JP2004129135A - Hierarchized network node and network constructed by the node - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently perform a path calculation by expanding a path calculation in a multilayer network to a large scale network and eliminating calculations to be invalid. <P>SOLUTION: A network to which a user himself/herself belongs is divided into cells consisting of a plurality of nodes, and these cells are defined as a virtual node. When there is a link connecting the inside of a virtual node to the outside of the virtual node, a contact point between the inside and the outside of the virtual node is defined as an interface of the virtual node. A virtual network composed of virtual nodes is further subjected to cell division and virtual node formation. The virtual network further subjected to cell division and virtual node formation is defined as an upper level network with respect to the initial virtual network. A hierarchized network is constructed by performing the operation of cell division and virtual node formation one time or several times. Furthermore, a path calculation from a sending node to a receiving node is distributed for each layer and hierarchically performed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a path network configuration technique for performing traffic engineering such as path selection and rearrangement.
[0002]
[Prior art]
When networks of a plurality of layers coexist, individual network management is often performed in each layer. At this time, the network management method differs depending on the layer, and one device grasps the state of the entire network and performs a centralized control method in which control is performed, and all nodes in the network share information by exchanging link states. There is a distributed control method and the like.
[0003]
There is also a method in which a network is divided into a plurality of areas and managed in each area only for control of one layer.
[0004]
[Problems to be solved by the invention]
When performing distributed control multi-layer traffic engineering in a situation where networks of a plurality of layers are mixed, traffic engineering has conventionally been performed on the entire network. Therefore, a routing protocol typified by OSPF (Open Shortest Path First) or the like collectively uses the same. Since the amount of information to be handled increases and the amount of calculation for traffic engineering becomes enormous, it is difficult to realize expansion to a large-scale network.
[0005]
The present invention has been made in such a background, and can be extended to a large-scale network. Further, it is possible to specify a range of a layer that requires route calculation before performing the calculation. Therefore, an object of the present invention is to provide a layered network node, a network, a layered path selection method, a program, and a recording medium which can eliminate invalid calculation and can perform path calculation efficiently.
[0006]
[Means for Solving the Problems]
The present invention is characterized in that the route calculation from the source node to the destination node is distributed in each layer and performed stepwise. As a result, the amount of calculation for each layer can be reduced as compared with the conventional example in which traffic engineering is performed on the entire network, and therefore, expansion to a large-scale network can be realized. Furthermore, since the calculation can be performed after specifying the range of the layer requiring the route calculation, invalid calculation can be eliminated, and the route calculation can be performed efficiently.
[0007]
That is, the first aspect of the present invention is provided in a network including one or a plurality of layers, and stores information on its own node and links connected to its own node (hereinafter, referred to as link state information) with other nodes. Means for exchanging between
Means for holding link state information of some or all nodes in the network obtained by the means for exchanging, and one or more types based on the link state information held by the means for holding according to a path setting request Means for selecting the path of the path of the layer of the layer, and means for changing the path selected and set by the selecting means in accordance with the path change request based on the link state information held in the holding means. Node.
[0008]
Here, the feature of the present invention is that the network to which the self belongs belongs to a cell composed of a plurality of nodes, and this cell is defined as a virtual node, and connects the inside and outside of the virtual node. If there is a link that exists, the contact between the inside and the outside of this virtual node is defined as the interface of the virtual node, and the virtual network configured by the virtual node is further divided into cells and converted into virtual nodes. The virtual network converted into a virtual node is defined as a higher-level network with respect to the initial virtual network. By performing the cell division and virtual node conversion operations one or more times, a hierarchical network is constructed, and the virtual network to which the virtual network belongs. Link that stores link state information advertised from other nodes or other virtual nodes within the node A border database is defined as a node within the virtual node or a node that plays the role of an interface with the outside of the virtual node among the virtual nodes. When oneself is located at this border node, link state information inside the virtual node is defined. There is provided a link state summarizing unit having means for generating interface information to the outside of the virtual node based on the above, and an advertising unit for advertising the generated interface information to the outside of the virtual node. Note that the node of the present invention will be referred to as a hierarchical network node.
[0009]
By defining such a layered structure, it is not necessary to collectively calculate the entire network, and calculations can be performed for each layer, thus realizing expansion to a large-scale network. Can be.
[0010]
Means for identifying a group of links connecting the same virtual node to the ground among a plurality of links connecting the virtual nodes, and regarding the links included in the group of links identified by the identifying means as one virtual link It is desirable to provide a means for performing the processing.
[0011]
As a result, one virtual link can be constituted by, for example, one wavelength-multiplexed optical path.
[0012]
Alternatively, the means for identifying a first link group connecting the same virtual node to the ground among a plurality of links connecting the virtual nodes, and the first link group identified by the identifying means are further identical. Means for classifying into the second link group sharing the switching capability of the above, and means for processing the links included in the second link group classified by the classifying means as one virtual link Is desirable.
[0013]
As a result, one virtual link sharing the same switching capability is defined, and one wavelength-multiplexed optical path is assigned to each switching capability, for example, so that hardware usage efficiency can be improved. .
[0014]
The link state summarizing unit allocates switching capabilities in a virtual node to which the own node belongs to a link connected to the own node and a link corresponding to an interface connecting the virtual node to which the self node belongs and the outside. And the switching capability allocating means, and the interface information may be information on switching capabilities allocated to the interface by the switching capability allocating means.
[0015]
That is, by using information on which switching capability is assigned to which link as interface information, each virtual node can grasp the connection relationship between the virtual nodes in units of switching capability.
[0016]
Alternatively, the link state summarizing unit may switch the switching capability in the virtual node to which the own node belongs by a link corresponding to the link connected to the own node and the interface connecting the virtual node to which the own node belongs to the outside. Switching capability allocating means for allocating the switching capability, and cost allocating means for allocating a transmission cost for each switching capability allocated by the switching capability allocating means, wherein the interface information is provided by the switching capability allocating means. It can be information on switching capability assigned to the interface and information on transmission cost assigned to the switching capability of the interface by the cost allocating means.
[0017]
According to this, the transmission cost in the case of using a link can be grasped together with the connection relationship between the virtual nodes, so that a path having a short physical distance is not simply used as the shortest path, but the transmission cost is used. Is the shortest path.
[0018]
The information of the switching capability assigned to the interface includes a layer of a path that can be set between the own node as a border node or a virtual border node and another border node or another virtual border node belonging to the same virtual node. It is desirable to be generated corresponding to each.
[0019]
As a result, information can be obtained for each layer, which is highly convenient in performing route calculation for each layer.
[0020]
Further, the information on the switching capability assigned to the interface is, for example, information on a switching capability of a border node or a virtual border node to which the link serving as the interface is directly connected.
[0021]
The advertisement unit may include a unit that performs advertisement outside the virtual node every time the switching capability of the border node changes, or the advertisement unit includes a unit that performs advertisement outside the virtual node at a constant period. It is desirable. Thereby, each virtual node can obtain the latest information. It should be noted that the advertisement load in the case where the advertisement is performed outside the virtual node at a constant cycle is often lower than the case where the advertisement is performed outside the virtual node every time the switching capability is changed.
[0022]
The transmission cost information is generated by, for example, the reciprocal of the total number of unused interfaces to which the switching capability of the layer included in the virtual node is allocated.
[0023]
That is, the larger the total number of unused interfaces, the larger the permissible interface acceptance amount, and thus the lower the transmission cost.
[0024]
Alternatively, the information on the transmission cost is, for example, regarding the number of used interfaces and the total number of interfaces to which the switching capability of the layer included in the virtual node is allocated.
Number of used interfaces / total number of interfaces
Generated by
[0025]
In other words, the smaller the number of used interfaces with respect to the total number of interfaces, the larger the permissible interface acceptance amount, and thus the lower the transmission cost.
[0026]
The transmission cost information is set as a cost when a path of an arbitrary layer is set between a border node in the virtual node and another border node belonging to the same virtual node as the border node. It is desirable that the information be determined for each layer of the path.
[0027]
As a result, information can be obtained for each layer, which is highly convenient in performing route calculation for each layer.
[0028]
The cost may be, for example, a link cost of a link along a path when a path is set between a border node in a virtual node and another border node belonging to the same virtual node as the border node, and the link cost of the node. It is desirable to have means for calculating the cost value of the route that minimizes the value obtained by adding the node cost of the node.
[0029]
As a result, it is possible to select the route with the lowest cost in consideration of both the link cost and the node cost.
[0030]
Alternatively, the cost may be, for example, a link cost of a link along a path of a minimum hop number set between a border node in a virtual node and another border node belonging to the same virtual node as the border node. Alternatively, the value is obtained by adding the node cost of the virtual node, and when there are a plurality of routes having the minimum hop number, the cost value candidate which is a set of a plurality of values obtained by adding the routes is included. It is desirable to have a means for selecting the one with the smallest value as the cost value.
[0031]
Thereby, both the link cost and the node cost are taken into consideration, and furthermore, the route with the smallest cost can be selected by the minimum hop number.
[0032]
The value obtained by the addition is, for example, the reciprocal of the number of unused interfaces to which the switching capability of the layer included in the node along the route is allocated.
[0033]
In other words, the larger the number of unused interfaces, the larger the permissible interface acceptance amount, and thus the smaller the value obtained by the addition. The difference between the transmission cost already described and the value obtained by the addition is that the transmission cost is a value predetermined for each link, whereas the value obtained by the addition is the It is a value calculated accordingly.
[0034]
Alternatively, the value obtained by the addition is, for example, regarding the number of used interfaces and the total number of interfaces to which the switching capability of the layer included in the node is assigned along the route.
Number of used interfaces / total number of interfaces
Given by
[0035]
In other words, the smaller the number of used interfaces with respect to the total number of interfaces, the larger the permissible interface acceptance amount, and thus the smaller the value obtained by the above addition.
[0036]
The node corresponding to the interface of the virtual node includes means for calculating the transmission cost information or the cost based on the link state information at a predetermined time interval, or the node corresponding to the interface of the virtual node is Means for notifying a change in the use state of the interface inside the virtual node by link state information advertisement, and calculating the transmission cost information or the cost based on the link state information every time the use state of the interface changes It is desirable. Thereby, each virtual node can obtain the latest information. It should be noted that the calculation load in a case where the calculation is performed at a constant cycle is lower than that in a case where the calculation is performed every time the usage status of the interface changes.
[0037]
A second aspect of the present invention is a network comprising the hierarchical network node of the present invention.
[0038]
A third aspect of the present invention is a hierarchical route selection method, which is characterized in that when setting a path of an arbitrary layer in a network configured by the hierarchical network nodes of the present invention, When selecting the route from the source node to the destination node, the destination node is referred to in the virtual node including the source node among the virtual nodes of the level 1 by referring to the link state database of the lowest level 1. Is determined, and if the source node and the destination node do not exist in the same virtual node, by referring to the link state database of the next higher level 2 in the virtual node including the source node of the level 2 It is determined whether a destination node exists in the virtual node, and this determination is repeated until the source node and the destination node are included in the same virtual node. When selecting a level N (N is a natural number) virtual node including both the destination node and the level N path from the source node to the destination node in the selected level N virtual node, The route selection of the virtual node group included in the selected level N virtual node is selected by the selecting means of the level N based on the link state database of the level N, and the selected level N is selected. When a route of the next lower level (N-1) from the source node to the destination node is further selected from among the virtual nodes included in the route, the next lower level (N-1) of the selected virtual node is selected. ) Is selected by the selecting means of the corresponding level (N-1) based on the link state database of (1), and this is repeated until the lowest level 1 There is to perform the steps of selecting a route from over de to the destination node.
[0039]
According to this, first, a level including both the source node and the destination node is searched, and the upper limit of the level is specified. As a result, invalid calculation can be omitted without setting a higher level than that as a route calculation target. The route calculation is performed for each level in order from the highest level searched to the lower level. As a result, even if the network becomes large-scale, the amount of calculation at each level is limited, so that it is possible to realize expansion to a large-scale network.
[0040]
Alternatively, a third aspect of the present invention is a hierarchical path selection method, which is characterized in that a path of an arbitrary layer is set in a network constituted by the hierarchical network nodes of the present invention. When selecting a route from a source node to a destination node, the network including the virtual node of the highest level N refers to the link state database of the level N so that the source node and the destination node are the same virtual node. And if the source node and the destination node are in the same virtual node, the link state database of the next lower level (N-1) in this virtual node is referred to. As a result, the source node and the destination node exist in the same virtual node in the network one level lower (N-1) in the virtual node. This determination is repeated until the originating node and the destination node are included in different virtual nodes, and the virtual node at the next higher level (N−k) (k is a natural number) is selected. When a virtual node of a level (N−k) including both a node and a destination node is selected, and a path of a level (N−k) from the source node to the destination node is selected in the virtual node, the selection is performed. Of the virtual node group included in the virtual node of the selected level (N−k) based on the link state database of the level (N−k) based on the selection of the level (N−k). Means for selecting a route of the next lower level (N−k−1) from the source node to the destination node among the virtual nodes included in the route of the selected level (N−k). The choice Based on the link state database of the next lower level (N−k−1) in the selected virtual node by the selecting means of that level (N−k−1), and selecting this up to the lowest level 1 The procedure for selecting a route from the source node to the destination node by repeating the procedure is to be executed.
[0041]
Comparing the former method and the latter method, the procedure for searching for a level including both the source node and the destination node is different. In the former method, the search is performed from the lower level to the upper level, whereas in the latter method, the search is performed from the upper level to the lower level.
[0042]
In a virtual node at a level lower than the level including both the source node and the destination node, the calculation for selecting a route in the own node is performed by inputting / outputting the route among the border nodes included in the virtual node. It can be performed by a border node assigned as an interface.
[0043]
Alternatively, in a virtual node at a level lower than the level including both the source node and the destination node, the calculation for selecting a route in the own node is performed in advance by the representative node among the border nodes included in the virtual node. That is performed by a border node defined as
[0044]
In this way, by determining in advance the node for which the route calculation is to be performed, the calculation process can be executed efficiently. In the latter case, the bias of the calculation load can be reduced by sequentially shifting the representative node to another node each time one calculation process ends.
[0045]
A fourth aspect of the present invention is a program. A feature of the present invention is that the information processing apparatus is configured with the hierarchical network node according to claim 1 by being installed in the information processing apparatus. When a path from an originating node to a destination node is selected when a path of an arbitrary layer is set in the network, by referring to the link state database of the lowest level 1, the virtual node of the level 1 can be selected. It is determined whether the destination node exists in the virtual node including the source node, and if the source node and the destination node do not exist in the same virtual node, the link state database of the next higher level 2 is referred to. Thus, it is determined whether or not the destination node exists in the virtual node including the source node of level 2 and this determination is made. Is repeated until it is included in the same virtual node, thereby selecting a level N (N is a natural number) virtual node that includes both the source node and the destination node. When selecting a level N route from a node to a destination node, the route selection of a virtual node group included in the selected level N virtual node is performed based on the level N link state database. When a route of the next lower level (N-1) from the source node to the destination node is further selected from among the virtual nodes included in the selected level N route selected by the selecting means of level N And means for selecting the level (N-1) based on the link state database of the level (N-1) one level lower in the selected virtual node. Ri selected which is from the source node by repeating to the level 1 the lowest at which the steps of selecting a route to the destination node.
[0046]
Alternatively, a fourth aspect of the present invention is a program, and a feature of the present invention is that the information processing apparatus is installed in the information processing apparatus and configured with the hierarchical network node according to claim 1. When setting a path of an arbitrary layer in a network to be set, when selecting a route from a source node to a destination node, the network composed of virtual nodes of the highest level N refers to the link state database of the level N. By determining whether the source node and the destination node exist in the same virtual node, if the source node and the destination node exist in the same virtual node, the next lower level in the virtual node By referring to the link state database of (N-1), the network of the next lower level (N-1) in this virtual node is In the network, it is determined whether the source node and the destination node exist in the same virtual node. This determination is repeated until the source node and the destination node are included in different virtual nodes. k) (k is a natural number) by selecting a virtual node, thereby selecting a level (N−k) virtual node including both the source node and the destination node, and from the source node to the destination node in the virtual node. When selecting a path of the level (N-k), the path selection of the virtual node group included in the virtual node of the selected level (N-k) is performed by the link state of the level (N-k). Based on the database, a selection is made by the selecting means of the level (N−k), and the virtual nodes included in the route of the selected level (N−k) further include a route from the source node to the destination node. Day When selecting the route of the next lower level (N-k-1), the level (N-k-1) is selected based on the link state database of the next lower level (N-k-1) in the selected virtual node. The procedure for selecting a route from the source node to the destination node by repeating selection up to the lowest level 1 by the selection means of k-1) is executed.
[0047]
A fifth aspect of the present invention is a recording medium readable by the information processing device, on which the program of the present invention is recorded. Since the program of the present invention is recorded on the recording medium of the present invention, the information processing apparatus can install the program of the present invention using the recording medium. Alternatively, the program of the present invention can be directly installed on the information processing apparatus via a network from a server holding the program of the present invention.
[0048]
This makes it possible to realize expansion to a large-scale network by using an information processing device such as a computer device, and to perform calculation after specifying a range of a layer that requires route calculation. Thus, it is possible to realize a layered network node, a network, and a layered path selection method that can eliminate invalid calculation and efficiently perform path calculation.
[0049]
BEST MODE FOR CARRYING OUT THE INVENTION
(First embodiment)
First, a network assumed by the hierarchical network node will be described. A schematic diagram of this network is shown in FIG. This network is composed of a network of a plurality of layers, and here, it is assumed that the network is composed of an IP layer, an SDH layer, and a wavelength layer. In this network, each node advertises a link state including information such as an IP address, a maximum bandwidth of a link, and a used bandwidth.
[0050]
Based on this link state, the node that sets the path determines whether to set up a new SDH path or wavelength path to set up an IP path, or to which path the new SDH path or wavelength path should be set up. A calculation is performed to determine whether the setting is the least costly, and the path is set. Further, when rearranging the route of a certain IP path, the necessity of changing the route of the wavelength path of the lower layer is calculated at the same time. In such a network, the amount of link state advertisement and the amount of calculation for route calculation increase as the network scale increases, so that scalability cannot be maintained at a certain fixed scale. The same can be said for an increase in the number of layers handled collectively.
[0051]
FIG. 2 shows how the above-described multi-layer network is divided into cells, virtual nodes, and hierarchies. Here, hierarchization is performed up to three layers (Level 3). FIG. 3 shows a state where the network is converted into virtual nodes.
[0052]
In the first embodiment, such a network is realized. FIG. 4 shows a schematic diagram of a node for this purpose. The node collects link state information indicating the state of the own node and the state of the link connected to the own node and stores the link state information in the link state database LSDB-L1. This link state information is advertised to other nodes through the advertising section P. Also, link state information is advertised from other nodes included in the same virtual node as the own node through the advertising unit P. The link state information of Level 1 is selected from the information advertised by the advertising section P and stored in the link state database LSDB-L1. If this node is located at the interface of the virtual node (nodes A, B, and C in FIG. 3), this node plays the role of a border node. The node selected as the border node summarizes the link state information of the link state database LSDB-L1 into the link state information for Level 2 in the LS summarizing section LS1, stores this in the link state database LSDB-L2, and Through the section P, an advertisement is issued to the outside of the virtual node as interface information of the virtual node.
[0053]
Similarly, the LS summarizing unit LS2 repeats the operation of obtaining the link state information to be stored in the link state database LSDB-L3 from the link state information of the link state database LSDB-L2 for the number of layers of the network.
[0054]
(Second embodiment)
In the second embodiment, as shown in FIG. 5, based on the link state information stored in the link state database LSDB-L1, the switching capability allocating unit (illustrated as an SC allocating unit) SC of the LS summarizing unit LS1 is used. , The switching capability of the interface of the virtual node of Level 2 is determined. It has a function of storing this result in the link state database LSDB-L2 and advertising it to the outside of the virtual node via the advertising unit P.
[0055]
Similarly, the LS summarizing unit LS2 repeats the operation of obtaining the link state information to be stored in the link state database LSDB-L3 from the link state information of the link state database LSDB-L2 for the number of layers of the network. FIG. 5 shows a functional block diagram of the node at this time.
[0056]
(Third embodiment)
In the third embodiment, as shown in FIG. 6, based on the link state information stored in the link state database LSDB-L1, the switching capability allocating unit SC of the LS summarizing unit LS1 interfaces the Level 2 virtual node interface. And the cost calculation unit C calculates the cost required for passing through the virtual node. It has a function of storing this result in the link state database LSDB-L2 and advertising it to the outside of the virtual node via the advertising unit P.
[0057]
Similarly, the LS summarizing unit LS2 repeats the operation of obtaining the link state information to be stored in the link state database LSDB-L3 from the link state information of the link state database LSDB-L2 for the number of layers of the network. FIG. 6 shows a functional block diagram of the node at this time.
[0058]
(Fourth embodiment)
In the fourth embodiment, the switching capabilities assigned in the second and third embodiments are defined. FIG. 7 shows a method of assigning switching capabilities to the interface of the virtual node. Here, a layer of a path that can be set between interfaces via a virtual node is assigned to an interface as switching capability. Therefore, the switching capability is assigned not only depending on the input port but also on the output port.
[0059]
Therefore, the switching capability of the interface a1 of the virtual node in FIG. 7 is PSC (Packet Switching Capability) + LSC (Lambda Switching Capability) for the interfaces a1, a2, and c2, whereas the switching capability of the interfaces b and c1 is PSC. By allocating the switching capability in consideration of the output port of the path in this way, it becomes possible to accurately advertise to the outside of the cell which interface can be used to set the path of which layer.
[0060]
(Fifth embodiment)
In the fifth embodiment, the switching capabilities assigned in the second and third embodiments are defined. FIG. 8 shows a method of assigning switching capabilities to the interface of the virtual node. Here, the switching capability of the border router in the cell for the interface of the virtual node is assigned as the switching capability of the interface of the virtual node.
[0061]
In FIG. 8, the interfaces a1 and a2 have the switching capability of LSC, the interfaces b and c1 have the switching capability of PSC, and the interface c2 has the switching capability of LSC + PSC. As a result, the amount of advertisement of the switching capability of the virtual router can be reduced.
[0062]
(Sixth embodiment)
It is conceivable that the network resources are consumed while the path is set in the network, and the switching capability of the interface of the virtual node changes. For this reason, the switching of the switching capability of the interface of the virtual node shown in the first to fifth embodiments is triggered, and by advertising to other virtual nodes, the route selection at the time of path setting changes the actual network state. It will be possible to accurately reflect them.
[0063]
(Seventh embodiment)
It is conceivable that the network resources are consumed while the path is set in the network, and the switching capability of the interface of the virtual node changes. For this reason, the change of the switching capability of the interface of the virtual node shown in the first to fifth embodiments is periodically advertised to other virtual nodes. Network state can be accurately reflected.
[0064]
(Eighth embodiment)
FIG. 9 shows an outline of the path setting cost in the virtual node network. The path setting cost in the virtual node network is the cost of the link and the cost of passing through the virtual node. That is,
Path setup cost in virtual node network =
Sum of link costs + sum of costs via virtual nodes
It is. At this time, the virtual node indicates a layer of a path that can be handled by the switching capability. That is, the switching capability attribute is assigned to the interface of the virtual node. At this time, the cost via the virtual node is given for each switching capability of the interface of the virtual node. This is because, when passing through a virtual node, the cost may be different between passing through a path of the IP layer and passing through a path of the wavelength layer. By comparing the cost values for each layer, it is possible to determine which layer path should be set.
[0065]
(Ninth embodiment)
FIG. 10 shows a method of providing a cost via a virtual node. The inside of the virtual node is configured by a network, and a link connected to the outside of the cell is used as an interface. At this time, a layer of a path that can be set between the input interface and the output interface in the virtual node differs depending on the interface. When the matrix between the input / output interface and the ground is configured, the example is as shown in FIG. Here, if the input / output interface is different, the path inside the cell is also different, so the cost is also different. Therefore, a cost is assigned to each switching capability of the matrix between the input / output interface of the virtual node and the ground.
[0066]
At this time, the cost to be assigned to each switching capability of the matrix between the input / output interface of the virtual node and the ground is determined by selecting the path with the minimum cost from the switching capability layer path candidates that can be set between the input / output interfaces. A settable route is selected in the cost selection unit. FIG. 11 shows functional blocks of the hierarchical network node at this time. The functional block in FIG. 11 has a configuration in which a cost selection unit C is further added to the functional block in FIG. 6, and is used for allocating switching capabilities by the switching capability allocating unit SC and calculating and allocating costs by the cost calculating unit C. In addition, the cost selection unit S selects a route that can set a path with the minimum cost. The setting cost of the path adopted in this way is assigned as the cost of the interface of the virtual node.
[0067]
As a result, not the via cost candidates of the virtual node but all the minimum ones are advertised to the outside, which leads to a reduction in the amount of advertisement.
[0068]
(Tenth embodiment)
FIG. 12 shows a method of assigning a cost via a virtual node. The inside of the virtual node is configured by a network, and a link connected to the outside of the cell is used as an interface. At this time, a layer of a path that can be set between the input interface and the output interface of the virtual node differs depending on the interface. When the matrix between the input / output interface and the ground is configured, the example is as shown in FIG. Here, if the input / output interface is different, the path inside the cell is also different, so the cost is also different. Therefore, a cost is assigned to each switching capability of the matrix between the input / output interface of the virtual node and the ground.
[0069]
At this time, the cost assigned to each switching capability of the matrix between the input / output interface of the virtual node and the ground is the setting cost of the minimum hop number path path of the layer that can be set during the combination of the input / output interface. If there are a plurality of routes with the minimum hop number, this is the minimum cost among the candidates.
[0070]
In this way, after limiting the route to a path that can be set with the minimum number of hops in the first stage, the method of selecting one from the candidates limited in the second stage is used. The search for a certain minimum hop route does not change unless a change in the network topology occurs, so that the search is performed once and can be omitted.
[0071]
With this method, it is possible to more easily determine the cost assigned to the interface of the virtual node.
[0072]
(Eleventh embodiment)
FIG. 13 shows a method for assigning costs to nodes. The route cost is obtained by adding the node cost to the link cost. The cost of passing through a node is determined by the number of interfaces that this node has. The cost of an arbitrary layer via a node is the reciprocal of the number of unused interfaces among the interfaces having the switching capability of this layer.
[0073]
(Twelfth embodiment)
FIG. 14 shows a method of assigning costs to nodes. The route cost is obtained by adding the node cost to the link cost. The cost of passing through a node is determined by the number of interfaces that this node has. The cost of an arbitrary layer via a node is the number / total number of interfaces in use among the interfaces having the switching capability of this layer.
[0074]
(Thirteenth embodiment)
FIG. 15 shows a method of assigning a cost via a virtual node. The cost via the virtual node is not allocated to each interface of the virtual node but is collectively allocated as one value. This allocation method is the reciprocal of the total number of unused interfaces among the interfaces having the switching capability of this layer possessed by the nodes included in the virtual node.
[0075]
(14th embodiment)
FIG. 16 shows a method of providing a cost via a virtual node. The cost via the virtual node is not allocated to each interface of the virtual node but is collectively allocated as one value. This allocation method is the total number / total number of interfaces in use among the interfaces having the switching capability of this layer which the nodes included in this virtual node have.
[0076]
(15th embodiment)
Since the cost via the virtual node changes depending on the availability of the interface for each switching capability existing inside the node, the node corresponding to the interface of the virtual node periodically recalculates the cost.
[0077]
(16th embodiment)
Since the cost via the virtual node changes depending on the availability of the interface for each switching capability existing inside the node, the node corresponding to the interface of the virtual node notified of the change recalculates the immediate cost I do.
[0078]
(17th embodiment)
FIG. 17 shows a route selection sequence of the seventeenth embodiment. First, a network range in which a route is selected is determined. When the destination node exists in the cell to which the source node belongs among the cells at the lowest level, the route is selected in this cell. If the destination node does not exist in the same cell, a cell including the source node is selected in the cell at the next higher level, and it is checked whether or not the destination node exists in this cell. If the destination node exists in the same cell, the route is selected in this cell. If not, the same examination is performed in another higher-level cell. This series of examinations is repeated until a destination node is found.
[0079]
In the network range where the route selection determined in this way is performed, the route selection of the virtual node network is performed by the route selection unit at the relevant level. Here, in the virtual node selected as the relay node, a route selection of the virtual node network is similarly performed in the cell by the route selection unit of the corresponding level. By repeating this route selection to the lowest level, a route from the source node to the destination node can be determined. FIG. 18 shows functional blocks of the hierarchical network node at this time. The functional block in FIG. 18 has a configuration obtained by adding an L1 route selector RS1, an L2 route selector RS2, and an L3 route selector RS3 to the functional block shown in FIG.
[0080]
In this way, by adopting a method that expands the range of consideration from the lower level to the discovery of the destination node, it is possible to find the destination node earlier in a network where paths are often set between nearby nodes It becomes.
[0081]
(Eighteenth embodiment)
FIG. 19 shows the sequence of the eighteenth embodiment.
[0082]
First, a network range in which a route is selected is determined.
[0083]
It is checked whether there is a cell including both the source node and the destination node among the cells of the highest level. If there is, in the network in this cell, similarly, check whether there is a cell including both the source node and the destination node, and perform this series of checks in a cell where the source node and the destination node are different. Repeat until included. After confirming that the source node and the destination node are included in different cells, the network including these cells is determined as a range in which a route is selected.
[0084]
In the network range where the route selection determined in this way is performed, the route selection of the virtual node network is performed by the route selection unit at the relevant level. Here, in the virtual node selected as the relay node, a route selection of the virtual node network is similarly performed in the cell by the route selection unit of the corresponding level. By repeating this route selection to the lowest level, a route from the source node to the destination node can be determined. FIG. 18 shows functional blocks of the hierarchical network node at this time.
[0085]
In this way, by adopting a method of searching for a network range in which a route is to be selected in order from a higher level, a network in which a path is often set between distant nodes can quickly find a destination node.
[0086]
(Nineteenth embodiment)
FIG. 20 shows a network management system according to the nineteenth embodiment.
[0087]
In the case of performing the route selection as in the seventeenth and eighteenth embodiments, it is necessary to perform the route selection in the network in the virtual node with only the input / output interface of the virtual node determined. Come out.
[0088]
At this time, a method is considered in which the route selection calculation of the internal network is handled by a node corresponding to the input / output interface of the predetermined virtual node or the virtual node.
[0089]
(20th embodiment)
FIG. 21 shows a network management method according to the twentieth embodiment. In the case of performing the route selection as in the seventeenth and eighteenth embodiments, it is necessary to perform the route selection in the network in the virtual node in a state where only the input / output interface of the virtual node is determined. .
[0090]
At this time, it is conceivable that a node selected from inside the virtual node or a virtual node is in charge of the route calculation of the internal network. Further, it can be changed every time a node or a virtual node to be selected is calculated. By adopting this method, it is possible to prevent the route selection calculation processing from being concentrated only on the border node.
[0091]
(Twenty-first embodiment)
FIG. 22 shows a link bundling method according to the twenty-first embodiment. If the network is divided into a plurality of cells and this is defined as a virtual node, the virtual nodes are connected by the same number of links as the number of links connecting the nodes inside the cell. When the virtualization of the network is performed in a hierarchical structure, the virtual nodes are connected by many links. At this time, considering that the link state is advertised between the virtual nodes, an increase in the number of links is considered to cause an increase in the ad link state.
[0092]
Therefore, when there are a plurality of links between the virtual node and the ground, it is possible to prevent the link state from increasing by bundling the plurality of links and treating them as one virtual link. It becomes. At this time, the cost assigned to the interface can be considered as a method of advertising the interface connected by the virtual link.
[0093]
(Twenty-second embodiment)
FIG. 23 shows a link bundling method according to the twenty-second embodiment. If the network is divided into a plurality of cells and this is defined as a virtual node, the virtual nodes are connected by the same number of links as the number of links connecting the nodes inside the cell. When the virtualization of the network is performed in a hierarchical structure, the virtual nodes are connected by many links. At this time, considering that the link state is advertised between the virtual nodes, an increase in the number of links is considered to cause an increase in the ad link state.
[0094]
Therefore, when there are a plurality of links between the virtual node and the ground, it is possible to prevent the link state from increasing by bundling the plurality of links and treating them as one virtual link. It becomes. At this time, a method of bundling links having the same switching capability can be considered. At this time, it is conceivable to advertise the minimum cost among the costs of the interface of the bundled link. With this method, it is possible to reduce the number of links and to advertise, for each switching capability, the minimum cost of passing through the route. Therefore, traffic engineering with higher accuracy can be performed.
[0095]
(23rd embodiment)
The hierarchical network node, the network, and the hierarchical route selection method according to the present embodiment can be realized by using a computer as an information processing device. That is, the twenty-third embodiment is a program, and the feature of the present embodiment is that, by being installed in a computer device, a network constituted by the hierarchical network nodes of the present embodiment is installed in the computer device. When a path from an originating node to a destination node is selected when a path of an arbitrary layer is set by referring to the link state database of the lowest level 1, the virtual node of the level 1 It is determined whether the destination node exists in the virtual node including the source node, and if the source node and the destination node do not exist in the same virtual node, refer to the link state database at the next higher level 2 Then, it is determined whether or not the destination node exists in the virtual node including the source node of the level 2 and this determination is made. By repeating the process until the node and the destination node are included in the same virtual node, a virtual node of level N (N is a natural number) including both the source node and the destination node is selected, and the virtual node of the selected level N is selected. When selecting a level N route from a source node to a destination node in a node, the route selection of a virtual node group included in the selected level N virtual node is performed based on the link state database of the level N. Then, in the virtual node included in the selected level N route, the route of the next lower level (N-1) from the source node to the destination node is selected by the selecting means of the level N. Is selected, based on the link state database of the next lower level (N-1) in the selected virtual node, the selection of the level (N-1) is performed. Selected by means of which the from source node by repeating to the level 1 the lowest at which the steps of selecting a route to the destination node.
[0096]
Alternatively, the twenty-third embodiment is a program, and a feature of the present embodiment is that a network configured by the layered network nodes of the present embodiment is installed in the computer so that the computer is installed in the computer. When a path from an originating node to a destination node is selected when a path of an arbitrary layer is set by referring to the link state database of the level N in a network composed of virtual nodes of the highest level N , The source node and the destination node exist in the same virtual node. If the source node and the destination node exist in the same virtual node, the next lower level (N- By referring to the link state database of 1), the next lower level (N-1) in this virtual node In the network, it is determined whether the source node and the destination node exist in the same virtual node, and this determination is repeated until the source node and the destination node are included in different virtual nodes, and one higher level (N- k) (k is a natural number) by selecting a virtual node, thereby selecting a level (N−k) virtual node including both the source node and the destination node, and from the source node to the destination node in the virtual node. When selecting a path of the level (N-k), the path selection of the virtual node group included in the virtual node of the selected level (N-k) is performed by the link state of the level (N-k). Based on the database, a selection is made by the selecting means of the level (N−k), and the virtual nodes included in the route of the selected level (N−k) further include a route from the source node to the destination node. When selecting the route of the next lower level (N−k−1), the level (N−k−1) is selected based on the link state database of the next lower level (N−k−1) in the selected virtual node. -K-1) The procedure of selecting a route from the source node to the destination node by repeating the selection up to the lowest level 1 by the selection means is executed.
[0097]
The program of the present embodiment is recorded on the recording medium of the present embodiment, so that the computer device can install the program of the present embodiment using the recording medium. Alternatively, the program of the present embodiment can be installed in a computer device directly from a server holding the program of the present embodiment via a network.
[0098]
This makes it possible to realize expansion to a large-scale network by using a computer device, and furthermore, it is possible to perform calculation after specifying the range of a layer that requires route calculation, thereby making calculation invalid. Can be eliminated, and a hierarchical network node, a network, and a hierarchical route selection method capable of efficiently performing route calculation can be realized.
[0099]
【The invention's effect】
As described above, according to the present invention, an extension to a large-scale network can be realized, and furthermore, the calculation can be performed after specifying the range of the layer requiring the route calculation. Can be eliminated, and the route calculation can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a multi-layer network.
FIG. 2 is a diagram showing how the multi-layer network of the first embodiment is divided into cells, virtual nodes, and hierarchies.
FIG. 3 is a diagram showing a state in which the network of the first embodiment is made into virtual nodes.
FIG. 4 is a schematic diagram of a node according to the first embodiment.
FIG. 5 is a functional block diagram of a node according to the second embodiment.
FIG. 6 is a functional block diagram of a node according to a third embodiment.
FIG. 7 is a diagram illustrating a method of assigning switching capabilities to interfaces of a virtual node according to a fourth embodiment.
FIG. 8 is a diagram illustrating a method of assigning switching capabilities to interfaces of a virtual node according to a fifth embodiment.
FIG. 9 is a diagram illustrating an outline of a path setting cost in a virtual node network according to an eighth embodiment;
FIG. 10 is a diagram illustrating a method of assigning a cost via a virtual node according to a ninth embodiment.
FIG. 11 is a functional block diagram of a hierarchical network node according to a ninth embodiment.
FIG. 12 is a diagram illustrating a method of assigning a cost via a virtual node.
FIG. 13 is a diagram showing a method for assigning costs to nodes according to the eleventh embodiment.
FIG. 14 is a diagram illustrating a method of assigning costs to nodes according to a twelfth embodiment.
FIG. 15 is a diagram illustrating a method of assigning a cost via a virtual node according to a thirteenth embodiment.
FIG. 16 is a diagram illustrating a method of assigning a cost via a virtual node according to a fourteenth embodiment.
FIG. 17 is a diagram showing a route selection sequence according to the seventeenth embodiment.
FIG. 18 is a functional block diagram of a hierarchical network node according to a seventeenth embodiment.
FIG. 19 is a diagram showing a route selection sequence according to the eighteenth embodiment.
FIG. 20 is a diagram showing a network management system according to a nineteenth embodiment.
FIG. 21 is a diagram showing a network management system according to the twentieth embodiment.
FIG. 22 is a diagram showing a link bundling method according to the twenty-first embodiment.
FIG. 23 is a diagram showing a link bundling method according to a twenty-second embodiment.
[Explanation of symbols]
a1, a2, b, c1, c2 interface
A to E nodes
C cost calculator
LSDB-L1, LSDB-L2, LSDB-L3 Link state database
LS1, LS2 LS summary section
P Advertising Department
RS1 L1 route selector
RS2 L2 route selector
RS3 L3 route selector
SC SC (switching capability) allocator
S cost selection section

Claims (26)

Means provided in a network comprising one or a plurality of layers, for mutually exchanging information of the own node and links connected to the own node (hereinafter referred to as link state information) with other nodes;
Means for holding link state information of some or all nodes in the network obtained by the means for exchanging;
Means for selecting a path of a path of one or more types of layers based on the link state information held in the holding means according to the path setting request;
Means for changing the path selected and set by the selecting means according to the path change request based on the link state information held in the holding means,
The network to which it belongs is divided into a cell composed of a plurality of nodes, and this cell is defined as a virtual node. If there is a link connecting the inside and outside of the virtual node, the cell of this virtual node The point of contact between the inside and the outside is defined as the interface of the virtual node, and the virtual network composed of the virtual nodes is further divided into cells and virtual nodes, and the virtual networks further divided into cells and virtual nodes are the original virtual networks. Is defined as a higher-level network, and a hierarchical network is constructed by performing the cell division and virtual node conversion operations once or more than once.
A link state database that stores link state information advertised from other nodes or other virtual nodes in the virtual node to which the node belongs;
A node within the virtual node or a node that plays the role of an interface with the outside of the virtual node among the virtual nodes is defined as a border node,
A link state summarizing unit having means for generating interface information to the outside of the virtual node based on link state information inside the virtual node when the self is located at the border node;
An advertising unit for advertising the generated interface information to the outside of the virtual node. Means for identifying a group of links connecting the same virtual node to the ground among a plurality of links connecting the virtual nodes;
2. The hierarchical network node according to claim 1, further comprising: means for processing a link included in the link group identified by the identifying means as one virtual link. Means for identifying a first link group connecting the same virtual node to ground among a plurality of links connecting the virtual nodes,
Means for further classifying the first link group identified by the identifying means into a second link group sharing the same switching capability;
2. The hierarchical network node according to claim 1, further comprising: means for processing a link included in the second link group classified by the classifying means as one virtual link. The link state summarizing unit allocates switching capabilities in a virtual node to which the own node belongs to a link connected to the own node and a link corresponding to an interface connecting the virtual node to which the self node belongs and the outside. A switching capability allocating means for performing
2. The hierarchical network node according to claim 1, wherein the interface information is information on a switching capability assigned to the interface by the switching capability assignment unit. The link state summarizing section includes:
Switching capability allocating means for allocating a switching capability in the virtual node to which the own node belongs to a link connected to the own node and a link corresponding to an interface connecting the virtual node to which the own node belongs to the outside When,
A cost allocating means for allocating a transmission cost for each switching capability allocated by the switching capability allocating means,
2. The interface information is information on a switching capability assigned to the interface by the switching capability allocating unit and information on a transmission cost assigned to the switching capability of the interface by the cost allocating unit. The described hierarchical network node. The information of the switching capability assigned to the interface includes a layer of a path that can be set between the own node as a border node or a virtual border node and another border node or another virtual border node belonging to the same virtual node. The hierarchical network node according to claim 4, wherein the hierarchical network node is generated corresponding to each of the following. 6. The hierarchical network according to claim 4, wherein the information on the switching capability assigned to the interface is information on a switching capability of a border node or a virtual border node to which the link serving as the interface is directly connected. node. 2. The hierarchical network node according to claim 1, wherein the advertisement unit includes means for performing advertisement outside the virtual node each time a change occurs in the switching capability of the border node. 3. The hierarchical network node according to claim 1, wherein the advertisement unit includes a unit that performs advertisement outside the virtual node at regular intervals. The hierarchical network node according to claim 5, wherein the transmission cost information is generated by a reciprocal of a total number of unused interfaces to which a switching capability of the layer included in the virtual node is allocated. 6. The hierarchy according to claim 5, wherein the information on the transmission cost is generated based on the number of used interfaces / the total number of interfaces with respect to the number of used interfaces and the total number of interfaces to which the switching capability of the layer included in the virtual node is allocated. Network node. The information on the transmission cost is a cost of setting a path of an arbitrary layer between a border node in the virtual node and another border node belonging to the same virtual node as the border node. 6. The hierarchical network node according to claim 5, which is information determined for each layer. The cost includes a link cost of a link and a link cost of a node or a virtual node along a route when a path is set between a border node in the virtual node and another border node belonging to the same virtual node as the border node. 13. The hierarchical network node according to claim 12, further comprising: means for calculating a cost value of a route having a minimum value obtained by adding the node cost. The cost is calculated based on the link cost of the link and the link cost of the node or the virtual node along a route with the minimum hop number set between the border node in the virtual node and another border node belonging to the same virtual node as the border node. It is a value obtained by adding the node cost and
When there are a plurality of routes with the minimum hop number, there is provided a means for selecting, as a cost value, a cost value candidate having the smallest value from among a plurality of cost value candidates obtained by adding the routes. The hierarchical network node according to claim 12. 15. The hierarchical network node according to claim 13, wherein the value obtained by the addition is a reciprocal of the number of unused interfaces to which the switching capability of the layer included in the node along the route is allocated. . The value obtained by the addition is given by (number of used interfaces / total number of interfaces) with respect to the number of used interfaces and the total number of interfaces to which the switching capability of the layer included in the node along the route is allocated. Item 15. The hierarchical network node according to item 13 or 14. 17. The node according to claim 5, wherein the node corresponding to the interface of the virtual node includes means for calculating the transmission cost information or the cost at predetermined time intervals based on the link state information. Layered network nodes. The node corresponding to the interface of the virtual node is notified of the change in the use state of the interface inside the virtual node by the advertisement of the link state information, and transmits the information of the transmission cost or the cost each time the use state of the interface changes. 17. The hierarchical network node according to claim 5, further comprising means for calculating based on state information. A network comprising the hierarchical network node according to any one of claims 1 to 18. When setting a path of an arbitrary layer in a network configured by the hierarchical network nodes according to claim 1,
When selecting the route from the source node to the destination node, the destination node is referred to in the virtual node including the source node among the virtual nodes of the level 1 by referring to the link state database of the lowest level 1. To determine if
If the source node and the destination node do not exist in the same virtual node, it is determined whether the destination node exists in the virtual node including the source node of the level 2 by referring to the link state database of the next higher level 2. Judge,
By repeating this determination until the source node and the destination node are included in the same virtual node, a virtual node of level N (N is a natural number) including both the source node and the destination node is selected,
When selecting the level N path from the source node to the destination node in the selected level N virtual node, the path selection of the virtual node group included in the selected level N virtual node is performed by the level Based on the N link state databases, selecting by the selecting means of the level N;
When selecting a route of the next lower level (N-1) from the source node to the destination node among the virtual nodes included in the selected level N route, one lower level in the selected virtual node is selected. The path from the source node to the destination node is selected by the selecting means of the level (N-1) based on the link state database of the level (N-1), and this is repeated up to the lowest level 1. A step of selecting a hierarchical route. When setting a path of an arbitrary layer in a network constituted by the hierarchical network nodes according to claim 1,
When selecting the route from the source node to the destination node, the source node and destination node are in the same virtual node by referring to the link state database of the level N in the network including the highest level N virtual nodes. To determine if it exists
When the source node and the destination node exist in the same virtual node, the link state database at the next lower level (N-1) in the virtual node is referred to, so that the next lower node in the virtual node is referred to. It is determined whether the source node and the destination node exist in the same virtual node in the level (N-1) network,
This determination is repeated until the source node and the destination node are included in different virtual nodes, and by selecting a virtual node at one higher level (N−k) (k is a natural number), the source node and the destination node Select a virtual node of level (N−k) that includes both,
When selecting a level (N−k) route from the source node to the destination node in this virtual node, the route selection of the virtual node group included in the selected level (N−k) virtual node is performed. Based on the link state database of the level (N−k), a selection is made by the selecting unit of the level (N−k);
When selecting a route of the next lower level (N-k-1) from the source node to the destination node among the virtual nodes included in the route of the selected level (N-k), the selected node is selected. Based on the link state database of the next lower level (N−k−1) in the virtual node that has been selected by the selecting means of the level (N−k−1),
A hierarchical route selection method characterized by executing a procedure of selecting a route from a source node to a destination node by repeating this to the lowest level 1. In a virtual node at a lower level than the level including both the source node and the destination node, calculation for selecting a path in the own node is performed by inputting / outputting the input / output of the path among border nodes included in the virtual node. 22. The hierarchical route selection method according to claim 20, wherein a border node assigned as an interface performs the method. In a virtual node at a level lower than the level including both the source node and the destination node, a calculation for selecting a route in the own node is determined in advance as a representative node among border nodes included in the virtual node. 22. The hierarchical route selection method according to claim 20, wherein the border node is used. When installed in an information processing apparatus, when setting a path of an arbitrary layer in the network configured by the hierarchical network node according to claim 1,
When selecting the route from the source node to the destination node, the destination node is referred to in the virtual node including the source node among the virtual nodes of the level 1 by referring to the link state database of the lowest level 1. To determine if
If the source node and the destination node do not exist in the same virtual node, it is determined whether the destination node exists in the virtual node including the source node of the level 2 by referring to the link state database of the next higher level 2. Judge,
By repeating this determination until the source node and the destination node are included in the same virtual node, a virtual node of level N (N is a natural number) including both the source node and the destination node is selected,
When selecting the level N path from the source node to the destination node in the selected level N virtual node, the path selection of the virtual node group included in the selected level N virtual node is performed by the level Based on the N link state databases, selecting by the selecting means of the level N;
When selecting a route of the next lower level (N-1) from the source node to the destination node among the virtual nodes included in the selected level N route, one lower level in the selected virtual node is selected. Based on the link state database of the level (N-1), and selecting by the selecting means of the level (N-1);
A program for executing a procedure of selecting a route from a source node to a destination node by repeating the process up to the lowest level 1. When installed in an information processing apparatus, when setting a path of an arbitrary layer in the information processing apparatus in a network configured by the hierarchical network node according to claim 1,
When selecting the route from the source node to the destination node, the source node and destination node are in the same virtual node by referring to the link state database of the level N in the network including the highest level N virtual nodes. To determine if it exists
When the source node and the destination node exist in the same virtual node, the link state database at the next lower level (N-1) in the virtual node is referred to, so that the next lower node in the virtual node is referred to. It is determined whether the source node and the destination node exist in the same virtual node in the level (N-1) network,
This determination is repeated until the source node and the destination node are included in different virtual nodes, and by selecting a virtual node at one higher level (N−k) (k is a natural number), the source node and the destination node Select a virtual node of level (N−k) that includes both,
When selecting a level (N−k) route from the source node to the destination node in this virtual node, the route selection of the virtual node group included in the selected level (N−k) virtual node is performed. Based on the link state database of the level (N−k), a selection is made by the selecting unit of the level (N−k);
When selecting a route of the next lower level (N-k-1) from the source node to the destination node among the virtual nodes included in the route of the selected level (N-k), the selected node is selected. Based on the link state database of the next lower level (N−k−1) in the virtual node that has been selected by the selecting means of the level (N−k−1),
A program for executing a procedure of selecting a route from a source node to a destination node by repeating the process up to the lowest level 1. A recording medium readable by the information processing device, wherein the program according to claim 24 or 25 is recorded.

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