JP2005217973A - Optical communication system and optical node device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication system which prevents an occurrence of a resource conflict upon establishment processing of an optical path, and which improves a network usage efficiency by the prevention. <P>SOLUTION: In a link L shared by an optical path whose establishment is requested, wavelength resources are preliminarily restricted upon resource request processing by a path establishment request message. Namely, resources less than wavelength resources (namely, remaining wavelength resources) which actually can be used in the link L concerning the path establishment is notified (advertised) to a node device concerning the path establishment. Thus, a possibility of a resource conflict is reduced with a probability, and the network usage efficiency in the entire optical networks is enhanced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical communication system that routes an optical signal as it is based on its wavelength, and an optical node device used in this system.

  In order to efficiently accommodate traffic that continues to increase due to the spread of the Internet and the like, an optical communication system using an optical node device has attracted attention. In this type of system, a so-called cut-through technique that forms an optical path by switching optical signals in units of wavelengths at each node is a key technology. The optical path is set end-to-end between nodes.

  In this type of system, MPLS (Multi-Protocol Label Switching) standardized by IETF (Internet Engineering Task Force) is used in order to appropriately allocate resources in the system to requesters (for example, Non-Patent Document 1). See). In recent years, extended G-MPLS (Generalized MPLS) is often used. In addition, label distribution protocol (LDP) and RSVP (Resource Reservation Protocol) used for resource reservation are known. By interpreting “label” as “wavelength”, these protocols can be used for path setting processing in an optical communication system.

  In a system using the above protocol, when setting an optical path, a label request message is first sent from a transmission node (also referred to as an upstream node) to a reception node (also referred to as a downstream node). In response to this, a reservation message for declaring the assigned label is returned from the receiving node to the transmitting node. Through such a procedure, an optical path is set in the system.

  By the way, optical node devices are roughly classified into those having a function of converting the wavelength of an optical signal and those having no function. In an optical communication system formed by an optical node device having a wavelength conversion function, a downstream node can freely select a wavelength to be reported to an upstream node. Therefore, it is relatively easy to effectively use resources. However, since the mainstream of current wavelength conversion technology is an O / E / O type that converts an optical signal into an electrical signal, each node needs to have an optical transmission / reception device for each wavelength port. This impairs the transparency of the optical path and increases the system cost in order to increase the size of the node device. Therefore, in recent years, it has been studied to form an optical communication system with an optical node device that does not have a wavelength conversion function in order to reduce the system cost and to reduce the size and price of the optical node device.

However, in an optical communication system formed by an optical node device that does not have a wavelength conversion function, the downstream node needs to declare the same wavelength as the wavelength declared from the downstream node to the upstream node when setting the optical path. . For this reason, contention is likely to occur in resource allocation, and the probability of failure in optical path setting increases. Each time the optical path setting fails, the transmission / reception traffic of the control signal in the system increases, and the time required for that is also consumed. Therefore, since the transmission / reception of data to be originally transmitted is delayed and the utilization efficiency of the network is lowered, some solution is desired.
“Nikkei Communication” Nikkei BP, December 22, 2003, p. 166-174

As described above, in an existing optical communication system formed by an optical node device that does not have a wavelength conversion function, resource contention is likely to occur when setting an optical path, and thus the network utilization efficiency is low. Yes.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical communication system and an optical node device that are capable of preventing the occurrence of resource contention during an optical path setting process, thereby improving network utilization efficiency. It is to provide.

  In order to achieve the above object, according to one aspect of the present invention, there is provided a plurality of optical node devices that are connected via a link in which optical signals of a plurality of wavelengths can coexist to form a network. In an optical communication system capable of setting a cut-through path passing through at least one optical node device, an optical node device serving as a start point of the cut-through path is defined as a start node, and an optical node device serving as a route point of the cut-through path is defined as a relay node. When the optical node device serving as the end point of the cut-through path is an end point node, the start point node and the relay node transmit a path setting request message including resource information including identifiers of the plurality of wavelengths. The end node is an optical node device adjacent to the start node Wavelength selection means for selecting any one wavelength as a wavelength for setting the cut-through path from the wavelength resources indicated in the resource information included in the received path setting request message, wherein the path message processing means includes the end point Provided is an optical communication system characterized in that resource information obtained by deleting at least one wavelength from wavelength resources that can be used in a link with an optical node device adjacent to the node side is included in the path setting request message. .

  By taking such measures, the resource information included in the path setting request message sent from the start node is rewritten to information from which at least one wavelength resource has been deleted, for example, at a relay node immediately below the start node. It is done. That is, for example, the identifier of the shortest wavelength (or the longest wavelength) and the identifier of the wavelength in use are deleted from the resource information in which identifiers of all wavelengths are described. As a result, when a path setup request message is transmitted from a plurality of optical node devices, it is possible to reduce the probability that the wavelength identifiers included in each path setup request message overlap. As a result, it is possible to reduce the possibility of contention during the path setting process, thus improving the network utilization efficiency.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to prevent generation | occurrence | production of resource competition at the time of an optical path setting process, and can provide the optical communication system and optical node apparatus which aimed at the improvement of network utilization efficiency by this.

  FIG. 1 is a system diagram showing an embodiment of an optical communication system formed with an optical node device according to the present invention. In FIG. 1, a plurality of optical node devices 101 to 108 (hereinafter referred to as nodes # 1 to # 8) are connected through a link L such as an optical fiber to form a network. The link L can coexist with optical signals of a plurality of wavelengths, and this type of system is a so-called wavelength multiplexing optical transmission system.

  Each of the nodes # 1 to # 8 has no optical signal wavelength conversion function, and transparently transmits the optical signal transmitted from the upstream node to the downstream node. The optical signal output ports in the nodes # 1 to # 8 are arbitrarily controlled by switching settings in the respective nodes # 1 to # 8. Each of the nodes # 1 to # 8 does not convert an optical signal into an electric signal. Therefore, the system of FIG. 1 is called a so-called all-optical network.

  FIG. 1 shows a state in which the optical path 0 from the node # 1 to the node # 8 is set. The wavelength of this optical path 0 is assumed to be wavelength 1. The optical path 0 starts from the node # 1 and terminates at the node # 8 via the nodes # 3 and # 6. At this time, regarding the optical path 0, the node # 1 is referred to as a start node, the node # 8 is referred to as an end node, and the nodes # 3 and # 6 are referred to as relay nodes. An optical path that passes through at least one relay node like the optical path 0 is referred to as a cut-through path. Next, a more detailed embodiment of the present invention will be described.

[First Embodiment]
FIG. 2 is a functional block diagram showing a first embodiment of the optical node device 101 of FIG. The optical node devices 102 to 108 have the same configuration. In FIG. 2, the optical node device 101 includes a router unit 20, an optical switch unit 100, and a control unit 200. The router unit 20 realizes switching at the packet level. The optical switch unit 100 realizes switching at the wavelength level, and switches the optical signals of the respective wavelengths while maintaining the respective wavelengths. The control unit 200 performs overall operation control in the apparatus including the router unit 20 and the optical switch unit 100.

  The control unit 200 includes a path message processing unit 210, a resource reservation message processing unit 220, a wavelength selection unit 230, and a switch control unit 240. Note that each unit in the control unit 200 is a processing function realized in software by, for example, arithmetic processing of a CPU (Central Processing Unit) based on a command described in a preloaded program.

  The path message processing unit 210 sequentially transmits a path setting request message including resource information including an identifier of each wavelength from the start point node to the end point node. More specifically, the path message processing unit 210 sends a label request message based on, for example, LDP (Label Distribution Protocol) or RSVP (Resource Reservation Protocol) as a path setting request message. The label request message is a part of a signaling message used in the above-described MPLS. Here, by interpreting “label” as “wavelength”, in G-MPLS in which MPLS is expanded, the label request message is rephrased as a path setting request message. Further, the path message processing unit 210 executes processing related to reception and interpretation of the path setting request message. As specific contents of the path setting request message, there is an object that informs a downstream node of a recommended label value. This object is called a LABEL_SET object, and is used here for the purpose of transmitting the recommended wavelength to the downstream node.

  The wavelength selection unit 230 selects a wavelength from available wavelength resources included in the path setting request message when the device itself is an end point node. That is, the wavelength selection unit 230 selects any one wavelength from the wavelength resources indicated in the resource information included in the received path setting request message as a wavelength for setting a cut-through path.

  The resource reservation message processing unit 220 transmits and receives a resource reservation message based on the wavelength selected by the wavelength selection unit 230. That is, the resource reservation message processing unit 220 transmits a resource reservation message including information indicating the wavelength selected by the wavelength selection unit 230 to the start point node. This resource reservation message is sequentially returned from the end point node to the start point node via the relay node. The switch control unit 240 controls the optical switch unit 100 and the router unit 20 based on optical layer and IP (Internet Protocol) layer signaling.

  By the way, in the present embodiment, the path message processing unit 210 includes, in the path setting request message, resource information obtained by deleting at least one wavelength from the wavelength resources that can be used in the link L immediately below the node itself. That is, the path message processing unit 210 rewrites the resource information included in the path setting request message sent from the start point node when the own node is a relay node adjacent immediately below the start point node, for example. Specifically, the path message processing unit 210 declares, for example, a wavelength resource that is smaller than the number of wavelengths that can be used (that is, remaining) in the link L directly under the own node to the downstream relay node (or end node). To do.

  FIG. 3 is a flowchart illustrating a first embodiment of a processing procedure performed when an optical path is set in the network illustrated in FIG. Although this flowchart will be described with node # 3 in FIG. 1 as the main subject, the same processing procedure is also performed in other nodes.

  When a control packet is received from the upstream adjacent node (node # 1) in step S1 of FIG. 3, the node # 3 determines whether the control packet includes a path setting request message or a resource reservation message. (Steps S2 and S3). If any message is not included, the node # 3 performs predetermined error processing (step S4).

  If the control packet includes a path setting request message (Yes in step S2), the node # 3 determines whether or not the own node is a destination node of this path setting request message, that is, an end node (step). S5). If it is not the destination node (No in step S5), node # 3 performs processing as a relay node. That is, the node # 3 first deletes the wavelength registered as the used wavelength from the wavelength resource included in the path setting request message. The registered wavelength means a wavelength already occupied for path setting in the link L adjacent on the downstream side. The wavelength already occupied for path setting in the link L adjacent to the downstream side is stored in the node # 3 when the path is set. Further, the node # 3 reduces at least one wavelength randomly from the wavelength resource from which the registered wavelength is deleted or according to a certain policy (step S12). Thereby, the wavelength resource included in the received path setting request message is rewritten. Next, the node # 3 transfers the path setting request message in a state where the wavelength resource is rewritten to a node adjacent on the downstream side (step S13).

  On the other hand, if the own node is the destination node (Yes in step S5), the node # 3 performs the process as the end node. That is, the node # 3 selects one wavelength randomly or according to a certain policy from the wavelength resource included in the path setting request message (step S6). Then, the node # 3 returns a resource reservation message including the identifier of the wavelength selected in step S6 to the upstream adjacent node (step S7). This resource reservation message is transmitted to the start node via the relay node.

  On the other hand, if the resource reservation message is included in the control packet in Step S3 (Yes in Step S3), the node # 3 determines whether or not the own node is the source node, that is, the start node (Step S8). If it is not the source node (No in step S8), node # 3 registers the used wavelength (step S10). That is, in step S10, the node # 3 stores the wavelength having the identifier described in the returned resource reservation message as a state occupied in the link L with the node that has transmitted the resource reservation message. Node # 3 then returns the returned resource reservation message to the starting node (step S7). Further, the node # 3 controls the optical switch unit 100 based on the registered wavelength, and sets the optical path appropriately (step S11).

  On the other hand, if the own node is the source node (Yes in step S8), the node # 3 executes the process as the starting point node. That is, node # 3 sets the wavelength having the identifier described in the resource reservation message returned from the end node as the transmission wavelength (step S9). The node # 3 controls the optical switch unit 100 based on the set transmission wavelength (step S11).

  FIG. 4 is a sequence diagram showing an example of messages exchanged between the nodes # 1 to # 8 by the processing based on the processing procedure of FIG. Hereinafter, each wavelength is distinguished by identifiers indicated by reference numerals 1 to 8. It is assumed that the wavelength is shorter as the identifier code is smaller. In FIG. 4, description will be made assuming that the cut-through path indicated by the solid line in FIG. 1 has already been set, and the maximum number of wavelengths that can be used in each link L is eight. In the sequence of FIG. 4, it is assumed that a protocol for MPLS (Multi Protocol Label Switching) such as LDP or RSVP is used.

  FIG. 4 shows a state in which an optical path setting request to the node # 7 is generated in the node # 2 in FIG. 1, and an optical path setting request to the node # 5 is generated in the node # 4 almost at the same time. An optical path connecting the node # 2 and the node # 7 is an optical path 1 (dotted line in FIG. 1), and an optical path connecting the node # 4 and the node # 5 is an optical path 2 (one-dot chain line in FIG. 1). As described above, when path setting requests are generated almost simultaneously in a plurality of nodes, processing based on a plurality of path setting request messages associated therewith may compete.

  In FIG. 1, an optical path does not yet exist in the link L from the node # 2 to the node # 3 (from now on, the optical path 1 is set). Therefore, in FIG. 4, the LABEL_SET object included in the path setting request message sent from the node # 2 to the node # 3 subtracts an arbitrary wavelength from the identifiers of all wavelengths from the wavelength 1 to the wavelength 8. For example, the wavelength 3 is subtracted and this path setting request message is expressed as Path (1, 2, 4, 5, 6, 7, 8). On the other hand, the optical path 0 using the wavelength 1 already exists in the link L from the node # 3 to the node # 6. Therefore, the node # 3 deletes the wavelength 1 from the path setting request message from the node # 2, and further sends a path setting request message Path (2, 4, 6, 7, 8) including the LABEL_SET object obtained by subtracting the wavelength 5, for example. Transmit to node # 6.

  An optical path does not yet exist in the link L from the node # 6 to the node # 7 (the optical path 1 is set from now on). Therefore, in principle, all wavelength resources can be used. The node # 6 subtracts, for example, the wavelength 7 from the LABEL_SET object of the received path setting request message and transfers it to the node # 7. The series of processes related to the path setting request message is performed by the path message processing unit 210.

  Receiving the path setting request message, the node # 7 randomly selects one wavelength from the LABEL_SET object in the message by the wavelength selection unit 230. In FIG. 4, it is assumed that wavelength 4 is selected. Then, the node # 7 returns a resource reservation message Resv (4) including the wavelength 4 identifier to the node # 2.

  This resource reservation message Resv (4) is received by the resource reservation message processing unit 220 of each of the nodes # 6 and # 3, and is sent again toward the upstream node. At this time, the resource reservation message processing unit 220 gives the switch control unit 240 information regarding the wavelength resource included in the resource reservation message Resv (4). Based on this information, the switch control unit 240 controls the optical switch unit 100 to set an optical path. The optical path 1 is set at the wavelength 4 through the above procedure.

  On the other hand, the node # 3 receives the path setting request message from the node # 4 before processing the resource reservation message from the node # 7. Since there is no optical path in the link L from the node # 4 to the node # 3, the LABEL_SET object of the path setting request message issued from the node # 4 has, for example, a wavelength resource reduced by the wavelength 4 as an attribute.

  In principle, the node # 3 can use resources other than the wavelength 1 at the time of receiving the path setup request message from the node # 4. In spite of this, in the present embodiment, the available resources are limited in the node # 3 at this time. That is, node # 3 deletes, for example, wavelength 5 in addition to wavelength 1 from the path setting request message received from node # 4. This is realized by rewriting the attribute of the LABEL_SET object, and is shown as Path (2, 3, 6, 6, 7, 8) in FIG. This makes it possible to reduce the probability of contention with resources for the optical path 1.

  Similarly, since no optical path exists yet in the link L from the node # 6 to the node # 5 (the optical path 1 is set from now on), all wavelength resources can be used. On the other hand, the wavelength resource is limited in the path setting request message received by the node # 6. Therefore, the node # 6 transfers the LABEL_SET object to the node # 5 by subtracting the wavelength 6, for example. Node # 5 randomly selects a wavelength from the received LABEL_SET object (selects wavelength 7 in FIG. 4). Thereafter, the optical path 2 is set with the wavelength 7 through the same processing as the optical path 1. The source node of each path setting request message returns a response message (Opt.Path ()) including the identifier of the occupied wavelength to the destination node after the optical path setting is completed. That is, node # 2 sends an Opt.Path (4) message to node # 7, and node # 4 sends an Opt.Path (7) message to node # 5.

  As described above, in the present embodiment, in the link L shared by the optical path for which setting is requested, the wavelength resource is limited in advance in the resource request processing by the path setting request message. In other words, the resources less than the wavelength resources that can actually be used (that is, the remaining wavelength resources) in the link L related to the path setting are notified (advertised) to the node device related to the path setting. This makes it possible to reduce the probability of resource contention probabilistically, and thus increase the network utilization efficiency in the all-optical network.

[Second Embodiment]
FIG. 5 is a functional block diagram showing a second embodiment of the optical node device 101 of FIG. The optical node devices 102 to 108 have the same configuration. Further, in FIG. 5, parts common to FIG. 2 are denoted by the same reference numerals, and only different parts will be described here. 5, the optical node device 101 includes a timer unit 250, a counter unit 260, and a resource detection unit 270 in the control unit 200 in addition to the configuration of FIG.

  The timer unit 250 is a functional object generated for each individual path setting request message processed by the path message processing unit 210. That is, the timer unit 250 disappears after being generated for a certain period from the time when the path setting request message is sent. That is, the timer unit 250 can be regarded as an object that performs a timing operation for a certain period from the time when the path setting request message is sent, and starts the timer every time the path message processing unit 210 transfers the path setting request message. Stop timer after time has elapsed.

  The counter unit 260 counts the number of timer units 250 in operation and obtains a count value. That is, the counter unit 260 counts the number of generated timer units 250 in real time, and obtains the number. The resource detection unit 270 detects a wavelength resource that can be used in the adjacent link L every time the timer unit 250 stops the timing operation, that is, every time the timer unit 250 disappears. That is, the resource detection unit 270 detects a wavelength resource that can be used in the downstream link L each time the timer unit 250 stops timing.

  Further, the path message processing unit 210 in FIG. 5 deletes the number of wavelengths based on the count value obtained by the counter unit 260 from the wavelength resources detected by the resource detection unit 270.

  Also in this embodiment, the wavelength selection unit 230 of each node adopts a policy of selecting the shortest wavelength from the wavelength resources indicated in the path setting request message. Further, the path message processing unit 210 adopts a policy of performing resource limitation in the order of shorter wavelengths from the wavelength resource indicated in the path setting request message.

  FIG. 6 is a flowchart illustrating a second embodiment of a processing procedure performed when an optical path is set in the network illustrated in FIG. In the following, only the part different from that in FIG. In FIG. 6, if the control packet includes a path setting request message (Yes in step S2), the node # 3 starts the procedure of step S5 and starts the timer (step S31). That is, the node # 3 generates one timer object for the received path setting request message, and starts the timing operation.

  Further, the counter unit 260 of the node # 3 counts the number of timers that have been started, that is, the number of timer objects that are currently performing the counting operation, and obtains a count value (step S32). Then, the path message processing unit 210 of the node # 3 deletes the wavelength resources from the wavelength resources detected by the resource detection unit 270 in ascending order of the wavelengths by, for example, twice the count value (step S33).

  FIG. 7 is a sequence diagram showing an example of messages exchanged between the nodes # 1 to # 8 by processing based on the procedure shown in FIG. Also in FIG. 7, it is assumed that the cut-through path indicated by the solid line in FIG. 1 has already been set, and the maximum number of wavelengths that can be used in each link L is 8.

  FIG. 7 shows a state in which optical path setting requests for sharing the link L between the nodes # 3 to # 6 are generated almost simultaneously in the nodes # 2, # 4, and # 1 of FIG. In FIG. 7, it is assumed that resource limitation is performed by deleting from the available resources the number of wavelengths twice the count value C in the counter unit 260. Since the optical path 0 occupies the wavelength 1 in the link L between the node # 3 and the node # 6, the resource detection unit 270 of the node # 3 has (2, 3, 4, 5) as usable resources. , 6, 7, 8). Hereinafter, the processing procedure in the node # 3 will be described.

  The LABEL_SET object included in the path setting request message Path-1 from the node # 2 has (1, 2, 3, 4, 5, 6, 7, 8) as attributes. When the path setting request message Path-1 is received, the count value C in the counter unit 260 of the node # 3 is C = 0. Based on this, the path message processing unit 210 of the node # 3, the resource (1, 2, 3, 4, 5, 6, 7, 8) of the LABEL_SET object of the path setting request message Path-1 and the resource detection unit 270 AND with the available resources (2,3,4,5,6,7,8) held in. The path message processing unit 210 of the node # 3 obtains the result (2,3,4,5,6,7,8) and stores it in the LABEL_SET object newly and updates the updated path setting request message Path-1 to the node Transfer to # 6.

  Simultaneously with the transfer of the path setting request message Path-1, the timer unit 250 of the node # 3 generates a timer object and starts a time measuring operation. Accordingly, the count value C becomes C = 1.

  Next, the node # 3 receives the path setting request message Path-2 from the node # 4. At this time, the resource reservation for the path request from the node # 2 is not completed. Therefore, the resources that can be used in the link L between the node # 3 and the node # 6 are (2, 3, 4, 5, 6, 7, 8). However, since the count value C in the counter unit 260 is C = 1, the path message processing unit 210 of the node # 3 deletes only two wavelengths from the short wavelength side among the available resources. That is, (4, 5, 6, 7, 8) can be assigned as the wavelength resource.

  The path message processing unit 210 of the node # 3 uses this resource (4, 5, 6, 7, 8) and the resource of the LABEL_SET object in the path setting request message Path-2 from the node # 4 (1, 2, 3, Logical AND with 4,5,6,7,8). The path message processing unit 210 of the node # 3 newly obtained (4, 5, 6, 7, 8) is newly stored in the LABEL_SET object, and the updated path setting request message Path-2 is transferred to the node # 6. To do.

  Simultaneously with the transfer of the path setting request message Path-2, the timer unit 250 of the node # 3 generates a timer object corresponding to the path setting request message Path-2 and starts a time measuring operation. Accordingly, the count value C becomes C = 2.

  The timer object stops counting and disappears after a certain period of time. In FIG. 7, it is assumed that the timer object corresponding to the path setting request message Path-1 disappears before the node # 3 receives the path setting request message Path-3 from the node # 1. Then, the count value C becomes C = 1, and the resource detection unit 270 of the node # 3 measures the resources that can be used in the direct link L to the node # 6 at this time.

  At this point, the process of returning the resource reservation message Resv-1 to the node # 2 and the process of returning the resource reservation message Resv-2 to the node # 4 have been completed. Assigned as. Therefore, the wavelength (3, 5, 6, 7, 8) is held in the resource detection unit 270 as a usable resource.

  Thereafter, the node # 3 receives the path setting request message Path-3 from the node # 1. At this time, since the count value C of the counter unit 260 is C = 1, the resources that can be allocated with the resource restriction are (6, 7, 8).

  The path message processing unit 210 of the node # 3 performs a logical product of the allocable resource (6, 7, 8) and the LABEL_SET object included in the path setting request message Path-3, and newly adds the result to the LABEL_SET. The path setting request message Path-3 stored in the object is transferred to the node # 6. Simultaneously with the transfer of the path setting request message Path-3, the timer unit 250 generates a timer object corresponding to the path setting request message Path-3, and the counter unit 260 sets the count value C to C = 2.

  Thus, in this embodiment, the timer unit 250, the counter unit 260, and the resource detection unit 270 are provided. Then, the timer object is activated simultaneously with the generation of the path setting request, and the time measuring operation is stopped as the fixed period elapses. In addition, the counter unit 260 counts the number of timer objects that are being timed, and limits the number of wavelength resources according to the number. As a result, the time limit operation of the timer object is stopped, and the resource that has been restricted in excess is released, and the resource can be reused. Accordingly, resource allocation can be performed efficiently, and wavelength resources can be used more effectively. Further, by limiting the number of resources based on the count value C, it is possible to perform resource notification with reduced possibility of resource contention even when a plurality of optical path setting request messages are received almost simultaneously. This makes it possible to further improve network utilization efficiency.

  In the above description, only the count value C is used as a reference when performing resource limitation. However, when the optical path is explicitly indicated in the path setting request message, the resource limitation is also considered in consideration of the number of relay nodes. May be performed.

<Another example of the second embodiment>
FIG. 8 is a sequence diagram showing another example of messages exchanged between the nodes # 1 to # 8 by the processing based on the procedure shown in FIG. In this example, only the parts different from FIG. 7 will be described. In FIG. 8, the timer object is operated for a certain period. In this example, the timer object is made to disappear when the resource reservation message is processed. That is, the timer is stopped and the count value C is subtracted when the resource reservation message corresponding to each path setting request message is processed.

  In FIG. 8, the resource reservation message Resv-1 corresponding to the path setting request message Path-1 is processed, and when the return is completed, the timer corresponding thereto is stopped. As a result, the count value C in the counter unit 260 is subtracted, and C = 1. In response to the timer being stopped, the resource detection unit 270 of the node # 3 measures available resources in the downstream link L and holds the result. In this case, since wavelength 2 is reserved as an optical path from node # 2 to node # 7, wavelength (3,4,5,6,7,8) is held in resource detection unit 270 as an available resource. Is done.

  Next, the resource reservation message Resv-2 corresponding to the path setting request message Path-2 is processed and returned to the node # 4. At this time, the timer corresponding to the path setting request message Path-2 is stopped, the count value C of the counter unit 260 is also subtracted, and C = 0. Even at this time, the resource detection unit 270 of the node # 3 measures available resources and holds the result. Here, since wavelength 4 is reserved as an optical path from node # 4 to node # 5, wavelength (3, 5, 6, 7, 8) is held in resource detection unit 270 as an available resource.

  Next, the path setting request message Path-3 from the node # 1 is received by the node # 3 and given to the path message processing unit 210. At this time, the count value C is C = 0. Therefore, the path message processing unit 210 of the node # 3 is held in the resource (2, 3, 4, 5, 6, 7, 8) of the LABEL_SET object of the path setting request message Path-3 and the resource detection unit 270. Path setting request message Path-3, which is the logical product of available resources (3,5,6,7,8) and the result (3,5,6,7,8) is newly stored in the LABEL_SET object To node # 6.

  Simultaneously with the transfer of the path setting request message Path-3, the timer unit 250 starts the timer, and the counter unit 260 sets the count value C to C = 1. The node # 6 that has received the path setting request message Path-3 selects the wavelength 3 in the wavelength selection unit 230 in accordance with the wavelength selection policy. In response to this, the resource reservation message processing unit 220 returns a resource reservation message Resv-3 (3) including the wavelength 3 as a label. As a result of such processing, wavelength 3 is assigned to the optical path from node # 1 to node # 6.

  As described above, when the return processing of the resource reservation message corresponding to each path setting request message is completed, the timer can be stopped and the counter value can be subtracted to enable further effective use of resources. become. As a result, the network utilization efficiency can be further improved.

  The present invention is not limited to the above embodiment. In the first embodiment, the path message processing unit transmits, as wavelength resource information to be included in the path setting request message, a wavelength resource in which at least one wavelength is further randomly reduced from the wavelength resource from which the registered wavelength is deleted. In the second embodiment, a policy is adopted in which wavelength resources are selected in order from the shortest wavelength side and the resources are limited. Instead of this, a policy may be adopted in which wavelength resources are selected in order from the longer wavelength side, and the resources are limited.

  Furthermore, the present invention can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a system diagram showing an embodiment of an optical communication system formed with an optical node device according to the present invention. 1 is a functional block diagram showing a first embodiment of an optical node device according to the present invention. The flowchart which shows 1st Embodiment of the process sequence implemented when setting an optical path in the network shown by FIG. FIG. 4 is a sequence diagram showing an example of messages exchanged between nodes # 1 to # 8 by processing based on the procedure shown in FIG. 3. The functional block diagram which shows 2nd Embodiment of the optical node apparatus concerning this invention. The flowchart which shows 2nd Embodiment of the process procedure implemented when setting an optical path in the network shown by FIG. FIG. 7 is a sequence diagram illustrating an example of messages exchanged between the nodes # 1 to # 8 by processing based on the procedure illustrated in FIG. 6. FIG. 7 is a sequence diagram showing another example of messages exchanged between nodes # 1 to # 8 by processing based on the procedure shown in FIG. 6.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Router part, 100 ... Optical switch part, 101-108 ... Optical node apparatus, 200 ... Control part, 210 ... Path message processing part, 220 ... Resource reservation message processing part, 230 ... Wavelength selection part, 240 ... Switch control part , 250 ... timer unit, 260 ... counter unit, 270 ... resource detection unit

Claims (8)

Optical communication comprising a plurality of optical node devices that are connected via a link in which optical signals of a plurality of wavelengths can coexist to form a network, and in which the cut-through path passing through at least one optical node device can be set in the network In the system,
When an optical node device that is the start point of the cut-through path is a start node, an optical node device that is a transit point of the cut-through path is a relay node, and an optical node device that is an end point of the cut-through path is an end node,
The start node and the relay node are:
Path message processing means for sending a path setting request message including resource information including identifiers of the plurality of wavelengths,
The end node is
Wavelength selection means for selecting any one wavelength as a wavelength for setting the cut-through path from the wavelength resource indicated in the resource information included in the path setting request message received from the optical node device adjacent to the start node. Prepared,
The path message processing means includes resource information obtained by deleting at least one wavelength from wavelength resources usable in a link with an optical node device adjacent to the end node side in the path setting request message. An optical communication system. The end point node and the relay node further include resource reservation message processing means for sequentially returning a resource reservation message including information indicating the wavelength selected by the wavelength selection means to the start point node. Item 4. The optical communication system according to Item 1. The relay node is
Resource detection means for detecting wavelength resources that can be used in a link between the optical node device adjacent to the end node side and the own node;
Determining means for determining the number of wavelengths to be deleted in the path message processing means,
The optical communication system according to claim 2, wherein the path message processing means of the relay node deletes the number of wavelengths determined by the determining means from the wavelength resources detected by the resource detecting means. The determining means includes
Time measuring means that is generated for each path setting request message and stops after operating for a certain period from the time of transmission of the path setting request message;
Counter means for obtaining the count value by counting the number of the time measuring means in operation,
The resource detection means detects the usable wavelength resource every time the time measuring means stops,
4. The optical communication system according to claim 3, wherein the path message processing unit of the relay node deletes the number of wavelengths based on the count value from the wavelength resource detected by the resource detection unit. The determining means includes
A timing means that is generated for each path setting request message and stops after operating for a period from the time of sending the path setting request message to the time of receiving the resource reservation message corresponding to the path setting request message;
Counter means for obtaining the count value by counting the number of the time measuring means in operation,
The resource detection means detects the usable wavelength resource every time the time measuring means stops,
4. The optical communication system according to claim 3, wherein the path message processing unit of the relay node deletes the number of wavelengths based on the count value from the wavelength resource detected by the resource detection unit. Optical communication comprising a plurality of optical node devices that are connected via a link in which optical signals of a plurality of wavelengths can coexist to form a network, and in which the cut-through path passing through at least one optical node device can be set in the network In the system,
When an optical node device that is the start point of the cut-through path is a start node, an optical node device that is a transit point of the cut-through path is a relay node, and an optical node device that is an end point of the cut-through path is an end node,
The start node and the relay node are:
Path message processing means for sending a path setting request message including resource information including identifiers of the plurality of wavelengths,
The end node is
Wavelength selection means for selecting any one wavelength as a wavelength for setting the cut-through path from the wavelength resource indicated in the resource information included in the path setting request message received from the optical node device adjacent to the start node. Prepared,
The path message processing means of the relay node includes, in the path setting request message, wavelength resource information that can use less wavelength resources than wavelength resources that can be used in a link with an optical node device adjacent to the end node side. An optical communication system characterized by being included. In a plurality of optical node devices that form a network by being connected via a link in which optical signals of a plurality of wavelengths can coexist,
An optical node device that is a start point of a cut-through path that passes through at least one optical node device is a start node, an optical node device that is a route point of the cut-through path is a relay node, and an optical node device that is an end point of the cut-through path is When it is set as the end node,
Path message processing means for transmitting a path setting request message including resource information including identifiers of the plurality of wavelengths when operating as the start node and the relay node;
When operating as the end node, to set the cut-through path to any one wavelength from the wavelength resources indicated in the resource information included in the path setting request message received from the optical node device adjacent to the start node Wavelength selection means for selecting as the wavelength of
The path message processing means of the relay node includes, in the path setting request message, resource information obtained by deleting at least one wavelength from the wavelength resources that can be used in the link with the optical node device adjacent to the end node. An optical node device. In a plurality of optical node devices that form a network by being connected via a link in which optical signals of a plurality of wavelengths can coexist,
An optical node device that is a start point of a cut-through path that passes through at least one optical node device is a start node, an optical node device that is a route point of the cut-through path is a relay node, and an optical node device that is an end point of the cut-through path is When it is set as the end node,
Path message processing means for transmitting a path setting request message including resource information including identifiers of the plurality of wavelengths when operating as the start node and the relay node;
When operating as the end node, to set the cut-through path to any one wavelength from the wavelength resources indicated in the resource information included in the path setting request message received from the optical node device adjacent to the start node Wavelength selection means for selecting as the wavelength of
The path message processing means of the relay node includes, in the path setting request message, wavelength resource information that can use less wavelength resources than wavelength resources that can be used in a link with an optical node device adjacent to the end node side. An optical node device characterized by being included.

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