Optical transmission device, optical transmission system, and method for updating optical transmission device

Abstract

To suppress an influence related to stop of a communication service at the time of updating an optical transmission device for transmitting frames.SOLUTION: An optical transmission device comprises a signal processing section, a first frame generating section, and a second frame generating section. The signal processing section stores client signals in one or more time slot strings of n time slot strings. The first frame generating section generates a frame including client signals stored in some time slot strings of the n time slot strings. The second frame generating section generates a frame including client signals stored in other time slot strings of the n time slot strings. When the first frame generating section stops and the second frame generating section operates, the signal processing section stores the client signals in the other time slot strings.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to an optical transmission device, an optical transmission system, and a method for updating an optical transmission device.

Background Art

[0002] As one of the technologies for realizing high-capacity optical communication, OTN (Optical Transport Network) has been widely put into practical use. OTN is defined in ITU-T Recommendation G.709. Further, as one of the technologies for transmitting traffic exceeding 100G in OTN, FlexO (or OTUCn) has been proposed. FlexO is defined in ITU-T Recommendations G.709.1 and G709.3. In FlexO, traffic exceeding 100G is transmitted using optical components for transmitting 100G traffic. Furthermore, FlexO for transmitting 200G / 400G traffic has also been proposed.

[0003] On the other hand, in order to improve the performance of an optical network, it is preferable to replace an old communication system with a new communication system. For example, an optical transmission device for transmitting 400G traffic is updated from a configuration including four sets of 100G FlexO components to a configuration including two sets of 200G FlexO components.

[0004] As related art, a technique for mapping a plurality of client signals to a FlexO frame and transmitting them has been proposed (for example, Patent Document 1). Also, a method for quickly recovering a line break that occurs when changing the setting of a communication standard has been proposed (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] When updating an optical transmission device, it is preferable that the influence related to the suspension of a communication service is sufficiently suppressed. For this reason, when updating the optical transmission device, it is preferable to stop a part of a plurality of components mounted in the optical transmission device and continue communication using the remaining components. However, in this case, it may be necessary to change the bandwidth of a frame (for example, an ODU frame) for storing a client signal in OTN.

[0007] However, in the prior art, when transmitting traffic exceeding 100G in OTN, a method of changing the bandwidth of a frame (or changing mapping) is not supported. For example, ODUflex Hitless adjustment defined in ITU-T Recommendation G.7044 is limited to traffic of 100G or less. In addition, Link capacity adjustment scheme defined in ITU-T Recommendation G.7042 supports only a link with a maximum of 40G. For this reason, in a communication system that transmits traffic exceeding 100G in OTN, the influence related to the suspension of the communication service becomes large when updating the optical transmission device.

[0008] An object according to one aspect of the present invention is to suppress the influence related to the suspension of a communication service when updating an optical transmission device that transmits a frame.

MEANS FOR SOLVING THE PROBLEMS

[0009] An optical transmission device according to one aspect of the present invention is An optical transmission device used in a communication system for transmitting a frame to a destination via a counterpart device, wherein the optical transmission device is connectable to the counterpart device via a first path, the counterpart device is connectable to the destination via a second path, and the optical transmission device includes a signal processing unit for accommodating a client signal, and a control unit for switching between a first state in which the client signal is accommodated in n time slot sequences and a second state in which the client signal is accommodated in h (h < n) time slot sequences when the optical transmission device is updated. When switching from the first state to the second state, mapping information representing conversion between the first path and the second path is transmitted.

EFFECTS OF THE INVENTION

[0010] According to the above aspect, when updating an optical transmission device that transmits frames, it is to suppress the influence related to the suspension of communication services.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0012] The OTN (Optical Transport Network) interface defined in ITU-T Recommendation G.709 is applied to optical transmission devices that realize long-distance and / or high-capacity optical communication. The OTN accommodates any client signal in a frame of a predetermined format. Also, the OTN provides a function (i.e., multiplexing accommodation function) of accommodating a plurality of frames in a faster frame.

[0013] Figure 1 shows the frame structure of the OTN. In the OTN, a client signal is accommodated in the payload of an OPUk (Optical Channel Payload Unit-k) frame. k identifies the transmission rate. The OPUk frame has an OPU overhead. The OPUk frame is accommodated in the payload of an ODUk (Optical Channel Data Unit-k) frame. The ODUk frame has an ODU overhead. The ODUk frame is accommodated in the payload of an OTUk (Optical Channel Transport Unit-k) frame. The OTUk frame has an OTU overhead. Also, an error correction code FEC is added to the OTUk frame. Note that the OTUk frame is a fixed-length frame.

[0014] In recent years, with the increase in the speed of client signals, OTN (B100G: Beyond 100G) exceeding 100 Gbps has been under consideration. In B100G, not only high-capacity transmission but also flexibility is considered. For this reason, an OTUCn frame in which n OTUC frames are multiplexed is defined. Also, in ITU-T Recommendation G.709.1, FlexO (Flexible OTN) that multiplexes a plurality of physical interfaces is defined. The signal accommodated in FlexO is, for example, OTUCn.

[0015] Figure 2 shows an example of the signal flow within the optical transmission device. Note that Figure 2 shows the signal flow within the transmission circuit that transmits the frame containing the client signal to the network. That is, in Figure 2, the receiving circuit that receives the frame from the network is omitted.

[0016] A client signal is input to the optical transmission device 1. The client signal is accommodated in the OPUCn frame. The OPUCn frame is accommodated in the ODUCn frame, and further, the ODUCn frame is accommodated in the OTUCn frame. After that, FlexO processing is performed. That is, each of the n OTUC frames constituting the OTUCn frame is accommodated in the FlexO frame. Then, the transceiver outputs an optical signal that transmits the FlexO frame to the network.

[0017] In this example, assume that the total bandwidth of the client signal is 400G. In this case, n = 4, and each of the 4 OTUC frames is accommodated in the payload of the FlexO frame. That is, 4 FlexO frames are generated. Then, each transceiver 11 transmits the FlexO frame. Note that each transceiver 11 can transmit a 100G optical signal.

[0018] By the way, the performance of the components constituting the optical transmission device is improving. For example, the speed of the optical components mounted on the transceiver is increasing. Therefore, the optical transmission device can be configured with a smaller number of components.

[0019] Figure 3 shows another example of the signal flow within the optical transmission device. Note that the method of generating n FlexO frames that accommodate the client signal is substantially the same in Figures 2 and 3.

[0020] In the optical transmission device 1B shown in FIG. 3, a FlexO-x frame is generated by combining a plurality of FlexO frames. In this embodiment, a FlexO-2 frame is generated by combining two FlexO frames. That is, x = 2. At this time, interleaving is performed as necessary. Further, an error correction code FEC is added to the FlexO-2 frame. Then, the transceiver 11b transmits the FlexO-2 frame to the network. In this example, each transceiver 11b can transmit a 200G optical signal.

[0021] As described above, in the configuration shown in FIG. 3, compared with the configuration shown in FIG. 2, the number of ports provided in the optical transmission device is reduced. Further, when the optical transmission devices 1 and 1B are WDM transmission devices and different wavelengths are assigned to each transceiver, in the configuration shown in FIG. 3, compared with the configuration shown in FIG. 2, the utilization efficiency of wavelength resources is improved.

[0022] However, in existing communication systems, in many cases, old optical transmission devices (for example, the optical transmission device 1 shown in FIG. 2) are installed in each node. Therefore, in order to obtain the above-described advantages in a communication system in which the optical transmission device 1 shown in FIG. 2 is installed in each node, it is preferable to update (that is, upgrade) the optical transmission device 1 to the optical transmission device 1B shown in FIG. 3.

[0023] FIG. 4 shows an example of the configuration of an optical transmission device. The optical transmission device 2 includes a client processing unit 21, an OPUCn processing unit 22, an ODUCn / OTUCn processing unit 23, a FlexO processing unit 24, a transceiver 25, a FlexO processing unit 26, an ODUCn / OTUCn processing unit 27, an OPUCn processing unit 28, a client processing unit 29, and a control unit 30. Note that the optical transmission device 2 may include other circuits or functions not shown in FIG. 4. Further, the optical transmission device 2 corresponds to the optical transmission device 1 shown in FIG. 2 or the optical transmission device 1B shown in FIG. 3.

[0024] The client processing unit 21 terminates the client signal generated by the client. Note that the client processing unit 21 includes a plurality of input ports. A transceiver (not shown) is provided for each input port. The OPUCn processing unit 22 accommodates the client signal in an OPUCn frame. The ODUCn / OTUCn processing unit 23 accommodates the OPUCn frame in an ODUCn frame and further accommodates the ODUCn frame in an OTUCn frame. Note that the OTUCn frame is composed of n OTUC frames.

[0025] The FlexO processing unit 24 accommodates each OTUC frame in a FlexO frame. That is, n FlexO frames are generated. Further, the FlexO processing unit 24 combines a plurality of FlexO frames to generate one or more FlexO-x frames as necessary.

[0026] FIG. 5 shows an example of the processing of the FlexO processing unit 24. In this example, the ODUCn / OTUCn processing unit 23 generates four OTUC frames. Also, the optical transmission device 2 includes two transceivers 25. In this case, the OTUC frame is accommodated in the payload of the FlexO frame. As a result, four FlexO frames are obtained. Note that the hatched area represents control information including an overhead. Subsequently, a FlexO-2 frame is generated by combining two FlexO frames. At this time, interleaving is performed. Also, a forward error correction code FEC is added. Note that the hatched area represents control information including an overhead.

[0027] Returning to the description of FIG. 4. The transceiver 25 transmits the FlexO frame or FlexO-2 frame generated by the FlexO processing unit 24 to the network. Also, the transceiver 25 terminates the optical signal received via the network.

[0028] The FlexO processing unit 26 reconstructs the FlexO frame from the received signal. Also, the FlexO processing unit 26 extracts the OTUC frame from the FlexO frame. The ODUCn / OTUCn processing unit 27 extracts the ODUCn frame from the OTUCn frame, and further extracts the OPUCn frame from the ODUCn frame. The OPUCn processing unit 28 extracts the client signal from the OPUCn frame. The client processing unit 29 transmits the client signal to the corresponding client. Note that the client processing unit 29 includes a plurality of output ports. A transceiver (not shown) is provided for each output port.

[0029] The control unit 30 controls the client processing unit 21, the OPUCn processing unit 22, the ODUCn / OTUCn processing unit 23, the FlexO processing unit 24, the transceiver 25, the FlexO processing unit 26, the ODUCn / OTUCn processing unit 27, the OPUCn processing unit 28, and the client processing unit 29. The configuration and processing of the control unit 30 will be described with reference to FIG. 6.

[0030] FIG. 6 shows an embodiment of the control unit 30. The control unit 30 includes a processor (CPU) 31, a memory 32, and a command transceiver 33. Note that the control unit 30 may include circuits or functions not shown in FIG. 6.

[0031] The processor 31 controls the operation of the optical transmission device 2 by executing the control protocol program stored in the memory 32. The processing procedure by the control protocol program will be described later.

[0032] Various control information is stored in the memory 32. The client information includes information representing the bandwidth of each client signal and information representing the priority of each client signal. The mapping table stores information for mapping each client signal to a tributary slot. Note that the tributary slot is an example of a time slot for accommodating client signals. The FlexO bandwidth information represents the bandwidth of the FlexO-x frame. Further, although not shown, information for generating overhead and the like is stored in the memory 32.

[0033] The command transceiver 33 receives a control command via the management interface. The control command is created by a network administrator. The control command also includes a command to stop or start each component implemented in the optical transmission device 2. When the command transceiver 33 receives the control command, the processor 31 controls the operation of the optical transmission device 2 according to the control command. Note that the alarm processing will be described later.

[0034] Note that each of the OPUCn processing unit 22, ODUCn / OTUCn processing unit 23, FlexO processing unit 24, FlexO processing unit 26, ODUCn / OTUCn processing unit 27, and OPUCn processing unit 28 includes, for example, a writing circuit for writing a signal to a memory and a reading circuit for reading a signal from the memory. In this case, the writing circuit is a hardware circuit and writes the input signal to an address corresponding to an instruction given from the control unit 30. The reading circuit is also a hardware circuit and reads a signal from an address corresponding to an instruction given from the control unit 30. However, a part of the functions of the OPUCn processing unit 22, ODUCn / OTUCn processing unit 23, FlexO processing unit 24, FlexO processing unit 26, ODUCn / OTUCn processing unit 27, and OPUCn processing unit 28 may be realized by software.

[0035] Next, the procedure for updating the optical transmission device will be described. The update of the optical transmission device includes the procedure of replacing components installed in the optical transmission device. As an example, a 100G transceiver is replaced with a 200G transceiver. Hereinafter, the transmission circuit that accommodates the client signal in a frame and transmits it will be described.

[0036] Figs. 7 to 8 show an example of the procedure for updating the optical transmission device. In this example, n = 4. That is, the ODUCn / OTUCn processing unit 23 generates an OTUC4 frame. The OTUC4 frame is composed of four OTUC frames. Further, the FlexO processing unit 24 includes four FlexO processing units 24a to 24d. Each of the FlexO processing units 24a to 24d accommodates an OTUC frame in a FlexO frame. That is, each of the FlexO processing units 24a to 24d generates a FlexO frame in which a client signal is accommodated. Therefore, the FlexO processing units 24a to 24d are an example of a frame generation unit that generates a frame in which a client signal is accommodated.

[0037] Furthermore, the optical transmission device includes four 100G transceivers 25a to 25d. Then, the 100G transceivers 25a to 25d output optical signals that transmit the FlexO frames generated by the respective FlexO processing units 24a to 24d to the network.

[0038] In the optical transmission device having the above configuration, an update from the configuration shown in Fig. 2 to the configuration shown in Fig. 3 is performed. Here, in order to continue the communication service, first, some components are updated. In this embodiment, the 100G transceivers 25a to 25b are replaced with one 200G transceiver. At this time, the 100G transceivers 25c to 25d continue to operate.

[0039] The control unit 30 is given a stop command for stopping the 100G transceivers 25a to 25b. Note that the stop command is created, for example, by a network administrator. Then, the control unit 30 stops the 100G transceivers 25a to 25b in response to this stop command. At this time, the control unit 30 may stop the drive current of the laser light sources of the 100G transceivers 25a to 25b. Also, the control unit 30 stops the FlexO processing units 24a to 24b.

[0040] Furthermore, the control unit 30 controls the signal processing of the ODUCn / OTUCn processing unit 23. Specifically, since the number of transceivers operating within the optical transmission device is temporarily reduced from 4 to 2, the transmission rate of the ODUCn / OTUCn processing unit 23 is controlled to be halved. That is, the control unit 30 causes the ODUCn / OTUCn processing unit 23 to generate an OTUCh frame. Here, h = n / 2. That is, in the example shown in FIG. 7, the control unit 30 causes the ODUCn / OTUCn processing unit 23 to generate an OTUC2 frame. The OTUC2 frame is composed of two OTUC frames. Note that the control of the transmission rate of the ODUCn / OTUCn processing unit 23 is realized by reducing the clock speed to half.

[0041] By the above procedure, the state shown in FIG. 8 is obtained. That is, the ODUCn / OTUCn processing unit 23 can generate an OTUC2 frame. Here, h = 2. That is, two OTUC frames are generated. Also, the FlexO processing units 24c to 24d can each accommodate an OTUC frame in a FlexO frame. Then, the 100G transceivers 25c to 25d each output an optical signal transmitting the FlexO frame to the network.

[0042] Subsequently, the control unit 30 changes the signal processing of the OPUCn processing unit 22. Here, as defined in ITU-T Recommendation G.709, the OPUCn processing unit 22 creates an OPUC frame by accommodating client signals in tributary slots. Then, an OPUCn frame is created by multiplexing n OPUC frames. In this way, the OPUCn processing unit 22 accommodates client signals in tributary slots. Therefore, the OPUCn processing unit 22 is an example of a signal processing unit that accommodates client signals in tributary slots.

[0043] Figure 9 shows an example of the mapping to tributary slots. Note that the tributary slot TS consists of 20 slots. Also, assume that the transmission rate per slot corresponds to 5 Gbps. In this case, 100 Gbps is achieved with 20 slots. Also, in this embodiment, the total bandwidth of the client signals is 400G. Therefore, the OPUCn processing unit 22 includes four tributary slots TS#1 to #4. Note that the tributary slot TS is an example of a time slot sequence that accommodates client signals.

[0044] In the following description, the total bandwidth of the client signals is 80 Gbps. Also, the client signals are evenly accommodated in the tributary slots TS#1 to #4. Furthermore, the slot numbers in which the client signals are accommodated are specified in advance. In this embodiment, as shown in FIG. 9(a), the client signals are accommodated in slots SL2, SL4, SL5, and SL10 of each tributary slot TS#1 to #4. As a result, four OPUC frames are generated. The transmission rate of the client signals transmitted by each OPUC frame is 20 Gbps. Then, an OPUCn (n = 4) frame is generated by multiplexing the four OPUC frames.

[0045] When updating the optical transmission device, as shown in FIG. 8, the ODUCn / OTUCn processing unit 23 generates an OTUCh (h = 2) frame. The control unit 30 gives an instruction to the OPUCn processing unit 22 to generate an OPUCh (h = 2) frame. Then, the OPUCn processing unit 22 generates an OPUCh (h = 2) frame according to the instruction from the control unit 30. That is, the OPUCn processing unit 22 accommodates the client signal in two tributary slots TS selected from among the tributary slots TS#1 to #4. In this embodiment, as shown in FIG. 9(b), the control unit 30 selects the tributary slots TS#1 to #2 from among the tributary slots TS#1 to #4. That is, the client signal is evenly accommodated in the tributary slots TS#1 to #2. At this time, in each selected tributary slot TS, the client signal is accommodated in eight slot numbers designated by each control unit 30. In this embodiment, the client signal is accommodated in the slots SL2 to SL5, SL7 to SL8, SL10, and SL20. As a result, two OPUC frames are generated. The transmission rate of the client signal transmitted by each OPUC frame is 40 Gbps. Then, an OPUCh (h = 2) frame is generated by multiplexing the two OPUC frames.

[0046] In this way, before the update, the client signal is accommodated in n tributary slots TS. At the time of update, the client signal is accommodated in h (h = n / 2) tributary slots TS. Therefore, at the time of update, an OPUCh frame is generated and an OTUCh frame is generated, so h FlexO frames are generated. Therefore, at the time of updating the optical transmission device, the client signal is transmitted using h transceivers. In the example shown in FIGS. 7 to 8, the client signal is transmitted using two transceivers 25c to 25d. That is, the communication service is continued.

[0047] Note that the operation during update is equivalent to the transition from the state of mapping the client signal (ODUk (k = 0 to 4, 2e, flex)) to ODTUCn to the state of mapping the client signal to ODTUCh. That is, it corresponds to the transition from the state of forming ODTUCn.ts and mapping it to OPUCn to the state of mapping it to ODTUCh.ts.

[0048] For example, in an optical transmission device in which tributary slots TS{1, ···, n}{1, ···, 20} are provided, the mapping destination of the client signal during update is limited to tributary slots TS{1, ···, h}{1, ···, 20}. {1, ···, n} represents n tributary slots TS, and {1, ···, h} represents h tributary slots TS. Also, {1, ···, 20} represents the slot numbers in which the client signal can be accommodated. And the client signal accommodated in tributary slot TS{1, ···, n}{i} is, during update, accommodated in tributary slot TS{1, ···, h}{j, k}. Note that either j or k may match i.

[0049] As an example, in the case shown in FIG. 9, "i = 2, j = 2, k = 3" is specified by the control unit 30. In this case, the client signal accommodated in slot SL2 of tributary slot TS#1 is, during update, accommodated in slot SL2 of tributary slot TS#1. Also, the client signal accommodated in slot SL2 of tributary slot TS#2 is, during update, accommodated in slot SL3 of tributary slot TS#1. Similarly, the client signal accommodated in slot SL2 of tributary slot TS#3 is, during update, accommodated in slot SL2 of tributary slot TS#2. Also, the client signal accommodated in slot SL2 of tributary slot TS#4 is, during update, accommodated in slot SL3 of tributary slot TS#2. As a result, the client signals accommodated in slot SL2 of 4 tributary slots TS are accommodated in slot SL2 and SL3 of 2 tributary slots TS.

[0050] Similarly, the control unit 30 designates "i = 4, j = 4, k = 7", "i = 5, j = 5, k = 8", and "i = 10, j = 10, k = 20". As a result, the client signals accommodated in the four tributary slots TS#1 to #4 will be accommodated in the two tributary slots TS#1 to #2 at the time of update.

[0051] Note that the process of mapping the client signal to the tributary slot TS is executed with reference to the client information and the mapping table. The client information and the mapping table are created in advance and stored in the memory 32 shown in FIG. 6.

[0052] FIG. 10 shows an example of the client information and the mapping table. In this example, the client information includes information representing the bandwidth of each client signal. The mapping table includes information designating the tributary slot TS in which each client signal should be accommodated. Note that this mapping table represents the update shown in FIG. 9. That is, by referring to the mapping table shown in FIG. 10, the OPUCn processing unit 22 realizes the signal processing shown in FIGS. 7 to 9.

[0053] In the above-described embodiment, since the total bandwidth of the client signals is equal to or less than the bandwidth of the tributary slot TS or the frame to which the client signals are assigned, all the client signals can be accommodated in the transfer frame even at the time of updating the optical transmission device. However, depending on the total bandwidth of the client signals, all the client signals cannot be accommodated in the transfer frame at the time of updating the optical transmission device. Therefore, the optical transmission device has a function of selecting and transmitting client signals according to the priority of the clients.

[0054] FIG. 11 shows an example of a function for selecting a client signal during the update of an optical transmission device. The function for selecting a client signal is mainly realized by the control unit 30 and the OPUCn processing unit 22. The OPUCn processing unit 22 includes an ODTUCn.ts frame forming unit 22a, a client selection unit 22b, a TS mapper 22c, an overhead addition unit 22d, and an OPUCn mapper 22e.

[0055] The ODTUCn.ts frame forming unit 22a accommodates the client signal in the ODTUCn.ts frame. The client selection unit 22b selects one or more client signals according to the selection instruction given from the control unit 30. Specifically, the client selection unit 22b selects the client signal specified by the control unit 30 from the client signals input to the optical transmission device. At this time, the control unit 30 selects one or more client signals based on the client information stored in the memory 32.

[0056] FIG. 12 shows another example of client information and a mapping table. In this embodiment, the maximum transmission rate of the optical transmission device is 400 Gbps, and the maximum transmission rate during update is 200 Gbps. Also, client signals ODU#1 to ODU#5 are input to the optical transmission device. The total bandwidth of the client signals ODU#1 to ODU#5 is 400 G.

[0057] The client information includes information representing the priority of each client signal. In this example, the priorities of the client signals ODU#1, ODU#2, and ODU#5 are high, and the priorities of the client signals ODU#3 and ODU#4 are low. Note that the priority of each client signal is determined in advance by a contract or the like, for example.

[0058] The mapping table is created in advance based on the priority of each client signal. The mapping information used at the time of update is created so as to be equal to or less than the maximum transmission rate of the optical transmission device in the total bandwidth of the client signals. At this time, the client signals with higher priority are selected in order. In the example shown in FIG. 12, the total bandwidth of the client signals ODU#1, ODU#2, and ODU#5 with high priority is 200G. Therefore, tributary slots TS are allocated to the client signals ODU#1, ODU#2, and ODU#5, but no tributary slots TS are allocated to the client signals ODU#3 and ODU#4. In this case, the control unit 30 gives an instruction to the client selection unit 22b to select the client signals ODU#1, ODU#2, and ODU#5. Then, the client selection unit 22b selects and outputs the client signals ODU#1, ODU#2, and ODU#5.

[0059] Note that when the client selection unit 22b does not select one or more client signals, it may generate alarm information. In this case, the alarm information identifies the client signals that were not selected. Then, this alarm information is passed to the ODUCn / OTUCn processing unit 23. However, the selection of the client signals is substantially performed by the control unit 30. Therefore, the control unit 30 may generate alarm information. In this case, the alarm information is given from the control unit 30 to the ODUCn / OTUCn processing unit 23.

[0060] Based on the mapping table, the TS mapper 22c accommodates the client signals selected by the client selection unit 22b in the tributary slots TS. Here, it is assumed that the mapping table shown in FIG. 12 is prepared.

[0061] FIG. 13 shows an example of mapping based on the mapping table shown in FIG. 12. Before the optical transmission device is updated, as shown in FIG. 13(a), client signals ODU#1 to ODU#5 are accommodated in four tributary slots TS#1 to #4. When the optical transmission device is updated, as described above, client signals ODU#1, ODU#2, and ODU#5 are selected. Then, the selected client signals ODU#1, ODU#2, and ODU#5 are accommodated in two tributary slots TS#1 to #2, as shown in FIG. 13(b). At this time, no client signal is accommodated in tributary slots TS#3 to #4.

[0062] The overhead addition unit 22d adds overhead OH to the output signal of the TS mapper 22c. As a result, the ODTUCn.ts frame is reconfigured. Note that the overhead OH is created by the control unit 30, for example. Then, the OPUCn mapper 22e maps the ODTUCn.ts frame to the OPUCn frame.

[0063] The ODUCn / OTUCn processing unit 23 generates an OTUCn frame from the OPUCn frame generated by the OPUCn processing unit 22. Note that the OTUCn frame is mapped to n FlexO frames, as described above. Also, when the above-described alarm information is given, the ODUCn / OTUCn processing unit 23 transfers the alarm information to the destination node of the optical transmission device. In this case, this alarm information may be inserted into the overhead of the ODUCn frame or the OTUCn frame, for example. Also, this alarm information may be transferred to the destination of the client signal that was not selected. Note that this alarm information may be CSF (Client Signal Fail).

[0064] FIG. 14 is a flowchart showing an example of a process for accommodating client signals during an update of an optical transmission device. The process of this flowchart is executed, for example, when a stop command is given to the control unit 30. Note that client information is stored in the memory 32. The client information is assumed to include information representing a client in communication, information representing the type (transmission rate or bandwidth) of each client information, and information representing the priority of each client signal.

[0065] In S1, the control unit 30 detects the number of client signals in communication. Note that the control unit 30 can detect the number of clients in communication by referring to the client information.

[0066] When the number of client signals is one, in S2, the control unit 30 determines whether the client signal is equal to or less than ODU4. When the client signal exceeds ODU4, in S3, the control unit 30 determines whether the transmission rate of the client signal is equal to or less than OPUCh. Note that the value of h corresponds to the transmission rate at the time of updating the optical transmission device and is specified in advance.

[0067] When the transmission rate of the client signal exceeds OPUCh, in S4, the control unit 30 determines whether the bandwidth of the client signal can be suppressed to OPUCh or less by the clench process. Here, in the clench process, the idle signal is deleted.

[0068] When the client signal exceeds ODU4, and the transmission rate of the client signal exceeds OPUCh, and the bandwidth of the client signal cannot be suppressed to OPUCh or less by the clench process, in S5, the control unit 30 generates alarm information. In this case, the alarm information indicates that the client signal cannot be accommodated in the transfer frame during the update of the optical transmission device.

[0069] When the client signal is ODU4 or less, or the bandwidth of the client signal is OPUCh or less, or the bandwidth of the client signal can be suppressed to OPUCh or less by the crunching process, the control unit 30 gives an OPUCn processing unit 22 a mapping instruction for accommodating the client signal in the tributary slot TS in S6. Note that the mapping instruction is created based on a mapping table.

[0070] When a plurality of client signals are input, the control unit 30 determines in S11 whether all the client signals can be accommodated in the OPUCh frame. The bandwidth of each client signal is represented by client information. Also, the capacity of the OPUCh frame is determined according to the value of h. When all the client signals can be accommodated in the OPUCh frame, the control unit 30 generates a mapping instruction for accommodating all the client signals in the tributary slot TS in S12.

[0071] When all the client signals cannot be accommodated in the OPUCh frame, the control unit 30 selects in S13 the client signals to be accommodated in the OPUCh with reference to the client information. Specifically, based on the priority of each client signal, the client signals to be accommodated in the OPUCh frame are selected. At this time, the client signals with higher priority are selected so that the total bandwidth of the selected client signals is equal to or less than the capacity of the OPUCh frame.

[0072] In S14, the control unit 30 gives the OPUCn processing unit 22 a mapping instruction for accommodating the selected client signals in the tributary slot TS. Note that the mapping instruction is created based on a mapping table. In S15, the control unit 30 generates alarm information including information for identifying the client signals that were not selected.

[0073] Note that the alarm process generated in S5 or S15 is transferred to the destination node of the optical transmission device as described with reference to FIG. 11. In this case, the alarm information may be inserted into the overhead of, for example, an ODUCn frame or an OTUCn frame. Further, this alarm information may be transferred to the destination of the unselected client signal.

[0074] Here, the procedure of the flowchart shown in FIG. 14 will be described with reference to the client information and the mapping table shown in FIG. 12. In the example shown in FIG. 12, a plurality of client signals ODU#1 to ODU#5 are input to the optical transmission device. Therefore, the process of the control unit 30 proceeds to S11. In S11, the capacity of the OPUCh frame is 200G, and the total bandwidth of the client signals ODU#1 to ODU#5 is 400G. That is, it is not possible to accommodate all the client signals in the OPUCh frame. Therefore, the process of the control unit 30 proceeds to S13.

[0075] In S13, the total bandwidth of the client signals with high priority (ODU#1, ODU#2, ODU#5) is 200G. Also, the capacity of the OPUCh frame is 200G. Therefore, the control unit 30 determines that these three client signals can be accommodated in the OPUCh frame. However, it is not possible to accommodate any more client signals in the OPUCh frame. Therefore, only the client signals ODU#1, ODU#2, and ODU#5 are selected.

[0076] In S14, the control unit 30 generates mapping information. The mapping information is as shown in FIG. 12 or FIG. 13. Then, in S15, the control unit 30 generates alarm information including information for identifying the unselected client signals (ODU#3, ODU#4).

[0077] FIGS. 15 to 16 show an example of the procedure for updating the receiving circuit of the optical transmission device. The procedure for updating the receiving circuit is substantially the same as the procedure for updating the transmitting circuit.

[0078] That is, when a stop command is given, the control unit 30 stops the transceivers 25a to 25b. At this time, the transceivers 25c to 25d receive optical signals. Then, the FlexO processing units 26c to 26d respectively regenerate FlexO frames from the optical signals received by the transceivers 25c to 25d, and regenerate OTUCh frames from the FlexO frames. Therefore, the FlexO processing units 26c to 26d are an example of a frame regeneration unit that regenerates frames from received optical signals.

[0079] The ODUCn / OTUCn processing unit 27 extracts an ODUCh frame from the OTUCh frame and extracts an OPUCh frame from the ODUCh frame. The OPUCn processing unit 28 extracts a client signal from the OPUCh frame. At this time, the OPUCn processing unit 28 refers to the client information and the mapping table shown in FIG. 12. Incidentally, when receiving alarm information from the transmitting node, the control unit 30 transfers the alarm information to the destination device that cannot receive the client signal at the time of update.

[0080] Thus, when the optical transmission device that generates OPUCn / ODUCn / OTUCn frames is updated, OPUCh / ODUCh / OTUCh frames are generated. Here, in the embodiments shown in FIGS. 7 to 16, h = n / 2. However, the present invention is not limited to h = n / 2.

[0081] FIGS. 17 to 18 are flowcharts showing an example of a procedure for updating a set of optical transmission devices. Note that FIG. 17 shows the operation of the optical transmission device that transmits frames, and FIG. 18 shows the operation of the optical transmission device that receives frames. Hereinafter, the optical transmission device that transmits frames may be referred to as a "transmitting node". The optical transmission device that receives frames may be referred to as a "receiving node".

[0082] When a stop command is given in FIG. 17, the transmitting node determines at S21 whether the optical module can be stopped. If the optical module cannot be stopped within a predetermined time after the stop command is given, for example, an error message is generated.

[0083] When the optical module can be stopped, the transmitting node selects a client signal at S22 - S23. If the client signal cannot be selected within a predetermined time after the stop command is given, for example, an error message is generated. At S24, the transmitting node reconfigures the ODUCn / OTUCn. That is, ODUCh / OTUCh is configured. As a result, the reconfiguration of OPUCn / ODUCn / OTUCn is completed (S25).

[0084] At S26, the transmitting node reconfigures FlexO. At S27, the transmitting node stops the optical module. At S28, the transmitting node determines whether the update process at the receiving node has been completed. For example, when the process of S36 shown in FIG. 18 ends, it is determined that the update process at the receiving node has been completed. When the update process of the receiving node is completed, the transmitting node provides the reconfigured FlexO at S29.

[0085] When a stop command is given in FIG. 18, the receiving node determines at S31 whether the update process at the transmitting node has been completed. For example, when the process of S27 shown in FIG. 17 ends, it is determined that the update process at the transmitting node has been completed. If the completion of the update process at the transmitting node cannot be confirmed within a predetermined time after the stop command is given, for example, an error message is generated.

[0086] When the update process at the transmitting node is completed, the receiving node reconfigures the OPUCn / ODUCn / OTUCn in S32. In S33, the receiving node sets the alarm processing to the on state. In S34, the receiving node stops the reception of the optical module. In S35, the receiving node reconfigures FlexO. As a result, the reception process is completed (S36). After that, in S37, the receiving node provides the reconfigured FlexO.

[0087] In the embodiments shown in FIGS. 7 to 18, when updating a set of optical transmission devices, stop commands are given to each optical transmission device (transmitting node, receiving node), but the present invention is not limited to this procedure. That is, a stop command may be given to one of a set of optical transmission devices, and then the stop command may be transferred to the other optical transmission device.

[0088] FIG. 19 shows an example of the cooperation operation for updating a set of optical transmission devices. In this example, a set of optical transmission devices 2A and 2B are connected to each other via a network. Each of the optical transmission devices 2A and 2B can transmit a FlexO frame with n = 4. That is, four FlexO frames are transmitted in parallel between the optical transmission devices 2A and 2B.

[0089] A stop command is given to the optical transmission device 2A. This stop command includes an instruction to stop two of the four transceivers (Tx / Rx). Then, the two transceivers specified by the stop command stop. Also, the corresponding two OTUC / FlexO processing units stop operating, and the remaining two OTUC / FlexO processing units continue to be in the active state. And information for identifying the two OTUC / FlexO processing units that are in the active state in the optical transmission device 2A is notified to the optical transmission device 2B.

[0090] The optical transmission device 2B detects the two OTUC / FlexO processing units that are in the active state in the optical transmission device 2A. Therefore, the optical transmission device 2B can perform the same update process as the optical transmission device 2A.

[0091] Figures 20 to 23 show other examples of the procedure for updating the optical transmission device. Note that Figure 20 shows the state of the optical transmission device when the procedure shown in Figures 7 to 8 is completed. Specifically, among the four transceivers 25a to 25d provided in the optical transmission device 2, the transceivers 25a to 25b are removed. The OPUCn processing unit 22 generates an OPUCh (h = 2) frame. The ODUCn / OTUCn processing unit 23 generates an OTUCh (h = 2) frame. The FlexO processing unit 24 generates two FlexO frames. Then, the transceivers 25c to 25d transmit the FlexO frames, respectively.

[0092] In the above state, as shown in Figure 21, an update command is given to the control unit 30 of the optical transmission device 2. The update command instructs the start of FlexO-2. At this time, it is assumed that the transceiver 25E is attached instead of the transceivers 25a to 25b shown in Figure 7. The transceiver 25E can transmit a 200G signal.

[0093] The control unit 30 gives an update instruction to the ODUCn / OTUCn processing unit 23 and the FlexO processing unit 24 in response to the update command. Then, the ODUCn / OTUCn processing unit 23 makes settings for generating an OTUCi frame in response to the update instruction. In this embodiment, i = h = 2. Also, the FlexO processing unit 24 generates two FlexO frames from the OTUCi frame and makes settings for generating two FlexO frames from the OTUCh frame. Further, a FlexO-2 processing unit 41a is generated. The FlexO-2 processing unit 41a can combine two FlexO frames to generate one FlexO-2 frame. Also, an error correction code FEC is generated by the FlexO-2 processing unit 41a and added to the FlexO-2 frame.

[0094] When the above-mentioned update and setting are completed, a conduction confirmation signal is sent from the ODUCn / OTUCn processing unit 23 to the control unit 30. Then, the control unit 30 gives a mapping switching instruction to the OPUCn processing unit 22. The mapping switching instruction represents the switching from the state of transmitting two FlexO frames to the state of transmitting four FlexO frames. For example, when the mapping table shown in FIG. 12 is stored in the memory 32, the switching instruction represents the switching from "during update" to "normal time". Then, the OPUCn processing unit 22 accommodates the client signal in the tributary slots TS#1 to #4 according to the mapping information corresponding to "normal time".

[0095] When the above-mentioned update is completed, the client signal is accommodated in the tributary slots TS#1 to #4. Also, one FlexO-2 frame and one FlexO frame are generated. Then, the transceiver 25E transmits the FlexO-2 frame, and the transceivers 25c to 25d each transmit a FlexO frame.

[0096] Subsequently, as shown in FIG. 22, the transceivers 25c to 25d are replaced with the transceiver 25F. This procedure is substantially the same as the procedure of replacing the transceivers 25a to 25b with the transceiver 25E. That is, part or all of the client signal accommodated in the OPUCh / ODUCh / OTUCh is accommodated in the OPUCi / ODUCi / OTUCi. Also, the FlexO-2 processing unit 41b is set.

[0097] After that, as shown in FIG. 23, the OPUCn processing unit 22 and the ODUCn / OTUCn processing unit 23 are reconfigured. That is, the OPUCn processing unit 22 is reconfigured from the state of generating the OPUCi frame and the OPUCh frame to the state of generating the OPUCn frame. Also, the ODUCn / OTUCn processing unit 23 is reconfigured from the state of generating the OTUCi frame and the OTUCh frame to the state of generating the OTUCn frame.

[0098] As described above, according to the embodiment of the present invention, in a communication system that transmits traffic exceeding 100G via OTN, the optical transmission device can be updated (i.e., upgraded) without stopping the communication service. At this time, depending on the traffic volume of the client signal, it may not be possible to continue all communication services. However, even in this case, the transmission of high-priority client signals is continued. Therefore, the impact of the stop of the communication service during the update of the optical transmission device is sufficiently suppressed.

[0099] In the operations described so far, an example in which n = 4 and h = 2 and a total transmission of 400 Gbps is performed has been described. However, as long as n > h, n and h can be other values. Also, for FlexO-x, an example related to the update from x = 1 (FlexO) to FlexO-2 has been described. However, other cases such as x = 4 are also applicable.

[0100] In the above-described embodiment, the optical transmission device is updated. Specifically, by replacing the 100G transceiver with a 200G transceiver, the number of ports is reduced, and the wavelength utilization efficiency is improved. However, the embodiment of the present invention is also applicable to the addition of an optical transmission device.

[0101] FIG. 24 shows an example of the addition of an optical transmission device. In this example, a 25G transceiver is added to the configuration shown in FIG. 23. That is, the capacity of the optical transmission device is increased from 400G to 600G. In this case, an OPUCh (h = 2) processing unit 22x is added to the OPUCn (n = 4) processing unit 22. Alternatively, the OPUCn (n = 4) processing unit 22 may be reconfigured into an OPUCn (n = 6) processing unit. Also, an ODUCh / OTUCh (h = 2) processing unit 23x is added to the ODUCn / OTUCn (n = 4) processing unit 23. Alternatively, the ODUCn / OTUCn (n = 4) processing unit 22 may be reconfigured into an ODUCn / OTUCn (n = 6) processing unit. In any case, the optical transmission device includes FlexO processing units 24a to 24f and also includes FlexO-2 processing units 41a to 41c.

[0102] In addition, when the total bandwidth of the client signals is 400 Gbps or less, 1+1 protection may be implemented. For example, among the input client signals, the client signals with high priority (priority traffic) are guided to the OPUCn processing unit 22 and are also copied and guided to the OPUCn processing unit 22x. Here, the priority traffic is limited to 200G or less. Then, the frames output from the OPUCn processing unit 22x are processed by the ODUCn / OTUCn processing unit 23x, the FlexO processing units 24e to 24f, and the FlexO-2 processing unit 41C, and are output to the network by the transceiver 25G. In this configuration, the priority traffic is transmitted to the receiving node via two different paths. Therefore, highly reliable transmission is realized.

[0103] <Other Embodiments> In the above-described embodiments, the update of the optical transmission device is realized by using FlexO. Here, FlexO is an extension of OTU and supports transmission on one link connecting adjacent nodes. However, the main body for transmitting the client signal is ODU, and in the OTN network, the client signal is often transmitted via a plurality of links End-End. Therefore, in other embodiments, the present invention is applied to a configuration for transmitting signals via a plurality of links.

[0104] FIG. 25 shows an example of an END-END path. In this example, the client accommodated in node A and the client accommodated in node C communicate via node B. Also, ODUCn (n = 4) is set between the nodes. Here, it is assumed that the optical transmission device mounted in node A is updated according to the procedure shown in FIGS. 7 to 8. As an example, ODUCh (h = 2) is set between nodes A and B. However, the path between nodes B and C remains ODUCn (n = 4).

[0105] In this case, if Node B does not have a switching function (or an OUD cross-connect), communication between clients may be interrupted. Also, an existing OTN network may include nodes without a switching function. Therefore, the procedure according to another embodiment of the present invention connects an ODUCn path and an ODUCh path without interrupting communication between clients without using the switching function at each node on the path.

[0106] In the following description, the optical transmission device implemented in Node i may be referred to as "Node Device i". For example, in the example shown in FIG. 25, Node Devices A to C respectively represent the optical transmission devices implemented in Nodes A to C.

[0107] When the update shown in FIG. 25 is performed, Node Device A transmits control information including the client information and the mapping table shown in FIG. 12 to Node Device B. The control information is stored, for example, in the overhead of the frame. Specifically, the control information may be transmitted using GCC (General Communication Channel) defined in ITU-T Recommendation G.709.

[0108] Node Device B uses the mapping table received from Node Device A to connect the ODUCh path and the ODUCn path shown in FIG. 25. Specifically, Node Device B extracts an OPUCh frame from the received frame and extracts tributary slots TS from each OPUC frame. Also, Node Device B performs mapping (i.e., rearrangement) of the tributary slots TS according to the mapping table. Then, Node Device B generates an OPUCn (n = 4) frame in which the tributary slots TS are rearranged, and further generates an ODUCn (n = 4) frame. At this time, the ODU overhead inherits the overhead extracted from the received ODU frame. After that, Node Device B generates an OTN frame and transmits it to Node Device C.

[0109] FIG. 26 shows an overview of the process of transferring frames using a mapping table. In this example, node device B uses the mapping table received from node A to connect the ODUCh (h = 2) path and the ODUCn (n = 4) path shown in FIG. 25.

[0110] Node device B extracts the ODUCh (h = 2) frame from the received OTU frame and extracts the OPUCh frame from the ODUCh frame. Then, node device B rearranges the tributary slot TS according to the mapping table. At this time, the "update time" information in the mapping table is used as the source-side TS configuration information of node device B, and the "normal time" information in the mapping table is used as the destination-side TS configuration information of node device B.

[0111] At the update time of node device A, the client signal is transmitted from node device A to node device B using the tributary slot TS represented by the source-side TS configuration information. Then, node device B maps the tributary slot TS represented by the source-side TS configuration information to the tributary slot TS represented by the destination-side TS configuration information. However, there are two OPUs set on the path between nodes A and B, and only some client signals are selected in node device A. Therefore, node device B maps only the client signals selected in node device A to the destination-side tributary slot TS.

[0112] Specifically, node device A selects client signals ODU#1, ODU#2, and ODU#5 from among client signals ODU#1 to ODU#5. That is, client signals ODU#3 and ODU#4 are not transmitted from node device A to node device B. Therefore, node device B maps only the client signals ODU#1, ODU#2, and ODU#5 selected in node device A to the output-side tributary slot TS.

[0113] For example, assume that the mapping shown in FIG. 13 is performed in node device A. In this case, node device B performs the mapping shown in FIG. 27 (i.e., the rearrangement of tributary slots TS) according to the mapping table received from node device A. Specifically, node device B receives tributary slots TS#1 to TS#2 shown in FIG. 27(a) and outputs tributary slots TS#1 to TS#4 shown in FIG. 27(b). At this time, the client signal ODU#1 stored in slots SL1 to SL10 of tributary slot TS#1 on the transmission source side is mapped to slots SL1 to SL10 of tributary slot TS#1 on the transmission destination side. The client signal ODU#2 stored in slots SL1 to SL10 of tributary slot TS#2 on the transmission source side is mapped to slots SL1 to SL10 of tributary slot TS#3 on the transmission destination side. The client signal ODU#2 stored in slots SL11 to SL20 of tributary slot TS#1 on the transmission source side is mapped to slots SL11 to SL20 of tributary slot TS#4 on the transmission destination side. The client signal ODU#5 stored in slots SL11 to SL20 of tributary slot TS#2 on the transmission source side is mapped to slots SL1 to SL10 of tributary slot TS#4 on the transmission destination side.

[0114] FIG. 28 shows an example of a node device that connects an ODUCn path and an ODUCh path. Here, the configuration of node device B is substantially the same as that of the optical transmission device 2 shown in FIG. 2. However, node device B includes at least two ports (port A and port C). Port A is connected to node device A and has a function of processing FlexO. Port C is connected to node device C and has a function of transferring traffic exceeding 100G using a technology other than FlexO.

[0115] As shown in FIG. 25, node device B receives an ODUCh (h = 2) frame from node device A. The ODUCh frame is terminated by port A. Also, node device B transmits an ODUCn (n = 4) frame to node device C. The ODUCn frame is transmitted via port C.

[0116] The node device B includes four transceivers 25A. However, in this embodiment, two of the four transceivers 25A receive FlexO frames. The ODUCn / OTUCn processing unit 27 extracts an OTU frame from the FlexO frame and extracts an ODU frame from the OTU frame. Note that the ODUCn / OTUCn processing unit 27 operates as an ODUCh / OTUCh processing unit.

[0117] The control information acquisition unit 51 acquires a mapping table stored in the overhead of the received frame. For example, when the node device A transmits a mapping table using the GCC of the ODU frame, the control information acquisition unit 51 acquires the mapping table from the GCC. In addition, the control information acquisition unit 51 acquires the overhead of the ODU frame (hereinafter referred to as the ODU overhead). The mapping table and the ODU overhead acquired by the control information acquisition unit 51 are provided to the setting unit 52.

[0118] The OPUCn processing unit 28 extracts an OPU frame from the ODU frame. Further, an ODTUCn.ts frame is extracted from the OPU frame. That is, the client signals stored in each slot SL of each tributary slot TS are extracted. In the example shown in FIG. 27(a), the client signals stored in each slot SL of tributary slots TS#1 to TS#2 are extracted. Note that the OPUCn processing unit 28 operates as an OPUCh processing unit.

[0119] The setting unit 52 sets the mapping table acquired by the control information acquisition unit 51 in the OPUCn processing unit 22. In addition, the setting unit 52 provides the ODU overhead acquired by the control information acquisition unit 51 to the ODUCn / OTUCn processing unit 23.

[0120] The OPUCn processing unit 22 reconfigures the tributary slot TS according to the mapping table. For example, the reconfiguration shown in FIGS. 26 to 27 is performed. Specifically, the tributary slots TS#1 to TS#2 represented by the source-side TS configuration information are reconfigured into the tributary slots TS#1 to TS#4 represented by the destination-side TS configuration information. In this case, four OPU frames are generated.

[0121] The ODUCn / OTUCn processing unit 23 generates an ODU frame by adding ODU overhead to the OPU frame. This ODU overhead inherits the content of the ODU overhead extracted from the received frame. Further, the ODUCn / OTUCn processing unit 23 generates an OTU frame by adding OTU overhead to the ODU frame. The OTU frame is transmitted to the node device C by the transceiver 25C.

[0122] As described above, when the update from the configuration that temporarily accommodates the ODUCn path to the configuration that accommodates the ODUCh path is performed in the node device A, the node device B receives a mapping table representing the conversion between the ODUCn path and the ODUCh path from the node device A. Then, the node device B realizes the connection between the ODUCh path and the ODUCn path by re-arranging the tributary slot TS using this mapping table. Therefore, even if the node device B does not have a switching function based on control information for transferring the client signal End-End, it can connect the ODUCh path and the ODUCn path. Further, since there is no need to implement a switching function, the circuit of the optical transmission device can be reduced.

[0123] FIG. 29 shows an example of a network in which three or more node devices are cascade-connected. In this embodiment, the node devices A, B, C... Z are connected in order. And the node device A is updated according to the procedure shown in FIGS. 7 to 8. As an example, an ODUCh (h = 2) path is set between the node devices A and B. Also, the path between the node devices B and Z remains ODUCn (n = 4).

[0124] As described with reference to FIGS. 26 to 28, the node device A transmits a mapping table to the node device B. Then, the node device B rearranges the tributary slot TS according to this mapping table. Thereby, the ODUCh path and the ODUCn path are connected in the node device B.

[0125] An ODUCn path is set between the node device B and the node device Z. That is, each node device (node device C etc. in FIG. 29) between the node device B and the node device Z performs normal frame transfer. Therefore, each node device between the node device B and the node device Z does not require the mapping table notified from the node device A to the node device B when transferring a frame. However, since the node device (node device Z in FIG. 29) that accommodates the destination client terminates the ODUCn, it is preferable that the node device recognizes the configuration of the tributary slot TS. Therefore, the node device B that has received the mapping table from the node device A creates TS configuration information (that is, destination-side TS configuration information) representing the configuration of the tributary slot TS used between the node device B and the node device Z and transmits it to the node device Z.

[0126] In this case, the node device B creates the destination-side TS configuration information to be transmitted to the node device Z by updating the destination-side TS configuration information received from the node device A as needed. For example, when all client signals are selected in the node device A, the node device B may transmit the destination-side TS configuration information received from the node device A as it is to the node device Z. Also, when some of all client signals are selected in the node device A, the node device B may create TS configuration information representing the configuration of the tributary slot TS that accommodates the client signals selected in the node device A. That is, the node device B may create TS configuration information representing the configuration of the tributary slot TS that accommodates the client signals to be transferred to the node device Z. In the example shown in FIG. 29, the node device B transmits to the node device Z the TS configuration information representing the configuration of the tributary slot TS that accommodates the client signals ODU#1, ODU#2, and ODU#5.

[0127] The destination-side TS configuration information represents the tributary slot TS used to transmit the client signal. In the example shown in FIG. 29, the destination-side TS configuration information includes information representing that "client signal ODU#1 is assigned to slots SL1 to SL10 of tributary slot TS#1", "client signal ODU#3 is assigned to slots SL1 to SL10 of tributary slot TS#3", "client signal ODU#2 is assigned to slots SL11 to SL20 of tributary slot TS#4", and "client signal ODU#5 is assigned to slots SL1 to SL10 of tributary slot TS#4". Note that the node device B may transmit a mapping table (source-side TS configuration information and destination-side TS configuration information) to the node device Z.

[0128] The TS configuration information (or mapping table) is transmitted, for example, using the above-described GCC. Then, the node device Z extracts the client signal from the tributary slot TS based on the TS configuration information and transfers it to the corresponding client. Also, the node device Z can detect a mismatch in the tributary slot TS based on the TS configuration information.

[0129] By the way, in the OTN network, in many cases, data is transmitted bidirectionally between End - End. That is, the node device Z transmits a frame toward the node device A. Here, assume that the client information shown in FIG. 12 is set in the node device Z. Also, the node device Z recognizes the transmission capacity between the node device A and the node device B at the time of updating the node device A based on the TS configuration information received from the node device B. In this embodiment, the transmission capacity is 200G. Then, the node device Z selects a client signal that can be transmitted from the node device Z to the node device A based on the client information and the transmission capacity. The procedure for selecting the client signal is substantially the same as the procedure shown in FIG. 14.

[0130] The node device Z generates TS configuration information representing the tributary slot TS that accommodates the selected client signal. Since this TS configuration information is applied to the path from the node device Z to the node device B, it may be referred to as "TS configuration information (Z→B)" in the following description. An example of the TS configuration information (Z→B) is shown in FIG. 30.

[0131] When the node device Z receives the mapping table from the node device B, it can recognize the configuration of the tributary slot TS between the node device A and the node device B. In this case, in addition to the TS configuration information (Z→B), the node device Z may generate TS configuration information (B→A) representing the configuration of the tributary slot TS between the node device A and the node device B. An example of the TS configuration information (B→A) is shown in FIG. 30.

[0132] Figure 31 shows another example of a node device that connects an ODUCn path and an ODUCh path. In this example, the node device Z transmits the TS configuration information (Z→B) shown in Figure 30 to the node device B. The TS configuration information (Z→B) is transmitted, for example, using GCC. Each node device between the node device Z and the node device B transfers it to the next node without using the TS configuration information (Z→B).

[0133] In the node device B, the control information acquisition unit 51 acquires the TS configuration information (Z→B) transmitted from the node device Z. Here, as shown in Figure 29, the node device B has previously received a mapping table from the node device A. That is, the node device B recognizes the configuration of the tributary slot TS between the node device A and the node device B. Therefore, the mapping table generation unit 53 can generate a mapping table for connecting the ODUCn path and the ODUCh path for transmitting the client signal from the node device Z to the node device A based on the TS configuration information (Z→B). Then, this mapping table is set in the OPUCn processing unit 28 by the setting unit 52. Also, the control information acquisition unit 51 acquires the overhead of the ODU frame (hereinafter, the ODU overhead). Then, this ODU overhead is given to the ODUCn / OTUCn processing unit 27 by the setting unit 52.

[0134] The frame conversion shown in Figure 31 is substantially the same as the operation shown in Figure 28. That is, the OPUCn processing unit 28 reconstructs the tributary slot TS according to the mapping table set by the setting unit 52. Also, the ODUCn / OTUCn processing unit 27 generates an ODUCn frame by adding the ODU overhead given from the setting unit 52 to the output frame of the OPUCn processing unit 28.

[0135] FIG. 32 shows still another example of a node device that connects an ODUCn path and an ODUCh path. In this example, node device Z transmits the TS configuration information (Z→B) and the TS configuration information (B→A) shown in FIG. 30 to node device B. Here, a set of the TS configuration information (Z→B) and the TS configuration information (B→A) is substantially the same as the mapping table generated by node device B in FIG. 31. Therefore, in this embodiment, by the control information acquisition unit 51 acquiring the TS configuration information (Z→B) and the TS configuration information (B→A) from the received frame, node device B can acquire the mapping table. Since other operations are substantially the same in FIGS. 31 and 32, the description thereof is omitted.

Explanation of Signs

[0136] 1, 1B, 2, 2A, 2B optical transmission devices 22, 28 OPUCn processing units 23, 27 ODUCn / OTUCn processing units 24(24a~24f), 26 FlexO processing units 25(25a~25d, 25E~25G) transceivers 30 control unit 31 processor (CPU) 32 memory 41a~41c FlexO-2 processing units 51 control information acquisition unit 52 setting unit

Claims

An optical transmission device used in a communication system for transmitting a frame to a destination via a counterpart device, comprising: The optical transmission device is connectable to the counterpart device via a first path; The counterpart device is connectable to the destination via a second path; a signal processing unit for accommodating a client signal; a control unit for switching, upon updating of the optical transmission device, between a first state in which the client signal is accommodated in n time slot sequences and a second state in which the client signal is accommodated in h (h < n) time slot sequences; and transmitting mapping information representing conversion between the first path and the second path when switching from the first state to the second state. An optical transmission device characterized by the above. The optical transmission device according to claim 1, further comprising: a first frame generation unit and a second frame generation unit for generating a frame including a client signal accommodated in a corresponding time slot sequence; when in the first state, the first frame generation unit and the second frame generation unit operate; when in the second state, the first frame generation unit stops and the second frame generation unit operates. The optical transmission device according to claim 1, characterized by the above.

3. When switching from the first state to the second state based on a given command, information indicating that the first frame generation unit has stopped or information indicating that the second frame generation unit is operating is transmitted to the counterpart device that communicates with the optical transmission device. The optical transmission device according to claim 2, characterized by the above.

4. An optical transmission device used in a communication system for transmitting a frame, comprising: a first frame reproduction unit for reproducing a frame from a first optical signal; a second frame reproduction unit for reproducing a frame from a second optical signal; A signal processing unit that extracts a client signal from at least one of the frame reproduced by the first frame reproduction unit and the frame reproduced by the second frame reproduction unit. When receiving information indicating that a part of the components of the opposing device is being updated from the opposing device that communicates with the optical transmission device. The first frame reproduction unit stops operating. The signal processing unit extracts a client signal from the frame reproduced by the second frame reproduction unit. An optical transmission device characterized by the above.

5. The optical transmission device Has a first frame generation unit and a second frame generation unit that generate a frame including a client signal accommodated in a corresponding time slot sequence. The signal processing unit Extracts the client signal from h time slot sequences, And accommodates the extracted client signal in one or more time slot sequences among n (n>h) time slot sequences. The optical transmission device according to claim 4, characterized by the above.

6. An optical transmission system that transmits a frame from a first optical transmission device to a third optical transmission device via a second optical transmission device. The first optical transmission device A first signal processing unit that accommodates a client signal in one or more time slot sequences among n time slot sequences, A first frame generation unit that generates a frame including a client signal accommodated in a part of the n time slot sequences, A second frame generation unit that generates a frame including a client signal accommodated in another time slot sequence different from the part of the n time slot sequences. First time slot configuration information representing a time slot sequence for accommodating the client signal when the first frame generation unit and the second frame generation unit operate, and second time slot configuration information representing a time slot sequence for accommodating the client signal when the first frame generation unit stops and the second frame generation unit operates, and a memory for storing the information; A control unit that switches the first signal processing unit from a first state in which the client signal is accommodated in one or more time slot sequences according to the first time slot configuration information to a second state in which the client signal is accommodated in one or more time slot sequences according to the second time slot configuration information when the first optical transmission device is updated; When the first frame generation unit stops and the second frame generation unit operates, the first time slot configuration information and the second time slot configuration information are transmitted from the first optical transmission device to the second optical transmission device; The second optical transmission device Comprises a second signal processing unit for accommodating client signals in n time slot sequences; When the first frame generation unit stops and the second frame generation unit operates, the second signal processing unit acquires a client signal from the received frame based on the second time slot configuration information, and accommodates the acquired client signal in n time slot sequences based on the first time slot configuration information. An optical transmission system characterized by the above.

7. Third time slot configuration information representing a time slot sequence in which a client signal is accommodated by the second signal processing unit is transmitted from the second optical transmission device to the third optical transmission device; The third optical transmission device determines a client signal to be transmitted from the third optical transmission device to the first optical transmission device based on the third time slot configuration information, and transmits fourth time slot configuration information representing a time slot sequence in which the determined client signal is accommodated to the second optical transmission device. The optical transmission system according to claim 6, characterized in that...

8. A method for updating an optical transmission device, comprising: a signal processing unit that accommodates a client signal in one or more of n time slot sequences; a first frame generation unit that generates a frame including the client signal accommodated in a part of the n time slot sequences; and a second frame generation unit that generates a frame including the client signal accommodated in another time slot sequence different from the part of the n time slot sequences, wherein... The signal processing unit shifts from a first state in which the client signal is accommodated in the n time slot sequences to a second state in which the client signal is accommodated in the other time slot sequences. While transmitting the frame generated by the second frame generation unit using a second transceiver, stop the first transceiver connected to the first frame generation unit. When the first transceiver is replaced by a third transceiver, the signal processing unit shifts from the second state to the first state. Transmit the frame generated by the first frame generation unit using the third transceiver, and transmit the frame generated by the second frame generation unit using the second transceiver. A method for updating an optical transmission device, characterized in that...

9. An optical transmission device comprising: a signal processing unit that accommodates a client signal in one or more of n time slot sequences; a first frame generation unit that generates a frame including the client signal accommodated in a part of the n time slot sequences; and a second frame generation unit that generates a frame including the client signal accommodated in another time slot sequence different from the part of the n time slot sequences, wherein... The signal processing unit transitions from a first state in which the client signal is accommodated in the n time slot sequences to a second state in which the client signal is accommodated in the other time slot sequences. While transmitting the frame generated by the second frame generation unit using the second transceiver, the first transceiver connected to the first frame generation unit is stopped. When the first transceiver is replaced by a third transceiver, the signal processing unit transitions from the second state to the first state. The frame generated by the first frame generation unit is transmitted using the third transceiver, and the frame generated by the second frame generation unit is transmitted using the second transceiver. An optical transmission device characterized by the above.

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