JP4373929B2 - Path route calculation method, path route calculation device, and communication system - Google Patents

Description

  The present invention relates to a path route calculation method, a path route calculation device, and a communication system.

  In recent years, data traffic including IP (Internet Protocol) traffic is increasing exponentially due to the rapid spread of the Internet and LAN (Local Area Network). In order to cope with an increase in traffic, a mechanism for realizing high-speed IP packet transfer in a backbone network is required. At the same time, IP-based applications are diversifying, and traditionally applications such as e-mail and web that do not require quality have been the main focus. Recently, however, networks such as IP telephones and electronic commerce have been improved in quality. Requested applications are also becoming popular.

  In the conventional IP router network, each router in the relay stage requires electrical packet processing, and since there is no mechanism for performing advanced quality control with End-End, it realizes high speed and high quality service. It was difficult to realize the provision. Here, as the quality, in addition to the transfer quality such as the packet delay time and the loss rate, the reliability such as the service interruption time seen by the user is an important index.

  As one means for solving the problems related to the IP router network, MPLS (Multi-Protocol Label Switching) has been proposed. MPLS assigns a fixed-length label to a packet to be transferred, and determines a path route to be transferred at each node in the communication network based on the label. By introducing this MPLS into the IP backbone network, high-speed IP packet transfer and advanced TE (Traffic Engineering) are possible.

  In recent years, a network architecture using layer 1 technology such as an optical cross-connect for a relay node of an IP network has been proposed. So far, ASON (Automated Switched Optical Network), GMPLS (Generalized Multi-Protocol Label Switching), and the like have been proposed. A feature common to these networks is that a path (connection) is dynamically set by signaling. For this reason, compared with the conventional layer 1 network, the time until path establishment can be significantly shortened, and more efficient network operation can be expected.

  A feature common to the MPLS and GMPLS is that it is necessary to set a path in advance when transferring user traffic including IP packets. In order to set a path, network topology information (information related to the connection configuration between nodes) is collected using a routing protocol, and a path relay route is calculated. Then, CR-LDP (constraint-based Label Distribution Protocol) is used. ) And RSVP-TE (Resource Reservation Protocol-Traffic Engineering).

  After the path setting is completed, traffic transfer on the corresponding path is started. Further, regarding the relationship between GMPLS and MPLS, GMPLS is a generalization of MPLS and basically includes MPLS.

  Next, a technique for realizing high network reliability using MPLS or GMPLS will be described. Here, the case of GMPLS will be described as an example, but the present invention can also be applied to the case of MPLS. As an example of high reliability of a network, for example, returning a network to a normal state before the failure in response to a network failure can be mentioned. In order to return to the normal state, for example, a switching operation from the active system to the standby system is performed.

  As a switching technique in GMPLS, path protection is well known (Non-patent Document 1, Patent Document 1). With path protection, two or more paths are set in advance between the communication node that is the starting point of communication and the communication node that is the end point, and one of them is used as a working path, and user traffic is transferred during normal times.

  When a failure occurs in a node or link on the working path, path switching is performed at the starting node (originating side), and user traffic is transferred onto the protection path. When a failure occurs on the path of the working path, switching to the backup path is immediately performed, thereby shortening the non-communication time of user traffic and realizing high reliability. In order to prevent the protection path from being affected by a failure on the working path, it is necessary to design the protection path so as not to share the link and node of the relay stage with the working path.

  In general, a communication network is composed of a plurality of layers. In the optical layer, the working path and the protection path do not share nodes and links in the relay stage, but considering the physical layer, the working path and the protection path share a fiber that is a link in the physical layer at one location. There is a case. In such a case, if a failure occurs in the shared fiber, the failure cannot be recovered by path protection, so that there is a problem that network reliability and service availability are significantly reduced.

  However, even if path protection is used, if a failure occurs in a resource on the backup path, the service is interrupted, so it is important to identify and restore the failed resource at an early stage.

  As a method for avoiding such a problem, an SRG (Shared Risk Group) number has been proposed (Non-Patent Document 2). SRG number is assigned to each fiber link in the physical layer, and the sum of the SRG numbers of the fibers in which each link in the optical layer is accommodated is advertised by the routing protocol as SRG information of the optical layer link to calculate the path route. Used for.

When implementing path protection path design in the optical layer, by considering SRG information in addition to the topology of the optical layer, it is possible to design a path protection that can be recovered from any physical layer resource failure. It becomes possible.
Japanese Patent Application No. 2002-235980 E. Oki et al., “A Disjoint Path Selection Scheme with SRLG in GMPLS networks”, 2002 WKsp. IEEE HPSR, May 2002, 88-92 Shiomoto Ko, "Restoration method based on hierarchical SRG", IEICE General Conference Proceedings, 2003

  The switching operation from the active system to the standby system deals with the failure after the failure has occurred. However, when a network is operated, a preventive viewpoint that prevents a failure by setting a highly reliable path is also important. However, the conventional method of setting a highly reliable path is only to set a disjoint path, which is high in reliability but poor in network use efficiency and not practical.

  For example, in the communication system of FIG. 7, three paths C (C1, C2, C3) are set, and an arrow indicates the path C. For example, when a failure occurs in the link L15, the two paths C (C2, C3) sharing the link L15 cannot be used. At this time, the two paths C (C2, C3) share the link L15. On the other hand, when the two paths C (C1, C3) do not have the shared link L and node N, they are referred to as disjoint paths C.

  By setting only such a disjoint path C, even if one part fails, only one failed path is required. However, since the constraints that satisfy the disjoint path C are strict, the number of paths that can be set on the network is very small. As a result, the network utilization efficiency deteriorates.

  As described above, the reason why the utilization efficiency of the network is deteriorated is that the reliability such as the failure occurrence frequency specific to each part constituting the network is not taken into consideration. In an actual network, failures occur due to different factors in various parts such as transmission devices other than fibers, TDM (Time Division Multiplexing) switches, routers, line cards, and interfaces. Since these parts are hardware parts, many of them have known reliability such as the frequency of occurrence of failures.

  Therefore, even if a highly reliable part is shared by a plurality of paths, since the possibility that the part will fail is low, the reliability of the shared plurality of paths is also increased. An example of such a highly reliable part is a fiber having a lower frequency than the disconnection frequency allowed for the connection. In other words, the reliability of the fiber itself is much higher than that of the node in the optical layer, and depending on the required service reliability, it may be possible to meet the specified reliability even if the fiber is shared at one place. Many.

  In addition, when designing a path of a path that requires less reliability, it is possible to set a path that consumes less resources by relaxing the sharing conditions of the parts, resulting in the use of network resources. Efficiency is improved.

  Therefore, the main object of the present invention is to solve the above-described problem and calculate a path route that improves the network utilization efficiency while satisfying the required reliability condition.

In order to solve the above-mentioned problems, the present invention provides a path route calculation method in a communication network that connects nodes for setting a path, and has storage means for storing reliability data of parts that are constituent elements in the communication network. A computer receiving a path route calculation request; a procedure for calculating a link cost of a link constituting the path based on reliability data of the parts read from the storage; and And a step of outputting the calculated path route to the node and setting a path, and calculating the path route includes the steps of: when calculating reliability condition is not included in the request, characterized by calculating one or more predetermined reliability satisfying path route To.

Thus, by calculating a path route that matches the reliability of the part, it is possible to calculate a path route that improves the network utilization efficiency while satisfying the required reliability condition. Furthermore, even if the requested reliability is uncertain, a path route calculation result can be obtained.

  The present invention is characterized in that the storage means stores correspondence data between a part type ID indicating the type of the part and a failure occurrence frequency of the part as the reliability data of the part.

  As a result, the reliability data need only be set once for parts with uniform quality, and the setting effort can be reduced.

  The present invention is characterized in that the storage means stores correspondence data between a part ID for uniquely identifying the part and a failure occurrence frequency of the part as reliability data of the part.

  As a result, it is possible to make fine settings for parts with varying quality by setting reliability data for each part.

  The present invention is characterized in that the storage means stores information on the part advertised from the node using a communication protocol and reliability data of the part.

  Thereby, since the part information only needs to be set in the node, management of the part information becomes easy.

The present invention is characterized in that the procedure for calculating the path route recalculates the path route by relaxing the reliability condition when a path satisfying the predetermined reliability condition cannot be found.

  Thereby, the calculation result of the path route can be obtained almost certainly.

The present invention relates to a path route calculation apparatus in a communication network that connects nodes for setting a path, the storage unit storing reliability data of parts that are constituent elements in the communication network, and a path route calculation request received And calculating a link cost of the link constituting the path based on the reliability data of the parts read from the storage unit, and calculating a path route of the path based on the link cost And a path route output unit that outputs the calculated path route to the node and sets a path, and the path route calculation unit includes a reliability condition in the path route calculation request. If there is not, a path route that satisfies one or more predetermined reliability conditions is calculated .

Thus, by calculating a path route that matches the reliability of the part, it is possible to calculate a path route that improves the network utilization efficiency while satisfying the required reliability condition. Furthermore, even if the requested reliability is uncertain, a path route calculation result can be obtained.

  The present invention is a communication system configured by connecting the path route calculation device, a node that sets the path, and the communication network.

  Thus, by calculating a path route that matches the reliability of the part, it is possible to calculate a path route that improves the network utilization efficiency while satisfying the required reliability condition.

  According to the present invention, it is possible to calculate a path route that improves the network utilization efficiency while satisfying the required reliability condition by calculating the path route according to the reliability of the parts.

  Hereinafter, an embodiment of a communication system 1 to which the present invention is applied will be described in detail with reference to the drawings. First, the configuration of the communication system 1 according to the present embodiment will be described with reference to FIGS. 1 to 5. The communication system 1 shown in FIG. 1 specifies that when a failure occurs in the communication network 2, the occurrence location is specified up to a unit of a part (fiber, device interface card, etc.) that is a component of the communication system 1. Features.

  The communication system 1 includes a node N that sets a path C, and a path route calculation device 3 that calculates a relay route of a path in the network that satisfies the requested constraint. The communication system 1 connects the nodes N with the communication network 2. In the communication network 2, the network protocol information and resource R information are collected by operating a routing protocol at each node N in the network. As a routing protocol, OSPF (Open Shortest Path First), IS-IS (Intermediate System-Intermediate System) and the like are usually used.

  In addition, although illustration is abbreviate | omitted for the apparatus (node N, the path | route path | route calculation apparatus 3) which comprises the communication system 1, the memory as a memory | storage means used when each performing arithmetic processing, and arithmetic processing which performs the said arithmetic processing It is comprised as a computer provided with an apparatus and the network interface for connecting to the communication network 2 at least. The memory is constituted by a RAM (Random Access Memory) or the like. Arithmetic processing is realized by an arithmetic processing unit configured by a CPU (Central Processing Unit) executing a program on a memory.

  Each node N is classified into a source side node NS, a relay node NM, and a destination side node NE. The originating node NS is a node N that is the starting point of the path C, and generates a signaling message for setting when setting a new path C. For example, in the case of a GMPLS network, the path C is set using a signaling protocol such as CR-LDP or RSVP-TE. The relay node NM mainly relays data transferred on the path C. The destination node NE is a node N that is a termination point of the path C. The originating node NS and the terminating node NE are connected to a user-side communication device (not shown), and the communication network 2 provides a connection for connecting the user-side communication device between two sites. Further, at least one path route calculation device 3 is provided in the communication system 1 and is connected to the originating node NS.

  The communication network 2 provides a connection for connecting user-side communication apparatuses between two sites. Since required conditions such as bandwidth and reliability required by users differ, the communication network designs and provides paths that satisfy various constraint conditions.

  Next, the concept of the resource R constituting the communication system 1 will be described.

  FIG. 2A shows a network configuration diagram in which devices of the communication system 1 are connected by a line (fiber). In the communication system 1, two paths C (working path C and backup path C) from the node N1 to the node N4 are set. In FIG. 2A, the node N1 is connected to the switch SW, and the switch SW branches to the node N2 or the node N3.

  FIG. 2B is a diagram in which logical layer information handled by the routing protocol is extracted in the communication system 1 of FIG. For example, the working path C is an ordered set of <node N1 → link L2 → node N3 → link L4 → node N4>. Here, the resource R is defined as a node N or a link L that is an element of a set of paths C. Therefore, the path C is an ordered set of a plurality of resources R. The protection path C is an ordered set of <node N1 → link L1 → node N2 → link L3 → node N4>, and includes five resources R. Each resource R is assigned a resource ID for uniquely identifying the resource R. The resource ID is, for example, SRG information that is a combination of SRG numbers.

  The link L is given additional information such as link cost and bandwidth information used in a normal routing protocol. The resource ID is associated with link cost and bandwidth information used in a normal routing protocol. A real link cost Ci is defined for each link i (i = 0, 1,...) In the network, and Ci is set by the network operator. As the initial value of the link cost Ci, a relative value of the delay time of each link, a value obtained by standardizing the reciprocal number of the link band, or the like is used. For example, when the bandwidth of link 1 is 1 [Gbps] and the bandwidth of link 2 is 10 [Gbps], C1 = 10 and C2 = 1 can be calculated.

  The link L1 in FIG. 2B is one, but the elements constituting this link L1 are two fibers (# 1, # 2) as shown in FIG. 2A. Further, although there is one link L2, the elements constituting the link L2 are two fibers (# 1, # 3) as shown in FIG. 2 (b). Therefore, the link L1 and the link L2 share the fiber # 1. As a result, when the fiber # 1 fails, the link L1 and the link L2 cannot be used at the same time. Therefore, it is desirable that the reliability required for the fiber # 1 is higher than that of the fiber # 3.

  FIG. 3 is an explanatory diagram showing assignment of part IDs. The part P is a component of the network or apparatus (hardware resource) that constitutes the resource R, and represents a component of a physical device in a lower layer that is not distributed by a normal routing protocol. Examples of the part P include a line card, an interface, and a fiber shown in FIG. The part ID is composed of a combination of <part type ID, part manufacturing ID>. The part ID is uniquely assigned to each part P in the communication system 1. The part ID is, for example, an SRG number.

  First, a part type ID is assigned in a unit that can identify a part P that becomes a failure factor. The type of the part P may be set to a unit for identifying the use of the part P, such as a line card or a fiber line. Even if the line card of the same Ethernet (registered trademark) is used, Different part type IDs may be assigned to the line cards manufactured by the company. Therefore, the communication system 1 may be composed of a plurality of parts P having the same part type ID.

  Next, the part manufacturing ID is an ID assigned for each part type ID. For example, a unique (separate) parts manufacturing ID is assigned to each of a plurality of line cards manufactured by Company A. For example, the part manufacturing ID is a manufacturing number assigned to each product by the manufacturer. Therefore, since the company A and the company B are independently assigned production numbers, the communication system 1 may be composed of a plurality of parts P having the same parts production ID. However, a part ID composed of a set of a part type ID and a part manufacturing ID is uniquely assigned to each part P in the communication system 1.

  Information regarding the part ID is held by each node N and distributed between the other nodes N in the network and the path route calculation device 3 by a routing protocol.

  FIG. 4 is a configuration diagram showing the path route calculation device 3. The path route calculation device 3 includes storage means (path information database 20, topology database 22, and reliability database 24) and control means (path route calculation unit 26 and path route output unit 28).

  First, the path information database 20 records information related to the relay route (used resource R) of the path C in the communication network 2. This information includes correspondence information between the path ID and the resource ID of the resource R on the route from the start point to the end point of the path ID. Note that the relay route of the path C is calculated by the path route calculation unit 26.

  FIG. 5A is a configuration diagram illustrating an example of the path information database 20. For each path in the path route list, the reliability of the path, the reliability of the requested path, and a set of resource IDs constituting the path are stored in association with each other. For example, path # 1 is a path having a reliability (70%) that satisfies the required reliability (70%), and the route uses resources indicated by three resource IDs R1 → R2 → R4. is doing.

  Next, the topology database 22 stores the network topology created from the route information distributed by the routing protocol. Further, the topology database 22 holds correspondence information between resource IDs and part IDs.

  FIG. 5B is a configuration diagram illustrating an example of the topology database 22. Each resource indicated by the resource ID is stored in association with a resource type classified as a node or a link, a part ID used by the resource, and a link cost of the resource. For example, the resource R1 is a node and is composed of two parts P1 and P2.

  The correspondence information between the resource ID and the part ID will be specifically described. In the example of FIG. 3, two links L (L1, L2) are connected to one node N, and the part P is composed of four layers of fiber, interface, line card, and apparatus. A different part type ID is assigned to each layer.

  The two links L (L1, L2) share a device and a line card, but use separate interfaces and fibers. Therefore, the resource ID (link #A) is associated with a set of part IDs <device # 1, line card # 2, interface # 31, fiber # 41>. The resource ID (link #B) is associated with <device # 1, line card # 2, interface # 32, fiber # 42>.

  The correspondence information between the resource ID and the part ID is distributed in the communication network 2 by a routing protocol, for example. From this information, there is a possibility that the link L1 and the link L2 may fail at the same time, and the cause is the failure of the shared device and the failure of the shared line card. On the other hand, regarding the failure of the interface or the fiber, when only one part P fails, only one of the links L is generated due to the failure and does not fail at the same time.

  The reliability database 24 stores information on the reliability of parts that are components of the communication network 2. The information on reliability is, for example, the frequency of part failure, the average operation period of parts, and the like. Then, the path route calculation device 3 updates the reliability database 24 with, for example, setting information input from the administrator.

  FIG. 5C and FIG. 5D are configuration diagrams showing an example of the reliability database 24, respectively. FIG. 5C shows a database in which reliability is associated with each part type ID that is a part of the part ID, and FIG. 5D shows that reliability is associated with each part ID. Indicates a database. First, FIG. 5C is a database that assumes that the same part type (for example, Ethernet (registered trademark) card of company A) has the same quality and is considered to have the same reliability. On the other hand, FIG. 5D shows a database in which parts with different part manufacturing IDs may have different reliability even if they are the same part type.

  Accordingly, either one of the methods shown in FIGS. 5C and 5D may be prepared, or two methods may be prepared together. Note that it is desirable to use the method shown in FIG. 5C for parts having the same quality, and use the method shown in FIG. 5D for parts having variations in quality.

  Here, when the method of FIG. 5 (d) is adopted, the part ID and the reliability correspondence information attached to the part ID may be collectively managed as the reliability database 24. The reliability correspondence information may be advertised using a communication protocol. Further, the path route calculating device 3 acquires the information of the parts advertised by the node N using the communication protocol (part ID, etc.) and the communication protocol or another method (such as reading from a storage means stored in advance). The reliability data may be associated with each other and managed by the database shown in FIG. 5C or 5D.

  Hereinafter, the operation of the communication system 1 will be described along the flowchart of FIG. 6 with reference to FIGS. 1 to 5.

  First, the path route calculation device 3 receives a path route calculation request (route calculation request message for resolving the relay route of the path C) from the originating node NS (S101). Examples of information included in the route calculation request message include the address of the originating node NS, the address of the called node NE, the requested reliability, the requested bandwidth, and the number of paths C to be set (one or more). can give.

  The path route calculation device 3 that has received the route calculation request message analyzes the content of the message, extracts information necessary for route calculation in the path route calculation unit 26, and transfers the information to the path route calculation unit 26. Information necessary for route calculation includes the address of the originating node NS, the address of the terminating node NE, the requested reliability, the requested bandwidth, and the number of paths C to be set (one or more). Hereinafter, the path route calculation unit 26 calculates a route of the path C that satisfies the request based on information necessary for route calculation.

  Next, the path route calculation device 3 calculates a link cost based on the reliability of the part P (S102). Therefore, first, the path route calculation unit 26 determines a part type ID to be considered in the route calculation of the backup path C from the requested reliability information. For example, if the path C requires the highest degree of reliability, all the part type IDs shown in FIG.

  Note that when the required reliability is the lowest, the path route calculation unit 26 considers only the disjoint property of the node N and the link L of the layer in which the path C is set without considering the part type ID at all. The path route calculation unit 26 selects one or more part type IDs to be considered in the calculation from the requested reliability information and the reliability of the part type ID shown in FIG.

  The part IDs included in the link L and the node N on the working path C having the selected part type ID are listed. Next, for the link L and node N assigned the same part ID as the part ID in the list, the link cost Ci is changed by the following formula 1.

  Ci = (1 + α) * Ci (Expression 1)

  Here, α is a real number of 0 or more. Since the link cost is not given to the node N, the link cost of the link L connected to the node N is changed. Moreover, as a determination method of (alpha), the same value may be used with all the links L in the communication system 1, and it shared by the following Numerical formula 2 using the reliability information attached | subjected to parts ID. Α may be determined for each SRG.

  α = F (X) (Formula 2)

  Here, X is a value of reliability information (failure frequency information) attached to the corresponding part ID, and F is a certain continuous increase function for X. By determining α in this way, α becomes larger and the link cost value itself becomes larger as the link L shares the part P having a high failure occurrence frequency, so that it becomes difficult to be selected as the link L of the protection path C. .

  Then, the path route calculation device 3 calculates a path route based on the link cost calculated in S102 (S103). Here, an example of processing when two paths, the working path C and the backup path C, are set will be described.

  The path route calculation unit 26 of the path route calculation device 3 first calculates the route of the working path C. Based on the information in the topology database 22, the path route calculation unit 26 calculates the route of the path C that satisfies the bandwidth constraint condition between the originating node NS and the terminating node NE. By using a CSPF (Constrained Shortest Path First) algorithm or the like as an algorithm necessary for route calculation, the route C of the shortest route satisfying the bandwidth constraint can be calculated.

  When the path of the working path C is resolved, the path path calculation unit 26 calculates the path of the protection path C next. The path route calculation unit 26 satisfies the required reliability based on the number of links L sharing the part P in each of the resource R of the working path C and the resource R of the protection path C, and the value of the part ID at that time. Calculate path C.

  Next, the route of the backup path C is calculated based on the link cost corrected in S102. Since the node N and the link L that share the part P with the working path C are modified so as to increase the cost, if the backup path C is calculated by the CSPF algorithm, the part P is within the possible range with the working path C. A route that does not share is obtained.

  When the route calculation for the working path C and the backup path C is completed in S103, the path route calculation device 3 determines whether or not the reliability of the calculated path route satisfies the calculation request (S104). This determination processing is performed by, for example, AGGARWAL described in the literature (KKAGGARWAL, JSGUPTA, AND KB MISRA, “A Simple Method for Reliability Evaluation of Communication System”, IEEE TRANSACTIONS ON COMMUNICATIONS, 563-566, MAY 1975.). Realized by law. Hereinafter, the determination process will be specifically described.

  First, the path route calculation unit 26 confirms whether there is a part ID shared by the working path C and the backup path C from the information on the obtained route. If there is no shared part ID, the calculated path route is output (S106). The output of the path route is a process of encoding calculation result information (path C route information and reliability information) in the route calculation response message and replying to the requesting node N. If the path C is not found even if the reliability is lowered, a route calculation response message in which the error result is encoded is returned.

  Next, when there is a shared part P, the path route calculation unit 26 checks whether the path C satisfies the required reliability condition. That is, the reliability of the path C is calculated based on the reliability (failure occurrence frequency) of the part P attached to the shared part P, and is compared with the reliability requested in S101. The reliability of the path C is, for example, the frequency at which failures occur simultaneously in a plurality of paths C that share the part P. If the requested reliability is satisfied (S104, YES), the path route calculation device 3 outputs the calculated path route (S106).

  On the other hand, when the calculation request is not satisfied (S104, NO), the path route calculation device 3 relaxes the reliability of the path route. The path route calculation unit 26 calculates, for example, a route with a reduced reliability. This is because the condition for the reliability of the more shared part P is eased by lowering the reliability, and the path is easily found.

  In the case of recalculating the route with the requested reliability lowered, the requested reliability is lowered by one step, the calculation returns to S102, and the working path C and the backup path C are calculated again. As a method of reducing the reliability by one level, first, the parts P considered in the original reliability are listed. Next, the part P having the lowest failure occurrence frequency in the list is deleted from the list. Based on this list, the paths of the working path C and the backup path C are calculated in the same manner as described above (S102, S103), and it is checked whether the obtained path C satisfies the reliability condition (S104). If the path C does not satisfy the reliability condition, the reliability is further lowered by one step and the route is recalculated.

  The embodiment described above relates to an apparatus and a method for calculating a relay route of each connection accommodated in a communication network. In the present embodiment, for example, a node N network that performs transfer based on layer 3 header information, an MPLS communication network that transfers within a communication network by attaching a fixed-length label to a packet to be transferred, a TDM time slot, The present invention is applied to GMPLS communication networks that handle light wavelengths as generalized labels, ATM (Asynchronous Transfer Mode) communication networks, and the like.

  In the present embodiment, when a connection is set up between a caller side node N and a callee side node N in a network, a part P (fiber, device in the middle) is calculated in calculating a redundant route in setting up a redundant route in preparation for a failure. The path that can satisfy the reliability required for the connection is calculated based on the reliability (such as cause of failure and frequency of failure occurrence) of the interface card.

  The present invention described above can be widely modified without departing from the spirit thereof as follows.

  For example, in the present embodiment, the method for realizing the path calculation of the path C satisfying the reliability condition specified in the path calculation request message has been described. However, the condition regarding the reliability explicitly requested in the path calculation request message May not be specified. At that time, the path route calculation device 3 assumes that a predetermined reliability prepared in advance (a history of reliability used in the past may be used) is included in the route calculation request message, and its reliability. Route calculation of the path C that satisfies the condition may be performed. The predetermined reliability may be one or a set of different values. In the case of a set of a plurality of different values, a set of reliability and a path route that satisfies the reliability is calculated by the number of reliability in the set. That is, the path route calculation device 3 repeats the process (S101 to S105) for calculating the route of the path C that meets the reliability condition by the number of reliability levels in the set.

  Each database in the storage means of the path route calculation device 3 may be stored inside the path route calculation device 3 as long as the data can be accessed by the path route calculation device 3, or separate from the path route calculation device 3. You may store in the apparatus of.

  Furthermore, although the path route calculation device 3 described in the present embodiment has been described as a device separate from the node N, the path route calculation device 3 may be provided in the node N, or may be provided to a plurality of devices. The functions of the path route calculation device 3 may be distributed.

  Then, the parts to be assigned part IDs may be all parts in the network, or may be excluded from the parts to be assigned. The parts to be excluded are, for example, parts that have very high reliability and do not need to consider a failure in the operation of the network. By not assigning a part ID to such a part, it is possible to reduce the calculation amount of the path calculation.

It is a block diagram which shows the communication system regarding one Embodiment of this invention. It is explanatory drawing which shows the concept of the resource regarding one Embodiment of this invention. It is explanatory drawing which shows the concept of the parts regarding one Embodiment of this invention. It is a block diagram which shows the path | route route calculation apparatus regarding one Embodiment of this invention. It is a block diagram of the database of the path | route route calculation apparatus regarding one Embodiment of this invention. It is a flowchart which shows the path | route path | route calculation process regarding one Embodiment of this invention. It is explanatory drawing of the concept of a disjoint (relatively disjoint) path | pass.

Explanation of symbols

C path L link N node P parts 1 communication system 2 communication network 3 path route calculation device 20 path information database 22 topology database 24 reliability database 26 path route calculation unit 28 path route output unit

Claims (7)

A method for calculating a path route in a communication network connecting nodes for setting a path,
A computer having storage means for storing reliability data of parts that are components in the communication network,
A procedure for receiving a path route calculation request;
A procedure for calculating a link cost of a link constituting the path based on reliability data of the parts read from the storage unit;
A procedure for calculating a path route of the path based on the link cost;
Outputting the calculated path route to the node and setting a path ; and
The path calculating procedure calculates a path route that satisfies one or more predetermined reliability conditions when a reliability condition is not included in the path route calculation request. Route calculation method.   2. The path path according to claim 1, wherein the storage unit stores correspondence data between a part type ID indicating the type of the part and a failure occurrence frequency of the part as reliability data of the part. Calculation method.   2. The path route according to claim 1, wherein the storage unit stores correspondence data between a part ID that uniquely identifies the part and a failure occurrence frequency of the part as reliability data of the part. Calculation method.   The said storage means stores the information of the said part advertised from the said node using the communication protocol, and the reliability data of the said part, The one of the Claims 1 thru | or 3 characterized by the above-mentioned. Path route calculation method. The procedure for calculating the path route includes relieving the reliability condition and recalculating the path route when a path satisfying the predetermined reliability condition cannot be found. Item 5. The path route calculation method according to any one of Items4. A path route calculation device in a communication network connecting nodes for setting a path,
Storage means for storing reliability data of parts as components in the communication network;
A path route calculation request is received, a link cost of a link constituting the path is calculated based on reliability data of the parts read from the storage unit, and a path route of the path is calculated based on the link cost. A path route calculation unit for calculating
A path route output unit that outputs the calculated path route to the node and sets a path ; and
The path route calculation unit calculates a path route that satisfies one or more predetermined reliability conditions when a reliability condition is not included in the path route calculation request. apparatus. A communication system configured by connecting the path route calculation device according to claim 6 and a node for setting the path through the communication network.

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