automatically set up an optical path using limited resources. [Means for solving the problem]

[0008] An optical transmission system according to one embodiment of the present invention comprises a connection device that connects one or more user terminals to a carrier's optical transmission network, and a control device that controls the connection device. The connection device comprises a certain number of measurement devices that measure the quality of the transmission path between the user terminals, a notification device that notifies the user terminals of Busy information, and a switching device that switches the connection destination of the user terminal to one of the measurement devices, the notification device, or the optical transmission network. The control device comprises a control unit that controls the switching device. The control unit detects a connection request from the user terminal, and if there is an available measurement device among the certain number of measurement devices, connects the user terminal to an available measurement device. If there is no available measurement device among the certain number of measurement devices, the control unit temporarily connects the user terminal to the notification device and then connects the user terminal to an available measurement device when an available measurement device becomes available. After the quality of the transmission path is measured by the connected measurement device, the user terminal is connected to the optical transmission network.

[0009] An optical path setting and congestion control method according to one embodiment of the present invention is an optical path setting and congestion control method performed by a connection device that connects one or more user terminals to a carrier's optical transmission network, and a control device that controls the connection device, wherein the connection device comprises a certain number of measurement devices for measuring the quality of the transmission path between the user terminals, a notification device for notifying the user terminal of Busy information, and a switching device for switching the connection destination of the user terminal to one of the measurement devices, the notification device, or the optical transmission network, and the control device comprises a control unit that controls the switching device, and the control unit detects a connection request from the user terminal, and if there is a vacant measurement device among the certain number of measurement devices, connects the user terminal to the vacant measurement device, and if there is no vacant measurement device among the certain number of measurement devices, connects the user terminal to the notification device once, and when a vacant measurement device becomes available, connects the user terminal to the vacant measurement device, and after the quality of the transmission path is measured by the connected measurement device, connects the user terminal to the optical transmission network. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a technique that can automatically set up an optical path using limited resources. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an optical transmission system. [Figure 2] FIG. 2 is a diagram illustrating an example of a network architecture. [Figure 3] FIG. 3 is a diagram illustrating an example of a network architecture. [Figure 4] FIG. 4 is a diagram illustrating an example of a network architecture. [Figure 5] FIG. 5 is a diagram illustrating an example of a network architecture. [Figure 6] FIG. 6 is a diagram illustrating an example of a network architecture. [Figure 7] FIG. 7 is a diagram showing a control sequence of the optical transmission system. [Figure 8] FIG. 8 is a diagram showing a processing image of the optical transmission system. [Figure 9] FIG. 9 is a diagram showing a processing image of the optical transmission system. [Figure 10] FIG. 10 is a diagram showing a processing image of the optical transmission system. [Figure 11] FIG. 11 is a diagram showing a processing image of the optical transmission system. [Figure 12] FIG. 12 is a diagram showing a processing image of the optical transmission system. [Figure 13] FIG. 13 is a diagram showing a processing image of the optical transmission system. [Figure 14] FIG. 14 is a diagram showing a processing image of the optical transmission system. [Figure 15] FIG. 15 is a diagram showing a processing image of the optical transmission system. [Figure 16] FIG. 16 is a diagram illustrating the first congestion control method. [Figure 17] FIG. 17 is a diagram illustrating the first congestion control method. [Figure 18] FIG. 18 is a diagram illustrating the first congestion control method. [Figure 19] FIG. 19 is a diagram illustrating a second congestion control method. [Figure 20] FIG. 20 is a diagram illustrating the third congestion control method. [Figure 21] FIG. 21 is a diagram illustrating a fourth congestion control method. [Figure 22] FIG. 22 is a diagram illustrating an example of transmission path information. [Figure 23] FIG. 23 is a diagram illustrating a fourth congestion control method. [Figure 24] FIG. 24 is a diagram illustrating a fifth congestion control method. [Figure 25] FIG. 25 is a diagram illustrating an example of transmission path information. [Figure 26] FIG. 26 is a diagram illustrating a fifth congestion control method. [Figure 27] FIG. 27 is a diagram showing a processing image of a specific embodiment. [Figure 28] FIG. 28 is a diagram showing a processing image of a specific embodiment. [Figure 29] FIG. 29 is a diagram showing a processing image of a specific embodiment. [Figure 30] FIG. 30 is a diagram showing a processing image of a specific embodiment. [Figure 31] FIG. 31 is a diagram showing a processing image of a specific embodiment. [Figure 32] FIG. 32 is a diagram showing a processing image of a specific embodiment. [Figure 33] FIG. 33 is a diagram illustrating a hardware configuration of the control device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0013] [Summary of the Invention] The present invention relates to a technology for automatically setting an optimal optical path based on a connection request from one or more user terminals connected to a carrier's optical transmission network (hereinafter referred to as the carrier network) via a dark fiber transmission line.

[0014] When setting up and establishing an optical path, the quality of the transmission path between the user terminal is measured, the optimal transmission mode is determined based on that transmission quality, and then a λ connection is made to the carrier network in that transmission mode. At this time, transmission quality measurement equipment is very expensive, and using multiple measurement equipment incurs huge costs. On the other hand, while preparing a small number of measurement equipment, it is desirable to accommodate each connection request from multiple user terminals without blocking (making them wait) as much as possible.

[0015] Therefore, the present invention discloses a connection device that connects a user terminal to a carrier network and a control device that controls the connection device. The connection device includes an optical path switching device, a small number of measurement devices, and a notification device that notifies Busy information. When there are no available measurement devices, the control device performs congestion control of connection requests based on the priority and urgency of the connection requests, temporarily connects the user terminal to the notification device to notify Busy information, and when an available measurement device becomes available, connects the connection request to the available measurement device.

[0016] This makes it possible to automatically set up many optical paths in response to multiple connection requests from one or more user terminals, even if there is an upper limit on the number of measurement devices. Furthermore, when connection requests become congested, it becomes possible to automatically set up appropriate optical paths taking into account factors such as priority and urgency.

[0017] [System Configuration] 1 is a diagram showing the configuration of an optical transmission system according to this embodiment. The optical transmission system includes a connection device 1 that connects a user terminal 3 to a carrier network, and a control device 2 that controls the connection device 1. The optical transmission system may be implemented as a single device (connection node), or may be implemented in combination with vendor devices.

[0018] The user terminal 3 is one or more user base terminals located outside the carrier network. The multiple user terminals 3 are connected to the connection device 1 via their respective transmission paths 100, and each includes a transceiver that transmits and receives optical signals to and from the connection device 1 via the respective transmission paths 100. The user terminal 3 is, for example, a communication device in a data center or the like, and more specifically, a transceiver or the like.

[0019] The connection device 1 includes a switching device 11 for switching the connection destination of the user terminal 3 to one of a measurement device 12, a notification device 13, and a carrier network, the measurement device 12 for measuring the quality of a transmission path 100 between the user terminal 3, and the notification device 13 for notifying the user terminal 3 of busy information, etc. The connection device 1 is, for example, located within the carrier network.

[0020] The switching device 11 is a device that terminates optical signals from the user terminal 3 and connects the user terminal 3 to the measurement device 12 and the notification device 13 in order to measure the quality of the transmission section and perform terminal authentication. After performing these processes, the switching device 11 connects the user terminal 3 to the carrier network if it is possible to connect to the carrier network, and blocks optical signals from abnormal terminals or user terminals 3 that are not permitted to be connected. The switching device 11 is, for example, an optical switch.

[0021] The measurement devices 12 are a fixed number of devices that measure the quality of the transmission path 100, which is a section where transmission quality is not measured. The fixed number is a small number (one or more) taking into consideration that the measurement devices 12 are expensive. The measurement devices 12 are, for example, coherent transceivers.

[0022] The notification device 13 is one or more devices that notify information such as Busy / OK / interrupt / connection denied using a predefined signal that can be distinguished / identified / determined by a user. For example, the notification device 13 generates and notifies Busy information, etc. on a main signal without preparing a separate wavelength, as in AMCC or OTN-GCC. Alternatively, the notification device 13 transmits Busy information, etc., using a signal in a specific wavelength band, as in OSC.

[0023] The control device 2 includes an optical signal control unit 21 that controls optical signals, a user terminal authentication unit 22 that authenticates the user terminal 3, a user terminal management unit 23 that manages information about the user terminal 3, a device characteristic storage unit 24 that stores device characteristics of the measurement device 12, a transmission path information estimation unit 25 that measures the quality of the transmission path 100 between the user terminal 3, and a notification control unit 26 that notifies the user terminal 3 of busy information, etc. The control device 2 is disposed, for example, in a server device in a carrier network.

[0024] The optical signal control unit 21 has the function of controlling and monitoring the switching device 11, the function of collecting information from the measuring devices 12 and monitoring the measuring devices 12, and the function of controlling the notification device 13. Specifically, the optical signal control unit 21 detects a connection request from the user terminal 3, and if a certain number of measuring devices 12 are available, connects the user terminal 3 to an available measuring device 12, and if the certain number of measuring devices 12 are not available, connects the user terminal 3 to the notification device 13 once, and connects to an available measuring device 12 when an available measuring device 12 becomes available, and after the connected measuring device 12 measures the quality of the transmission path, connects the user terminal 3 to the carrier network.

[0025] The user terminal authentication unit 22 has the function of referencing the information on the user terminal 3 held in the user terminal management unit 23, authenticating the user terminal 3 connecting from outside the carrier network, and determining whether or not it is possible to connect to the carrier network.

[0026] The user terminal management unit 23 has a function of retaining user terminal information of the user terminal 3 that connects from outside the carrier network. The user terminal information includes, for example, a user name, a registration number assigned by the carrier, a line ID, a terminal ID / model number / serial number / MAC address of the user terminal, and a port number of the switching device 11 to which the user terminal connects.

[0027] The device characteristics storage unit 24 has a function of storing the actual device characteristics of a certain number of measuring devices 12. The actual device characteristics are data required to estimate the quality of the transmission section from the BER value, such as data representing the relationship between BER and OSNR.

[0028] The transmission path information estimation unit 25 has an estimation function for estimating and calculating the transmission quality of the transmission section between the user terminal 3 and the carrier network, and a storage function for storing the estimated transmission quality information and the time when the transmission quality was last measured, etc. The estimation function and the storage function may be separate functional units.

[0029] The notification control unit 26 has a function of controlling and managing the notification device 13. The notification control unit 26 may be disposed inside the optical signal control unit 21.

[0030] [Network Architecture] The connection configuration on the user terminal side can be one in which one user terminal is connected to one transmission line, one in which one or more user terminals are connected to one transmission line and a multiplexer is connected, or a combination of these two configurations.

[0031] On the other hand, the connection form of the carrier side inlet can be a form in which a demultiplexer is connected or a form in which a demultiplexer is not connected. The types of switching device 11 include FXC and WXC (wavelength switch including WSS / ROADM).

[0032] By combining these, for example, if the connection topology on the user terminal side is one user terminal per transmission path, the connection topology at the carrier side entrance can be either with a splitter connected or without a splitter connected, and switching device 11 can be either FXC or WXC, which is a possible network architecture.

[0033] Another possible network architecture is one in which, for example, when the connection topology on the user terminal side is one or more user terminals on one transmission line and there is a multiplexer, and the connection topology on the carrier side entrance does not connect a demultiplexer, the switching device 11 is a WXC.

[0034] Alternatively, for example, if the connection topology on the user terminal side is one or more user terminals on one transmission line and there is a multiplexer, and the connection topology on the carrier side entrance is to connect a demultiplexer, then a network architecture is also possible in which the switching device 11 can be either FXC or WXC.

[0035] Of course, network architectures with combinations other than those described above are also possible.

[0036] 1 illustrates a typical example of a network architecture.

[0037] FIG. 2 shows a network architecture in which one user terminal 3 is connected to one transmission line 100 and an FXC is used as a switching device 11.

[0038] Figure 3 shows a network architecture in which one or more user terminals 3 are connected to one transmission path 100, a multiplexer 4 is placed on the user terminal side, a demultiplexer 5 is placed at the carrier side entrance, and an FXC is used as a switching device 11.

[0039] FIG. 4 shows a network architecture in which one or more user terminals are connected to one transmission line 100, a multiplexer 4 is arranged on the user terminal side, and a WXC is used as a switching device 11.

[0040] FIG. 5 shows a network architecture in which only one or more user terminals are connected to one transmission path 100, a multiplexer 4 is placed on the side of the user terminal to which one or more user terminals are connected, a demultiplexer 5 is placed at the carrier side entrance corresponding to the user terminal side on which the multiplexer 4 is placed, and a WXC is used as a switching device 11.

[0041] FIG. 6 shows a network architecture in which only one or more user terminals are connected to one transmission path 100, a multiplexer 4 is placed on the user terminal side to which one or more user terminals are connected, and a WXC is used as a switching device 11.

[0042] The multiplexer 4 and the demultiplexer 5 are, for example, wavelength multiplexing / demultiplexing devices.

[0043] [Overall system operation] FIG. 7 is a diagram showing a control sequence of the optical transmission system.

[0044] Step S1; First, the carrier recognizes and detects a connection request from a user. Specifically, the optical signal control unit 21 monitors the optical signal indicating the arrival of the connection request. Then, the user notifies the carrier that they have sent the connection request using an API or the like dedicated to communication with the carrier.

[0045] At this time, if the user behaves differently from what the carrier expects, the optical signal control unit 21 cuts off the optical signal from that user using the function of connecting to the Parking-State (a default position prepared in advance for unexpected behavior) / optical signal disconnection function of the switching device 11. The notification device 13 may notify the user of the connection failure / connection stop command.

[0046] Step S2; Next, user authentication is performed. Specifically, the user terminal authentication unit 22 authenticates the user terminal 3 that sent the connection request based on the terminal ID and line ID. The user terminal authentication unit 22 may perform one or more authentications (two-step authentication, etc.) at one or more layers.

[0047] In this case, if the user behaves differently from what the carrier expects, the optical signal control unit 21 cuts off the optical signal from the user using the function of connecting to the Parking-State / optical signal disconnection function of the switching device 11. The notification device 13 may notify the user of a connection failure / connection stop command.

[0048] Step S3; Next, the carrier measures and acquires the transmission path information of the user. Specifically, the transmission path information estimation unit 25 measures the quality of the transmission path 100 between the carrier and the user terminal 3 that has sent the connection request.

[0049] At this time, if the time elapsed since the previous measurement time is equal to or less than a threshold and there is no information about construction work on the transmission line, the transmission line information estimating unit 25 may not measure the quality of the transmission line and may reuse the past measurement results. Also, if the connection request is from a user terminal 3 that has been connected in the past, the transmission line information estimating unit 25 may reuse the past measurement results.

[0050] Thereafter, if the transmission path information estimating unit 25 does not or cannot reuse past measurement results, it checks whether there is available space in the measuring device 12. If there is available space in the measuring device 12, the process proceeds to step S6, and if there is no available space in the measuring device 12, the process proceeds to step S4.

[0051] Step S4; If there is no available measuring device 12, the carrier notifies the user of busy information. Specifically, the notification control unit 26 transmits busy information from the notification device 13 to the user terminal 3. At this time, the carrier may suspend quality measurement of a user with a low priority among users currently measuring the quality of the transmission path, notify the suspension information, and forcibly make the measuring device 12 that was measuring the quality of the transmission path available.

[0052] Step S5; After step 4, the user recognizes that it is his / her turn and that there is an available space in the measuring device 12. For example, the notification control unit 26 and the notification device 13 send an OK signal to the user terminal 3.

[0053] The user may periodically attempt to reconnect until an OK signal is received. Periodic connection methods include connecting at a predetermined time interval, or reconnecting using an existing retransmission timer setting (e.g., exponential backoff).

[0054] Alternatively, the notification device 13 may notify a retry time using a Busy signal, and the user may attempt to reconnect at that retry time. The optical signal control unit 21 may use the ID of the user terminal 3 to schedule the connection time and the allocation of a measurement device 12 for each user terminal 3. The user terminal 3 may include information indicating high priority in the optical signal of the connection request, and instruct the creation of an available measurement device 12 so that the user terminal 3 can be connected preferentially. The carrier may dynamically change the priority of the user terminal 3 according to the behavior of the user terminal 3, and prioritize the connection of user terminals 3 with high priority.

[0055] Step S6; After step 5 or when the measuring device 12 has free space, the transmission path measurement is performed. Specifically, the transmission path information estimating unit 25 measures the quality of the transmission path 100 between the user terminal 3 that has sent the connection request. The transmission path information estimating unit 25 may record the measurement result together with the measurement completion time.

[0056] The control device 2 then determines the optimal transmission mode based on the measured transmission quality, notifies the user of the determined transmission mode, and establishes a λ connection with the carrier network in that transmission mode. Note that existing methods are used for determining and notifying the transmission mode.

[0057] Step S7 (not shown in FIG. 7 ); Steps S1 to S6 are based on normal connection requests. However, emergency connection requests may be received. When such emergency communication occurs, the control device 2 notifies the user currently measuring the quality of the transmission path of interruption / busy information, interrupts the quality measurement of the transmission path, and prioritizes the quality measurement of the transmission path related to the emergency connection request. Thereafter, the control device 2 processes the interrupted quality measurement as usual using an available measurement device.

[0058] So far, the overall operation of the optical transmission system has been described. Note that steps S2 to S4 can be performed in any order. For example, user authentication may be performed after determining whether the measuring device 12 is available, and if the measuring device 12 is available and the user authentication is successful, the quality of the transmission path may be measured.

[0059] [Specific processing of steps S1 to S7] Specific processing of step S1; The user terminal 3a transmits a connection request and terminal information on an optical signal to the carrier side (see FIG. 8). At this time, the user may explicitly notify the carrier side that he or she has sent a connection request. The user terminal 3 may also include in the connection request the priority of the connection request (e.g., an urgent connection request) and the purpose of the connection (e.g., periodic data backup).

[0060] The optical signal control unit 21 monitors and detects the level of the optical signal from the user terminal 3 a. When the user notifies the carrier side that he or she has sent a connection request, the optical signal control unit 21 receives the notification.

[0061] Specific processing of step S2; The optical signal control unit 21 checks the availability of the measurement devices 12a to 12n, and if there is availability among the measurement devices 12a to 12n, connects the user terminal 3a to the available measurement device 12a (see FIG. 9). If there is no availability among the measurement devices 12a to 12n, congestion control, which will be described later, is performed.

[0062] The user terminal authentication unit 22 extracts the terminal information carried in the optical signal received by the measurement device 12a and acquires information about the connected user terminal 3a. The user terminal authentication unit 22 then refers to the user terminal management unit 23 and compares it with the acquired information about the user terminal 3a.

[0063] Specific processing of step S3; The transmission path information estimation unit 25 acquires the actual device characteristics (data representing the relationship between BER and OSNR) of the measuring device 12a to which the connection request has arrived from the device characteristics storage unit 24, and estimates the transmission quality of the transmission path 100a, which is a section where transmission quality has not been measured, using the actual device characteristics of the measuring device 12a (see Figure 10).

[0064] In this case, the transmission path information estimation unit 25 may implement "Takeo Sasai and five others, 'Digital Backpropagation for Optical Path Monitoring: Loss Profile and Passband Narrowing Estimation', 2020 European Conference on Optical Communications (ECOC), 2020" to estimate transmission path information (level diagram, loss, fiber type), and estimate transmission quality based on the transmission path information.

[0065] As described above, if the time elapsed since the previous measurement is equal to or less than a threshold and there is no information about construction work on the transmission line, the transmission line information estimating unit 25 may not measure the quality of the transmission line and may reuse the results of past measurements. Also, if the connection request is from a user terminal 3 that has previously been connected, the transmission line information estimating unit 25 may reuse the results of past measurements.

[0066] Specific processing of step S4; If there is no available capacity among the measuring devices 12a to 12n, the optical signal control unit 21 connects the user terminal 3a to the notification device 13 (see FIG. 11). Thereafter, the notification control unit 26 and the notification device 13 notify the user terminal 3a of Busy information.

[0067] At this time, as described above, the optical signal control unit 21 may interrupt the quality measurement of a user with a low priority among the users currently measuring the quality of the transmission path, notify the interruption information, and forcibly make the measuring device 12 that was measuring the quality of the transmission path available. The priority of the user is determined, for example, based on information registered in the user terminal management unit 23 and the priority explicitly specified by the user when making a connection request.

[0068] Specific processing of step S5; After the measuring device 12 becomes available, the optical signal control unit 21 connects the user terminal 3 (user terminal 3a) for which user authentication and transmission quality estimation have not been completed to the notification device 13 (see FIG. 12). Thereafter, the notification control unit 26 and the notification device 13 transmit an OK signal to the user terminal 3a to be connected.

[0069] At this time, the notification device 13 may notify the user to periodically attempt to reconnect until a free connection becomes available on one of the measurement devices 12a to 12n. Alternatively, the user may periodically attempt to reconnect. Alternatively, the notification device 13 may estimate the time when a free connection will become available on one of the measurement devices 12a to 12n, notify the user of the estimated time as a retry time, and control the user to attempt to reconnect at the retry time.

[0070] Furthermore, the optical signal control unit 21 may use information about the user terminals 3 to schedule the connection time and the allocation of measurement devices 12 for each user terminal. The user terminals 3 may include information indicating high priority in their connection request signals and instruct the creation of an available measurement device so that they can be connected preferentially. The carrier may dynamically change the priority of the user terminals 3 according to the behavior of the user terminals 3, and prioritize the connection of user terminals 3 with high priority.

[0071] Specific processing of step S6; After a vacant measuring device 12a to 12n becomes available, the optical signal control unit 21 connects the vacant measuring device 12b to a user terminal 3 (user terminal 3a) for which user authentication and transmission quality estimation have not been completed, and notifies the transmission path information estimating unit 25 of information for connecting to the vacant measuring device 12b (e.g., the location of the measuring device, the slot number) (see Figure 13).

[0072] The transmission path information estimating unit 25 connects to the measuring device 12b notified by the optical signal control unit 21 and measures the transmission quality of the transmission path 100a, which is a section where transmission quality has not been measured. After completing the measurement of the transmission quality, the transmission path information estimating unit 25 may record the measurement result together with the measurement completion time.

[0073] Thereafter, the optical signal control unit 21 establishes the route of the optical path related to the connection request of the user terminal 3a within the carrier network, and then controls the switching device 11 to connect the user terminal 3a to the carrier network (see FIG. 14).

[0074] Specific processing of step S7; When an emergency call occurs, the optical signal control unit 21 notifies the user terminals 3a to 3c currently measuring the quality of the transmission path of interruption / busy information, interrupts the quality measurement of the transmission path, and gives priority to the quality measurement of the transmission path related to the emergency connection request (see Figure 15).

[0075] [Congestion control] Congestion control will now be described. Each of the five congestion controls described below may be implemented individually or in combination of two or more of the five congestion controls.

[0076] [First congestion control method] The first congestion control method is a FIFO method in which connection requests are processed in the order in which they arrive (see FIGS. 16 to 18). Specifically, when there are multiple connection requests when a certain number of measurement devices 12 are full, the method connects the user terminals 3 to available measurement devices 12 in the order in which the connection requests arrive.

[0077] The connection device 1 is assumed to include three measuring devices 12a to 12c. The three measuring devices 12a to 12c are each line synchronized with each of the user terminals 3a to 3c, and it takes several minutes to complete the estimation of transmission quality from the BER.

[0078] When all three measurement devices 12a to 12c are in use and a connection request signal is received from user terminal 3m (step S101), optical signal control unit 21 connects user terminal 3m to notification device 13 to notify that it is busy (step S102).

[0079] Thereafter, the notification control unit 26 and the notification device 13 notify the user terminal 3m of the Busy information (step S103). For example, an AMCC / GCC / pilot tone indicating Busy, or a signal OSC of a specific wavelength indicating Busy, is transmitted.

[0080] Next, when a connection request signal arrives from the user terminal 3n (step S104), the optical signal control unit 21 connects the user terminal 3n to the notification device 13 to notify that the user terminal 3n is busy (step S105). Thereafter, the notification control unit 26 and the notification device 13 notify the user terminal 3n of the busy information in the same manner as above (step S106).

[0081] The optical signal control unit 21 repeatedly switches the connection destination of the notification device 13 to the user terminal 3m or the user terminal 3n, and the notification control unit 26 and the notification device 13 periodically send a Busy signal to the user terminal 3m and the user terminal 3n until an available space becomes available in the measurement devices 12a to 12c.

[0082] Thereafter, when a vacant measuring device 12a to 12c becomes available, the optical signal control unit 21 connects the user terminal 3m to the vacant measuring device 12c (step S107), and then connects the user terminal 3n to the vacant measuring device 12b (step S108).

[0083] [Second congestion control method] The second congestion control method is a preemptive method that processes connection requests in order of priority (see Fig. 19). Specifically, when there are multiple connection requests, including a connection request currently measuring the quality of a transmission path, and there is no available capacity in a certain number of measurement devices 12, if the priority of the new connection request is higher than the priority of the connection request currently measuring the quality of the transmission path, the method switches the connection destination of the measurement device 12 currently measuring the quality of the transmission path to the user terminal of the new connection request.

[0084] When a high-priority connection request signal arrives from user terminal 3m while all three measurement devices 12a to 12c are in use (step S201), optical signal control unit 21 switches the connection destination of measurement device 12c, which is measuring the quality of the low-priority connection request, from user terminal 3c to user terminal 3m (step S202), and connects user terminal 3c to notification device 13 (step S203). Thereafter, notification control unit 26 and notification device 13 notify user terminal 3c of the interruption of transmission path estimation (step S204).

[0085] [Third congestion control method] The third congestion control method is a control method that prioritizes urgent connection requests (see FIG. 20). Specifically, when a connection request from a user terminal 3 is an urgent connection request, this method connects the user terminal 3 to one of a certain number of measurement devices 12 that is used only in emergencies.

[0086] One or more of the multiple measurement devices 12 are prepared for emergency connection. The measurement device 12a for emergency connection is not used normally, but is used only in emergencies. When an emergency connection request signal is received from the user terminal 3m (step S301), the optical signal control unit 21 connects the user terminal 3m to the measurement device 12a for emergency connection (step S302).

[0087] [Fourth congestion control method] The fourth congestion control method is a control method that takes into account the final estimated time of transmission path quality (see Figs. 21 to 23). Specifically, when a certain number of measurement devices 12 are full, this method connects the user terminal 3 to an available measurement device 12 in order of the earliest measurement device's completion time of transmission path quality measurement.

[0088] It is assumed that all three measurement devices 12a to 12c are in use, and that transmission path information such as the measurement completion time of each of the transmission paths 100a to 100c is held in the transmission path information estimation unit 25. When a connection request signal arrives from the user terminal 3m (step S401), the optical signal control unit 21 determines that there is almost no change in the transmission path information for the transmission section of the transmission path 100c where the transmission path information was most recently measured, and connects the user terminal 3m to the measurement device 12c to yield the quality measurement process to the connection request from the newly arrived user terminal 3m (step S402).

[0089] [Fifth congestion control method] The fifth congestion control method is a time-specified control method that takes into account the estimated final time of the transmission path (see Figs. 24 to 26). Specifically, when a certain number of measurement devices 12 are not available, this method connects the user terminal 3 to an available measurement device 12 in the order of the specified times of the reconnection requests.

[0090] It is assumed that all three measurement devices 12a to 12c are in use, and that transmission path information such as how many seconds ago measurement of each of the transmission paths 100a to 100c started is held in transmission path information estimation unit 25. When a connection request signal arrives from user terminal 3m (step S501), optical signal control unit 21 connects user terminal 3m to notification device 13 to notify that it is busy (step S502).

[0091] Thereafter, the notification control unit 26 and the notification device 13 determine the reconnection time as the measurement completion time of the measurement device 12c that becomes available earliest among the measurement devices 12a to 12c based on the transmission path information of the transmission path information estimation unit 25, and notify the user terminal 3m of the reconnection time (step S503). For example, a request for reconnection is made at ____ time 30 seconds later.

[0092] Thereafter, the optical signal control unit 21 receives a reconnection request signal transmitted from the user terminal 3m at the reconnection time (step S504), and connects the user terminal 3m to the now-available measuring device 12c (step S505).

[0093] [Specific examples (use cases)] As shown in Fig. 27, users A to C are a group of users who have their own data centers outside the carrier network and can connect via the carrier network. Since actual communication is bidirectional, terminal authentication / transmission path quality estimation is performed in both section A and section B, but for simplicity, a specific example of section A will be explained. The same applies to section B. Only one measuring device 12 and one notifying device 13 are each located within the carrier on the section A side.

[0094] The SLAs (Service Level Agreements) of users A to C are SLA_A, SLA_B, and SLA_C, respectively, and the higher the priority of the SLA, the higher the priority of the connection request. Here, SLA_A>SLA_B>SLA_C.

[0095] The user terminal management unit 23 registers information about each of the user terminals 3a to 3c (for example, user number, terminal ID, line ID, SLA, port number of the switching device 11 to which the user terminal is connected).

[0096] To prepare for an imminent disaster, each of users A to C connects user terminals 3a to 3c to the carrier network to back up data and starts data transfer. To do this, user terminals 3a to 3c transmit connection requests into the carrier network (see FIG. 28).

[0097] First, the optical signal control unit 21 detects connection requests from each of the user terminals 3a to 3c and determines the user terminal 3 to connect to the measurement device 12. In this embodiment, the optical signal control unit 21 determines the user terminal 3a with the longest SLA as the user terminal to connect to the measurement device 12 first.

[0098] Thereafter, optical signal control unit 21 refers to user terminal management unit 23, identifies the port number of switching device 11 to which user terminal 3a is connected, and connects user terminal 3a to measurement device 12. For users B and C who were unable to obtain a connection to measurement device 12, optical signal control unit 21 controls switching device 11 and notification device 13, respectively, to temporarily connect users B and C to notification device 13 and have notification device 13 notify them of a Busy signal and a retry time.

[0099] Next, optical signal control unit 21 acquires the contents of the connection request from user terminal 3a that has arrived at measurement device 12 and information about user terminal 3a, and passes the acquired information to user terminal authentication unit 22. User terminal authentication unit 22 performs authentication by referring to user terminal management unit 23 (see FIG. 29).

[0100] After the authentication, if the user terminal is permitted to connect to the carrier network, the process proceeds to transmission path quality estimation processing. If the user terminal is not permitted to connect, the optical signal control unit 21 blocks the optical signal using the optical signal disconnection function of the switching device 11 to reject the connection to the carrier network. At this time, the notification device 13 may transmit a connection rejection signal to notify the user terminal that the connection request has been rejected.

[0101] Next, the transmission path information estimator 25 estimates the transmission quality of the transmission path 100a to which the user terminal 3a is connected (see FIG. 30). Specifically, the transmission path information estimator 25 inquires of the optical signal controller 21 about the BER recorded in the measuring device 12, acquires the actual device characteristics of the measuring device 12 from the device characteristics storage unit 24, and uses this information to estimate the transmission quality of the transmission path 100a in section A connecting the user terminal 3a and the carrier network.

[0102] A similar control sequence is also carried out in section B.

[0103] Next, the optical signal control unit 21 searches for a route that can be opened within the carrier network or a route that satisfies the user's bandwidth and other requirements, and determines an appropriate route. The optical signal control unit 21 also estimates the transmission quality of the determined route. The optical signal control unit 21 adds up the transmission quality of each transmission section, including the carrier network, and calculates the optimal transmission mode based on this sum. The optical signal control unit 21 then sets the calculated transmission mode to the user terminal 3a and notifies it.

[0104] Finally, the optical signal control unit 21 opens a route through which the optical path passes within the carrier network (see FIG. 31). The optical signal control unit 21 also controls the switching device 11 to provide an optimal optical path between the bases of user A.

[0105] Thereafter, users B and C reconnect at the retry time, so the optical signal control unit 21 performs the same procedure as for user A for users B and C in that order (see FIG. 32).

[0106] [effect] According to this embodiment, the optical signal control unit 21 of the control device 2 detects a connection request from a user terminal 3 in the connection device 1, and if a certain number of measuring devices 12 are available, it connects the user terminal 3 to an available measuring device 12, and if there are not certain number of measuring devices 12 available, it temporarily connects the user terminal 3 to a notification device 13 and connects it to an available measuring device 12 when an available measuring device 12 becomes available, and after the connected measuring device 12 measures the quality of the transmission path 100, it connects the user terminal 3 to the optical transmission network.Therefore, even if there is an upper limit to the number of measuring devices 12, it is possible to automatically set many optical paths in response to multiple connection requests from one or more user terminals 3.

[0107] Furthermore, according to this embodiment, the optical signal control unit 21 of the control device 2 uses a first congestion control method in which, when there are multiple connection requests in a case where a certain number of measurement devices 12 are not available, the user terminal 3 is connected to an available measurement device 12 in the order of arrival or priority of the connection requests; a second congestion control method in which, when there are multiple connection requests including a connection request in the middle of measuring the quality of the transmission path in a case where there are multiple connection requests in a case where there are multiple measurement devices 12 not available, the connection destination of the measurement device 12 in the middle of measuring the quality of the transmission path is switched to the user terminal 3 of the new connection request if the priority of the new connection request is higher than the priority of the connection request in the middle of measuring the quality of the transmission path; In the case where the connection request from the user terminal 3 is an urgent connection request, a third congestion control method is performed in which the user terminal 3 is connected to a measuring device 12 that is used only in emergencies out of a certain number of measuring devices 12; a fourth congestion control method is performed in which, when a certain number of measuring devices 12 are not available, the user terminal 3 is connected to an available measuring device 12 in order of the earliest completion time of transmission path quality measurement in each measuring device 12; or a fifth congestion control method is performed in which, when a certain number of measuring devices 12 are not available, the user terminal 3 is connected to an available measuring device 12 in the order of the specified time of the reconnection request, thereby making it possible to automatically set up an optical path appropriately.

[0108] [others] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention.

[0109] The control device 2 of the present embodiment described above can be realized, for example, by using a general-purpose computer system including a CPU 901, a memory 902, a storage 903, a communication device 904, an input device 905, and an output device 906, as shown in Fig. 33. The memory 902 and the storage 903 are storage devices. In the computer system, the CPU 901 executes a predetermined program loaded onto the memory 902, thereby realizing each function of the control device 2.

[0110] The control device 2 may be implemented by one computer. The control device 2 may be implemented by multiple computers. The control device 2 may be a virtual machine implemented on a computer. The program for the control device 2 may be stored in a computer-readable recording medium such as an HDD, SSD, USB memory, CD, or DVD. The program for the control device 2 may also be distributed via a communication network. [Explanation of symbols]

[0111] 1: Connection device 11: Switching device 12: Measuring equipment 13: Notification device 2: Control device 21: Optical signal control unit 22: User terminal authentication unit 23: User terminal management unit 24: Device characteristics holding section 25: Transmission path information estimation unit 26: Notification control section 3: User terminal 4: Multiplexer 5: Duplexer 100: Transmission line 901:CPU 902: Memory 903:Storage 904:Communication equipment 905: Input device 906: Output device< / url:>

Claims

1. An optical transmission system comprising a connection device that connects one or more user terminals to a carrier's optical transmission network, and a control device that controls the connection device, The connection device is a certain number of measurement devices for measuring the quality of a transmission path between the user terminal and the device; a notification device for notifying the user terminal of busy information; a switching device for switching a connection destination of the user terminal to any one of the measurement device, the notification device, and the optical transmission network; The control device a control unit for controlling the switching device, The control unit An optical transmission system that detects a connection request from the user terminal, and if there is a vacant measuring device among the certain number of measuring devices, connects the user terminal to the vacant measuring device, and if there is no vacant measuring device among the certain number of measuring devices, temporarily connects the user terminal to the notification device and then connects it to a vacant measuring device when a vacant measuring device becomes available, and after measuring the quality of the transmission path using the connected measuring device, connects the user terminal to the optical transmission network.

2. The control unit 2. The optical transmission system according to claim 1, wherein when there are no available measurement devices among the certain number of measurement devices and there are multiple connection requests, the system connects the user terminal to an available measurement device in order of arrival or priority of the connection requests.

3. The control unit 2. The optical transmission system according to claim 1, wherein when there are no available measurement devices among the certain number of measurement devices and there are multiple connection requests including a connection request during quality measurement of the transmission path, if the priority of the new connection request is higher than the priority of the connection request during quality measurement of the transmission path, the connection destination of the measurement device during quality measurement of the transmission path is switched to the user terminal of the new connection request.

4. The control unit 2. The optical transmission system according to claim 1, wherein when a connection request from said user terminal is an urgent connection request, said user terminal is connected to one of said certain number of measurement devices that is used only in emergencies.

5. The control unit 2. The optical transmission system according to claim 1, wherein when there are no available measuring devices among the certain number of measuring devices, the user terminals are connected to available measuring devices in order of earliest completion time of quality measurement of the transmission path in each measuring device.

6. The control unit 2. The optical transmission system according to claim 1, wherein when there are no available measurement devices among the certain number of measurement devices, the user terminals are connected to available measurement devices in the order of the designated times of the reconnection requests.

7. An optical path setting and congestion control method performed by a connection device that connects one or more user terminals to an optical transmission network of a carrier and a control device that controls the connection device, comprising: The connection device is a certain number of measurement devices for measuring the quality of a transmission path between the user terminal and the device; a notification device for notifying the user terminal of busy information; a switching device for switching a connection destination of the user terminal to any one of the measurement device, the notification device, and the optical transmission network; The control device a control unit for controlling the switching device, The control unit An optical path setting and congestion control method that detects a connection request from the user terminal, and if there is a vacant measuring device among the certain number of measuring devices, connects the user terminal to the vacant measuring device, and if there is no vacant measuring device among the certain number of measuring devices, temporarily connects the user terminal to the notification device, and when a vacant measuring device becomes available, connects the user terminal to the vacant measuring device, and after measuring the quality of the transmission path using the connected measuring device, connects the user terminal to the optical transmission network.

8. The control unit When there are no available measurement devices among the certain number of measurement devices and there are multiple connection requests, connecting the user terminal to an available measurement device in the order of arrival or priority of the connection requests; When there are no available measurement devices among the certain number of measurement devices and there are a plurality of connection requests including a connection request during quality measurement of a transmission path, if the priority of a new connection request is higher than the priority of the connection request during quality measurement of the transmission path, switch the connection destination of the measurement device during quality measurement of the transmission path to the user terminal of the new connection request; If the connection request from the user terminal is an urgent connection request, connect the user terminal to a measurement device that is used only in emergencies among the certain number of measurement devices; When there are no free measuring devices among the certain number of measuring devices, connecting the user terminal to a free measuring device in order of the earliest completion time of the quality measurement of the transmission path in each measuring device; Or, 8. The optical path setting and congestion control method according to claim 7, wherein when there are no available measurement devices among said certain number of measurement devices, user terminals are connected to available measurement devices in the order of the times designated in the reconnection requests.

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