Communication network, node device and path route calculating method

[0001] [Technical field to which the invention belongs] The present invention is a communication network,<u style="single">Optical cross connect</u>Regarding the device and path route calculation method, especially in a communication network including multiple domains configured by interconnecting XC (cross-connect) devices, the physical characteristics and management restrictions of the XC device Due to this, there is a limit to the connectivity between XC devices inside each region, and when it is not always possible to set an arbitrary path route inside the region, a path calculation method for a path that spans multiple regions. Regarding. [0002] [Conventional technology] Conventionally, an optical communication network is composed of a network in which a large number of XC (cross-connect) devices are interconnected in a mesh shape by an optical link. In some cases, a wavelength division multiplexing transmission device is arranged between XC devices, and a plurality of wavelength channels are wavelength-multiplexed and transmitted on an optical link. [0003] The XC device switches the data signal transmitted on the wavelength channel of a specific input interface to the wavelength channel of a specific output interface selected from a plurality of output interfaces, and transfers the data signal in units of wavelength channels. It is a device. There are two types of XC devices: an electric XC device that temporarily converts a data signal on a wavelength channel from an optical signal to an electric signal and processes it by optical-electric conversion in an interface, and an optical XC device that does not use optical-electric conversion. [0004] The optical XC device has the characteristic of being able to process data signals of any speed and format, but when the data signal passes through a large number of optical XC devices or is transmitted over a long distance, noise accumulates, etc. There is a problem that the quality such as the bit error rate of the data signal is deteriorated due to this. [0005] The XC device is not only interconnected with other XC devices, but also a SONET (synchronous optical network) multiplexing / separation device, an ATM (asynchronous transfer mode) switch, and an IP (internet). protocol) It is also connected to a device that is a client of an optical communication network such as a router. [0006] Optical communication networks use one or more wavelengths to provide a service that provides an optical path between multiple client devices. The optical path is set from the transmitting side XC device to which the client device is connected to the receiving side XC device to which the other client device is connected via a plurality of relay XC devices. A technique related to such an XC device is disclosed in Japanese Patent Application Laid-Open No. 2000-004460. [0007] The optical communication network is generally divided into a plurality of areas for the convenience of efficient network control and management between operators. The area contains multiple XC devices. Therefore, the optical path between the client devices connected to the XC devices belonging to different areas is set across a plurality of areas. [0008] An example of such an optical communication network is shown in FIG. In the optical communication network 2 shown in FIG. 22, four areas (# 1 to # 4) are arranged. Client devices 51,61,62,71,72 are connected to the XC devices belonging to areas # 1, # 3, and # 4. An optical link and a control channel for transmitting a data signal are arranged between the areas # 1 to # 4 and the client devices 51,61,62,71,72. Control channels are used to transfer various control messages between devices. [0009] The client devices 51,61,62,71,72 can request the optical communication network 2 to set or open an optical path through the control channel. The boundary between areas # 1 to # 4 and client devices 51,61,62,71,72 is called UNI (usertonetwork interface). [0010] The optical link and the control channels 111,112,211,212,311,312 are also arranged between the regions # 1 to # 4 in the same manner as described above. The boundary between regions # 1 to # 4 is called NNI (network-to-network interface). [0011] The cross-connect device in each area # 1 to # 4 or the management system that manages the area # 1 to # 4 maintains the relay route management table 81 to 84 that describes the relay route for each destination device of the optical path. There is. The relay route management tables 81 to 84 describe a series of sets of regions # 1 to # 4 that pass through to reach the destination device, and are also called a routing table. Figures 23 to 26 show examples of relay route management tables 81 to 84 that describe a series of sets of areas # 1 to # 4 that pass through each of the client devices 51, 61, 62, 71, 72. [0012] In the relay path management table 81 of the area # 1, as shown in FIG. 23, "area # 1" is the relay path of the client device 51, and "area # 1-area # 2-area" is the relay path of the client device 61. "# 4" is the "area # 1-area # 2-area # 4" as the relay route of the client device 62, and "area # 1-area # 2-area # 3" is the client as the relay route of the client device 71. "Region # 1-Region # 2-Region # 3" are described as relay routes for the device 72, respectively. [0013] As shown in FIG. 24, in the relay path management table 82 of the area # 2, area # 2-region # 1 is the relay path of the client device 51, and region # 2-region is the relay path of the client device 61. "# 4" is "Area # 2-Area # 4" as a relay route of the client device 62, "Area # 2-Area # 3" is a relay route of the client device 71, and "Area # 2-Area # 3" is a relay route of the client device 72. # 2-Area # 3 "is described respectively. [0014] As shown in FIG. 25, the relay path management of the area # 3 shows that the relay path of the client device 51 is "area # 3-area # 2-area # 1" and the relay path of the client device 61 is "area". # 3-Area # 4 is "Area # 3-Area # 4" as a relay route of the client device 62, "Area # 3" is a relay route of the client device 71, and "Area # 3" is a relay route of the client device 72. # 3 "is described respectively. [0015] As shown in FIG. 26, the relay path management of the area # 4 shows that the relay path of the client device 51 is "area # 4-area # 2-area # 1" and the relay path of the client device 61 is "area". "# 4" is "Area # 4" as a relay route of the client device 62, "Area # 4-Area # 3" as a relay route of the client device 71, and "Area # 4-Area" as a relay route of the client device 72. # 3 "is described respectively. [0016] When the optical path setting is requested through UNI, the regions # 1 to # 4 calculate the route to the destination by referring to the relay route management tables 81 to 84, and set the optical path using the control channels 111,112,211,212,311,312. A control message requesting is sent along the route. [0017] For example, when the client device 51 requests the area # 1 to set the optical path # 1 to the client device 71, the area # 1 is the path area # 1-area # 2-area # described in the relay path management table 81. The control message is transferred according to "3" and the optical path # 1 is set. Regions # 2 and # 3 can be determined independently with respect to the detailed internal path of regions # 2 and # 3 through which the optical path # 1 passes. [0018] As a typical example of a routing protocol that operates between regions # 1 to # 4 to maintain the relay route management tables 81 to 84 used for route calculation across multiple regions # 1 to # 4. , There is a BGP (border-gateway-protocol) routing protocol used as an EGP (exterior-gateway-protocol) for IP (internet-protocol) communication networks. The BGP routing protocol is a distance vector routing protocol that operates on TCP (transmission control protocol) / IP. [0019] The BGP routing protocol uses BGP Open control messages and BGP Keepalives control messages to discover and maintain interconnection relationships between adjacent regions. Also, in the BGP routing protocol, BGP New relay route information is calculated and announced from the relay route information for each destination device advertised from the adjacent area using the update control message and the relay route management table inside the own area, and at the same time relayed. Update the route management table. When the operation of the announcement is repeated many times, the relay route management table converges to a certain state and can be used for the route calculation. [0020] For details on the BGP routing protocol, see RFC1771 of Y.Rehker and T.Li in the RFC (request-for-comments) specified in the IETF (internet-engineering-task-force), which is an international standardization machine for IP. Described in "A Border Gateway Protocol 4 (BGP4)" (March 1995). [0021] [0021] [Problems to be Solved by the Invention] However, in the above-mentioned conventional optical communication network, the connectivity between XC devices is limited inside each region, and it may not always be possible to set a route of an arbitrary path inside the region. For example, since the data signals pass through a large number of optical XC devices inside the region, the signal transmission quality of the data signal may deteriorate and the path may not be set. [0022] In addition, an OADM (optical add-drop multiplexer) type optical XC device may only be able to add-drop a specific wavelength, and the optical XC device may not provide perfect connectivity, that is, non-blocking characteristics in the first place. Optical path # 2 shown in FIG. 22 is an example in which the optical path setting fails due to the limitation of connectivity in area # 4. [0023] Therefore, in a conventional optical communication network, even if an attempt is made to set an optical path along a path calculated using a BGP routing protocol or the like, the optical path setting may fail inside each region via the optical path. .. [0024] Therefore, an object of the present invention is to solve the above-mentioned problems and to set an optical path inside each region. A communication network that never fails,<u style="single">Optical cross connect</u>The purpose is to provide an apparatus and a method for calculating a path route. [0025] [Means for solving problems] A plurality of communication networks according to the present invention each execute a cross-connect function of a path.<u style="single">Optical cross connect</u>A communication network in which devices are composed of a plurality of interconnected areas and provide a service for dynamically setting and opening the path. The inside of the area<u style="single">Optical cross connect</u>A connectivity management table that describes the connectivity between devices, A relay route management table describing the area related to the relay route to the destination device of the path and the edge device connected to the device outside the area. A control channel for notifying the relay route management table to the adjacent area, and From the connection management table and the relay route management table announced from the adjacent area under the route selection rule set to calculate the relay route to the destination device of the path.<u style="single">A new relay route is calculated, and at that time, the route that cannot be set due to the limitation of connectivity inside the area is excluded from the connectivity management table, and the relay route management table is based on the calculated result. Is updated and maintained, and advertised in the adjacent area as information about the relay route.</u>A relay route processing unit is provided in each of the plurality of regions. [0026] According to the present invention<u style="single">Optical cross connect</u>A device constitutes an area by executing a cross-connect function of the path and interconnecting with an adjacent device in a communication network that provides a service of dynamically setting and opening a path.<u style="single">Optical cross connect</u>It s a device, A connectivity management table that describes the connectivity between adjacent devices inside the area, A relay route management table describing the area related to the relay route to the destination device of the path and the edge device connected to the device outside the area. A control channel for notifying the relay route management table to the adjacent area, and From the connection management table and the relay route management table announced from the adjacent area under the route selection rule set to calculate the relay route to the destination device of the path.<u style="single">A new relay route is calculated, and at that time, the route that cannot be set due to the limitation of connectivity inside the area is excluded from the connectivity management table, and the relay route management table is based on the calculated result. Is updated and maintained, and the relay route management table is advertised in the adjacent area as information on the relay route.</u>It is equipped with a relay route processing unit. [0027] The path path calculation method according to the present invention has a plurality of paths that execute the cross-connect function of each path.<u style="single">Optical cross connect</u>A communication network that consists of multiple areas in which devices are interconnected and provides a service that dynamically sets and opens the path.<u style="single">Used for</u>It is a path route calculation method The inside of the area<u style="single">Optical cross connect</u>A connectivity management table that describes the connectivity between devices, A relay route management table describing the area related to the relay route to the destination device of the path and the edge device connected to the device outside the area. Each of the plurality of areas is provided with a control channel for notifying the relay route management table to adjacent areas. From the connection management table and the relay route management table announced from the adjacent area under the route selection rule set to calculate the relay route to the destination device of the path.<u style="single">A new relay route is calculated, and at that time, the route that cannot be set due to the limitation of connectivity inside the area is excluded from the connectivity management table, and the relay route management table is based on the calculated result. Is updated and maintained, and the relay route management table is advertised in an adjacent area as information on the relay route.</u>.. [0028] That is, the communication network of the present invention manages the connectivity between the adjacent area management table that describes the relationship between the XC (cross-connect) device inside the area and the XC device belonging to the adjacent area and the XC device inside the area. Maintain the connectivity management table and the relay route management table that describes the relay route of the optical path for each destination device and the XC device located at the region edge on the route, and the relay route announced from the adjacent area. A new relay route is calculated from the information about the relay route and the connectivity management table inside the area, and is announced to the adjacent area as information about the relay route. In this case, the route that cannot be set due to the limitation of connectivity inside the area is excluded from the information on the relay route. [0029] By repeating the operation of this announcement, information on the relay route that describes only the configurable route considering the connectivity management table of all areas is obtained, and each XC device uses this as the final relay route management table. It is characterized by holding. Therefore, the relay route management table for each area considers the connectivity management table for all areas, and the optical path of the route described in this relay route management table can always be set, and the optical path setting failure occurs. It becomes possible to avoid it. [0030] As described above, by realizing the method of maintaining the relay route management table considering the limitation of connectivity inside the area and the route calculation method based on it, an optical communication network that does not fail to set the optical path is provided. It will be possible. [0031] BEST MODE FOR CARRYING OUT THE INVENTION Next, examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an optical communication network according to an embodiment of the present invention. In FIG. 1, four regions # 1 to # 4 including four optical XC devices 11 to 14,21 to 24,31 to 34,41 to 44 are arranged in the optical communication network 1, and three client devices 51 are arranged. , 61,62 are connected. [0032] Here, the optical XC device connected to the device outside the area is called an edge device. The optical path is transferred out of the region through the edge device. Each region # 1 to # 4 has region-specific connectivity restrictions and passes between any optical XC device 11 to 14,21 to 24,31 to 34,41 to 44 within regions # 1 to # 4. Is not always possible. [0033] The boundary between regions # 1 to # 4 is NNI (network-to-network) At interface), control messages required for route calculation and optical path configuration are exchanged via NNI. The boundary between the optical XC device 11,43,44 and the client device 51,61,62, or the boundary between areas # 1, # 4 and the client device 51,61,62 is UNI (usertonetwork interface). The client devices 51, 61, 62 send a control message requesting the setting or opening of the optical path to the optical communication network 1 through the UNI. NNIs and UNIs are equipped with optical links for transmitting data signals and control channels for exchanging control messages. It is assumed that two-way communication is possible with two optical links and control channels as a set. [0034] FIG. 2 is a block diagram showing a detailed configuration of the optical XC device 44 shown in FIG. In FIG. 2, the optical XC device 44 includes an input interface (IF # 1 to # 4) 441 to 444, a 4 × 4 optical switch 445, an output interface (IF # 1 to # 4) 446 to 449, and a switch control unit. It is composed of 450, a control message processing unit 451, an adjacent area management table 453, a connectivity management table 454, a relay route management table 455, and a routing protocol processing unit 452 that maintains the management table and performs route calculation. ing. [0035] The routing protocol processing unit 452 of the edge device such as the optical XC device 44 processes two, a routing protocol that operates between areas # 1 to # 4 and a routing protocol that operates inside areas # 1 to # 4. [0036] No optical-electric converter or electric-optical converter is used for the interface of the optical XC device 44. The 4 × 4 optical switch 445 controlled by the switch control unit 450 switches the data signal on the optical link in units of wavelength channels, and sets and opens the optical path. The interface is equipped with a light intensity detector (not shown) for each wavelength channel to monitor the signal quality of the optical path and the failure of the optical link. [0037] The interface includes a control channel termination unit (not shown) and sends and receives control messages processed by the control message processing unit 451 to and from the control channel. The control channel is connected to the area # 1 to # 4 external devices including the optical XC devices 11 to 14,21 to 24,31 to 34,41 to 44 inside the areas # 1 to # 4 and the client devices 51,61,62. Will be done. Areas # 1 to # 4 Control channels connected to external devices operate as NNIs or UNIs. A dedicated out-band channel prepared separately from the optical link can be used as the control channel. [0038] Control messages are stored in IP packets and transmitted over the control channel. In particular, protocols such as RSVP (resource-reservation-protocol) and LDP (label-distribution-protocol) are used for exchanging control messages regarding the setting and opening of optical paths. A wavelength separator may be arranged on the input interfaces 441 to 444 and a wavelength multiplier may be arranged on the output interfaces 446 to 449 as control channels, and an in-band channel transmitted by wavelength division multiplexing on an optical link may be used as a control channel. it can. [0039] The control channel operating as NNI or UNI is arranged between the centralized control device (not shown) provided for the entire optical communication network 1 and the areas # 1 to # 4 and the client devices 51, 61, 62. You can also do it. In this case, the control messages exchanged between the areas # 1 to # 4 are transferred via the centralized control device. [0040] When an optical-electric converter and an electric-optical converter are used for the interface, SONET (synchronous optical) of the signal transmitted on the optical link The data communication channel (DCC) in the overhead contained in the network) frame can also be used as an in-band channel. With appropriate protocols, control messages can also be multicast forwarded to multiple regions or multiple optical XC devices. [0041] Adjacent area management Table 453 describes the connection relationship between the edge device inside the area # 4 to which the own device belongs and the device outside the area # 4 connected to the edge device. Although not shown, other optical XC devices 11 to 14,21 to 24,31 to 34,41 to 43 have the same configuration as the above optical XC device 44. [0042] FIG. 3 is a diagram showing a configuration example of the adjacent area management table 453 of the area # 4 stored in the optical XC device 44 shown in FIG. For example, interface # 4 of optical XC device 34 in region # 3 is connected to interface # 3 of optical XC device 44. [0043] That is, in the adjacent area management table 453 of the area # 4, the adjacent area # 2 and the adjacent area edge device corresponding to the own area edge device IF # 2 of the own area edge device optical XC device 41 are shown. The adjacent area edge device IF "# 4" of the "optical XC device 23" corresponds to the own area edge device IF "# 3" of the own area edge device "optical XC device 42" and is associated with the adjacent area "# 3". , The adjacent area edge device IF "# 4" of the adjacent area edge device "optical XC device 33" corresponds to the own area edge device IF "# 4" of the own area edge device "optical XC device 43". The "client area" and the adjacent area edge device IF "# 1" of the adjacent area edge device "client device 61" correspond to the local area edge device IF "# 3" of the local area edge device "optical XC device 44". Then, the adjacent area "# 3" and the adjacent area edge device IF "# 4" of the adjacent area edge device "optical XC device 34" are combined with the own area edge device IF "# 4" of the own area edge device "optical XC device 44". The adjacent area "client area" and the adjacent area edge device IF "# 1" of the adjacent area edge device "client device 62" are described corresponding to "# 4", respectively. [0044] Adjacent area management Table 453 can be automatically generated by using the neighbor-discovery function of the routing protocol that operates between areas # 1 to # 4, but it is created in advance by the centralized controller. You may. In addition, the adjacent area management table 453 is created when the optical communication network 1 is started, and is updated when the configuration of areas # 1 to # 4 is changed, such as when a new optical XC device is added. Does not change. [0045] Adjacent area management Instead of showing the edge device number and interface number in Table 453, it is also possible to use a unique IP address assigned to the entire optical communication network 1 or an optical link number that straddles areas # 1 to # 4. It is possible, and incidental information such as the wavelength of the optical link and the usage cost can be added. [0046] In the example shown in Figure 3, all edge devices inside region # 4 are listed, but each edge device maintains an adjacent region management table that lists only its own devices and uses control channels as needed. There is also a configuration in which the adjacent area management table of other edge devices is obtained. [0047] Connectivity management Table 454 describes the possibility of setting optical paths between all optical XC devices 41 to 44 inside area # 4 to which the own device belongs. Optical XC device 44 holds connectivity management table 454 inside region # 4. The other optical XC devices 41 to 43 also hold the connectivity management table 454 inside the same area # 4 as the optical XC devices 44, but one of the devices holds it on behalf of them and provides control channels as needed. There is also a configuration that uses the connectivity management table 454 to obtain it. [0048] Connectivity management for each optical XC device 11-14, 21-24, 31-34, 41-44 Table 454 lists only the connectivity from its own device and uses control channels as needed. There is also a configuration in which the connectivity management table between devices is obtained. [0049] FIG. 4 is a diagram showing an example of a connectivity management table in region # 1 of FIG. 1, FIG. 5 is a diagram showing an example of a connectivity management table of region # 2 of FIG. 1, and FIG. 6 is a diagram showing an example of a connectivity management table of region # 2. It is a figure which shows the example of the connectivity management table of area # 3, and FIG. 7 is a figure which shows the example of the connectivity management table of area # 4 of FIG. For example, in region # 1, an optical path can be set between all optical XC devices 11 to 14, and in region # 2, an optical path can be set between optical XC device 21 and optical XC device 24. In region # 3, an optical path cannot be set between the optical XC device 31 and the optical XC device 34 and between the optical XC device 32 and the optical XC device 33, and in region # 4, the optical XC cannot be set. An optical path cannot be set between device 41 and optical XC device 44. [0050] The connectivity management table for each of the above areas # 1 to # 4 is created when the optical communication network 1 is started, and is updated when the configuration of areas # 1 to # 4 is changed, such as when a new optical XC device is added. And usually does not change otherwise. [0051] The connectivity management table is created by the centralized controller, but if the connectivity restrictions can be expressed as formalized constraints for each area # 1 to # 4, then areas # 1 to # 4 An internally operating routing protocol can also be automatically created by determining the connectivity between optical XC devices 11-14, 21-24, 31-34, 41-44. For example, if the maximum number of hops of the optical XC device that can be relayed inside region # 3 is determined to be 1, the routing protocol operating inside region # 3 determines the connectivity possibility under this condition, and Fig. 6 shows. The connectivity management table inside the indicated area # 3 can be created automatically, and the connectivity management table can be updated immediately even if the configuration of area # 3 is changed. [0052] The relay route management table 455 shows a set of a series of regions (relay route) representing the relay route from the own region for each client device 51, 61, 62, and the output edge device from the own region on the relay route. And "input edge device to own area" in the case of a route relaying to own area are described. The routing protocol that operates between areas # 1 to # 4 automatically creates a relay route management table while announcing the relay route information using the control channel between areas # 1 to # 4. [0053] The relay route management table 455 is created when the optical communication network 1 is started, and when the configuration of areas # 1 to # 4 is changed, such as when a new optical XC device is added, or when a new relay is announced at regular intervals. It is updated sequentially with reference to the route information. [0054] FIG. 8 is a diagram showing an example of the relay route management table of the area # 4 after the announcement (1) of the relay route management table of FIG. 1, and FIG. 9 is a diagram after the announcement (1) of the relay route management table of FIG. It is a figure which shows the example of the relay route management table of area # 2, and FIG. 10 is the figure which shows the example of the relay route management table of area # 3 after the announcement (1) of the relay route management table of FIG. Further, FIG. 11 is a diagram showing an example of the relay route management table of the area # 2 after the announcement of the relay route management table of FIG. 1 (2), and FIG. 12 is a diagram showing the announcement of the relay route management table of FIG. 1 (3). It is a figure which shows the example of the relay route management table of the latter region # 1, and FIG. 13 is the flowchart which shows the flow of the process of making the relay path management table by one Embodiment of this invention. The procedure for creating a relay route management table in which the client devices 61 and 62 are described in the areas # 1 to # 4 will be described with reference to FIGS. 8 to 13. [0055] The routing protocol processing unit of the optical XC devices 41 to 44 inside the area # 4 to which the client devices 61 and 62 are connected creates the relay route management table 455 of the area # 4 shown in FIG. 8 (step S41 in FIG. 13). For the client device 61, the "output edge device from its own area" is the "optical XC device 43". This relationship is described in the adjacent area management table 453 inside the area # 4 shown in FIG. The "input edge device to the own area" is the "optical XC device 41,42,44" that can be connected to the "optical XC device 43" which is the "output edge device from the own area". This relationship is described in Connectivity Management Table 454 inside Region # 4 shown in Figure 7. The "relay route" is only "area # 4". [0056] For the client device 62, the "output edge device from its own area" is the "optical XC device 44". This relationship is described in the adjacent area management table 453 inside the area # 4 shown in FIG. The "input edge device to the own area" is an "optical XC device 42,43,44" that can be connected to the "optical XC device 44" which is the "output edge device from the own area". This relationship is described in Connectivity Management Table 454 inside Region # 4 shown in Figure 7. The "relay route" is only "area # 4". [0057] The optical XC devices 41, 42, 44, which are the edge devices of the area # 4, store the relay route management table 455 inside the area # 4 as the relay route information in the control message and notify the adjacent areas # 2, # 3. [See Announcement (1) in Figure 1] (step S42 in Figure 13). Since both the optical XC devices 42 and 44 are connected to area # 3, the announcement (1) may be made from only one of them. [0058] [0058] The output edge device from own area described in the relay route management table 455 is not always necessary for creating the relay route management table in other areas, and may be omitted. If an in-band channel is used as the control channel and only the edge device described in "Input edge device to own area" makes a public notice, "Input edge device to own area" is added to the relay path information. It does not have to be explicitly indicated. [0059] The optical XC device 23 in which the relay route information is announced from the area # 4 further transfers the relay route information to the optical XC devices 21, 22, 24 inside the area # 2 (Fig. 13, step S21). The routing protocol processing unit 452 of the optical XC devices 21 to 24 creates a relay route management table for region # 2 shown in FIG. 9 using the announced relay route information (Fig. 13, step S22). Since the "input edge device to the own area" announced from the area # 4 is the "optical XC device 41,42,44" for the client device 61, the "output edge device from the own area" is ". It becomes the "optical XC device 23", and the "optical XC device 21, 22, 24" that can be connected to the optical XC device 23 becomes the "input edge device to its own area". The "relay route" is "area # 2-area # 4". [0060] On the other hand, for the client device 62, the "optical XC devices 42, 43, 44" of the "input edge device to the own area" announced from the area # 4 are not connected to the area # 2, and are relay paths. Without it, it becomes "unreachable". [0061] The same process as the above process is performed in the area # 3, and the relay route management table for the area # 3 shown in FIG. 10 is created (steps S31 and S32 in FIG. 13). That is, since the "input edge device to the own area" announced from the area # 4 is the "optical XC device 41,42,44" for the client device 61, the "output edge device from the own area". Becomes "optical XC device 33" and "optical XC device 34", and "optical XC device 33, 34" that can be connected to optical XC device 33 becomes "input edge device to own area" and is connected to optical XC device 34. The possible "optical XC device 33" becomes the "input edge device to its own area". The "relay route" is "area # 3-area # 4". [0062] On the other hand, for the client device 62, since the "input edge device to the own area" announced from the area # 4 is the "optical XC device 42,43,44", the "output edge device from the own area". Becomes "optical XC device 33" and "optical XC device 34", and "optical XC device 33, 34" that can be connected to optical XC device 33 becomes "input edge device to own area" and is connected to optical XC device 34. The possible "optical XC device 33" becomes the "input edge device to its own area". The "relay route" is "area # 3-area # 4". In this way, when there are a plurality of combinations of the "output edge device from the own area" and the "input edge device to the own area", all of them are described in the relay path management table. [0063] Areas # 2 and # 3 announce the created relay route management table to the adjacent area as relay route information [see announcement (2) in Fig. 1] (Fig. 13, steps S23, S33). "Optical XC device 33" is described as "input edge device to own area" in the relay route information for the client device 62 announced from the area # 3 to the area # 2. Therefore, area # 2 updates the relay route management table described as "unreachable" (Fig. 13, step S24). [0064] Figure 11 shows the relay route management table for area # 2. The "output edge device from its own area" is the "optical XC device 24" connected to the optical XC device 33, and the "relay path" is "area # 2-area # 3-area # 4". [0065] On the other hand, in area # 3, the relay route management table is not updated. It is possible to reach the client device 61 from region # 3 via region # 2, but this route is not selected because it is a detour via region # 2. [0066] As a route selection rule when updating the relay route management table, "select a route with a smaller number of transit areas" is adopted. This rule means "do not select a route that goes through the same area more than once". A route that goes through the same area more than once is called a loop and is generally excluded when applying other selection rules. As a route selection rule, other rules that reflect the control policy may be adopted, or all possible routes may be retained in the relay route management table. [0067] Area # 2 announces the updated relay route management table to the adjacent area # 1 as relay route information [see announcement (3) in Fig. 1] (Fig. 13, step S25). Area # 1 where the relay route information is announced creates a relay route management table for area # 1 shown in FIG. 12 (steps S11 and S12 in FIG. 13). At this stage, the creation of the relay route management table in all areas # 1 to # 4 is completed. After that, if the configuration of each area # 1 to # 4 is changed inside each area, or the relay route information is announced at regular intervals, the relay route management table is maintained in the latest state. [0068] When there is a request from the client device 51 to set the optical path to the area # 1, the optical XC device 11 calculates the path by referring to the relay path management table and sends a control message requesting the setting of the optical path to the adjacent area. To do. For example, when the destination device is the client device 62, the relay path is "region # 1-region # 2-region # 3-region # 4", and the output edge device from region # 1 to region # 2 is optical. Must be optical XC device 14, not XC device 13. [0069] The route setting inside the areas # 2, # 3, and # 4 is performed independently by using the relay route management table for each area and the routing protocol that operates inside the area. If you try to set the optical path with the optical XC device 13 as the output edge device, the optical path cannot reach the client device 41 due to the limitation of connectivity inside the area # 2 or area # 4, and the setting is made. Fail. However, in this embodiment, the limitation of the connectivity of each area # 1 to # 4 is considered in advance in the relay path management table, and the optical path setting failure does not occur. [0070] As described above, in this embodiment, the relay route management table of each area considers the connectivity management table inside all areas, and the optical path of the route described in this relay route management table can always be set. , It is possible to avoid the failure of setting the optical path. In addition, since it is possible to avoid a failure in setting the optical path, there is no need to retry the setting in a different route, and the optical path setting time and non-conduction until the detour optical path is set when a failure occurs. You can save time. [0071] FIG. 14 is a block diagram showing a configuration of an optical communication network according to another embodiment of the present invention. The basic configuration of the other embodiment of the present invention is as described above, but the selection of the relay route in the relay route management table is further devised. In FIG. 14, the optical communication network 1 consists of four regions # 1 to # 4 including four optical XC devices 11 to 14,21 to 24,31 to 34,41 to 44, and has the same configuration as that shown in FIG. It has a configuration, and three client devices 51,71,72 are connected. The configurations of these optical XC devices 11 to 14,21 to 24,31 to 34,41 to 44 are the same as those shown in FIG. [0072] FIG. 15 is a diagram showing an example of the relay route management table of area # 3 after the announcement (1) of the relay route management table of FIG. 14, and FIG. 16 is a diagram after the announcement (1) of the relay route management table of FIG. It is a figure which shows the example of the relay route management table of area # 2, and FIG. 17 is a figure which shows the example of the relay route management table of area # 4 after the announcement (1) of the relay route management table of FIG. Further, FIG. 18 is a diagram showing an example of the relay route management table of the area # 3 after the announcement of the relay route management table of FIG. 14 (2), and FIG. 19 is a diagram showing the announcement of the relay route management table of FIG. 14 (3). It is a figure which shows the example of the relay route management table of the latter area # 2, and FIG. 20 is a figure which shows the example of the relay route management table of the area # 1 after the announcement (4) of the relay route management table of FIG. , FIG. 21 is a flowchart showing the flow of the process of creating the relay route management table according to another embodiment of the present invention. The procedure for creating a relay route management table in which the client devices 71 and 72 are described in the areas # 1 to # 4 will be described with reference to FIGS. 15 to 21. [0073] The routing protocol processing unit of the optical XC devices 31 to 34 inside the area # 3 to which the client devices 71 and 72 are connected refers to the adjacent area management table and connectivity management table inside the area # 3, and the area # shown in FIG. Create the relay route management table of 3 (Fig. 21, step S131). [0074] For the client device 71, the "output edge device from the own area" is the "optical XC device 31", and the "input edge device to the own area" is the "output edge device from the own area" "optical XC". It is an "optical XC device 32,33" that can be connected to the "device 31", and the "relay path" is only "area # 3". [0075] For the client device 72, the "output edge device from the own area" is the "optical XC device 32", and the "input edge device to the own area" is the "output edge device from the own area" "optical XC". It is an "optical XC device 31, 34" that can be connected to the "device 32", and the "relay path" is only "area # 3". [0076] The optical XC devices 33 and 34, which are the edge devices of the area # 3, store the relay route management table inside the area # 3 as the relay route information in the control message and notify the adjacent areas # 2 and # 4 [Fig. 14]. (See Announcement (1)] (Fig. 21, Step S132). [0077] The optical XC device 24 in the area # 2 where the relay route information is announced further transfers the relay route information to the optical XC devices 21, 22, 23 inside the area # 2 (FIG. 21, step S122). The routing protocol processing unit of the optical XC devices 21 to 24 uses the announced relay route information to create a relay route management table for region 2 shown in FIG. 16 (FIG. 21, step S122). [0078] Since the "input edge device to the own area" announced from the area # 3 is the "optical XC device 32,33" for the client device 71, the "output edge device from the own area" is the "optical XC". The "device 24" and the "optical XC devices 22, 23" that can be connected to the optical XC device 24 are the "input edge devices to the own area". The "relay route" is "area # 2-area # 3". [0079] On the other hand, for the client device 72, the "input edge device to own area" announced from the area # 3 is not connected to the area # 2 of the optical XC devices 31 and 34, and "reaches" without a relay route. It becomes "impossible". [0080] [0080] The same process as the above process is performed in the area # 4, and the relay route management table for the area # 4 shown in FIG. 17 is created (FIGS. 21 steps S141 and S142). That is, since the "input edge device to the own area" announced from the area # 3 is the "optical XC device 32,33" for the client device 71, the "output edge device from the own area" is ". The "optical XC device 42" becomes the "optical XC device 42", and the "optical XC device 41, 42, 43" that can be connected to the optical XC device 42 becomes the "input edge device to the own area". The "relay route" is "area # 4-area # 3". [0081] On the other hand, for the client device 72, since the "input edge device to the own area" announced from the area # 3 is the "optical XC device 31,34", the "output edge device from the own area" is ". The "optical XC device 44" becomes "optical XC device 44", and the "optical XC device 42,43" that can be connected to the optical XC device 44 becomes the "input edge device to its own area". The "relay route" is "area # 4-area # 3". [0082] Areas # 2 and # 4 announce the created relay route management table to the adjacent area as relay route information [see announcement (2) in Fig. 14] (Fig. 21, steps S123, S143). In the relay route information for the client device 72 announced from the area # 4 to the area # 3, "optical XC devices 42, 43" are described as "input edge devices to the own area". In FIG. 18, in the relay path management table of the area # 3 for the client device 72, the input edge device to the own area is optical XC device 31, 34, optical XC device 33, and output edge from the own area. The "devices" are "optical XC device 32" and "optical XC device 33". [0083] On the other hand, in the relay route information announced from the area # 4, the "input edge device to the own area" is "optical XC device 42,43", that is, the "output edge device from the own area" in the area # 3 is " It means that it is the "optical XC device 33" connected to the "optical XC device 42". This means that a new route from the optical XC device 33 to the client device 72, which is not listed in the relay route management table in FIG. 15, has been discovered. [0084] Here, as a route selection rule when updating the relay route management table, if "a route that passes through the same area more than once is not selected", this new route is excluded because it passes through area # 3 twice. Will be done. If this route is excluded, the client device 72 cannot be reached from the area # 2. [0085] Therefore, by improving the selection rule, under the condition that "the route that passes through the same input edge device or the same output edge device more than once in the same area is excluded", "the number of areas that pass through" Choose a smaller route. " By doing so, a route that is looped at the region level but not looped at the device level is added to the options, and the degree of freedom in setting the optical path is increased. If there is no limitation of connectivity inside area # 3, all optical XC devices 31, 33, 34 can be connected to optical XC device 32, which is an edge output device, and a path that passes through area # 3 more than once. Is useless and it is reasonable to exclude it. Due to connectivity restrictions, the selection rules described above are required. Area # 3 updates the relay route management table shown in Fig. 17 (Fig. 21, step S133). [0086] Area # 3 announces the updated relay route management table to the adjacent area # 2 as relay route information [see announcement (3) in FIG. 14] (Fig. 21, step S134). The area # 2 in which the relay route information is announced updates the relay route management table in the area # 2 shown in FIG. 19, and the client device 72 is no longer "unreachable". Area # 2 announces the updated relay route management table to the adjacent area # 1 as relay route information [see Fig. 14 Announcement (4)] (Fig. 21, step S134). [0087] In the area # 1 where the relay route information is announced, the relay route management table of the area # 1 shown in FIG. 20 is created (FIG. 21, steps S111 and S112). At this stage, the creation of the relay route management table in all areas is completed. After that, if the configuration of each area # 1 to # 4 is changed inside each area, or the relay route information is announced at regular intervals, the relay route management table is maintained in the latest state. [0088] As described above, in this embodiment, the route selection rule has been improved so that a route that is looped at the region level but is not looped at the device level can be selected. The effect is that a complicated relay route can be found and the area where the destination device can be reached increases. This means that the route calculation has become more sophisticated. [0089] In addition, the connectivity management table shows not only the possibility of setting the optical path between the optical XC devices inside the area, but also the output interface of the optical XC device inside the area and the input interface of other optical XC devices in more detail. The possibility of setting the optical path between them can be described. In addition, the possibility of setting an optical path between the input interface and the output interface inside the optical XC device can be described. Similarly, in the relay path management table, not only "output edge device from own area" and "input edge device to own area" on the relay path, but also "output of output edge device from own area" in more detail. "Interface" and "input interface of the input edge device to the own area" can be described. [0090] In such a case, under the condition that the route selection rule is "exclude routes that pass through the same interface of the same input edge device or output edge device more than once within the same area", "via" It is possible to adopt "select a route with a smaller number of regions or devices". When this selection rule is used, a path that is looped at the region level and the device level but is not looped at the interface level is added to the options, further increasing the degree of freedom in setting the optical path. [0091] As described above, in the optical communication network according to the present invention, the relay route management table of each area # 1 to # 4 considers the connectivity management table inside all the areas, and the relay route management table described in this relay route management table is taken into consideration. The optical path can always be set, and when setting the optical path across multiple areas, the connectivity between the optical XC devices is limited inside each area, and the path of any path is not necessarily set inside the area. Even if it cannot be done, it is possible to avoid the failure of setting the optical path. [0092] Further, in the optical communication network according to the present invention, since it is possible to avoid the failure of the optical path setting, it is not necessary to retry the setting in a different route, and the optical path setting time or the detour optical path when a failure occurs. The non-conduction time until is set can be shortened. [0093] Further, in the optical communication network according to the present invention, it is possible to select a route that is looped at the area level but not at the device level, and to find a more complicated relay route in consideration of the limitation of connectivity inside the area. It is possible to realize more advanced route calculation. [0094] [Effect of the invention] As described above, the present invention is in a communication network that provides a service that dynamically sets and opens a path, which is composed of a plurality of regions in which a plurality of node devices that execute a cross-connect function of each path are interconnected. , A connectivity management table that describes the connectivity between node devices inside the area, and a relay path management table that describes the area related to the relay path to the destination device of the path and the edge device connected to the device outside the area. And a control channel for notifying the relay route management table to the adjacent region are arranged in each of the plurality of regions, and under the route selection rule set to calculate the relay route to the destination device of the path. By updating and maintaining the relay route management table from the connectivity management table and the relay route management table announced from the adjacent area, a communication network that does not fail to set the optical path inside each area is realized. The effect of being able to do is obtained. [Simple explanation of drawings] FIG. 1 is a block diagram showing a configuration of an optical communication network according to an embodiment of the present invention. FIG. 2 is a block diagram showing a detailed configuration of the optical XC device 44 shown in FIG. FIG. 3 is a diagram showing a configuration example of an adjacent area management table for area # 4 stored in the optical XC apparatus shown in FIG. FIG. 4 is a diagram showing an example of a connectivity management table in region # 1 of FIG. FIG. 5 is a diagram showing an example of a connectivity management table in area # 2 of FIG. FIG. 6 is a diagram showing an example of a connectivity management table in region # 3 of FIG. FIG. 7 is a diagram showing an example of a connectivity management table in region # 4 of FIG. FIG. 8 is a diagram showing an example of a relay route management table of area # 4 after the announcement (1) of the relay route management table of FIG. FIG. 9 is a diagram showing an example of a relay route management table of area # 2 after the announcement (1) of the relay route management table of FIG. FIG. 10 is a diagram showing an example of a relay route management table in area # 3 after the announcement (1) of the relay route management table in FIG. FIG. 11 is a diagram showing an example of a relay route management table of area # 2 after the announcement (2) of the relay route management table of FIG. FIG. 12 is a diagram showing an example of a relay route management table of area # 1 after the announcement (3) of the relay route management table of FIG. FIG. 13 is a flowchart showing a flow of a process of creating a relay route management table according to an embodiment of the present invention. FIG. 14 is a block diagram showing a configuration of an optical communication network according to another embodiment of the present invention. FIG. 15 is a diagram showing an example of a relay route management table of area # 3 after the announcement (1) of the relay route management table of FIG. FIG. 16 is a diagram showing an example of a relay route management table of area # 2 after the announcement (1) of the relay route management table of FIG. FIG. 17 is a diagram showing an example of a relay route management table of area # 4 after the announcement (1) of the relay route management table of FIG. FIG. 18 is a diagram showing an example of a relay route management table of area # 3 after the announcement (2) of the relay route management table of FIG. FIG. 19 is a diagram showing an example of a relay route management table of area # 2 after the announcement (3) of the relay route management table of FIG. FIG. 20 is a diagram showing an example of a relay route management table of area # 1 after the announcement (4) of the relay route management table of FIG. FIG. 21 is a flowchart showing a flow of a process of creating a relay route management table according to another embodiment of the present invention. FIG. 22 is a block diagram showing a configuration of an optical communication network according to a conventional example. FIG. 23 is a diagram showing an example of a relay route management table of region # 1 in FIG. 22. FIG. 24 is a diagram showing an example of a relay route management table in region # 2 of FIG. FIG. 25 is a diagram showing an example of a relay route management table in region # 3 of FIG. 22. FIG. 26 is a diagram showing an example of a relay route management table in region # 4 of FIG. 22. [Explanation of symbols] 1 Optical communication network 11 ~ 14,21 ~ 24, 31 ~ 34,41 ~ 44 Optical XC device 51,61,62,71, 72 Client device 441 ~ 444 Input interface 445 4x4 optical switch 446 ~ 449 Output interface 450 switch control unit 451 Control message processing unit 452 Routing protocol processing unit 453 Adjacent area management table 454 Connectivity management table 455 Relay route management table