JP2016082529A - Node and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a node capable of collecting the information, required for establishment of protection upon occurrence of a failure.SOLUTION: A node is constituted to include communication means 1, information collection means 2, and information generation means 3. The communication means 1 performs communication of wavelength multiplexed optical signals with other node, via a plurality of routes. The information collection means 2 collects the information of wavelength and routes used for communication by other node, as the first protection information from other node. The information generation means 3 generates the information about the communication path for each wavelength of the optical signal and each optical signal, as the second protection information, based on the information of wavelength and routes used by own device for communication with other node, and the first protection information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication system, and more particularly, to a technique for improving communication reliability.

  With the development of the information and communication society, the importance of optical communication networks capable of high-capacity high-speed communication is increasing. In an optical communication network, WDM (Wavelength Division Multiplexing) communication that multiplexes and transmits optical signals of a plurality of wavelengths may be performed to increase capacity. Also, due to the increasing importance, optical communication networks are required to have high reliability capable of continuous communication without stopping.

  In order to continue communication when a failure occurs, for example, a method of making each communication device or transmission path redundant is used. By making it redundant, it is possible to suppress the time during which communication is stopped by switching to the standby system when a failure occurs in the active system. However, if the transponders that perform transmission / reception of optical signals of respective wavelengths and the transmission paths are made redundant, the entire system becomes larger. For this reason, an optical communication network using a CDC (Colorless Directionless Contentionless) function capable of flexibly changing a wavelength and a route when a failure occurs using a wavelength tunable transponder may be used.

  By configuring an optical communication network using the CDC function, it is possible to change the wavelength setting of an optical signal when a failure occurs, and to flexibly set an alternative communication path. Such an operation of changing an optical signal wavelength setting or the like and establishing an alternative communication path when a failure occurs is called protection. If switching to an alternative communication path in an optical communication network using the CDC function, that is, route protection, can be performed quickly, the time for which communication is stopped can be suppressed even when a failure occurs. Against this background, technological development relating to optical communication networks using the CDC function has been actively conducted. As a technique related to the optical communication network using the CDC function, for example, a technique as disclosed in Patent Document 1 is disclosed.

  Patent Document 1 relates to an optical communication system having a CDC function. The optical communication system of Patent Document 1 is configured by R-OADM (Reconfigurable Optical Add / Drop Multiplexing) that can change the wavelength of an optical signal and reconstruct a path. In addition, the optical communication system disclosed in Patent Document 1 uses an NMS (Network Management System) that monitors the entire network to manage changes in the wavelength of the optical signal of each device. In the optical communication system of Patent Document 1, such a configuration may enable communication to be continued by resetting the wavelength and path of the optical signal even when an abnormality occurs in the communication path. It is said.

  Further, Patent Document 2 discloses an optical communication system including an active system and a standby system transmission path and a network monitoring system. In the optical communication system of Patent Document 2, a predetermined optical signal is monitored by a network monitoring system. In the optical communication system of Patent Document 2, when a predetermined optical signal is monitored and a failure is detected, an alternative communication path and wavelength for performing communication of the predetermined optical signal by the network monitoring system are determined. Further, in the optical communication system of Patent Document 2, an alternative communication path or the like of another optical signal is set using information on a predetermined optical signal. Japanese Patent Laid-Open No. 2004-26883 discloses that it is not necessary to monitor all optical signals by adopting such a configuration, and the network monitoring system can be simplified.

JP 2012-248958 A JP 2002-325054 A

  However, the technique of Patent Document 1 is not sufficient in the following points. In the optical communication system of Patent Document 1, an NMS that monitors the entire network monitors whether or not a failure has occurred, and when a failure occurs, the NMS determines an alternative path and wavelength setting. Each node performs wavelength setting and path switching based on the determination of the NMS. Therefore, in Patent Document 1, an NMS having an advanced function capable of establishing an alternative communication when a failure occurs while monitoring the entire network is required. If an NMS having such advanced functions is used, the system can be large and complex. In addition, if an NMS substitute path or wavelength setting is determined, it may take time to restore communication. Therefore, the technique of Patent Document 1 is not sufficient as a technique used in an optical communication system that requires continuous communication.

  In the optical communication system of Patent Document 2, the setting of communication paths for optical signals other than the predetermined optical signal is set using information on the predetermined optical signal. Therefore, the optical communication system of Patent Document 2 requires a function for monitoring a predetermined optical signal in the entire communication system and determining the communication path and wavelength setting of the optical signal. However, in an optical communication system using the CDC function, since each optical signal is added or dropped at each node on the network, one optical signal hardly covers the entire network. In the optical communication system of Patent Document 2, when there is a transmission path in which a predetermined optical signal is not communicated and a monitoring system is not established in advance, it is difficult to set an alternative communication path for another optical signal. There is a possibility. Therefore, Patent Document 2 is not sufficient as a technique for use in an optical communication system that requires high reliability such as continuous communication when a failure occurs in an optical communication system using the CDC function. Absent.

  An object of the present invention is to obtain a node capable of collecting information necessary for establishing protection when a failure occurs without requiring a complicated system.

  In order to solve the above problems, the node of the present invention includes a communication unit, an information collection unit, and an information generation unit. The communication means performs communication of wavelength-multiplexed optical signals with other nodes via a plurality of routes. The information collecting means collects the wavelength and route information used by other nodes for communication as the first protection information from the other nodes. The information generation unit is configured to determine the wavelength of the optical signal and the communication path for each optical signal based on the information on the wavelength and route of the optical signal used by the own device for communication with other nodes and the first protection information. Is generated as the second protection information.

  The communication method of the present invention performs communication of wavelength-multiplexed optical signals with other nodes via a plurality of routes, and information on wavelengths and routes used by other nodes for communication. Collect as first protection information from the node. Further, the communication method of the present invention is based on the information on the wavelength and route of the optical signal used by the own device for communication with other nodes and the first protection information, and the wavelength of the optical signal and the optical signal. Information on each communication path is generated as second protection information.

  According to the present invention, it is possible to collect information necessary for establishing protection when a failure occurs without requiring a complicated system.

It is a figure which shows the outline | summary of a structure of the 1st Embodiment of this invention. It is a figure which shows the outline | summary of a structure of the 2nd Embodiment of this invention. It is a figure which shows the outline | summary of a structure of the apparatus of the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the outline | summary of the operation | movement flow in the 2nd Embodiment of this invention. It is a figure which shows the example of the network structure in the 2nd Embodiment of this invention. It is a figure which shows the example of the location where the failure generate | occur | produced in the communication system of the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the data table in the 2nd Embodiment of this invention. It is a figure which shows the example of the network structure after addressing a failure in the 2nd Embodiment of this invention. It is a figure which shows the example of the communication system of the structure contrasted with this invention.

(First embodiment)
A first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an outline of the configuration of a node according to this embodiment. The node of this embodiment includes a communication unit 1, an information collection unit 2, and an information generation unit 3. The communication means 1 performs wavelength-multiplexed optical signal communication with other nodes via a plurality of routes. The information collecting unit 2 collects information on wavelengths and routes used by other nodes for communication as first protection information from other nodes. The information generation means 3 communicates the wavelength of the optical signal and the communication for each optical signal based on the information on the wavelength and route of the optical signal used by the own device for communication with other nodes and the first protection information. Information about the route is generated as second protection information.

  In the node according to the present embodiment, the information collecting unit 2 collects information on the wavelength and route used for communication from other nodes that are performing communication of wavelength-multiplexed optical signals as first protection information. ing. Further, the information generating means 3 is based on the information on the wavelength and route of the optical signal used by the device itself for communication and the information on the communication path for each optical signal based on the first protection information. Is generated as the second protection information. Since the node device according to the present embodiment can generate information on the wavelength of the optical signal and the communication path by itself, it is not necessary to obtain the information from a network management system or the like. Therefore, the node according to the present embodiment can collect information necessary for establishing protection when a failure occurs without requiring a complicated system. As a result, the node of this embodiment can autonomously establish protection when a failure occurs without requiring a complicated system.

(Second Embodiment)
A second embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 shows an outline of the configuration of the communication system of the present embodiment. The communication system according to this embodiment includes a first node 11, a second node 12, a third node 13, and a fourth node 14. The communication system according to the present embodiment is configured as a network having a ring configuration in which each node is connected via an optical communication line. In addition, the communication system of the present embodiment is configured as a transmission network that performs optical signal communication of a WDM (Wavelength Division Multiplexing) method. Each node constituting the network corresponds to a CDC (Colorless Directionless Contentionless) function.

  The communication system of the present embodiment has a function of performing route protection for performing communication using an alternative route when a failure occurs. Further, when communication is performed using an alternative route, if the wavelength of the optical signal is the same as the wavelength of another optical signal, the wavelength assigned to the optical signal is changed. In the communication system of the present embodiment, the nodes constituting the network autonomously perform route protection when a failure occurs and resetting of the wavelength of the optical signal.

  The first node 11 and the third node 13, the third node 13 and the second node 12, the second node 12 and the fourth node 14, and the fourth node 14 and the first node 11 are Are connected via a communication line using optical fibers. In addition, communication lines are provided between the nodes so that bidirectional communication is possible. The communication system of this embodiment is configured using four nodes, but the number of nodes may be four or more, or may be three or less. Further, another communication device such as a relay device or a node may be further provided between the nodes. The communication system according to the present embodiment includes an NE-OpS (Network Element Operation System) that monitors whether there is a failure on the network or the like as a network management system. When the NE-OpS detects an abnormality on the network, it sends information indicating that the abnormality has been detected to each node.

  In the communication system of this embodiment, when viewed from the first node 11, the transmission path on the third node 13 side is the route 1, and the transmission path on the fourth node 14 side is the route 2. . Further, the transmission path on the second node 12 side when viewed from the third node 13 is defined as a route 1, and the transmission path on the first node 11 side is defined as a route 2. Similarly, the transmission path on the fourth node 14 side when viewed from the second node 12 is defined as a route 1, and the transmission path on the third node 13 side is defined as a path 2. Similarly, the transmission path on the first node 11 side when viewed from the fourth node 14 is defined as a route 1, and the transmission path on the second node 12 side is defined as a route 2.

  A configuration of a node of the communication system according to the present embodiment will be described. FIG. 3 shows the outline of the configuration of each node of this embodiment, that is, the first node 11, the second node 12, the third node 13, and the fourth node 14 as a node 20.

  The node 20 of the present embodiment includes a control unit 21, a protection control unit 22, a transponder unit 23, an optical switch unit 24, a protection information insertion unit 25, a monitor unit 26, a protection information insertion unit 27, and a monitor. A portion 28 is provided. The communication device 20 according to the present embodiment further includes a multiplexing unit 31, a demultiplexing unit 32, a multiplexing unit 33, and a demultiplexing unit 34. The protection control unit 22 further includes a protection management information storage unit 29.

  The control unit 21 has a function of performing overall control of the communication device 20. The node 20 receives information on the failure from the network management system or the like, and controls other parts of the node 20. When the node 20 detects the failure information of the transmission path, the node 20 sends the information on the location where the failure has occurred to the protection control unit 22 as the control signal S11. In addition, the control unit 21 controls each part by sending information such as initial settings to the protection control unit 22. The control unit 21 can also be configured by software, that is, a computer program and a semiconductor device that executes the computer program. Further, the control unit 21 may be configured to perform information transmission and alarm processing at the time of failure occurrence and recovery.

  The protection control unit 22 has a function of performing control related to wavelength and route protection. The protection control unit 22 has a function of generating and storing information necessary for transmission destinations, paths, wavelength assignments, and other communications of each signal as protection information. The protection control unit 22 stores the generated protection information in the protection management information storage unit 29. The protection control unit 22 performs control related to wavelength and route protection based on the protection information stored in the protection management information storage unit 29. The protection information refers to information necessary for construction of an alternative path when a failure occurs in communication of an optical signal such as a transmission destination node of the optical signal and a wavelength used in the optical signal. Examples of protection information generated by each node according to the present embodiment are shown in FIGS. 4, 5, 6, and 7.

  FIG. 4 shows the protection information generated by the first node 11. As shown in FIG. 4, the protection information is composed of transmission node information, main signal wavelength number information, used wavelength band, failure information, route protection information, XC information, and adjacent node information. The transmission node information is composed of information on the node name of the own device and the identifier of the route corresponding to the connected transmission path. The main signal wavelength number information indicates information on the number of wavelengths of the main signal transmitted and received by each node. The used wavelength band indicates the wavelength band of each main signal and the presence / absence of use for each wavelength band. In the present embodiment, the wavelength band used for the main signal is recorded as “◯”. The failure information is recorded on the presence or absence of a failure in the corresponding route. If a failure has occurred in the corresponding route, it is recorded as “◯”.

  In the route protection information, presence / absence of a request for execution of route protection is indicated as an item “request”, and information on whether or not execution has been executed is indicated as “execution presence / absence”. When there is a request and execution of route protection, information indicating that there is a request or execution is recorded as “◯”. The XC information indicates information on the optical signal path in the cross-connect function of the switch unit 24. From indicates the input side to the cross-connect function unit, and To indicates the output side from the cross-connect unit. For example, when From is TPND and To is route 1, it indicates that the optical signal input from the transponder unit 24 is output to the route to route 1. The adjacent node information indicates information on the node name of the adjacent node and the identifier of the route connected to the node. The XC information in FIG. 4 shows information in the case of transmitting an optical signal from the first node 11 to the third node 13 and the fourth node 14 side. In the present embodiment, the transmission of the optical signal from the third node 13 and the fourth node 14 to the first node 11 is performed by the same wavelength setting as the setting when transmitting from the first node 11 side. Is called. When different wavelength settings are used for transmission and reception, protection information is set for each.

  FIG. 5 similarly shows protection information generated by the second node 12. FIG. 6 shows protection information generated by the third node 13, and FIG. 7 shows protection information generated by the fourth node 14. The information indicated by each item in FIGS. 5, 6 and 7 is the same as that of the first node 11 in FIG.

  FIG. 8 shows an example of a protection information management table generated by the first node 11 based on the protection information received from other nodes. The information indicated by each item in the protection information management table in FIG. 8 is the same as the item of protection information generated by each node. The first node 11 receives the protection information shown in FIGS. 5, 6, and 7 from each node, and generates a protection information management table together with the protection information generated by the own device.

  The protection control unit 22 sends information on the wavelength of the optical signal generated by the transponder unit 23 to the transponder unit 23 as a transponder unit control signal S12 based on the protection information management table. Further, the protection control unit 22 sends a signal instructing switching of the optical switch unit 24 to the optical switch unit 24 as a switch unit control signal S13 based on the protection information management table. The protection control unit 22 corresponds to the information collection unit 2 and the information generation unit 3 of the first embodiment.

  The transponder unit 23 has a function of transmitting and receiving optical signals. The transponder unit 23 generates an optical signal for transmission based on a signal input from the outside, and outputs the optical signal to the optical switch unit 24 as an optical signal S14 for transmission. The wavelength of the optical signal generated by the transtransponder unit 23 is variable and is set based on the transponder unit control signal S12 sent from the protection control unit 22. The transponder unit 23 receives the optical signal transmitted as the received optical signal S15 from the optical switch unit 24, converts it into a signal of a predetermined format, and outputs it.

  The optical switch unit 24 has a cross-connect function for outputting each input optical signal to a predetermined path. The optical switch unit 24 includes a demultiplexing element, a switch element, and a multiplexing element. The optical switch unit 24 separates the input optical signal into optical signals of each wavelength by the demultiplexing element, switches the path for each optical signal of each wavelength by the switch element, multiplexes the multiplexed signals by the multiplexing element, and outputs them. That is, the optical switch unit 24 outputs an optical signal of each wavelength addressed to another node input from the transmission path to a transmission path of a predetermined path. Further, the optical switch unit 24 branches and drops an optical signal having a predetermined wavelength addressed to itself from the optical signal input from the transmission path, and sends the optical signal to the transponder unit 23 as a received optical signal S15. The optical switch unit 24 adds the optical signal transmitted as the transmission optical signal S14 from the transponder unit 23, and outputs the optical signal to a predetermined transmission path.

  For example, an arrayed waveguide diffraction grating can be used for the demultiplexing element and the multiplexing element of the optical switch unit 24. In addition, as the switch element, for example, an optical switch element by MEMS (Micro Electro Mechanical Systems) can be used. The optical switch unit 24 switches the switch based on the switch unit control signal S13 sent from the protection control unit 22 and sets the path of the optical signal. The transponder unit 23 and the optical switch unit 24 correspond to the communication unit 1 of the first embodiment.

  The protection information insertion unit 25 has a function of outputting an optical signal indicating protection information to the transmission path of a predetermined path via the multiplexing unit 31. The protection information insertion unit 25 generates an optical signal for sending protection information to another node based on the transmission information signal S16 sent from the protection control unit 22. The protection information insertion unit 25 outputs the generated optical signal to the multiplexing unit 31 as the transmission information optical signal S20. The protection information insertion unit 25 generates an optical signal in a wavelength band that is not used in the main signal. The wavelength of the optical signal for sending the protection information is set in advance according to the design of the communication system.

  The monitor unit 26 has a function of receiving protection information sent from other nodes included in the received signal S2 and sending it to the protection control unit 22. The monitor unit 26 receives the reception signal S2 including the protection information branched from the transmission path by the demultiplexing unit 32, converts the received signal S2 into an electric signal of a predetermined format, and sends it to the protection control unit 22. The monitor unit 26 separates and receives an optical signal having a predetermined wavelength assigned to an optical signal indicating protection information among the input optical signals. Separation of the optical signal indicating the protection information can be performed, for example, by providing a prism in front of the light receiving element so as to separate each wavelength and inputting an optical signal having a predetermined wavelength to the light receiving element. The monitor unit 26 decodes the received signal to extract protection information, and sends the extracted protection information to the protection control unit 22 as a reception information signal S18.

  The protection information insertion unit 27 has the same function as the protection information insertion unit 25. The protection information insertion unit 27 receives the protection information from the protection control unit 22 as a transmission information signal S17. The protection information insertion unit 27 generates an optical signal based on the transmission information signal S17 and sends the optical signal to the multiplexing unit 32 as the transmission information optical signal S21. The optical signals generated by the protection information insertion unit 25 and the protection information insertion unit 27 can be transmitted at a lower transmission rate than the main signal generated by the transponder unit 23. By reducing the transmission rate of the optical signal for transmitting the protection information, it is possible to transmit the protection information between the nodes even when nodes having different transmission rates corresponding to the communication network coexist.

  The monitor unit 28 has the same function as the monitor unit 26. The monitor unit 28 receives the received signal S4 including the protection information input from the transmission path and branched by the demultiplexing unit 34, separates the optical signal of a predetermined wavelength, converts it into an electrical signal, decodes it, and protects it. Extract information. The monitor unit 28 sends the extracted protection information to the protection control unit 22 as a reception information signal S19.

  The protection management information storage unit 29 has a function of storing a protection information management table generated based on the protection information generated by the own device and the protection information received from another node.

  The multiplexing unit 31 multiplexes the transmission signal S1 sent from the optical switch unit 24 and the transmission information optical signal S20 sent from the protection information insertion unit 25, and transmits it to the route 1 as the transmission signal S5. To do. Further, the multiplexing unit 33 multiplexes the transmission signal S3 sent from the optical switch unit 24 and the transmission information optical signal S21 sent from the protection information insertion unit 27, and outputs the route 2 as the transmission signal S6. Send to. For the multiplexing unit 31 and the multiplexing unit 33, for example, an optical coupler can be used.

  The demultiplexing unit 32 and the demultiplexing unit 34 respectively branch the optical signal transmitted from the transmission path of the route 1 and the route 2, that is, a part of the reception signal S2 or the reception signal S4. Or it has the function to send to the monitor part 28, respectively. In the present embodiment, the optical signals branched by the demultiplexing unit 32 and the demultiplexing unit 34 include optical signals of all wavelengths. For example, an optical coupler can be used for the demultiplexing unit 32 and the demultiplexing unit 34. In the demultiplexing unit 32 and demultiplexing unit 34, only an optical signal having a predetermined wavelength including protection information may be branched and sent to the monitor unit 26 or the monitor unit 28, respectively.

The operation of the communication system of this embodiment will be described. In the communication system of this embodiment, during normal times, optical signals are transmitted and received between nodes based on the wavelength and path set according to protection information or initial settings. In normal times, the protection information is generated at a predetermined timing. The predetermined timing is set, for example, as a change in the network configuration or during maintenance every predetermined period. First, the operation when each node sends protection information generated by itself to other nodes will be described. In the following, when the third node 13 sends the protection information generated by the own device to the first node 11 as an example, each node sends the protection information generated by the own device to the other nodes. The operation of will be described. When the third node 13 sends the protection information to the first node 11, the protection information of the third node 13 is also sent to the second node 12 adjacent to the other route in the same way. When the protection information is generated, the control unit 22 sends the generated protection information to the protection information insertion unit 27 as a transmission information signal S17. Further, when there is protection information received from another node, the protection control unit 22 adds the protection information of the other node to the node of the own device and sends it. When the protection information is received as the transmission information signal S17, the protection information insertion unit 27 generates an optical signal based on the received information. When the protection information insertion unit 27 generates the optical signal, the protection information insertion unit 27 sends the generated optical signal to the multiplexing unit 33 as the transmission information optical signal S21.

  When receiving the transmission information optical signal S21 from the protection information insertion unit 27, the multiplexing unit 33 multiplexes the transmission information optical signal S3 transmitted from the optical switch unit 24 and outputs it to the transmission line as a transmission signal S6. The transmission signal S6 output to the transmission path is sent to the first node 11 and input to the first node 11 as the reception signal S2.

  When an optical signal is input to the first node 11 as the received signal S2, a part is branched by the demultiplexing unit 32 and sent to the monitor unit 26. The monitor unit 26 separates and extracts an optical signal having a predetermined wavelength, and converts the extracted optical signal into an electrical signal. The monitor unit 28 decodes the electrical signal converted from the optical signal, and sends the decoded signal to the protection control unit 22 as a reception information signal S18. When receiving the reception information signal S18, the protection control unit 22 saves the protection information of the third node 13 included in the received signal. Further, the protection control unit 22 updates the protection information management table stored in the protection management information storage unit 29 based on the protection information of the third node 13. The protection control unit 22 compares the received information with the stored information, and if there is a difference, updates the information regarding the nodes other than the third node 13 based on the information received from the third node 13. . The protection information management table generated at this time is, for example, a data table as shown in FIG. The protection information sharing operation between the nodes is thus completed.

  Next, an operation when a failure occurs in any part of the communication system and communication is performed on a new route will be described. FIG. 9 shows an outline of an operation flow when an alternative transmission path is configured and route protection is performed when a failure occurs in the communication system of the present embodiment.

  When a failure occurs on the transmission path of the communication system, the control unit 21 of the node 20 detects that a failure has occurred. For example, the control unit 21 determines that a failure has occurred when it is detected that optical signal communication with another node is not possible. When it is detected that a failure has occurred, the control unit 21 sends information on the route in which the failure has occurred to the protection control unit 22 as a control signal S11. When receiving the control signal S11 indicating that a failure has occurred, the protection control unit 22 starts an operation for performing route protection.

  When the protection control unit 22 receives information indicating that a failure has occurred as the control signal S11, the protection control unit 22 confirms information of a signal that is performing communication via the location where the failure has occurred. When a route in which an abnormality has occurred in communication with another node is not used (No in step 101), the protection control unit 22 determines that an alternative route is established, that is, route protection is unnecessary. If it is determined that it is not necessary to establish an alternative route, the protection control unit 22 ends the operation related to the failure handling.

  When a path in which an abnormality has occurred in communication with another node is used (Yes in step 101), the protection control unit 22 sets an alternative path, that is, a wavelength of a signal that requires path protection. Check the route information. Upon confirming the setting of the alternative route, that is, the information related to the signal that requires the route protection, the protection control unit 22 extracts the information of the route that can construct the alternative route (step 102).

  When the information of candidate routes that can construct an alternative route is extracted, the protection control unit 22 confirms whether the wavelength used so far, that is, the currently set wavelength can be used for communication with the adjacent node of the alternative route. . If the currently set wavelength cannot be used because it is already used (No in step 103), the protection control unit 22 substitutes an unused wavelength as a temporary wavelength with an adjacent node on the candidate path. Assignment to a signal for communication on the route is performed (step 104).

  If an unused wavelength is assigned temporarily, the protection control unit 22 determines whether or not to transmit a signal also on a route after the next node. When all the signals are dropped at the next node and communication through the subsequent path is not performed (No in step 105), the protection control unit 22 determines that the temporarily assigned wavelength can be used in the alternative path. To do. When the protection control unit 22 determines that the assigned wavelength can be used, the protection control unit 22 determines the assigned wavelength as a wavelength used for communication on the alternative route. When all the assignments of the wavelengths to the signals that need to be set as alternative paths are completed, the protection control unit 22 updates the protection information and the protection information management table. When the protection information or the like is updated, the protection control unit 22 starts communication control based on the assigned signal (step 109). In addition, the protection control unit 22 transmits protection information based on information on the newly set wavelength to the adjacent node.

  Further, when signal communication is performed after the next node (Yes in Step 105), the protection control unit 22 determines whether or not the assigned wavelength can be used in the next transmission path. If it is possible on the next transmission path (Yes in step 106), the protection control unit 22 determines whether the signal is further used in the subsequent nodes in the temporarily assigned state.

  When communication is not performed after the next node (No in Step 108), the protection control unit 22 determines the temporarily assigned wavelength as a wavelength to be assigned to a signal for performing route protection. When the wavelength to be allocated is determined, the protection control unit 22 sets protection information based on the determined wavelength, and starts a communication control operation using the set wavelength (step 109). In addition, the protection control unit 22 transmits protection information based on information on the newly set wavelength to the adjacent node. When the adjacent node receives the protection information, the protection information management table is updated based on the received information.

  If the assigned wavelength is already used (No in step 106), the protection control unit 22 assigns again from an unused wavelength (step 107). When the allocation from the unused wavelength is performed again, the protection control unit 22 performs the operation from step 108 as confirmation of the path ahead from the adjacent node. That is, when the wavelength assignment is performed again, the protection control unit 22 redoes the determination of whether or not the wavelength can be used from the first node.

  When the currently set wavelength can be used in step 103 (Yes in step 103), the protection control unit 22 regards the currently set wavelength as equivalent to the wavelength to be temporarily assigned, and performs the operations in and after step 105. As described above, when an abnormality occurs on the transmission path of the communication system according to the present embodiment, communication in the alternative path, that is, the operation when setting the wavelength of the optical signal and the communication path for establishing the path protection is performed. It is explanation of.

  An operation when a failure occurs and route protection is performed in the communication system of the present embodiment will be described more specifically. A case where communication as shown in FIG. 10 is performed in the communication system of this embodiment will be described as an example. In FIG. 10, the first node 11 is indicated as Node (1), the second node 12 is indicated as Node (2), the third node 13 is indicated as Node (3), and the fourth node 14 is indicated as Node (4). Has been.

  In the example of FIG. 10, the optical signal having the wavelength λ <b> 1 is between the first node 11 and the third node 13 and between the first node 11 and the second node 12 via the fourth node 14. Used in communications. Similarly, the optical signal having the wavelength λ <b> 2 is used in communication between the first node 11 and the second node 12 via the third node 13. The optical signal having the wavelength λ3 is used in communication between the third node 13 and the second node 12. The optical signal having the wavelength λ4 is used for communication between the first node 11 and the fourth node 14. The optical signal having the wavelength λ5 is used for communication between the fourth node 14 and the second node 12. Each optical signal is added at a node at one end and dropped at a node at the other end.

  In a communication system in which communication as shown in FIG. 10 is normally performed, as shown in FIG. 11, an example in which a failure occurs in the transmission path between the first node 11 and the third node 13 is shown. Next, the operation when performing route protection will be described. As shown in FIG. 11, when a failure occurs in the transmission path between the first node 11 and the third node 13, the first node 11 transmits and receives via the transmission path of the route 1. Communication of optical signals having the wavelengths λ1 and λ2 that has been performed cannot be performed. In addition, the third node 13 cannot communicate the optical signal having the wavelength λ1 that has been transmitted / received via the transmission path of the route 2 and the wavelength λ2 that has passed through the own device.

  When a failure is detected, the protection control unit 22 extracts information on an optical signal that needs to secure an alternative route. The protection control unit 22 determines that it is necessary to secure an alternative route to the third node 13 for the optical signal having the wavelength λ1. In addition, the protection control unit 22 determines that it is necessary to secure an alternative path to the second node 12 for the optical signal having the wavelength λ2.

  Since a failure has occurred in the transmission path on the path 1 side, the protection control unit 22 starts the path protection and wavelength switching processing of the optical signal using the transmission path on the path 2 side.

  The protection control unit 22 refers to the wavelength setting of the route 2 in the protection management table, and confirms whether λ1 and λ2 used in the route 1 are used. In order to give priority to the transfer with the wavelength used in the route 1, the protection control unit 22 first determines whether communication is possible on the route 2 side with the wavelength used in the route 1.

  Since λ1 is already used on the path 2 side of the first node 11, the protection control unit 22 determines that it is necessary to select another wavelength. Since λ2 is not used with the fourth node 14 on the route 2 side, the protection control unit 22 temporarily sets λ2.

  Since it is necessary to select another wavelength for the wavelength λ1, the protection control unit 22 investigates the wavelength that is not used. Since λ3 is vacant on the path 2 side of the first node 11, the protection control unit 22 temporarily sets the wavelength λ3 as an alternative candidate for the wavelength λ1.

  After the provisional setting of the wavelength used with the fourth node 14 is completed, the protection control unit 22 can communicate with the wavelength that has been provisionally set between the fourth node 14 and the second node 12. Start investigating whether there is.

  The protection control unit 22 refers to the protection management table to check whether the temporarily set wavelength λ2 and wavelength λ3 are used between the fourth node 14 and the second node 12. Since the wavelength λ2 and the wavelength λ3 are not used between the fourth node 14 and the second node 12, the protection control unit 22 temporarily sets the wavelength between the fourth node 14 and the second node 12. Judge that no change is required.

  Next, the protection control unit 22 performs confirmation between the second node 12 and the third node 13. At this time, since the wavelength λ2 is dropped at the second node 12, the protection control unit 22 determines that it is not necessary to check whether or not the wavelength λ2 is used between the second node 12 and the third node 13. To do. The protection control unit 22 confirms whether the wavelength λ3 is used between the second node 12 and the third node 13.

  Since the wavelength λ3 is already used between the second node 12 and the third node 13, the protection control unit 22 determines that the wavelength λ3 cannot be used. Since the wavelength λ3 cannot be used, the protection control unit 22 selects another wavelength as a wavelength to be temporarily allocated. Since the wavelength λ5 is not used between the first node 11 and the fourth node 14, the protection control unit 22 temporarily sets the wavelength λ5.

  When the wavelength λ5 is temporarily set, the protection control unit 22 checks whether the wavelength λ5 is used between the fourth node 14 and the second node 12. Since the wavelength λ5 is already used between the fourth node 14 and the second node 12, the protection control unit 22 determines that the wavelength λ5 cannot be used.

  Further, the protection control unit 22 confirms the usage status between the first node 11 and the fourth node 14 and selects the wavelength λ6 as the temporarily set wavelength. If the wavelength λ6 is selected as the wavelength to be allocated, the protection control unit 22 confirms whether or not the wavelength λ6 is used between the fourth node 14 and the second node 12. Since the wavelength λ6 is not used between the fourth node 14 and the second node 12, the protection control unit 22 determines whether the wavelength λ6 is used between the second node 12 and the third node 13. Confirm. Since the wavelength λ6 is not used between the second node 12 and the third node 13, the protection control unit 22 determines that the wavelength 6 can be used. Further, the protection control unit 22 determines that the confirmation in the further path is unnecessary because the optical signal temporarily set at the wavelength λ6 is the optical signal dropped at the third node 13. As described above, since the wavelength to be assigned to the signal that needs to be set for the alternative path is determined, the protection control unit 22 starts the update operation of the protection information management table based on the determined path and wavelength information.

  FIG. 12, FIG. 13, FIG. 14 and FIG. 15 show the protection information generated by the first node 11, the second node 12, the third node 13, and the fourth node 14, respectively, when the above operation is performed. This is an example. FIG. 16 shows an example of the protection management table generated by the first node 11 based on the protection information generated by each node. When all the alternative wavelengths have been determined, the protection control unit 22 refers to the protection information management table and starts a setting operation for performing communication at the newly set wavelength.

  The protection control unit 22 of the first node 11 controls the transponder unit 23 and the optical switch unit 24 to transmit a signal indicating that the optical signal of the wavelength λ1 is changed to the wavelength λ6 and output to the path 2 side. It sends as signal S12 and switch part control signal S13. In addition, the protection control unit 22 of the first node 11 sends a signal indicating a change in setting for outputting the optical signal having the wavelength λ2 to the transponder unit 23 and the optical switch unit 24, and the transponder unit control signal S12. And it sends as switch part control signal S13. When the transponder unit control signal S12 is received as a signal indicating the setting change, the transponder unit 23 changes the wavelength of the optical signal output at the wavelength λ1 to the wavelength λ6 when receiving the switch unit control signal S13. The optical switch unit 24 switches the switch so that an optical signal having a wavelength λ6 is output to the path 2 side. The optical switch unit 24 further switches the switch so that an optical signal having a wavelength λ2 is output to the path 2 side.

  Next, the protection control unit 22 transmits the changed protection information to the fourth node 14. Similar to the first node 11, the fourth node 14 changes the wavelength and switches the switch.

  The fourth node 14 transmits the protection information to the second node 12 when the setting of the own device is completed. Similarly, the second node 12 changes the setting of its own device, and sends the protection information to the third node 13 when the setting change is completed. When the setting of the third node 13 is completed, the communication from the first node 11 to the third node 13 can be performed in place of the communication performed at the location where the failure has occurred.

  As described above, when the setting change is completed at each node, the route protection is completed, and communication on the alternative route is started. Further, even when multiple failures occur in the network, it is possible to secure an alternative communication path by checking the free bandwidth of the protection path and changing the wavelength setting by the same process.

  FIG. 17 shows the wavelength and path of each signal after the above route protection is completed. The communication performed with the optical signal having the wavelength λ1 between the first node 11 and the third node 13 is replaced with the communication performed with the optical signal having the wavelength λ6 via the fourth node 14 and the second node 12. Has been. In addition, the communication that has been performed with the optical signal having the wavelength λ2 between the first node 11 and the second node 12 via the third node 13 passes through the fourth node 14 without changing the wavelength. It is replaced by communication on the route.

  FIG. 18 shows an example in which the wavelength is not changed when the route is changed for comparison with the present embodiment. If communication of the optical signal having the wavelength λ1 is performed through the route via the fourth node 14 and the second node 12 without changing the wavelength, the communication is already performed between the first node 11 and the second node 12. There is a collision with the optical signal of the communication. Therefore, normal communication cannot be continued if only the path is changed without changing the wavelength setting. Therefore, as described above, it is possible to perform route protection without causing a collision with other signals by changing the wavelength.

  The node of the communication system according to the present embodiment receives protection information including information on the wavelength and route of the optical signal with which communication is performed from another node, and the protection management table together with information generated by the own device. Is generated. Thus, each node generates a protection management table based on the protection information, so that each node does not need to obtain information for determining the wavelength or route of the optical signal from the network management system or the like.

  Each node can set a route and a wavelength when performing communication autonomously using an alternative route based on the protection management table generated by the own device when a failure in the transmission line is detected. Therefore, the node of the communication system of the present embodiment can autonomously establish route protection without obtaining information from the network management system or the like when a failure occurs. As a result, the communication system of this embodiment can establish protection autonomously when a failure occurs without requiring a complicated system. Further, in the communication system of the present embodiment, each node can autonomously establish protection, so that protection can be executed even when multiple failures occur on the network. In addition, each node autonomously establishes protection, so that it is possible to reduce the time required to restore communication when a failure occurs, compared to the case where protection is established by judgment of the network management system etc. Become.

  In the communication system according to the second embodiment, each node generates the protection information management table. However, only some nodes may generate the protection information management table and share information with other nodes. . For example, one of a plurality of nodes constituting the ring network may generate a protection information management table, and the protection information management table may be transmitted and shared in the order of connection to the ring network. Further, a configuration may be adopted in which some nodes generate the protection information management table and individually transmit them to other nodes. By adopting such a configuration, it is possible to simplify the configuration of the apparatus because it is not necessary to provide a function for generating the protection information management table in all nodes.

  Alternatively, the nodes constituting the communication system may be divided into groups, and for each group, a predetermined node may collect protection information for each node in the group. In such a case, the protection information collected for each group may be further transmitted to a predetermined node or a dedicated management device, and a protection information management table may be generated. The generated protection information management table is sent to each node. With such a configuration, it is possible to achieve both the dispersion of processing and the simplification of the apparatus and the system.

  In the communication system according to the second embodiment, each node detects a failure. However, a predetermined node may perform failure detection and transmission. For example, a configuration may be adopted in which a node that detects a failure in an adjacent transmission path or node transmits information that the failure has occurred to another node. In addition, it is also possible to adopt a configuration in which a node that detects a failure generates information for generating a protection information management table and route protection, and transmits the generated information to other nodes together with the information that detects the failure. . By adopting such a configuration, it is possible to increase the rate of autonomous operation by the node and to simplify the network management system and the like.

DESCRIPTION OF SYMBOLS 1 Communication means 2 Information collection means 3 Information generation means 11 1st node 12 2nd node 13 3rd node 14 4th node 20 Node 21 Control part 22 Protection control part 23 Transponder part 24 Optical switch part 25 Protection information Insertion unit 26 Monitor unit 27 Protection information insertion unit 28 Monitor unit 29 Protection management information storage unit 31 Multiplexing unit 32 Demultiplexing unit 33 Multiplexing unit 34 Demultiplexing unit 101-109 Operation steps of communication system S1 Transmission signal S2 Reception signal S3 Transmission signal S4 Reception signal S5 Transmission signal S6 Transmission signal S11 Control signal S12 Transponder control signal S13 Switch control signal S14 Transmission optical signal S15 Reception optical signal S16 Transmission information signal S17 Transmission information signal S18 Reception information signal S1 Received information signal S20 transmitted information optical signal S21 transmitted information optical signal

Claims (10)

Communication means for performing wavelength multiplexed optical signal communication with other nodes via a plurality of routes;
Information collecting means for collecting, as the first protection information, information on the wavelength and route used by the other node for communication;
Based on the information on the wavelength and route of the optical signal used by the own device for communication with the other node and the first protection information, the wavelength of the optical signal and the communication path for each optical signal A node comprising: information generation means for generating information regarding the second protection information. An anomaly detection means for detecting information on anomalies in the route;
When the abnormality detecting unit detects any abnormality in the route, based on the second protection information, an alternative communication route using a route in which no failure has occurred and the alternative communication route The node according to claim 1, further comprising: path setting means for setting a wavelength used in the node.   The node according to claim 1, wherein the second protection information is transmitted to the other node.   The path setting means, when detecting the abnormality, determines whether or not the wavelength used before detecting the abnormality can be used in the alternative communication path, and selects another wavelength when it cannot be used. The node according to claim 2 or 3, characterized in that: A plurality of nodes according to any one of claims 1 to 4,
The communication system, wherein the second protection information generated by any one of the nodes is transmitted to the nodes other than the one generating the second protection information. Each of the nodes constitutes a ring network,
6. The second protection information generated by any one of the nodes is transmitted to another node in the order in which the second protection information is connected to the ring network via the ring network. Communications system. Communication of wavelength-multiplexed optical signals with other nodes via multiple paths,
Collecting wavelength and route information used by the other node for communication as first protection information from the other node;
Based on the information on the wavelength and route of the optical signal used by the own device for communication with the other node and the first protection information, the wavelength of the optical signal and the communication path for each optical signal The communication method characterized by generating the information regarding as 2nd protection information. Detecting information on anomalies in the route,
When any abnormality in the route is detected, based on the second protection information, an alternative communication path using a route in which no failure has occurred and a wavelength used in the alternative communication route The communication method according to claim 7, wherein the communication method is set.   The communication method according to claim 7, wherein the second protection information is transmitted to the other node.   When detecting the abnormality, it is determined whether or not the wavelength used before the abnormality is detected can be used in the alternative communication path, and another wavelength is selected when it cannot be used. The communication method according to claim 8 or 9.

Images