JP7139739B2 - Optical transmission device, optical transmission method, and optical transmission system - Google Patents

Description

The present invention relates to an optical transmission device, an optical transmission method, and an optical transmission system.

In recent years, there has been an increasing demand for high-capacity point-to-point (PtoP) optical networks among data center operators. High-capacity P-to-P optical networks are implemented using, for example, wavelength division multiplexing (WDM) technology. In WDM transmission, a plurality of optical paths with different wavelengths are multiplexed.

FIG. 1 shows a configuration example of a WDM transmission system. In the example shown in FIG. 1A, an AWG (Arrayed Waveguide) is mounted at each site, and a plurality of transponders (TR) are connected to each AWG. Each transponder houses a client or router and transmits and receives optical signals to and from the opposite transponder. Also, each transponder uses a different wavelength.

In the example shown in FIG. 1B, a wavelength selective switch (WSS) is mounted at each site, and a plurality of transponders (TR) are connected to each WSS. Similar to the configuration shown in FIG. 1(a), each transponder accommodates a client or router and transmits and receives optical signals to and from the opposite transponder. Also, each transponder uses a different wavelength. However, the WDM transmission system shown in FIG. 1(b) includes an optical network controller. An optical network controller centrally manages the entire network. For example, the optical network controller controls the wavelength used by each transponder and the wavelength selection of the WSS.

As a related technique, a technique has been proposed for facilitating the addition or removal of child devices in a CWDM system in which communication is performed between a parent device and a plurality of child devices (for example, Patent Document 1). Also, an optical network controller has been proposed for the purpose of improving the utilization efficiency of the optical frequency band (for example, Patent Document 2). Further, related techniques are also described in Patent Documents 3 to 5.

JP 2012-209818 A WO2015/162874 JP 2010-41444 A JP-A-2008-54093 JP 2007-124568 A

In the configuration shown in FIG. 1A, each port of the AWG has its own available wavelength. Therefore, for example, when wavelength λ1 is assigned to communication between clients x1 and y1, the transponder accommodating client x1 and the transponder accommodating client y1 must each be connected to the port corresponding to wavelength λ1. . That is, in the configuration shown in FIG. 1A, the optical path cannot be flexibly set or changed.

In the configuration shown in FIG. 1(b), the optical path can be flexibly set or changed. However, some users may desire a configuration that does not require an optical network controller that centrally manages the entire network.

SUMMARY OF THE INVENTION It is an object of one aspect of the present invention to provide a configuration and method for flexibly setting optical paths without providing a controller for centrally managing a network.

An optical transmission device according to one aspect of the present invention is installed at a first site in an optical transmission system that transmits wavelength division multiplexed optical signals between a first site and a second site. This optical transmission device includes an optical transmission unit that uses a first wavelength to transmit a first optical signal including first identification information to the second site; an optical receiver that receives a transmitted second optical signal including second identification information from the second base. When the first identification information and the second identification information extracted from the second optical signal are the same, the optical transmission unit uses the first wavelength to perform the following in the optical transmission system: Sending a wavelength notification to the second site indicating a second wavelength that is not in use. When the optical receiving unit receives a completion notification indicating that the wavelength notification has been received at the second base, which is transmitted using the first wavelength, the optical transmitting unit performs the An optical signal with a second wavelength is transmitted to the second site, and the optical receiver stops receiving the optical signal with the first wavelength transmitted from the second site.

According to the above aspect, the optical path can be flexibly set without providing a controller for centrally managing the network.

1 is a diagram showing a configuration example of a WDM transmission system; FIG. 1 illustrates an example of an optical transmission system; FIG. FIG. 2 is a diagram showing an example of a transponder; FIG. FIG. 4 is a diagram showing an example of a wavelength allocation sequence; FIG. FIG. 4 is a diagram showing an example of a wavelength allocation sequence according to the first embodiment; FIG. FIG. 3 is a diagram showing an example of arrangement of wavelengths for transmitting control signals; FIG. 3 is a diagram illustrating an example of a method of avoiding wavelength conflicts between transponder pairs; 10 is a flowchart (part 1) showing an example of transponder processing; FIG. 11 is a flowchart (part 2) showing an example of transponder processing; FIG. FIG. 10 is a diagram showing an example of a transponder variation; FIG. 10 is a diagram showing another example of a transponder variation; FIG. 2 is a diagram (part 1) showing an example of a variation of a network configuration; FIG. 2 is a diagram (part 2) showing an example of a variation of the network configuration; FIG. 11 is a diagram (part 3) showing an example of a variation of the network configuration; FIG. 12 is a diagram (part 4) showing an example of a variation of the network configuration; FIG. 11 is a diagram (No. 5) showing an example of a variation of the network configuration; FIG. 11 is a diagram (part 6) showing an example of a variation of the network configuration; FIG. 10 is a diagram illustrating an example of an optical transmission system according to a second embodiment; FIG. FIG. 10 is a diagram showing an outline of a wavelength selection sequence according to the second embodiment; FIG. It is a figure which shows an example of an optical transmitter-receiver. It is a figure which shows an example of a usable wavelength determination part. FIG. 10 is a diagram showing an example of a wavelength selection sequence according to the second embodiment; FIG. 4 is a flow chart showing an example of processing of an optical transmitter/receiver; FIG. 10 is a diagram showing variations of usable wavelength determination units; FIG. 10 is a diagram showing another variation of the usable wavelength determining section; It is a figure which shows an example of the variation of an optical transmitter-receiver. FIG. 10 is a diagram showing another example of variation of the optical transmitter/receiver; FIG. 10 is a diagram showing still another example of a variation of the optical transmitter/receiver; 1 is a diagram illustrating an example of a configuration for implementing link aggregation; FIG.

FIG. 2 shows an example of an optical transmission system according to an embodiment of the invention. The optical transmission system 100 according to the embodiment of the present invention transmits a wavelength division multiplexed (WDM) signal between sites X and Y, as shown in FIG.

Each site is equipped with multiple routers and multiple transponders. That is, the site X is equipped with a plurality of routers 1 (1a-1n) and a plurality of transponders 2 (2a-2n). Also, at the site Y, a plurality of routers 3 (3a-3n) and a plurality of transponders 4 (4a-4n) are mounted.

The router 1 guides the client signal to be transmitted to the site Y to the corresponding transponder 2, and guides the client signal output from the corresponding transponder 2 to the client. Similarly, the router 3 guides the client signal to be transmitted to the site X to the corresponding transponder 4, and guides the client signal output from the corresponding transponder 4 to the client.

The transponder 2 transmits a client signal input from the corresponding router 1 to the site Y, and outputs a client signal received from the site Y to the corresponding router 1 . At this time, the transponder 2 generates an optical signal for transmitting the client signal and transmits the optical signal to the site Y. FIG. The transponders 2a-2n may be implemented in one device (ie a WDM transmission device). Similarly, the transponder 4 transmits a client signal input from the corresponding router 3 to the site X, and outputs a client signal received from the site X to the corresponding router 3 . At this time, the transponder 4 generates an optical signal for transmitting the client signal and transmits the optical signal to the base X. The transponders 4a-4n may be implemented in one device (ie a WDM transmission device). Each transponder 2, 4 is an example of an optical transmission device (or an optical transceiver).

Transponders 2a-2n transmit client signals to site Y using different wavelengths. Similarly, transponders 4a-4n transmit client signals to site X using different wavelengths.

Here, in this embodiment, it is assumed that signals are transmitted bidirectionally between the routers 1 and 3. FIG. In the example shown in FIG. 2, signals are bidirectionally transmitted between routers 1a and 3a, bidirectionally transmitted between routers 1b and 3b, and bidirectionally transmitted between routers 1n and 3n. In this case, the transmission wavelength of the transponder 2a connected to the router 1a and the transmission wavelength of the transponder 4a connected to the router 3a are controlled to be the same. Similarly, the transmission wavelength of transponder 2b and the transmission wavelength of transponder 4b are the same, and the transmission wavelength of transponder 2n and the transmission wavelength of transponder 4n are the same.

In the example shown in FIG. 2, the transponder 2a transmits an optical signal with wavelength λa to the site Y. In the example shown in FIG. Here, this optical signal carries the client signal. Also, in the following description, an optical signal of wavelength λi may be referred to as an "optical signal λi" (i=a to n). Also, a path to which the wavelength λi is assigned is sometimes called an “optical path λi” or a “wavelength path λi”. That is, the transponder 2a transmits the optical signal λa to the base Y. Similarly, transponders 2b-2n transmit optical signals λb-λn to site Y, respectively. Also, the transponders 4a to 4n transmit optical signals λa to λn to the site X, respectively.

The optical coupler 5T multiplexes the optical signals λa-λn output from the transponders 2a-2n to generate a WDM signal. A WDM signal generated by the optical coupler 5T is transmitted to the site Y via the optical network. The optical coupler 6R splits the WDM signal received from the site X and guides it to the transponders 4a to 4n. That is, the optical coupler 6R functions as an optical splitter, and the same WDM signal is guided to the transponders 4a-4n.

Similarly, the optical coupler 6T multiplexes the optical signals λa-λn output from the transponders 4a-4n to generate a WDM signal. A WDM signal generated by the optical coupler 6T is transmitted to the site X via the optical network. The optical coupler 5R branches the WDM signal received from the site Y and guides it to the transponders 2a to 2n. That is, the optical coupler 5R functions as an optical splitter, and the same WDM signal is guided to the transponders 2a-2n.

Note that the optical couplers 5T and 5R may be installed at the base X or belong to the optical network. Similarly, the optical couplers 6T, 6R may be implemented at site Y or belong to the optical network.

In the optical transmission system 100 configured as described above, each of the transponders 2a to 2n and 4a to 4n has a function of selecting a wavelength not used in the optical transmission system 100. FIG. Then, each transponder 2a-2n, 4a-4n uses the selected wavelength to transmit the client signal to the opposite site. Further, each transponder 2a-2n, 4a-4n extracts an optical signal of a selected wavelength from the WDM signal received from the opposite site.

For example, in a case where a client signal is transmitted between routers 1a and 3a, transponder 2a (or transponder 4a) selects wavelength λa. In this case, the transponder 2a generates an optical signal .lambda.a from the client signal given from the router 1a and transmits the optical signal .lambda.a to the site Y. FIG. Then, the transponder 4a extracts the optical signal λa from the WDM signal in which the optical signals λa to λn are multiplexed and reproduces the client signal. The regenerated client signal is led from the transponder 4a to the router 3a. Similarly, the transponder 4a generates an optical signal λa from the client signal given from the router 3a and transmits the optical signal λa to the base X. Then, the transponder 2a extracts the optical signal λa from the WDM signal in which the optical signals λa to λn are multiplexed and reproduces the client signal. The regenerated client signal is led from the transponder 2a to the router 1a.

Thus, since each transponder has the function of selecting an unused wavelength, the optical transmission system 100 need not have a controller for centralized management of the entire network. Optical signals generated by each transponder are multiplexed using an optical coupler. Here, unlike the AWG, each port of the optical coupler is configured so that any wavelength can pass through. Thus, each transponder can select the desired wavelength, and each router can connect to the desired transponder.

FIG. 3 shows an example of a transponder. The following description describes the configuration and operation of transponder 2 . However, the transponders 2, 4 are substantially identical to each other. Therefore, description of the transponder 4 is omitted.

The transponder 2 includes an identification information acquisition section 11, a shutter 12, a transmitter 13, a coherent receiver 14, a shutter 15, and a controller 16, as shown in FIG. Note that the transponder 2 may have other elements or functions not shown in FIG.

The identification information acquisition unit 11 has a Snoop function and acquires identification information from the input client signal. A client signal, in the following description, is not limited to a user data signal, but represents a signal input from the router 1 to the transponder 2 . For example, client signals include signals for neighbor discovery/neighbor confirmation generated by router 1 . Neighbor discovery/neighbor confirmation protocols are, for example, OSPF (open shortest path first) Hello, LLDP (link layer discovery protocol), PING, and the like. Note that identification information may be referred to as an "identifier".

The identification information identifies the communication involving the source of the client signal (ie router 1). For example, when the client signal includes the source IP address, the identification information acquisition unit 11 may acquire the source IP address or part of the source IP address. As part of the IP address, for example, the value of the network address part is obtained. The network address part identifies the subnet under the router 1. FIG. The identification information acquired by the identification information acquiring section 11 is passed to the controller 16 .

The shutter 12 can block client signals from being input to the transmitter 13 according to instructions given from the controller 16 . For example, the shutter 12 blocks client signals according to instructions given from the controller 16 during a period in which a wavelength allocation sequence, which will be described later, is being executed. Also, when the transponder 2 transmits a client signal to the opposite site, the shutter 12 allows the client signal to pass according to an instruction given from the controller 16 .

The transmitter 13 in this embodiment comprises a digital signal processor (DSP) 13a, a digital/analog converter (DAC) 13b, a light source (LD) 13c and a modulator 13d. The DSP 13a generates a drive signal from the client signal according to the designated modulation method. The DSP 13a can also generate drive signals from control signals given from the controller 16. FIG. The digital/analog converter 13b converts the drive signal generated by the DSP 13a into an analog signal. The light source 13 c is a variable wavelength light source and generates continuous light with a wavelength designated by the controller 16 . The modulator 13d modulates the continuous light generated by the light source 13c with a drive signal to generate a modulated light signal. An optical signal generated by the transmitter 13 is transmitted to the opposite site via the optical network.

Coherent receiver 14 comprises a local light source (LO) 14a, a front end circuit 14b, an analog-to-digital converter (ADC) 14c, and a digital signal processor (DSP) 14d. The local light source 14a is a wavelength tunable light source and generates local light with a wavelength specified by the controller 16. FIG. The front-end circuit 14b extracts light having the same wavelength as the local light generated by the local light source 14a from the input light. The front-end circuit 14b then generates an electric field information signal representing the electric field information of the light extracted from the input light. The analog/digital converter 14c converts the electric field information signal generated by the front end circuit 14b into a digital signal. DSP 14d recovers control and/or client signals from the electric field information signal. The DSP 14d passes the control signal to the controller 16 when it reproduces the control signal.

The shutter 15 can block the received signal from being led to the router 1 according to instructions given from the controller 16 . For example, the shutter 15 cuts off the received signal according to an instruction given from the controller 16 during a period in which a wavelength allocation sequence, which will be described later, is being executed. Also, when the transponder 2 receives a client signal from the opposite site, the shutter 15 allows the received signal (that is, the client signal) to pass according to an instruction given from the controller 16 .

Controller 16 executes a wavelength allocation sequence that selects the wavelengths used by transponder 2 . For example, the controller 16 starts the wavelength allocation sequence when the identification information is given from the identification information acquisition unit 11 before the transponder 2 starts data communication.

The controller 16 can generate a control signal including the identification information obtained from the incoming client signal and use the transmitter 13 to transmit the control signal to the opposite site. Controller 16 may also utilize coherent receiver 14 to detect wavelengths not used in optical transmission system 100 . At this time, the controller 16 controls the oscillation wavelength of the local light source 14a so as to scan the WDM signal band. The local light source 14 a sequentially generates continuous light corresponding to each wavelength channel of the WDM signal under the control of the controller 16 . Then, the controller 16 sequentially determines whether each wavelength channel is being used based on the output signal of the DSP 14d. For example, if the amplitude of the output signal from the DSP 14d is smaller than a predetermined threshold while the local light source 14a is generating continuous light of wavelength λa, the controller 16 determines that the wavelength λa is unused. The controller 16 then determines a wavelength to be used by the transponder 2 from among the detected unused wavelengths. It should be noted that the controller 16 controls the shutters 12 and 15 to cut off the signals when executing the wavelength allocation sequence described above.

The controller 16 is implemented by, for example, a processor system including a processor and memory. In this case, the processor provides functions related to the wavelength allocation sequence by executing programs stored in the memory. However, the processor may also provide functions other than wavelength assignment sequences. Also, some of the functions of the controller 16 may be realized by hardware circuits.

FIG. 4 shows an example of a wavelength allocation sequence. In this example, clients in each subnet of site X communicate with clients in the corresponding subnet of site Y. FIG. A subnet is identified by the value of the network address part of the IP address of each router 2, 4 in the example shown in FIG. For example, the IP address of router 1a is 192.168.10.1 and the IP address of router 3a is 192.168.10.2. Here, it is assumed that the upper 24 bits of the IP address are the network address part. In this case, the client under the router 1a and the client under the router 3a belong to the same subnet (that is, the subnet identified by 192.168.10). A client under the router 1a communicates with a client under the router 3a. That is, it is required to set an optical path between transponder 2a and transponder 4a.

Also, in this example, each router 1 and 3 periodically outputs OSPF Hello packets. OSPF Hello packets are used by routers 1 and 3 to notify neighboring nodes of their existence. Therefore, the data area of the OSPF Hello packet stores the IP address of the source of the OSPF Hello packet.

For example, as mentioned above, the IP address of router 1a is 192.168.10.1. Therefore, this IP address is stored in the data area of the OSPF Hello packet output from the router 1a. Similarly, 192.168.20.1 is stored in the data area of the OSPF Hello packet output from the router 1b, and 192.168.30.1 is stored in the data area of the OSPF Hello packet output from the router 1n.

Upon receiving the OSPF Hello packet from the router 1a, the transponder 2a snoops the data area. The transponder 2a then acquires the IP address of the source of this OSPF Hello packet (that is, the router 1a). At this time, the transponder 2a may acquire only the network address portion of the IP address of the router 1a.

Subsequently, transponder 2 a detects wavelengths that are not used in optical transmission system 100 . The unused wavelengths are detected, for example, by scanning the oscillation wavelength of the local light source 14a in the WDM signal band, as described above. Then, the transponder 2a selects a wavelength to be used by the transponder 2a from among the detected unused wavelengths according to a predetermined policy. As an example, the shortest wavelength is selected from among the unused wavelengths.

Similarly, the transponder 4a acquires the IP address of the router 3a or part thereof from the OSPF Hello packet transmitted from the router 3a. The transponder 4a also detects unused wavelengths and selects the wavelength to be used by the transponder 4a from among them.

After that, the transponder 2a transmits the identification information and the wavelength information to the base Y. The identification information represents the value of the network address part in the IP address of the router 1a in this embodiment. The wavelength information represents the wavelength selected in transponder 2a. Similarly, the transponder 4a transmits identification information and wavelength information to the site X. The identification information represents the value of the network address part in the IP address of the router 3a in this embodiment. The wavelength information represents the wavelength selected in the transponder 4a. In this embodiment, the identification information and the wavelength information are transmitted using the wavelength λ cont which is pre-designated for transmitting the control signal in the WDM signal.

In the example shown in FIG. 2, at site X, the transponder 2a that received the OSPF Hello packet from the router 1a acquires the IP address 192.168.10.1 of the router 1a from the packet. At this time, it is assumed that the wavelength λa is unused in the optical transmission system. In this case, the transponder 2a transmits "identification information: 192.168.10" and "wavelength information: λa" to the base Y. On the other hand, at site Y, the transponder 4a that has received the OSPF Hello packet from the router 3a acquires the IP address 192.168.10.2 of the router 3a from the packet. At this time, it is assumed that the wavelength λa is unused in the optical transmission system. In this case, the transponder 4a transmits "identification information: 192.168.10" and "wavelength information: λa" to the base X.

The transponder 2a receives the WDM signal transmitted from the site Y via the optical network. The WDM signal transmitted from site Y is guided to all transponders 2a to 2n mounted at site X by optical coupler 5R. The transponder 2a then extracts identification information and wavelength information from the control channel in the received WDM signal.

When the value of the network part of the IP address of the router 1a matches the identification information received from the site Y, the transponder 2a receives the optical signal of the wavelength (that is, λa) specified by the received wavelength information. It controls the coherent receiver 14 . Also, the transponder 2a controls the transmitter 13 so as to transmit the optical signal of the wavelength (ie, λa) selected by itself.

Similarly, when the value of the network part of the IP address of the router 3a matches the identification information received from the site X, the transponder 4a receives the optical signal of the wavelength (that is, λa) specified by the received wavelength information. so that the coherent receiver 14 is controlled. Also, the transponder 4a controls the transmitter 13 so as to transmit the optical signal of the wavelength (ie, λa) selected by itself.

The wavelength λa is assigned to the communication between the transponder 2a and the transponder 4a by the above wavelength assignment procedure. As a result, the client under the router 1a and the client under the router 3a can bi-directionally communicate via the wavelength path λa.

However, the procedure shown in FIG. 4 may result in inappropriate wavelength allocation. For example, assume that wavelengths λ1 and λ2 are not used in the optical transmission system. At base X, it is assumed that an OSPF Hello packet is transmitted from router 1b, and then an OSPF Hello packet is transmitted from router 1n. On the other hand, at the site Y, it is assumed that the router 3n transmits an OSPF Hello packet, and then the router 3b transmits an OSPF Hello packet. In this case, for example, λ1 may be assigned to the path transmitting the signal from the transponder 2b to the transponder 4b, and λ2 may be assigned to the path transmitting the signal from the transponder 4b to the transponder 2b. Similarly, λ2 may be assigned to the path transmitting the signal from the transponder 2n to the transponder 4n, and λ1 may be assigned to the path transmitting the signal from the transponder 4n to the transponder 2n. That is, the wavelengths of a set of optical paths for bi-directional communication may differ from each other.

Also, for example, when router 1b and router 1n transmit OSPF Hello packets at approximately the same time, transponder 2b and transponder 2n may select the same wavelength. In this case, the bases X and Y cannot communicate with each other.

Therefore, the optical transmission device according to the embodiment of the present invention has a function of avoiding inappropriate wavelength allocation as described above.

<First Embodiment>
FIG. 5 shows an example of a wavelength allocation sequence according to the first embodiment of the invention. In the embodiment shown in FIG. 5, as in the example shown in FIG. 4, it is assumed that clients in each subnet of site X communicate with clients in the corresponding subnet of site Y. FIG. Moreover, each router 1 and 3 shall output an OSPF Hello packet periodically.

Upon receiving the OSPF Hello packet from the router 1a, the transponder 2a snoops the data area. Specifically, the identification information acquisition unit 11 of the transponder 2a acquires the IP address of the source of this OSPF Hello packet (that is, the router 1a). At this time, the identification information acquisition unit 11 may acquire only the value of the network address part in the IP address of the router 1a. In this case, "192.168.10" is obtained as identification information.

The transponder 2a transmits this identification information to the base Y. In this embodiment, the control signal including the control information (including the identification information) transmitted between the transponder 2 mounted at the site X and the transponder 4 mounted at the site Y in the wavelength allocation sequence is It is transmitted through the specified wavelength path λcont. The wavelength path λcont is set in the WDM signal band as shown in FIG. 6(a). Therefore, the identification information transmitted from the transponder 2a is transmitted to the site Y via the wavelength path λcont multiplexed in the WDM signal. It is assumed that each transponder is set to receive the optical signal of the wavelength path λcont during the period during which the wavelength allocation sequence is executed or during the period during which data communication is not performed.

At site Y, a WDM signal transmitted from site X is guided to all transponders 4a to 4n mounted at site Y by optical coupler 6R. At this time, it is assumed that the transponder 4a is not performing data communication. In this case, the transponder 4a waits for control information. That is, the transponder 4a waits for a signal on the signal path λcont. Therefore, the transponder 4a can receive the identification information transmitted from the transponder 2a.

Similarly, when transponder 4a receives an OSPF Hello packet from router 3a, it acquires an IP address from the packet. Specifically, the identification information acquisition unit 11 of the transponder 4a acquires "identification information: 192.168.10". The transponder 4a then transmits this identification information to the site X via the wavelength path λcont. As a result, transponder 2a receives the identification information transmitted from transponder 4a.

When the identification information obtained from the router 1a matches the identification information received from the site Y, the transponder 2a executes a master/slave determination procedure. Similarly, when the identification information obtained from the router 3a matches the identification information received from the site X, the transponder 4a executes the master/slave determination procedure.

Master/slave determination is not particularly limited, but may be realized by a known technique. For example, transponders 2a, 4a each generate a random number. Subsequently, the transponders 2a and 4a notify the counterpart apparatus of the generated numbers. At this time, this number is transmitted to the partner device via the wavelength path λcont. In addition, each of the transponders 2a and 4a also notifies the partner device of the previously acquired identification information together with the generated number.

Then, each of the transponders 2a and 4a determines that it operates as a master device if the number generated by itself is greater than the number notified from the partner device. On the other hand, each of the transponders 2a and 4a determines that it operates as a slave device if the number generated by itself is smaller than the number notified by the partner device. Incidentally, when the two numbers match each other, the transponders 2a and 4a perform the above procedure again. As a result, in the example shown in FIG. 5, transponder 2a operates as a master device and transponder 4a operates as a slave device.

The master/slave determination may be implemented in other ways. For example, transponders 2a and 4a each record the time of reception of the OSPF Hello packet. Subsequently, the transponders 2a and 4a each notify the reception time of the OSPF Hello packet to the partner device. Then, each of the transponders 2a and 4a determines that it operates as a master device if the reception time of its own device is earlier than the reception time of the partner device.

When control information is transmitted between the transponder 2 mounted at the site X and the transponder 4 mounted at the site Y in the wavelength allocation sequence, the control information is transmitted together with the identification information. Then, the device on the receiving side (that is, the transponder) determines whether to acquire or discard the received control information based on the identification information included in the received signal. Specifically, if the identification information obtained from the received OSPF Hello packet matches the identification information received from the partner device, the transponder obtains the control information received together with the identification information. For example, in the embodiment shown in FIG. 5, the transponders 2a, 4a obtain the control information from the signal received via the wavelength path λcont when the signal contains "identification information: 192.168.10".

Thus, in the wavelength allocation sequence, transponders receiving control information via the wavelength path λcont can use the identification information transmitted along with the control information to determine whether or not to acquire the control information. . That is, control information transmitted from a transponder at one site to another site reaches all transponders at the other site, but by transmitting identification information together with the control information, the transponders belonging to the same subnet can be controlled. Information will arrive. Therefore, sending the control information with the identification information added to the receiving site is equivalent to sending the control information to the target transponder.

Transponders 2 a and 4 a each detect wavelengths that are not used in optical transmission system 100 . Unused wavelengths are detected by scanning the oscillation wavelength of the local light source 14a in the WDM signal band, as described above.

The transponder (slave device) 4a transmits wavelength information representing the detected unused wavelength to the base X. The wavelength information is transmitted to site X via wavelength path λcont. Also, "identification information: 192.168.10" is transmitted together with the wavelength information. That is, the transponder 4a transmits wavelength information to the transponder 2a via the wavelength path λcont.

A transponder (master device) 2a acquires wavelength information from a transponder 4a. Then, the transponder 2a allocates a wavelength (hereinafter referred to as , selected wavelength). At this time, for example, the shortest wavelength among common unused wavelengths is selected as the selected wavelength.

The transponder 2a controls the oscillation wavelength of the light source 13c of the transmitter 13 so as to transmit the main signal to the opposite base at the selected wavelength. Also, the transponder 2a controls the oscillation wavelength of the local light source 14a of the coherent receiver 14 so as to receive the optical signal of the selected wavelength from the opposite site.

The transponder (master device) 2a transmits to the site Y a wavelength notification indicating the wavelength (that is, the selected wavelength) assigned for communication between the transponders 2a and 4a. At this time, the wavelength notification is transmitted to the site Y via the wavelength path λcont. Also, "identification information: 192.168.10" is transmitted together with the wavelength notification. That is, the transponder 2a transmits a wavelength notification to the transponder 4a via the wavelength path λcont. At this time, a control signal including wavelength notification and identification information is transmitted to site Y via wavelength path λcont.

Upon receiving the wavelength notification from transponder 2a, transponder (slave device) 4a controls transmitter 13 and coherent receiver 14 according to the selected wavelength designated by the wavelength notification. That is, the transponder 2a controls the oscillation wavelength of the light source 13c of the transmitter 13 so as to transmit the main signal at the selected wavelength. Also, the transponder 2a controls the oscillation wavelength of the local light source 14a of the coherent receiver 14 so as to receive the optical signal of the selected wavelength. After that, the transponder 4a transmits a setting completion notification to the transponder 2a. Note that the setting completion notification corresponds to a signal indicating that the control signal including the wavelength notification has been received, and is transmitted to the site X via the wavelength path λcont.

Upon receiving the setting completion notification, the transponder 2a stops the operation of receiving the optical signal via the wavelength path λcont, and then transmits the optical signal at the selected wavelength (that is, the wavelength assigned for communication between the transponders 2a and 4a). Send to base Y. Thereafter, the transponders 2a, 4a transmit data in both directions using the selected wavelength.

Thus, the transponder according to the embodiment of the present invention can appropriately determine the wavelength to be used in WDM transmission without receiving instructions from the controller for centrally managing the entire network. In addition, since one of a pair of transponders (transponders 2a and 4a in FIG. 5) connected to the same subnet operates as a master device, wavelengths are appropriately allocated for communication between the pair of transponders. be done. Specifically, for example, the wavelengths of a set of lightpaths for bidirectional communication are not different from each other. However, when a plurality of transponder pairs execute the wavelength allocation sequence at the same time, there is a possibility of wavelength contention between the transponder pairs.

FIG. 7 shows an example of how to avoid wavelength conflicts between transponder pairs. In this example, transponders 2a, 4a are connected to subnet 192.168.10 and transponders 2b, 4b are connected to subnet 192.168.20. In a transponder pair a composed of transponders 2a and 4a, transponder 2a operates as a master device and transponder 4a operates as a slave device. Similarly, in a transponder pair b composed of transponders 2b and 4b, transponder 2b operates as a master device and transponder 4b operates as a slave device.

Each of the transponders (master devices) 2a and 2b tentatively determines the wavelength to be used from among the unused wavelengths. In this example, transponders 2a and 2b both select wavelength λ1.

The transponders 2a and 2b each transmit the wavelength provisional allocation information to the opposite base. The wavelength provisional allocation information represents the provisionally determined wavelength. Also, the wavelength provisional allocation information is transmitted together with the identification information. FIG. 7 shows the tentative wavelength allocation information transmitted from the transponder 2b. That is, "identification information: 192.168.20" and "wavelength provisional allocation information: λ1" are transmitted from the transponder 2b to the base Y.

At site Y, the tentative wavelength allocation information transmitted from transponder 2 b is guided to all transponders 4 . At this time, since the transponder 4a is connected to a different subnet from the transmission source of the temporary wavelength allocation information (that is, the transponder 2b), it discards the received temporary wavelength allocation information. On the other hand, since the transponder 4b is connected to the same subnet as the transmission source of the temporary wavelength allocation information, it returns the received temporary wavelength allocation information to the base X.

At the site X, the tentative wavelength allocation information returned from the transponder 4b is guided to all the transponders 2. FIG. At this time, the transponder 2a is connected to a different subnet from the transmission source of the tentative wavelength allocation information (that is, the transponder 2b), but since it operates as a master device, it acquires the received tentative wavelength allocation information. Then, the transponder 2a compares the wavelength temporarily determined by itself with the wavelength notified by the wavelength temporary allocation information. In this example, both wavelengths are λ1.

In this case, a master/slave determination procedure is performed between the two master devices (ie transponders 2a, 2b). This procedure is the same as the master/slave decision procedure within a transponder pair. As a result, in the example shown in FIG. 7, the transponder 2a operates as a master device between the transponder pairs, and the transponder 2b operates as a slave device between the transponder pairs. Note that when two master devices are installed in the same site, control information exchanged between the two master devices (for example, random numbers generated within transponders) may be transferred to another site. It is transmitted through the installed slave device.

Since the transponder 2a is the master device between the transponder pairs, the previously tentatively determined wavelength (ie, λ1) is assigned to the communication between the transponders 2a and 4a. Thereafter, as described with reference to FIG. 5, the transponders 2a and 4a exchange wavelength notification and setting completion notification, and communication of the main signal is started. In this case, the main signal is transmitted through the wavelength path λ1 between the transponders 2a and 4a.

On the other hand, since the transponder 2b is a slave device between the transponder pairs, it selects a new wavelength from among previously detected unused wavelengths. In FIG. 7, wavelength λ2 is newly selected. Then, the transponder 2b allocates the wavelength λ2 to communication between the transponders 2b and 4b unless the wavelength λ2 is provisionally allocated by another transponder pair.

Thus, in the sequence shown in FIG. 7, if multiple transponder pairs select the same wavelength at the same time, arbitration is performed between them. Thus, situations in which multiple subnets are assigned the same wavelength are avoided.

8 and 9 are flowcharts showing an example of transponder processing. The processing of this flowchart is executed, for example, after the router is connected to the transponder.

At S1, the transponder receives an OSPF Hello packet from the router. In S2, the identification information acquisition unit 11 acquires the IP address from this packet. In the following description, the value of the network part of this IP address is called identification information. Also, this identification information is denoted as ID in FIG.

In S3, the controller 16 transmits the identification information obtained from the input packet to the counter base. At S4, the controller 16 receives the identification information from the opposing site. In S5, the controller 16 determines whether the identification information obtained in S2 matches the identification information received in S4. Then, when these pieces of identification information match each other, the controller 16 executes a master/slave determination procedure in S6-S7 with the transponder that transmitted the identification information received in S4.

In the master/slave determination procedure, when it is determined that the self device operates as the master device, the process of the controller 16 proceeds to S21. On the other hand, when it is determined that the own device operates as a slave device, the process of the controller 16 proceeds to S11.

S11-S15 are executed when the transponder operates as a slave device. At S<b>11 , the controller 16 detects wavelengths that are not used in the optical transmission system 100 . In S12, the controller 16 transmits wavelength information representing the detected unused wavelengths to the master device. At S13, the controller 16 receives the wavelength notification from the master device. The wavelength notification indicates a wavelength (hereinafter referred to as a selected wavelength) assigned for communication with the opposite transponder installed at the opposite base.

At S14, the controller 16 controls circuitry within the transponder according to the received wavelength notification. Specifically, the controller 16 controls the settings of the transmitter 13 such that the client signal is transmitted on the selected wavelength. The controller 16 also controls the settings of the coherent receiver 14 to receive the optical signal at the selected wavelength and regenerate the client signal. After that, the controller 16 transmits a setting completion notice to the master device in S15.

S21-S34 are executed when the transponder operates as a master device. At S<b>21 , the controller 16 detects wavelengths that are not used in the optical transmission system 100 . At S22, the controller 16 receives wavelength information from the slave device. This wavelength information represents unused wavelengths detected in the slave device.

In S23, the controller 16 performs tentative wavelength allocation. That is, the controller 16 tentatively determines the wavelength to be used for transmitting the client signal within the transponder pair from among the wavelengths common to the unused wavelengths detected by itself and the unused wavelengths detected by the slave device.

In S24, the controller 16 transmits tentative allocation information representing the wavelength tentatively determined in S23 to the opposite base. At S25, the controller 16 starts a timer.

In S26-S27, the controller 16 waits for provisional allocation information transmitted from the opposite base. The tentative assignment information represents wavelengths tentatively determined to be assigned to communications within the transponder pair, as described above. Controller 16 then monitors whether the same wavelength is selected in other transponder pairs.

When the same wavelength is selected in another transponder pair, the controller 16 performs a master/slave determination procedure between the transponder pairs in S28-S29.

In the master/slave determination procedure between the transponder pair, when it is determined that the self device operates as the master device between the transponder pair, the controller 16, in S30, transfers the wavelength tentatively determined in S23 to the transponder including the self device. Allocate communication between pairs. At S31, the controller 16 transmits a wavelength notification to the slave device. This wavelength notification indicates the wavelength (hereinafter referred to as selected wavelength) allocated for communication between transponders in S30. At S32, the controller 16 receives a setting completion notification from the slave device. Thereafter, at S33, the controller 16 controls circuits within the transponder according to the wavelength assignment of S30. Specifically, the controller 16 controls the settings of the transmitter 13 such that the client signal is transmitted on the selected wavelength. The controller 16 also controls the settings of the coherent receiver 14 to receive the optical signal at the selected wavelength and regenerate the client signal.

In the master/slave determination procedure, when it is determined that the own device operates as a slave device between the transponder pairs (S29: No), the controller 16 selects other unused wavelengths from the previously detected unused wavelengths in S34. select the wavelength of That is, a new provisional allocation is made. After that, the processing of the controller 16 returns to S24.

In the above-described embodiment, the IP address of the router (or a value identifying the subnet under the router) is used as the identification information, but the present invention is not limited to this form. For example, the MAC address of the router or the device name of the router may be used as the identification information. In this case, it is preferable that the MAC address or device name of the router belonging to each subnet is known and registered in each transponder in advance. Also, in the above embodiment, the identification information is extracted from the OSPF Hello packet, but the present invention is not limited to this form. For example, identification information may be extracted from packets of neighbor discovery/neighbor confirmation protocols such as LLDP or PING.

<Transponder variations>
FIG. 10 shows an example of a transponder variation. In the example shown in FIG. 3, the control signal is transmitted using one or a plurality of channels among a plurality of wavelength channels multiplexed on the WDM signal. On the other hand, in the example shown in FIG. 10, the wavelength band for transmitting data signals and the wavelength band for transmitting control signals are separated from each other. For example, as shown in FIG. 6B, data signals are transmitted using the 1.5 μm band, and control signals are transmitted using the 1.3 μm band. In this case, the light source 13c and the local light source 14a each generate continuous light in the 1.5 μm band.

The transponder shown in FIG. 10 includes a transmission circuit 21, WDM couplers 22 and 23, and a reception circuit 24 in addition to the configuration shown in FIG. The transmission circuit 21 has a light source that generates continuous light in the 1.3 μm band, and generates an optical signal that transmits control information given from the controller 16 . The optical coupler 22 multiplexes the WDM signal generated by the transmitter 13 and the optical signal generated by the transmission circuit 21 . This multiplexed optical signal is then output to the optical network. The optical coupler 23 separates the 1.3 μm band light from the input light and guides it to the receiving circuit 24 . Then, the receiving circuit 24 reproduces the control information from the received light in the 1.3 μm band.

Thus, in the configuration shown in FIG. 10, control signals are transmitted using a wavelength band different from the wavelength band for transmitting data signals. Therefore, according to the configuration shown in FIG. 10, compared with the configuration shown in FIG. 3, more wavelength channels can be allocated for data transmission, so the WDM signal capacity increases.

FIG. 11 shows another example of a transponder variation. This transponder comprises a signal generator 13e instead of the DSP 13a and digital/analog converter 13b shown in FIG. 3 or FIG. The signal generator 13e generates drive signals based on control information given from the controller 16 in the wavelength allocation sequence. Also, the signal generator 13e generates a drive signal based on the client signal during data communication. The modulator 13d then generates an optical signal from this drive signal.

A receiver 31 is provided instead of the coherent receiver 14 shown in FIG. 3 or 10 and comprises a band pass filter (BPF) 31a and a signal regenerator 31b. The BPF 31a allows light of a wavelength specified by the controller 16 to pass therethrough. Therefore, when the transponder detects an unused wavelength in the wavelength allocation sequence, the BPF 31a scans the passing wavelengths according to the instructions given by the controller 16. FIG. Also, during data communication, the BPF 31a passes light of a wavelength selected from the wavelength allocation sequence. A signal regenerator 31b regenerates a signal from the output light of the BPF 31a. The controller 16 can then execute the wavelength allocation sequence using the signal regenerated by the signal regenerator 31b. The controller 16 can also determine whether each wavelength is being used based on the output signal of the signal regenerator 31b.

<Variation of network configuration>
In the example shown in FIG. 12, an optical amplifier 41 is provided on the optical transmission line between the site X and the site Y. In the example shown in FIG. The optical amplifier 41 is, for example, an erbium-doped fiber amplifier (EDFA), and can collectively amplify WDM signals. Also, the optical amplifier 41 may be provided only on the transmitting side, only on the receiving side, or both on the transmitting side and the receiving side.

A WDM signal transmitted via an optical network is branched by an optical coupler at a base on the receiving side and distributed to each transponder. Therefore, when the number of branches of the optical coupler is large (that is, when the number of transponders is large), the received power of the WDM signal arriving at each transponder is small. Therefore, the optical amplifier 41 is implemented so as to compensate for the loss of optical power. That is, the number of optical amplifiers 41 provided on the optical transmission line is preferably determined according to the transmission distance and the number of branches of the optical coupler.

In the example shown in FIG. 13, an optical circulator 51 is mounted between the transponder and the optical coupler. For example, an optical circulator 51 mounted between the transponder 2a and the optical coupler 5T guides the optical signal output from the transponder 2a to the optical coupler 5T, and guides the WDM signal output from the optical coupler 5T to the transponder 2a. With this configuration, an optical coupler (optical coupler 6T in the example shown in FIG. 2) for multiplexing a plurality of optical signals and an optical coupler (optical coupler 6T in the example shown in FIG. 2) for guiding WDM signals to a plurality of transponders Two-way communication is realized without using the coupler 5R).

The wavelength assignment sequence is simplified when unidirectional communication is performed between bases instead of bidirectional communication. For example, when selecting a wavelength for transmitting a client signal from site X to site Y, the following sequence is executed.

(1) At base X, transponder 2a acquires identification information from the OSPF Hello packet received from router 1a. Then, the transponder 2a transmits the identification signal to the site Y via the wavelength path λcont. This identification information is received by each transponder 4 at site Y. FIG.

(2) Each transponder 4 at site Y acquires identification information from the OSPF Hello packet received from router 3 . When the identification information received from the transponder 2a matches the identification information obtained from the OSPF Hello packet, the transponder 4a selects a wavelength to be used from unused wavelengths. The transponder 4a then transmits wavelength information representing the selected wavelength to the site X together with the identification information obtained from the OSPF Hello packet. This wavelength information is received by each transponder 2 at site X. FIG.

(3) In the transponder 2a, the identification information obtained from the OSPF Hello packet matches the identification information received together with the wavelength information from the transponder 4a. Therefore, the transponder 2a transmits the client signal to the site Y at the wavelength indicated by the wavelength information received from the transponder 4a.

(4) The transponder 4a sets its receiver to receive the optical signal of the wavelength selected in (2) above. This completes the setting of the optical path for transmitting the client signal from the transponder 2a to the transponder 4a.

In the example shown in FIG. 14, at either site X or site Y, an AWG is used instead of the optical coupler. In the example shown in FIG. 14, the site X uses an AWG 61 that multiplexes optical signals output from the transponders 2a to 2n and an AWG 62 that separates the WDM signals by wavelength and guides them to the transponders 2a to 2n. It is assumed that the transponder 2a is connected to the λa input port of AWG61 and the λa output port of AWG62. In this case, for example, the following wavelength allocation sequence is executed.

(1) At base X, transponder 2a acquires identification information from the OSPF Hello packet received from router 1a. The transponder 2a then transmits the identification signal to the site Y via the wavelength path λa. This identification information is received by each transponder 4 at site Y. FIG.

(2) Each transponder 4 at site Y acquires identification information from the OSPF Hello packet received from router 3 . The transponder 4a transmits the identification information obtained from the OSPF Hello packet to the site X when the identification information received from the transponder 2a matches the identification information obtained from the OSPF Hello packet. Here, the transponder 4a receives identification information from the transponder 2a via the wavelength path λa. Therefore, the transponder 4a transmits the identification information obtained from the OSPF Hello packet to the site X via the wavelength λa.

(3) When the transponder 2a receives from the site Y the same identification information as the identification information obtained from the OSPF Hello packet, the transponder 2a transmits a client signal to the site Y at the wavelength λa.

(4) When the transponder 4a receives the client signal with the wavelength λa from the base X, it transmits the client signal to the base X with the wavelength λa. This completes the setting of the optical path between the transponders 2a and 4a.

In the example shown in FIG. 15, the functions of the controller 16 shown in FIG. 2 are implemented by a controller provided outside the transponder. Specifically, the controller 71 implements the function of the controller 16 of each transponder 2a-2n, and the controller 72 implements the function of the controller 16 of each transponder 4a-4n.
In this case, transponders 2a-2n and controller 71 are preferably implemented in the same station building. Similarly, transponders 4a-4n and controller 72 are preferably implemented in the same station building. Further, each transponder 2a-2n, 4a-4n has a function of transmitting and receiving control signals to and from the corresponding controller 71, 72. FIG. Note that each of the controllers 71 and 72 may be shared by a plurality of transponders, or may be provided for one transponder.

In the optical transmission system configured as described above, each transponder obtains identification information from the input signal. Then, for example, when the identification information acquired from the input signal by the transponder 2a and the identification information acquired from the input signal by the transponder 4a match each other, the controllers 71 and 72 determine which one operates as the master device. . Transponders 2a and 4a detect unused wavelengths in optical transmission system 100, respectively. When the controller 71 acts as a master device, the controller 71 selects the first wavelength among the unused wavelengths for communication between the transponders 2a, 4a. If the first wavelength has not been selected for communication between other optical transmission devices, controller 71 assigns the first wavelength to communication between transponders 2a, 4a.

In the example shown in FIG. 16, a ROADM (reconfigurable optical add drop multiplexer) node is provided between bases X and Y. In the example shown in FIG. A wavelength selective switch (WSS) is implemented in the ROADM node. A wavelength selective switch can guide an optical signal to a desired route for each wavelength. However, in the ROADM node provided between sites X and Y, the wavelength selective switch guides all optical signals received from site X to site Y, and directs all optical signals received from site Y to site X. lead.

In the example shown in FIG. 17, a relay node is provided between bases X and Y. In the example shown in FIG. An optical coupler for branching an input optical signal is mounted in the relay node. This optical coupler is used as an optical splitter and can split an input optical signal and direct it to one or more paths. Further, the relay node is equipped with an optical coupler for multiplexing a plurality of optical signals. This optical coupler can multiplex optical signals received from sites X and Y and optical signals received from other nodes.

In the configuration shown in FIG. 17, the wavelengths belonging to wavelength group A and the wavelengths belonging to wavelength group B are determined so as not to conflict with each other. Wavelength group A is composed of wavelengths assigned to communication between sites X and Y. FIG. Wavelength group B consists of wavelengths assigned to communication between site X and other nodes or communication between site Y and other nodes. Further, in the configuration shown in FIG. 17, the optical signal is branched by the optical coupler mounted on the relay node, so the optical loss increases. Therefore, although not shown, it is preferable to provide an optical amplifier between the site X and the relay node and/or between the site Y and the relay node.

<Second embodiment>
In the embodiments shown in FIGS. 5-9, dedicated wavelength channels are provided for transmitting control signals (in the example shown in FIG. 5, identification information, wavelength information, wavelength notification, configuration completion notification, etc.). In the example shown in FIG. 6, the control signal is transmitted using the wavelength λcont. Also, in the embodiments shown in FIGS. 5-9, a procedure is performed to determine the wavelength between the master device and the slave device. This may increase the time required to determine the wavelength. For example, in the case where many transponders are connected to the network at the same time, arbitration between master devices is also required, which increases the time required to determine the wavelength. The embodiments described below solve or mitigate these problems.

FIG. 18 shows an example of an optical transmission system according to the second embodiment of the invention. Similarly to the first embodiment, the optical transmission system of the second embodiment also transmits WDM signals between sites X and Y. FIG.

A site X is provided with a plurality of client devices 201 (201a to 201n) and a plurality of optical transceivers 202 (202a to 202n). Site Y is provided with a plurality of client devices 203 (203a to 203n) and a plurality of optical transceivers 204 (204a to 204n). Each client device 201, 203 is, for example, a layer 3 device. The client devices 201 and 203 correspond to the routers 1 and 3 shown in FIG. 2, and the optical transceivers 202 and 204 correspond to the transponders 2 and 4 shown in FIG.

The optical transceiver 202 transmits a client signal input from the corresponding client device 201 to the site Y, and outputs a client signal received from the site Y to the corresponding client device 201 . Similarly, the optical transmitter/receiver 204 transmits a client signal input from the corresponding client device 203 to the site X, and outputs a client signal received from the site X to the corresponding client device 203 .

The optical transceivers 202a to 202n transmit client signals to site Y using different wavelengths. Similarly, optical transceivers 204a-204n transmit client signals to site X using different wavelengths.

The optical coupler 205 multiplexes the optical signals λa to λn output from the optical transceivers 202a to 202n to generate a WDM signal. A WDM signal generated by the optical coupler 205 is transmitted to the site Y via the optical network. The optical coupler 206 splits the WDM signal received from the base X and guides it to the optical transceivers 204a to 204n. That is, the optical coupler 206 functions as an optical splitter and the same WDM signal is directed to the optical transceivers 204a-204n.

The optical coupler 206 multiplexes the optical signals λa to λn output from the optical transceivers 204a to 204n to generate a WDM signal. A WDM signal generated by the optical coupler 206 is transmitted to the site X via the optical network. The optical coupler 205 splits the WDM signal received from the site Y and guides it to the optical transceivers 202a to 202n. That is, optical coupler 205 functions as an optical splitter, and the same WDM signal is directed to optical transceivers 202a-202n.

In the optical transmission system configured as described above, each of the optical transceivers 202a to 202n and 204a to 204n has a function of selecting wavelengths not used in the optical transmission system. Then, each of the optical transceivers 202a-202n, 204a-204n uses the selected wavelength to transmit the client signal to the opposite site. Further, each of the optical transceivers 202a to 202n and 204a to 204n extracts an optical signal with a selected wavelength from the WDM signal received from the opposing site. Thus, a point-to-point WDM network is built.

FIG. 19 shows an overview of the wavelength selection sequence according to the second embodiment. In this embodiment, at site X, the optical transmitter/receiver 202a acquires the identification information of the client device 201a. At site Y, the optical transmitter/receiver 204a acquires the identification information of the client device 203a, and the optical transmitter/receiver 204b acquires the identification information of the client device 203b.

As in the first embodiment, each of the client devices 201 and 203 periodically transmits neighbor discovery packets (eg, OSPF Hello). The neighbor discovery packet contains the IP address of the source client device. Then, each of the optical transceivers 202 and 204 acquires the value of the network part of the source IP address of the neighbor discovery packet as identification information. The network portion value of the IP address identifies the subnet. That is, each of the optical transceivers 202 and 204 acquires identification information for identifying the subnet to which it is connected.

Here, client devices 202a and 204a are connected to subnet a, and client device 204b is connected to subnet b. In this case, the optical transceivers 202a and 204a each acquire "ID_a" for identifying subnet a as identification information. Also, the optical transceiver 204b acquires "ID_b" for identifying the subnet b as identification information.

The optical transmitter/receiver 202a transmits the identification information ID_a to the site Y. FIG. At this time, the optical transmitter/receiver 202a selects an unused wavelength channel from wavelength channels prepared for data communication, and transmits the identification information ID_a to the site Y using the selected wavelength channel. . In FIG. 19, the identification information ID_a is transmitted from the optical transmitter/receiver 202a to the site Y using the wavelength channel λ1. Further, the optical signal of wavelength channel λ1 is multiplexed into the WDM signal together with the optical signals of other wavelength channels. This WDM signal is transmitted from base X to base Y, branched by optical coupler 206 at base Y, and guided to optical transceivers 204a to 204n.

At site Y, each optical transceiver 204 that is not in data communication waits for identification information transmitted from site X while sequentially selecting each wavelength channel of the WDM signal. Therefore, in this embodiment, each optical transmitter/receiver 204 not in data communication receives the identification information transmitted from the optical transmitter/receiver 202a when the wavelength channel λ1 is selected.

Then, the optical transmitter/receiver 204 compares the identification information received from the site X with the identification information obtained from the corresponding client device 203 . In this embodiment, the optical transceiver 204a obtains identification information ID_a from the client device 203a. That is, in the optical transceiver 204a, the identification information received from the site X and the identification information obtained from the client device 203a match each other. In this case, the optical transmitter/receiver 204a determines that data communication can be performed with the site X via the wavelength channel (that is, the wavelength channel λ1) that received the same identification information as its own identification information. Then, the optical transceiver 204a transmits its own identification information (that is, ID_a obtained from the client device 203a) to the site X via this wavelength channel λ1.

The optical signal of wavelength channel λ1 is multiplexed into a WDM signal together with the optical signals of other wavelength channels. This WDM signal is transmitted from site Y to site X, branched by optical coupler 205 at site X, and guided to optical transceivers 202a to 202n.

The optical transmitter/receiver 202a transmits its own identification information to the site Y using the wavelength channel λ1. In this case, the optical transceiver 202a waits for identification information transmitted from the site Y on the wavelength channel λ1. Therefore, the optical transmitter/receiver 202a receives the identification information transmitted from the optical transmitter/receiver 204a. Here, in the optical transmitter/receiver 202a, the identification information acquired from the client device 201a and the identification information received from the base Y match each other. In this case, the optical transmitter/receiver 202a determines that data communication can be performed with the site Y via the wavelength channel (that is, the wavelength channel λ1) that received the same identification information as its own identification information.

The optical transmitter/receiver 204b acquires the identification information ID_b from the client device 203b. That is, in the optical transceiver 204b, the identification information received from the site X and the identification information obtained from the client device 203a are different from each other. In this case, the optical transmitter/receiver 204b does not transmit an optical signal to the base X.

According to the sequence described above, the optical transmitter/receiver 202a selects λ1 as the wavelength channel used for communication with site Y, and the optical transmitter/receiver 204a selects λ1 as the wavelength channel used for communication with site X. select. Therefore, thereafter, data is bidirectionally transmitted between the optical transceivers 202a and 204a via the wavelength channel λ1.

Thus, in the wavelength selection sequence according to the second embodiment, control information for wavelength selection is transmitted using one of the wavelength channels prepared for data communication. Therefore, there is no need to prepare a dedicated wavelength channel for transmitting control information, and the wavelength utilization efficiency of WDM transmission is improved. Also, in the sequence according to the second embodiment, since arbitration is not performed between the master/slave or between the master/master, the processing time for determining the wavelength channel for data communication can be shortened.

FIG. 20 is a diagram showing an example of the optical transceiver 202. As shown in FIG. Note that the optical transceiver 202 and the optical transceiver 204 are substantially the same as each other. Therefore, description of the optical transceiver 204 is omitted.

The optical transceiver 202 includes a packet extraction unit 211, an identification information acquisition unit 212, a usable wavelength determination unit 213, a wavelength selection unit 214, a transmission timer 215, a transmission waiting timer 216, an identification information insertion unit 217, an optical transmission unit 218, an optical It has a receiver 221 , an identification information extractor 222 and a collator 223 . Note that the optical transceiver 202 may include other circuits or functions not shown in FIG.

The packet extraction unit 211 extracts the neighbor discovery packet from the output signal of the client device 201 and guides it to the identification information acquisition unit 212 . The neighbor discovery packet is, for example, an RFC2328 OSPF Hello packet, and is periodically transmitted from the client device 201 . The identification information acquisition unit 212 extracts the source IP address of the neighbor discovery packet. Then, the identification information acquisition unit 212 acquires the value of the network part in the source IP address as identification information. Note that the identification information acquisition unit 212 stores the acquired identification information.

The usable wavelength determination unit 213 determines wavelength channels that can be used by the optical transceiver 202 based on the identification information acquired by the identification information acquisition unit 212 . The wavelength selection unit 214 selects a wavelength channel to be used by the optical transmitter/receiver 202 from among the available wavelength channels determined by the available wavelength determination unit 213 (that is, wavelength channel candidates to be used by the optical transmitter/receiver 202). do.

The transmission timer 215 counts the period during which the optical transmitter/receiver 202 transmits the optical signal in the wavelength selection sequence. The transmission wait timer 216 counts the period during which the optical transmitter/receiver 202 waits for an optical signal transmitted from the opposite base without transmitting an optical signal in the wavelength selection sequence. The identification information insertion unit 217 acquires the identification information stored in the identification information acquisition unit 212 in the wavelength selection sequence, and inserts the identification information into the signal transmitted to the opposite base.

The optical transmitter 218 generates an optical signal. The configuration of the optical transmitter 218 is the same as that of the transmitter 13 shown in FIG. 3, for example. That is, the optical transmitter 218 has a wavelength tunable light source and can generate an optical signal with a designated wavelength. Specifically, the optical transmitter 218 uses the wavelength channel selected by the wavelength selector 214 to transmit the optical signal. Note that the optical signal generated by the optical transmitter 218 is multiplexed into the WDM signal together with other optical signals.

The optical receiver 221 receives an optical signal with a specified wavelength from among multiple optical signals multiplexed on the input WDM signal. The configuration of the optical receiver 22 is the same as that of the coherent receiver 14 shown in FIG. 3, for example. The optical receiver 221 receives the optical signal via the wavelength channel selected by the wavelength selector 214 .

The identification information extractor 222 extracts identification information from the optical signal received by the optical receiver 221 . The collation unit 223 compares the identification information stored in the identification information acquisition unit 212 and the identification information extracted by the identification information extraction unit 222 . The optical transmitter/receiver 202 compares its own identification information with the identification information received from the opposite site.

Note that each function of the optical transceivers 202 and 204 is implemented by, for example, a processor system including a processor and memory. In this case, the processor implements the functions of the optical transceivers 202 and 204 by executing programs stored in the memory. However, part of the functions of the optical transceivers 202 and 204 may be realized by hardware circuits.

FIG. 21 shows an example of the usable wavelength determining section 213. As shown in FIG. In this example, it is assumed that the optical transmission system can use 12 wavelength channels (ch1 to ch12) for data communication. Also, 12 wavelength channels are assigned to 4 wavelength blocks (#1 to #4). In this case, each wavelength block contains three usable wavelength channels.

As shown in FIG. 21(a), the usable wavelength determination unit 213 includes a remainder calculation unit 213a, an addition unit 213b, and a block_wavelength conversion unit 213c. Then, the identification information acquired by the identification information acquisition section 212 is given to the usable wavelength determination section 213 . The identification information represents the value of the network portion of the IP address of the client device, as described above.

The remainder calculator 213a divides the identification information by the number of wavelength blocks. The adder 213b adds "1" to the remainder value of the division result of the remainder calculator 213a. Here, the value of this addition result represents the wavelength block corresponding to the identification information. For example, when the remainder value obtained by dividing the identification information by "4" is "zero", the output value of the adder 213b is "1". In this case, wavelength block #1 is specified for this identification information.

As shown in FIG. 21B, the block_wavelength converter 213c has a table representing the correspondence between wavelength blocks and available wavelength channels. Then, the block_wavelength converter 213c determines a usable wavelength channel corresponding to the wavelength block specified by the remainder calculator 213a and the adder 213b.

FIG. 21(c) shows an example of the result of allocation by the usable wavelength determining section 213. FIG. In this embodiment, wavelength channels ch1, ch2 and ch3 belong to wavelength block #1, wavelength channels ch4, ch5 and ch6 belong to wavelength block #2, wavelength channels ch7, ch8 and ch9 belong to wavelength block #3, Wavelength channels ch10, ch11, and ch12 belong to wavelength block #4. In this case, for example, when the identification information "11.12.12" is given, the remainder value "zero" is obtained and the addition result "1" is obtained. Therefore, wavelength block #1 is identified. Then, the usable wavelength determination unit 213 outputs information representing usable wavelength channels (that is, wavelength channel candidates used by the optical transmitter/receiver 202) for the given identification information. For example, when the optical transceiver #3 acquires the identification information "11.12.12", ch1, ch2, and ch3 are determined as available wavelength channels.

FIG. 22 shows an example of a wavelength selection sequence according to the second embodiment. In this example, a wavelength channel is selected for data communication between the clients 201a and 203a. Clients 201a and 203a are connected to the same subnet (subnetwork identified by ID_a). In addition, in FIG. 22, the optical transmitter/receiver is displayed as "TxRx."

At site X, a client device 201a is connected to an optical transceiver 202a. The client device 201a transmits a neighbor discovery packet (OSPF Hello). The optical transceiver 202a acquires the identification information ID_a from the neighbor discovery packet. Also, the optical transmitter/receiver 202a selects a wavelength block corresponding to the acquired identification information ID_a, and identifies usable wavelength channels belonging to that wavelength block. It should be noted that the identification information acquired from the client device with which the optical transmitter/receiver is compatible is stored in its own device. Therefore, in the following description, the identification information acquired by the optical transmitter/receiver from the corresponding client device may be referred to as "own identification information".

When the optical transmitter/receiver 202a acquires the identification information ID_a from the client device 201a, the optical transmitter/receiver 202a executes standby processing. In the standby process, the optical transmitter/receiver 202a waits for an optical signal transmitted from the site Y while sequentially selecting reception wavelengths one by one without transmitting an optical signal to the site Y. FIG. At this time, the optical transceiver 202a may scan all wavelength channels, or may scan only wavelength channels belonging to the selected wavelength block. Also, the period during which the standby process is executed is timed by the transmission wait timer 216 . In this embodiment, it is assumed that the optical transmitter/receiver 202a does not receive an optical signal from the site Y during this standby period.

After the standby period ends, the optical transmitter/receiver 202a performs transmission/reception processing. In the transmission/reception process, the optical transceiver 202a selects an unused wavelength channel from wavelength channels belonging to the selected wavelength block. In this example, wavelength channel ch3 is selected. Then, the optical transmitter/receiver 202a transmits its own identification information (that is, the identification information obtained from the client device 201a) to the site Y using the selected wavelength channel. That is, the identification information ID_a is transmitted via the wavelength channel ch3. Further, the optical transmitter/receiver 202a repeatedly transmits the identification information at predetermined time intervals in the transmission/reception process. Also, the period during which the transmission/reception process is executed is clocked by the transmission timer 215 .

In transmission/reception processing, the optical transmitter/receiver 202a waits for an optical signal transmitted from the site Y on the selected wavelength channel. That is, the optical transmitter/receiver 202a waits for an optical signal transmitted from the site Y on the same wavelength channel as the wavelength channel transmitting the identification information. In this embodiment, the optical transceiver 202a transmits identification information to site Y on wavelength channel ch3, and waits for an optical signal transmitted from site Y on wavelength channel ch3. However, at this time, the transmitter/receiver 202a does not receive the optical signal in the wavelength channel ch3. Then, when the transmission/reception period ends, the optical transmitter/receiver 202a executes the standby process again.

At site Y, a client device 203a is connected to an optical transceiver 204a. Client device 203a transmits a neighbor discovery packet. The optical transceiver 204a acquires the identification information ID_a from the neighbor discovery packet. The optical transmitter/receiver 204a also selects a wavelength block corresponding to the acquired identification information ID_a, and identifies usable wavelength channels belonging to that wavelength block. Here, the identification information acquired by the optical transceivers 202a and 204a is the same. Therefore, the optical transceivers 202a and 204a select the same wavelength block. That is, the same usable wavelength channel is determined in the optical transceivers 202a and 204a.

When the optical transmitter/receiver 204a acquires the identification information ID_a from the client device 203a, the optical transmitter/receiver 204a executes standby processing. In the standby process, the optical transmitter/receiver 204a waits for an optical signal transmitted from the site X while sequentially selecting reception wavelengths one by one without transmitting an optical signal to the site X. FIG. At this time, the optical transceiver 204a may scan all wavelength channels, or may scan only wavelength channels belonging to the selected wavelength block.

At the site X, when the standby period ends, the optical transmitter/receiver 202a executes the transmission process again. At this time, the optical transceiver 202a selects another unused wavelength channel from among the wavelength channels belonging to the selected wavelength block. In this example, wavelength channel ch1 is selected. Then, the optical transmitter/receiver 202a transmits its own identification information to the site Y using the selected wavelength channel. That is, the identification information ID_a is transmitted via the wavelength channel ch1.

At site Y, the optical transceiver 204a waits for an optical signal transmitted from site X while sequentially selecting reception wavelengths one by one. Therefore, the optical transmitter/receiver 204a receives the identification information ID_a transmitted from the optical transmitter/receiver 202a via the wavelength channel ch1. Then, the optical transmitter/receiver 204a compares the identification information received from the optical transmitter/receiver 202a with its own identification information (that is, the identification information obtained from the client device 203a). In this example, the received identification and my identification match each other. In this case, the optical transceiver 204a selects the wavelength channel that has received the same identification information as its own identification information as the wavelength channel used for data communication. That is, the wavelength channel ch1 is selected as the wavelength channel used for data communication. After that, the optical transmitter/receiver 204a transmits its own identification information to the site X using the selected wavelength channel ch1.

When the optical transceiver 204a transmits the identification information, the optical transceiver 202a is executing transmission/reception processing. Here, the optical transmitter/receiver 202a waits for an optical signal transmitted from the site Y on the wavelength channel ch1. Therefore, the optical transmitter/receiver 202a can receive the identification information transmitted from the optical transmitter/receiver 204a via the wavelength channel ch1. Then, the optical transmitter/receiver 202a compares the identification information received from the optical transmitter/receiver 204a with its own identification information (that is, the identification information obtained from the client device 201a). In this example, the received identification and my identification match each other. In this case, the optical transceiver 202a selects the wavelength channel that has received the same identification information as its own identification information as the wavelength channel used for data communication. That is, the wavelength channel ch1 is selected as the wavelength channel used for data communication.

After that, the optical transceiver 202a transmits a client signal to site Y using wavelength channel ch1, and receives a client signal from site Y via wavelength channel ch1. Also, the optical transceiver 204a transmits a client signal to site X using wavelength channel ch1, and receives a client signal from site X via wavelength channel ch1. That is, the client devices 201a and 203a perform bidirectional data communication using the wavelength channel ch1.

FIG. 23 is a flowchart illustrating an example of processing of the optical transceiver. The processing of this flowchart is executed when the client device is connected to the optical transmitter/receiver. This flowchart also shows the process of selecting a wavelength channel.

In S101, the identification information acquisition unit 212 acquires identification information from the client device. In this embodiment, the identification information acquisition unit 212 acquires, as identification information, the value of the network portion of the source IP address of the OSPF Hello packet transmitted from the client device. The identification information acquisition unit 212 saves the identification information. In the description below, the identification information acquired from the client device may be referred to as "own identification information".

In S102, the usable wavelength determination unit 213 selects a wavelength block corresponding to the identification information and identifies usable wavelength channels belonging to the wavelength block. As a result, usable wavelength channels corresponding to the identification information are identified. At S103, the transmission wait timer 216 is started. Then, the optical transceiver executes standby processing in S104 to S107.

In S<b>104 , the wavelength selection unit 214 selects a wavelength channel to be used by the optical transmitter/receiver from among the wavelength blocks selected by the usable wavelength determination unit 213 . In S<b>105 , the optical receiver 221 waits for an optical signal transmitted from the opposite base in the wavelength channel selected by the wavelength selector 214 . When the optical receiver 221 receives an optical signal, the identification information extractor 222 extracts identification information from the optical signal. In S106, the collation unit 223 compares its own identification information with the identification information received from the opposing site.

When the optical receiver 221 does not receive the optical signal, or when the identification information of itself does not match the identification information received from the opposite site, the process of the optical transceiver returns to S104. Then, in S<b>104 , the wavelength selection unit 214 selects the next wavelength channel from the wavelength blocks selected by the usable wavelength determination unit 213 . That is, the optical transceiver sequentially selects wavelength channels belonging to the selected wavelength block one by one until its own identification information matches the identification information received from the opposite site.

If the own identification information matches the identification information received from the opposite site, the processing of the optical transmitter/receiver proceeds to S108. In S108, the identification information inserting unit 217 inserts the identification information stored in the identification information acquisition 212 (that is, its own identification information) into the packet to be transmitted to the opposite base. Then, the optical transmission unit 218 transmits this packet to the opposite base. At this time, the optical transmitter 218 transmits the optical signal using the wavelength channel selected by the wavelength selector 214 in S104.

If the transmission waiting timer 216 expires in S107 before the own identification information and the identification information received from the opposite site match, the process of the optical transmitter/receiver proceeds to S111. That is, the standby process ends.

In S<b>111 , the wavelength selection unit 214 selects a wavelength channel to be used by the optical transmitter/receiver from among the wavelength blocks selected by the usable wavelength determination unit 213 . At S112, the transmission timer 215 is started. Then, the optical transceiver executes transmission/reception processing of S113 to S115.

In S113, the identification information inserting unit 217 inserts the identification information stored in the identification information acquisition unit 212 (that is, its own identification information) into the packet to be transmitted to the counter base. Then, the optical transmission unit 218 transmits this packet to the opposite base. At this time, the optical transmitter 218 transmits the optical signal using the wavelength channel selected by the wavelength selector 214 in S111. In addition, the optical receiver 221 waits for an optical signal transmitted from the opposite base in the wavelength channel selected by the wavelength selector 214 in S111.

In the transmission/reception processing of S113 to S115, the optical transmitter/receiver waits for an optical signal transmitted from the opposite point while repeatedly transmitting identification information to the opposite point. Then, when the optical receiver 221 receives the optical signal, the identification information extractor 222 extracts the identification information from the received optical signal. In addition, the collating unit 223 compares its own identification information with the identification information received from the opposing site.

When the own identification information matches the identification information received from the opposite site, the processing of the optical transmitter/receiver ends. On the other hand, if the transmission timer 215 expires in S115 before the own identification information matches the identification information received from the opposite site, the transmission/reception processing ends and the processing of the optical transceiver returns to S103. That is, the transmission waiting processing of S104-S107 and the transmission/reception processing of S113-S115 are alternately executed until it is determined in S106 or S114 that the identification information of the self and the identification information received from the opposing site match.

In this way, when it is determined in S106 that the identification information of its own and the identification information received from the opposite site match, the optical transmitter/receiver transmits bi-directionally to the opposite site using the wavelength channel selected in S104. data communication to Further, when it is determined in S114 that the identification information of itself and the identification information received from the opposite site match, the optical transmitter/receiver transmits data bidirectionally to and from the opposite site through the wavelength channel selected in S111. communicate.

In the example shown in FIG. 23, the standby process ends when the transmission wait timer 216 expires, but the second embodiment is not limited to this procedure. For example, the standby process may end when scanning of all available wavelength channels determined by the available wavelength determination unit 213 is completed. In this case, the optical transmitter/receiver may not have the transmission wait timer 216 .

The flow chart shown in FIG. 23 will now be described with reference to the embodiment shown in FIG. In the following description, first, at site X, the client device 201a is connected to the optical transceiver 202a. Then, the optical transceiver 202a acquires its own identification information (ID_a). Then, the optical transmitter/receiver 202a executes standby processing of S104 to S107. However, the optical transmitter/receiver 202a does not receive the same identification information as its own identification information from the site Y in this standby process.

Subsequently, after selecting the wavelength channel ch3 in S111, the optical transceiver 202a executes transmission/reception processing in S113 to S115. That is, the optical transceiver 202a transmits the identification information ID_a to the site Y using the wavelength channel ch3, and waits for an optical signal transmitted from the site Y on the wavelength channel ch3. However, in this transmission/reception processing, the optical transmitter/receiver 202a does not receive the optical signal via the wavelength channel ch3.

When the transmission/reception period ends, the optical transmitter/receiver 202a executes the standby process of S104 to S107 again. However, even in this standby process, the optical transceiver 202a does not receive the same identification information as its own identification information.

When the client device 203a is connected to the optical transmitter/receiver 204a at the site Y, the optical transmitter/receiver 204a acquires its own identification information (ID_a) in S101 and selects a wavelength block in S102. Then, the optical transmitter/receiver 204a executes standby processing of S104 to S107. At this time, the optical transceiver 204a waits for identification information transmitted from the site X while sequentially selecting wavelength channels in the selected wavelength block one by one.

When the standby period ends, the optical transmitter/receiver 202a executes the transmission/reception processing of S113 to S115 again. At this time, the optical transceiver 202a selects the wavelength channel ch1 in S111. That is, the optical transceiver 202a transmits the identification information ID_a to the site Y using the wavelength channel ch1, and waits for an optical signal transmitted from the site Y on the wavelength channel ch1.

The optical transceiver 204a receives the identification information ID_a transmitted from the site X via the wavelength channel ch1 in the standby process. Then, the optical transceiver 204a compares its own identification information with the identification information received from the site X in S106. At this time, the identification information of oneself and the identification information received from the site X match. In this case, in the optical transceiver 204a, the optical transmitter 218 is set to transmit an optical signal to the site X using the wavelength channel ch1, and the optical receiver 221 transmits the optical signal from the site X via the wavelength channel ch1. configured to receive optical signals. Thereafter, the optical transmitter/receiver 204a transmits its own identification information to the site X using the wavelength channel ch1 in S108.

When the identification information is transmitted from the optical transmitter/receiver 204a, the optical transmitter/receiver 202a is executing the transmission/reception processing of S113 to S115. At this time, the optical transmitter/receiver 202a is waiting for an optical signal transmitted from the site Y on the wavelength channel ch1. Therefore, the optical transceiver 202a receives the optical signal transmitted from the site Y via the wavelength channel ch1, and extracts the identification information ID_a from the received optical signal. Then, the optical transceiver 202a compares its own identification information with the identification information received from the site Y in S114. At this time, his own identification information and the identification information received from the base Y match. In this case, in the optical transceiver 202a, the optical transmitter 218 is set to transmit an optical signal to the site Y using the wavelength channel ch1, and the optical receiver 221 transmits the optical signal from the site Y via the wavelength channel ch1. configured to receive optical signals.

Thus, in the wavelength selection sequence according to the second embodiment, wavelength channels for data communication are used to transmit control information for wavelength selection. Therefore, there is no need to prepare a dedicated wavelength channel for transmitting control information, and the wavelength utilization efficiency of WDM transmission is improved.

<Variation of Usable Wavelength Determining Unit>
When the identification information is a numerical value, it is easy to calculate the remainder by performing division with the configuration shown in FIG. However, if the identification information is a combination of multiple numerical values or a character string, the configuration shown in FIG. 21 is not necessarily appropriate.

FIG. 24 shows a variation of the usable wavelength determining section 213. FIG. In this example, the usable wavelength determination unit 213 includes a hash value calculation unit 213d, a hash value conversion unit 213e, and a block_wavelength conversion unit 213c. The hash value calculator 213d calculates a hash value from the identification information acquired by the identification information acquisition unit 212 . The hash value converter 213e converts the hash value obtained by the hash value calculator 213d into a wavelength block number. Then, the block_wavelength converter 213c determines usable wavelength channels corresponding to the identified wavelength blocks, as in the example shown in FIG. Note that if the hash value obtained by the hash value calculator 213d uniquely identifies the wavelength block, the usable wavelength determination unit 213 need not include the hash value converter 213e.

FIG. 25 shows another variation of usable wavelength determining section 213 . The usable wavelength determination unit 213 shown in FIG. 25 is used, for example, in cases where the identification information is known. The usable wavelength determination unit 213 includes an ID_block conversion unit 213f and a block_wavelength conversion unit 213c, as shown in FIG. 25(a).

As shown in FIG. 25B, the ID_block conversion unit 213f has a table representing the correspondence between pre-designated identification information and wavelength blocks. The ID_block converter 213f identifies the wavelength block corresponding to the given identification information, as in the example shown in FIG. Then, the block_wavelength converter 213c determines usable wavelength channels corresponding to the identified wavelength blocks, as in the example shown in FIG.

Note that the usable wavelength determination unit 213 may have a table showing the correspondence between predesignated identification information and usable wavelength channels, as shown in FIG. 25(c). In this case, the usable wavelength determination unit 213 can directly determine the corresponding usable wavelength channel when the identification information is given.

<Variation of optical transceiver>
FIG. 26 shows an example of a variation of the optical transceiver. The optical transceiver shown in FIG. 26 includes an allocation completion information inserting section 231 and an allocation completion information extracting section 232 in addition to the circuits shown in FIG.

The allocation completion information inserting unit 231 generates allocation completion information when the wavelength allocation processing by the optical transceiver is completed. The assignment completion information includes information representing wavelength channels selected for data communication (ie, assigned wavelength channels). The allocation completion information is then sent to the opposite base in the same manner as the identification information. For example, the allocation completion information is inserted into a packet transmitted to the opposing base. Alternatively, the allocation completion information may be multiplexed with the signal transmitted to the opposite base. In these cases, the allocation completion information is transmitted to the opposing site using the wavelength channel selected by the wavelength selector 214, for example.

The allocation completion information extraction unit 232 extracts allocation completion information from the signal received from the opposite base. In the transmission waiting period, the optical transmitter/receiver waits for an optical signal transmitted from the opposing base while sequentially selecting each wavelength channel of the WDM signal. Therefore, the optical transmitter/receiver can receive the allocation completion information regardless of which wavelength channel the allocation completion information is transmitted.

The received allocation completion information is guided to the wavelength selector 214 . Then, the wavelength selector 214 excludes the allocated wavelength channel specified by the allocation completion information from the usable wavelength channels determined by the usable wavelength determiner 213 . Then, the wavelength selection unit 214 selects a wavelength channel to be used by the optical transmitter/receiver from available wavelength channels (that is, remaining wavelength channels) from which the allocated wavelength channels have been excluded.

Thus, in the optical transmitter/receiver shown in FIG. 26, when selecting a wavelength channel for data communication, wavelength channels used in other optical transmitter/receivers are excluded. That is, the wavelength selection unit 214 selects the wavelength channel to be used from among the smaller number of candidates. Therefore, the number of wavelength channels waiting in S104 to S107 shown in FIG. 23 is reduced. In addition, since the wavelength selection unit 214 does not select wavelength channels used in other optical transceivers, the efficiency of the wavelength selection sequence increases.

FIG. 27 shows another example of variation of the optical transceiver. The optical transceiver shown in FIG. 27 includes a transmission timer adjusting section 233 in addition to the circuit shown in FIG. The transmission timer adjustment unit 233 adjusts the transmission time clocked by the transmission timer 215 according to the number of wavelength channels that can be selected by the wavelength selection unit 214 (that is, the number of remaining wavelength channels).

In the configuration shown in FIG. 26, when wavelength channels are selected in other optical transceivers, the number of available wavelength channels decreases. For example, it is assumed that wavelength channels ch1 to ch10 belong to a wavelength block corresponding to identification information, and wavelength channel ch1 is used by another optical transceiver. In this case, the wavelength selector 214 selects the wavelength channel to be used from among the wavelength channels ch2 to ch10.

Here, in the transmission waiting process of S104 to S107, the optical transceiver waits for an optical signal while sequentially selecting available wavelength channels one by one. In addition, in order for the optical signal transmitted using an arbitrary channel in the transmission/reception processing of S113 to S115 to be reliably received by the optical transmitter/receiver at the opposite site, An operation of repeatedly transmitting the optical signal is required. In other words, if the optical signal is repeatedly transmitted for the time required for the process of sequentially selecting available wavelength channels one by one in the transmission waiting process, the optical signal can be reliably received by the optical transmitter/receiver at the opposite site. is considered to be The period during which the optical transmitter/receiver repeatedly transmits the optical signal in the transmission/reception process is timed by the transmission timer 215 .

The transmission timer adjustment unit 233 adjusts the transmission time clocked by the transmission timer 215 according to the number of wavelength channels that can be selected by the wavelength selection unit 214 . For example, if the number of usable wavelength channels is 10, and an optical signal is awaited for a time T for one wavelength channel in the transmission waiting process, the time required for the transmission waiting process is 10T. When the number of usable wavelength channels is reduced from 10 to 9, the time required for transmission waiting processing is also reduced from 10T to 9T. In this case, transmission timer adjustment section 233 updates the transmission time counted by transmission timer 215 from 10T to 9T. As a result, the processing time required for the wavelength selection sequence is shortened.

FIG. 28 shows still another example of variation of the optical transceiver. The optical transceiver shown in FIG. 28 includes a wavelength block resetter 234 in addition to the circuit shown in FIG. The wavelength block resetting unit 234 resets the correspondence between identification information and wavelength blocks.

Here, in the above-described embodiment, the wavelength block corresponding to the identification information is assigned to the optical transmitter/receiver requesting the start of data communication. At this time, in the above-described method of determining a wavelength block using a remainder value or a hash value, a plurality of optical transceivers may be intensively assigned to a specific wavelength block. Also, some wavelength channels may become unavailable due to transmission line conditions. In these cases, when a certain wavelength block is assigned to an optical transceiver that newly requests a wavelength channel, there may be no selectable wavelength channels left in that wavelength block.

Therefore, in the configuration shown in FIG. 28, when all wavelength channels belonging to a certain wavelength block are assigned to other optical transceivers, the wavelength selector 214 determines that there are remaining selectable wavelength blocks in that wavelength block. Generate a zero notification to indicate none. Upon receiving the zero notification, the wavelength block resetting unit 234 resets the correspondence between the identification information and the wavelength blocks.

For example, in the embodiment shown in FIG. 21, as an initial setting, wavelength block #1 is assigned to identification information whose remainder value when divided by "4" is zero (hereinafter referred to as attention identification information). shall be It is assumed that all wavelength channels belonging to wavelength block #1 are assigned to other optical transceivers. In this case, the wavelength selector 214 generates a zero notification specifying wavelength block #1. Then, the wavelength block resetting unit 234 allocates a wavelength block other than wavelength block #1 to the identification information of interest according to a predetermined rule. As an example, a wavelength block with a wavelength block number greater by one is assigned. In the above case, wavelength block #2 is assigned to the identification information of interest. It is assumed that all optical transceivers recognize the rule for resetting the wavelength block.

Thus, when the number of remaining wavelength channels in the selected wavelength block becomes zero, the wavelength block resetting section 234 resets the correspondence between the identification information and the wavelength blocks. Then, the usable wavelength determining section 213 selects another wavelength block. As a result, new wavelength channel candidates are determined. Then, the wavelength selection unit 214 selects a wavelength channel for data communication from among the new wavelength channel candidates.

In the communication systems shown in FIGS. 18 to 28, one client device is connected to one optical transceiver, but the second embodiment is not limited to this configuration. For example, as shown in FIG. 29, one client device may be connected to a plurality of optical transceivers.

In the embodiment shown in FIG. 29, data communication is performed between the L3 client device (router 241) provided at the site X and the L3 client device (router 244) provided at the site Y. FIG. The router 241 performs data communication with the router 244 via a plurality of optical transceivers 202 (202a-202k). Also, the router 244 performs data communication with the router 241 via a plurality of optical transceivers 204 (204a to 204k). That is, the routers 241 and 244 set multiple links by link aggregation (IEEE802.3.ad). Note that L2 equipment is provided between the router 241 and the optical transceivers 202a to 202k. Also, L2 equipment is provided between the router 244 and the optical transceivers 204a to 204k.

In the communication system having the above configuration, when setting a plurality of links (that is, a plurality of wavelength channels) between the optical transceivers 202a to 202k and the optical transceivers 204a to 204k, each of the optical transceivers 202 and 204 Get identity information. Here, if layer 2 identification information (for example, a Link Layer Discovery Protocol identifier) is obtained from the L2 device, the optical transceivers 202 and 204 can identify each wavelength channel. However, when link aggregation is performed between L2 devices, the address of the L3 device may be required depending on the capability of the L2 device.

However, when the L3 device address is used as the identification information, the optical transceivers 202a to 202k obtain the same identification information (router 241 subnet value), and the optical transceivers 204a to 204k obtain the same identification information (router 244 subnet value). value). Therefore, when setting a plurality of wavelength channels between the optical transmitter-receivers 202a to 202k and the optical transmitter-receivers 204a-204k, the optical transmitter-receiver 202 at the site X and the optical transmitter-receiver 204 at the site Y A wavelength channel between is set. That is, a wavelength channel may be set between the optical transceivers 202a and 204a, and a wavelength channel may be set between the optical transceivers 202a and 204k.

The following notes are further disclosed with respect to embodiments, including the above examples.
(Appendix 1)
An optical transmission device mounted at a first site in an optical transmission system for transmitting wavelength division multiplexed optical signals between a first site and a second site,
an optical transmitter that uses a first wavelength to transmit a first optical signal including first identification information to the second base;
an optical receiver that receives from the second base a second optical signal that includes second identification information and is transmitted using the first wavelength;
When the first identification information and the second identification information extracted from the second optical signal are the same, the optical transmission unit uses the first wavelength to perform the following in the optical transmission system: sending a wavelength notification to the second site indicating a second wavelength that is not in use;
When the optical receiving unit receives a completion notification indicating that the wavelength notification has been received at the second base, which is transmitted using the first wavelength, the optical transmitting unit performs the An optical signal with a second wavelength is transmitted to the second site, and the optical receiving unit stops receiving the optical signal with the first wavelength transmitted from the second site. Optical transmission equipment.
(Appendix 2)
an acquisition unit that acquires the first identification information from an input signal;
further comprising a controller for controlling communication between the optical transmission device and the opposing optical transmission device mounted at the second base;
The controller is
determining which of the optical transmission device and the opposed optical transmission device operates as a master device when the first identification information and the second identification information are the same;
detecting unused wavelengths in the optical transmission system;
wherein, when the optical transmission device operates as a master device, the second wavelength is determined based on the unused wavelength detected by the controller and the unused wavelength detected in the opposite optical transmission device; The optical transmission device according to Supplementary Note 1.
(Appendix 3)
2. The method according to claim 2, wherein the acquisition unit acquires, as the first identification information, information identifying a transmission source of the input signal or part of information identifying a transmission source of the input signal. Optical transmission equipment.
(Appendix 4)
the input signal is a packet for neighbor discovery or neighbor confirmation transmitted from a router;
3. The optical transmission device according to claim 3, wherein the acquisition unit acquires, as the first identification information, a value of a network address part in an address that identifies the router from the packet.
(Appendix 5)
2. The optical transmission device according to claim 2, wherein the controller transmits a wavelength notification representing the second wavelength to the opposing optical transmission device.
(Appendix 6)
the optical transmitter includes a wavelength tunable light source,
the optical receiver includes a tunable local light source,
The controller controls the wavelength tunable light source such that the optical transmitter transmits the optical signal of the second wavelength, and the optical receiver coherently receives the optical signal of the second wavelength. The optical transmission device according to appendix 2, wherein the wavelength tunable local light source is controlled.
(Appendix 7)
the optical transmitter includes a wavelength tunable light source,
The optical receiver includes a variable bandpass filter,
The controller controls the wavelength tunable light source such that the optical transmitter transmits the optical signal of the second wavelength, and the optical receiver receives the optical signal of the second wavelength. The optical transmission device according to appendix 2, wherein the band-pass filter is controlled.
(Appendix 8)
An optical transmission method used by an optical transmission device mounted at a first site in an optical transmission system for transmitting wavelength division multiplexed optical signals between a first site and a second site,
using a first wavelength to transmit a first optical signal including a first identification to the second location;
receiving from the second site a second optical signal including second identification information transmitted using the first wavelength;
If the first identification information and the second identification information extracted from the second optical signal are the same, the first wavelength is used to obtain a second identification information that is not used in the optical transmission system. transmitting a wavelength notification indicating the wavelength of to the second base;
light to the second site at the second wavelength upon receiving a completion notification indicating that the wavelength notification has been received at the second site, transmitted using the first wavelength; An optical transmission method characterized by transmitting a signal and stopping reception of the optical signal of the first wavelength transmitted from the second base.
(Appendix 9)
An optical transmission system for transmitting wavelength division multiplexed optical signals between a first site where a plurality of optical transmission devices are mounted and a second site where a plurality of optical transmission devices are mounted,
A first optical transmission device among the plurality of optical transmission devices mounted at the first base transmits a first optical signal including first identification information to the second optical transmission device using a first wavelength. to the base of
A second optical transmission device among the plurality of optical transmission devices mounted at the second base transmits a second optical signal including second identification information using the first wavelength. Send to base 1,
When the first identification information and the second identification information are the same, the first optical transmission device uses the first wavelength to transmit the second wavelength not used in the optical transmission system. transmitting a wavelength notification indicating the wavelength of to the second base;
Upon receiving the wavelength notification from the first base, the second optical transmission device uses the first wavelength to transmit to the first base a completion notification indicating that the wavelength notification has been received. death,
Upon receiving the completion notification from the second base, the first optical transmission device transmits an optical signal to the second base at the second wavelength, and transmits the optical signal transmitted from the second base to the second base. 1. An optical transmission system characterized by stopping reception of an optical signal of a first wavelength.
(Appendix 10)
An optical transmission system for transmitting wavelength division multiplexed optical signals between a first site where a plurality of optical transmission devices are mounted and a second site where a plurality of optical transmission devices are mounted,
Acquiring identification information from an input signal in each optical transmission device,
Identification information obtained from an input signal by the first optical transmission device mounted at the first base and identification information obtained from the input signal by the second optical transmission device mounted at the second base match each other, the first optical transmission device and the second optical transmission device determine which one acts as the master device;
the first optical transmission device and the second optical transmission device each detect an unused wavelength in the optical transmission system;
When the first optical transmission device operates as a master device, the first optical transmission device is used for communication between the first optical transmission device and the second optical transmission device. selecting a first wavelength from unused wavelengths not used in the optical transmission system;
If the first wavelength is not selected for communication between other optical transmission devices, the first optical transmission device transmits the first wavelength between the first optical transmission device and the second optical transmission device. An optical transmission system characterized by assigning to communication with an optical transmission device.
(Appendix 11)
when the first wavelength is selected by a third optical transmission device for communication between the third optical transmission device and the fourth optical transmission device, the first optical transmission device and the third optical transmission device determines which one acts as the master device;
When the first optical transmission device operates as a master device with respect to the third optical transmission device, the first optical transmission device transmits the first wavelength to the first optical transmission device and the assigned to communication between the second optical transmission device, and the third optical transmission device assigns the first optical transmission device for communication between the third optical transmission device and the fourth optical transmission device 11. The optical transmission system of claim 10, wherein a second wavelength different from the wavelength is selected.
(Appendix 12)
a first optical coupler for generating a wavelength division multiplexed optical signal by multiplexing a plurality of optical signals output from a plurality of optical transmission devices mounted at the first base;
a first optical splitter that splits the wavelength division multiplexed optical signal generated by the first optical coupler and guides it to a plurality of optical transmission devices mounted at the second base;
a second optical coupler that multiplexes a plurality of optical signals output from a plurality of optical transmission devices mounted at the second base to generate a wavelength division multiplexed optical signal;
a second optical splitter that splits the wavelength division multiplexed optical signal generated by the second optical coupler and guides it to a plurality of optical transmission devices mounted at the first base, 11. The optical transmission system according to claim 10.
(Appendix 13)
a first AWG (Arrayed Waveguide) that multiplexes a plurality of optical signals output from a plurality of optical transmission devices mounted at the first base to generate a wavelength division multiplexed optical signal;
an optical splitter that splits the wavelength division multiplexed optical signal generated by the first AWG and guides it to a plurality of optical transmission devices mounted at the second base;
an optical coupler for generating a wavelength division multiplexed optical signal by multiplexing a plurality of optical signals output from a plurality of optical transmission devices mounted at the second base;
a second AWG that demultiplexes the wavelength division multiplexed optical signal generated by the optical coupler by wavelength and guides it to the corresponding optical transmission device mounted at the first site. 11. The optical transmission system according to appendix 10.
(Appendix 14)
An optical transmission system for transmitting wavelength division multiplexed optical signals between a first site where a plurality of optical transmission devices are mounted and a second site where a plurality of optical transmission devices are mounted,
a first controller that controls a plurality of optical transmission devices mounted at the first base;
a second controller that controls a plurality of optical transmission devices mounted at the second base;
Each optical transmission device acquires identification information from the input signal,
Identification information obtained from an input signal by the first optical transmission device mounted at the first base and identification information obtained from the input signal by the second optical transmission device mounted at the second base match each other, the first controller and the second controller determine which one acts as the master device;
the first optical transmission device and the second optical transmission device each detect an unused wavelength in the optical transmission system;
When the first controller operates as a master device, the first controller operates in the optical transmission system for communication between the first optical transmission device and the second optical transmission device. selecting a first wavelength among unused unused wavelengths;
If the first wavelength is not selected for communication between other optical transmission devices, the first controller causes the first wavelength to be used between the first optical transmission device and the second optical transmission device. An optical transmission system characterized by assigning to communication between devices.
(Appendix 15)
An optical transmission device mounted at a first site in an optical transmission system for transmitting wavelength division multiplexed optical signals between a first site and a second site,
an optical transmission unit that transmits an optical signal to the second base;
an optical receiver that receives an optical signal from the second base,
The optical transmission unit uses a first wavelength selected from available wavelengths to transmit a first optical signal including first identification information to the second base,
The optical receiving unit receives a second optical signal of the first wavelength transmitted from the second base,
When the first identification information and the second identification information extracted from the second optical signal are the same, the optical transmitter transmits the optical signal to the second base at the first wavelength. and the optical receiving unit receives the optical signal of the first wavelength transmitted from the second base.
(Appendix 16)
a usable wavelength determination unit that determines the usable wavelength based on the first identification information;
16. The optical transmission device according to appendix 15, further comprising: a wavelength selection unit that selects the first wavelength from the available wavelengths.
(Appendix 17)
when the optical receiving unit receives from the second base information indicating the allocated wavelengths allocated for communication between the first base and the second base, the wavelength selection unit selects the first wavelength from remaining wavelengths remaining after excluding the allocated wavelengths from the usable wavelengths determined by the usable wavelength determination unit. Optical transmission equipment.
(Appendix 18)
further comprising an adjusting unit that adjusts the length of the transmission period according to the number of remaining wavelengths,
18. The optical transmission device according to claim 17, wherein the optical transmission unit repeatedly transmits the first optical signal to the second base in the transmission period whose length is adjusted by the adjustment unit.
(Appendix 19)
when the number of remaining wavelengths becomes zero, the usable wavelength determination unit determines wavelength candidates different from the usable wavelengths determined based on the first identification information;
17. The optical transmission device according to appendix 16, wherein the wavelength selection unit selects a wavelength from among the wavelength candidates.
(Appendix 20)
An optical transmission method for transmitting wavelength division multiplexed optical signals between a first base where a plurality of optical transmission devices are mounted and a second base where a plurality of optical transmission devices are mounted,
A first optical transmission device among the plurality of optical transmission devices mounted at the first base acquires first identification information from an input signal to the first optical transmission device;
A second optical transmission device among the plurality of optical transmission devices mounted at the second base acquires second identification information from an input signal to the second optical transmission device;
the second optical transmission device sequentially selects wavelengths usable by the second optical transmission device one by one, and waits for an optical signal transmitted from the first base at each selected wavelength;
The first optical transmission device transmits a first optical signal including the first identification information using a first wavelength selected from wavelengths usable by the first optical transmission device. transmitting to the second base;
extracting the first identification information from the first optical signal when the second optical transmission device receives the first optical signal;
When the second optical transmission device determines that the first identification information and the second identification information are the same, the second optical transmission device transmits the first identification information at the first wavelength. setting the optical transmission unit and the optical reception unit of the second optical transmission device to perform data communication with the base of the second optical signal using the first wavelength and including the second identification information to the first location; and
The first optical transmission device extracts the second identification information from the second optical signal,
When the first optical transmission device determines that the first identification information and the second identification information are the same, the first optical transmission device transmits the second identification information at the first wavelength. An optical transmission method characterized by setting the optical transmission unit and the optical reception unit of the first optical transmission device so as to perform data communication with the base of the optical transmission.

1 (1a-1n) Router 2 (2a-2n) Transponder 3 (3a-3n) Router 4 (4a-4n) Transponder 5T, 6T Optical coupler 5R, 6R Optical coupler (optical splitter)
11 identification information acquisition units 12, 15 shutter 13 transmitter 13c light source 14 coherent receiver 14a local light source 21 transmission circuit 24 reception circuit 31a band pass filter (BPF)
41 optical amplifier 51 optical circulator 61, 62 AWG
71, 72 controller 100 optical transmission system 201 (201a to 201n), 203 (203a to 203n) client device 202 (202a to 202n), 204 (204a to 204n) optical transceiver 212 identification information acquisition unit 213 usable wavelength determination unit 214 wavelength selector 218 optical transmitter 221 optical receiver 222 identification information extractor 223 collator

Claims (9)

An optical transmission device mounted at a first site in an optical transmission system for transmitting wavelength division multiplexed optical signals between a first site and a second site,
an optical transmitter that transmits a wavelength division multiplexed optical signal to the second base;
an optical receiver that receives a wavelength division multiplexed optical signal transmitted from the second base;
a controller that controls the optical transmitter and the optical receiver;
The optical transmission unit uses a first wavelength to transmit a first optical signal including first identification information identifying a network to which a first communication device connected to the optical transmission device belongs to the second optical transmission device. send to base
The optical receiving unit transmits second identification information using the first wavelength to identify a network to which a second communication device connected to an opposing optical transmission device provided at the second base belongs. receiving from the second site a second optical signal comprising
When the first identification information and the second identification information extracted from the second optical signal are the same,
The controller detects a wavelength not used in the optical transmission system based on the wavelength division multiplexed optical signal received by the optical receiver from the second base,
the controller selects a second wavelength from among unused wavelengths in the optical transmission system;
The optical transmission device, wherein the optical transmission unit uses the first wavelength to transmit a wavelength notification indicating the second wavelength to the second base. Further comprising an acquisition unit that acquires the first identification information from the input signal,
The controller is
determining which of the optical transmission device and the opposed optical transmission device operates as a master device when the first identification information and the second identification information are the same;
detecting unused wavelengths in the optical transmission system;
wherein, when the optical transmission device operates as a master device, the second wavelength is determined based on the unused wavelength detected by the controller and the unused wavelength detected in the opposite optical transmission device; The optical transmission device according to claim 1. 3. The method according to claim 2, wherein the acquisition unit acquires, as the first identification information, information identifying the transmission source of the input signal or part of information identifying the transmission source of the input signal. optical transmission equipment. the input signal is a packet for neighbor discovery or neighbor confirmation transmitted from a router;
4. The optical transmission device according to claim 3, wherein the acquisition unit acquires, as the first identification information, a value of a network address part in an address that identifies the router from the packet. 2. The optical transmission device according to claim 1, wherein said controller transmits a wavelength notification representing said second wavelength to said opposing optical transmission device. An optical transmission method used by an optical transmission device mounted at a first site in an optical transmission system for transmitting wavelength division multiplexed optical signals between a first site and a second site,
An optical transmission unit of the optical transmission device uses a first wavelength to transmit a first optical signal including first identification information for identifying a network to which a first communication device connected to the optical transmission device belongs. transmitting to the second base;
The optical receiving unit of the optical transmission device identifies a network to which a second communication device connected to the opposite optical transmission device provided at the second base, transmitted using the first wavelength, belongs. receiving a second optical signal from the second location that includes identification information of 2;
When the first identification information and the second identification information extracted from the second optical signal are the same,
the controller of the optical transmission device detects a wavelength not used in the optical transmission system based on the wavelength division multiplexed optical signal received by the optical receiving unit from the second base;
the controller selects a second wavelength from among unused wavelengths in the optical transmission system;
The optical transmission method, wherein the optical transmission unit uses the first wavelength to transmit a wavelength notification indicating the second wavelength to the second base. An optical transmission system for transmitting wavelength division multiplexed optical signals between a first site where a plurality of optical transmission devices are mounted and a second site where a plurality of optical transmission devices are mounted,
A first optical transmission device among the plurality of optical transmission devices mounted at the first site uses a first wavelength to connect to the first optical transmission device. transmitting to the second site a first optical signal including first identification information identifying a network to which it belongs;
A second optical transmission device among the plurality of optical transmission devices mounted at the second base is a second communication device that uses the first wavelength to connect to the second optical transmission device. transmitting to the first site a second optical signal containing second identification information identifying the network to which the
When the first identification information and the second identification information are the same, the first optical transmission device
detecting unused wavelengths in the optical transmission system based on the wavelength division multiplexed optical signal received from the second base;
selecting a second wavelength from wavelengths not used in the optical transmission system;
using the first wavelength to send a wavelength notification indicating the second wavelength to the second location;
Upon receiving the wavelength notification from the first base, the second optical transmission device uses the first wavelength to send a completion notification indicating that the wavelength notification has been received to the first base. send and
The optical transmission system, wherein the first optical transmission device, upon receiving the completion notification from the second base, transmits an optical signal to the second base using the second wavelength. An optical transmission method for transmitting wavelength division multiplexed optical signals between a first base where a plurality of optical transmission devices are mounted and a second base where a plurality of optical transmission devices are mounted,
A first optical transmission device among the plurality of optical transmission devices mounted at the first site is connected to the first optical transmission device from an input signal to the first optical transmission device. obtaining first identification information identifying a network to which the communication device of
A second optical transmission device out of the plurality of optical transmission devices mounted at the second base is connected to the second optical transmission device from an input signal to the second optical transmission device. obtaining second identification information identifying the network to which the communication device of
The second optical transmission device receives from the first base among wavelengths prepared for wavelength division multiplexing data communication between the first base and the second base. detecting unused wavelengths based on the wavelength division multiplexed optical signal, sequentially selecting the detected unused wavelengths one by one, and waiting for an optical signal transmitted from the first base at each of the selected wavelengths;
wherein the first optical transmission device detects unused wavelengths based on the wavelength division multiplexed optical signal received from the second base, among the wavelengths prepared for the wavelength division multiplexed data communication; using a first wavelength selected from the detected unused wavelengths to transmit a first optical signal including the first identification information to the second base;
extracting the first identification information from the first optical signal when the second optical transmission device receives the first optical signal;
When the second optical transmission device determines that the first identification information and the second identification information are the same, the second optical transmission device transmits the first identification information at the first wavelength. setting the optical transmission unit and the optical reception unit of the second optical transmission device to perform data communication with the base of the second optical signal using the first wavelength and including the second identification information to the first location; and
The first optical transmission device extracts the second identification information from the second optical signal,
When the first optical transmission device determines that the first identification information and the second identification information are the same, the first optical transmission device transmits the second identification information at the first wavelength. An optical transmission method characterized by setting the optical transmission unit and the optical reception unit of the first optical transmission device so as to perform data communication with the base of the optical transmission. The first optical transmission device,
determining a selectable wavelength from wavelengths prepared for the wavelength division multiplexing data communication based on the first identification information;
9. The optical transmission method according to claim 8, wherein said first wavelength is selected from among said selectable wavelengths.

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