KR101600231B1 - Path computation method and apparatus - Google Patents

Abstract

Disclosed are a path computation method and an apparatus thereof. The path computation method comprises the steps of: initializing a path cost of each node; and computing a path by applying a port cost within a node and a link cost between nodes. In addition, in a case of multiple domains, the method comprises the steps of: simplifying a sub domain to be an abstract node having an external link as a port and doing abstraction of path costs between nodes within a sub domain to be a cost between ports; and exchanging abstraction node information containing information on the cost between ports.

Description

[0001] Path calculation method and apparatus [0002]

The present invention relates to a path calculation method and apparatus for calculating a path in consideration of a port cost of a node.

In the conventional shortest path algorithm, the Dijkstra shortest path method calculates the shortest path from the source node to the destination node only considering the cost of the link between the nodes constituting the network. However, the routers and switches constituting each network may include a plurality of ports having different performance between ports and different performance of the ports asymmetrically.

In the case of a node including a heterogeneous interface, dijkstra's shortest path method internally generates different costs depending on the connection between the port and the port. However, Dijkstra's shortest path method does not consider port characteristics for all nodes in the network, There is a problem that the path is calculated by considering only the path.

Also, in the case of a multi-domain network, it is common to exchange the topology or link cost information for the domain between the domains using a routing protocol. However, there are restrictions on network synchronization and traffic information exchange using routing protocols.

The first constraint is that there is no delivery method for the inter-port cost within the node. The second exchanges only the link information between all the nodes and the nodes.

Currently, there is no way to deliver differentiated costs between ports using routing protocols. Even if the topology and the traffic status information are exchanged with the simplified routing information using the routing protocol, the cost information between the ports can not be exchanged. In the case of a multi-domain network, abstraction of abstraction information (node information and link information is simplified by abstracting one virtual node and exchanging connectivity with external nodes) without exchanging all topology / The virtualized node sends the link to the virtualized node. In this case, since the link cost due to the segment routing between the internal nodes of the virtualized node, that is, the link cost between the virtual node and the virtual node is exchanged without the cost information between the ports of the virtualized node, Even if node information is exchanged or configured as an abstracted virtual node, it is difficult to accurately calculate the cost for the segment path in the abstracted domain.

For this reason, in the case of a multi-domain network, the route is selected by applying the policy method without directly calculating the route cost in the segment. However, the method of abstracting the information in the current domain and using the route in the calculation of the route in the multi- Most of them do not select the segment path that goes through policy. In this case, inter-domain route computation is optimized by taking into account the intra-domain segment path cost (the cost between the inbound port and the outbound port in the simplifying virtual node) since the inter-domain route is calculated without considering the cost calculation for the segment route of the other domain. There is a problem that a decision can not be made.

(01) Japanese Patent Application Laid-Open No. 2014-103656 (May 2014, 2015)

The present invention provides a topology configuration method, a path calculation method, and a device for calculating a path by reflecting a port cost and a link cost between nodes in a node constituting a topology.

Also, the present invention provides a topology configuration method, an information transfer method, a path calculation method, and a device capable of designating a part of a node disclosed to the outside among nodes of a sub domain in a multi-domain structure as an internal port of a node of a parent domain .

According to a first aspect, in the case of a multi-domain network, a link between a domain and a domain is designated as an internal port of a virtualized node provided in an upper layer through a link with a node connected to the external network, The link provides a way to compute the path taking into account the cost between the ports in the virtualized node.

According to the first embodiment, there is provided a method of controlling a method of managing a plurality of external connection nodes, the method comprising: selecting a part of external connection nodes of a sub- Abstracting the sub-domain into a virtual node on the external domain, and designating the selected node as an internal port of the virtual node; And exchanging information, including the cost between the designated internal ports, may be provided.

The external domain is a parent domain having a hierarchical structure with the lower domain.

The lower domain is a communication network provided by a communication provider different from the external domain.

After the step of designating the internal port, the external domain and the sub-domain may independently calculate paths individually reflecting the port cost and the inter-node link cost of each node.

The port cost is the inter port cost between the incoming port to the node and each outgoing port for connection from the incoming port to the neighboring node.

According to a first embodiment, there is provided a method comprising: initializing a path cost for each node; And

There is provided an information exchange method comprising exchanging a port cost within a node and a link cost between nodes.

The step of exchanging the information may include transmitting information to a neighbor or an upper node including a port cost in a target node and a link cost to a neighboring node adjacent to the target node.

The port cost is the inter port cost between the ingress port to the node and the egress port for connection to the neighbor node.

The link cost is the link cost between the inbound port to the node and the inbound port to the neighbor node.

The step of exchanging the information may further include forwarding the inter-port cost and the link cost after initializing the path cost for each node, wherein the step of communicating information between the nodes or the node Can be repeatedly performed.

According to a second embodiment, there is provided a method comprising: initializing a path cost for each node; And calculating a path reflecting the port cost within the node and the link cost between the nodes.

The step of calculating the path may include calculating a path cost for the path to the neighbor node using the port cost in the target node and the link cost to the neighboring node adjacent to the target node.

The port cost is the inter port cost between the ingress port to the node and the egress port for connection to the neighbor node.

The step of calculating the path may further include selecting a neighboring node having the minimum path cost among path costs for each path to the neighboring node as the target node after calculating the path cost, , And calculating the path cost according to the selection of the target node until the remaining nodes do not exist in the topology.

Wherein the step of selecting as the target node sequentially selects a neighboring node having the minimum path cost as a target node when the neighboring node having the minimum path cost is a plurality of neighboring nodes, Can be repeatedly performed.

The step of calculating the path may further include the step of summing the path cost to the target node and the path cost calculated from the target node to the neighbor node to update the path cost to the neighboring node have.

If the calculated path cost for the path to the neighbor node is greater than the previously set path cost, the path cost for the path to the neighbor node may not be updated.

The method may further include setting a port cost of each node and a link cost for a link between the nodes before calculating the path cost.

If each node is connected to a lower domain before the step of calculating the path, each node selects a part of the external connection nodes included in the lower domain and designates the part as an internal port of each node .

According to the second aspect, there is provided an apparatus capable of designating some nodes among the nodes connected to the external network as internal ports of nodes of an upper layer, and calculating paths by considering the cost between ports in the node

According to the first embodiment, the selection unit selects a part of the external connection nodes of the lower domain connected to the external domain. And a port designation unit that abstracts the subdomain as a virtual node on the external domain and designates the selected selected node as an internal port of the virtual node.

And a path calculation unit for calculating the path by reflecting the port cost of each node and the inter-node link cost.

According to the second embodiment, an initialization unit for initializing a path cost for each node; And a path calculation unit for calculating a path reflecting the port cost within the node and the link cost between the nodes.

The path calculation unit may include a path calculation unit for calculating a path cost for the path to the neighboring node using the port cost in the target node and the link cost to the neighboring node adjacent to the target node.

And a port designation unit for designating a portion of the external public nodes included in the lower domain to designate the internal ports of the respective nodes when the nodes are connected to the lower domain.

The topology configuration method, the path calculation method, and the apparatus according to an embodiment of the present invention can calculate the path by reflecting the port cost and the inter-node link cost in the node constituting the topology.

In addition, according to the present invention, it is possible to designate, as a port of a higher layer node, some nodes connected to an external domain among nodes of a lower domain in a multi-domain structure, thereby reducing an increase in complexity due to path calculation in a higher multi- There is an advantage.

1 is a flowchart showing a path calculation method according to a first embodiment;
2 shows a topology in a network according to the first embodiment;
3 shows a path cost matrix according to the first embodiment;
4 is a table showing path costs to each node according to the first embodiment;
5 is a diagram showing a pseudo code for a path calculation method according to the first embodiment;
6 is a diagram for explaining a path calculation method in a multi-domain structure according to the second embodiment;
7 is a block diagram schematically showing an internal configuration of a path calculation device according to the first embodiment;

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The present invention is for calculating an optimal path from a source node to a destination node in a network. The present invention can calculate an optimal path in a network considering the cost of a link between nodes as well as the cost of a port within a node.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating a topology in a network according to the first embodiment. FIG. 3 shows path cost metrics according to the first embodiment, and FIG. FIG. 4 is a table showing the path cost to each node according to the first embodiment, and FIG. 5 is a diagram illustrating a pseudo code for the path calculation method according to the first embodiment.

In step 110, the path calculation device 100 initializes the path cost of each node in the network.

In the initialization step, the path calculation apparatus 100 allocates the port cost in each node and the link cost to the link between each node. Here, the port cost may be the inter port cost from the ingress port to each node to the egress port for connection from each node to the neighboring neighbor.

As shown in FIG. 2, port costs depending on which internal port of each node is used may be different from each other. However, conventionally, the port cost between the internal ports of each node is not reflected in the path calculation, so there is a limit to calculate the optimal path.

Therefore, in the first embodiment, the path with the minimum path cost can be calculated by considering both the port cost in each node and the link cost between the nodes.

In the first embodiment, each node may be a switch or a router, but may be an independent network internally composed of a plurality of switches or routers. A method of setting an internal port for each node in the multi-domain structure will be described in detail with reference to FIG.

In FIG. 1, a method of calculating a path to one domain will be described in detail in order to facilitate understanding and explanation.

In step 115, the path calculation device 100 selects a minimum path cost node.

At initial start-up, the minimum path cost node may be the source node.

The minimum path cost node may then be selected as the node with the minimum path cost for each path.

In addition, the minimum path cost node may be plural. If there are a plurality of minimum path cost nodes, a minimum path cost node may be sequentially selected to sequentially calculate a path cost for a path from the minimum path cost node to the neighboring neighboring node.

For example, assume that the network is configured as shown in FIG. 2, the transmitting node (source node) is the A node, and the receiving node (destination node) is the F node. In this case, the minimum path cost at the minimum start can be selected as the A node (source node).

When the minimum path cost node is selected, in step 120, the path calculation apparatus 100 determines whether there are other remaining nodes.

If there are no other remaining nodes, the path calculation device 100 may determine that the minimum path cost node does not exist in the network as a destination node and calculate the path to the network, and terminate the path calculation process.

However, if there are other remaining nodes, the path calculation device 100 detects neighboring nodes adjacent to the minimum path cost node in step 125. [

In step 130, the path calculation device 100 determines whether a neighboring node exists.

If there is no neighbor node, the process proceeds to step 115. [

However, if a neighboring node exists, the path calculating apparatus 100 calculates the path cost for the new path to the neighboring node in step 135. [

For example, the path calculation apparatus 100 may calculate the path cost to the minimum path cost node and the path cost to the neighbor path by summing the path cost from the minimum path cost node to the neighbor node.

In order to facilitate the calculation, the path calculation device 100 generates path calculation metrics as shown in FIG. 3, and can use them to update the path costs for each node, respectively.

As shown in FIG. 3, for the A node, the path cost for the path up to the B-node can be calculated considering the port cost and the link cost with the B-node, and then updated.

As a result, the path cost to each node represents the path cost to the path to the incoming port of each node.

FIG. 4 shows the path cost metrics for each node, and the A node does not set the path cost to the source node. Since the node B is connected to the node A through the port a, the path cost to Ba can be set to 7.

In step 140, the path calculation apparatus 100 determines whether the newly calculated path cost is smaller than the path cost previously set for the corresponding neighbor node.

If the newly calculated path cost is greater than the path cost previously set for the neighboring node, the path calculation device 100 ignores the path and proceeds to step 125. [

However, if the newly calculated path cost is less than the path cost previously set for that neighbor node, the path calculation device 100 updates the path cost for the neighbor node in step 145. [ Then, the path calculation device 100 proceeds to step 125. [

Referring to FIG. 2, the path to the destination node (F node) based on the s port of node A is calculated as follows. However, the final receiving port may be composed of a connection having an independent node. Therefore, it is assumed that different costs may occur depending on the incoming port.

The s port of A node is a port of A node, and there is a cost between the port and the port for going to the neighboring node. In order to move from node A to node B, the path should be configured to port a of node B after being drawn to port b from port s of node A. In this case, the path cost is obtained by adding the link cost (5) from the port A to the port b of the node A to the port a of the node B by using the port b of the node A and the port b of the node A, The path cost up to < RTI ID = 0.0 > 7 < / RTI >

The path cost from node A to node C is the sum of the cost (5) from port s to port c of node A, and the cost from port c of node A to port a of node C The cost (2) can be summed and calculated as 7.

The minimum cost path to the neighbor node around the A node is 7, and the path cost to the B node and the path cost to the C node are the same.

Then, the path calculation device 100 arbitrarily selects either the B node or the C node because the path cost is the same. Suppose that a C node is selected to facilitate understanding and explanation.

The path calculation device 100 recalculates the path cost for the neighbor nodes based on the port a of the C node.

First, the path cost to the node B connected to the node C is calculated by multiplying the path cost from the node A to the node C by the path cost (7) from the node C to the node B (that is, (2) between port C to the port b of the C node and the link cost (2) for the connection of the port c of the B node to the port b of the C node are added together.

This is larger than the path cost 7 from node A to node B, so the path is ignored.

Next, the path cost to the E node connected to the C node is calculated as follows. (5) between the port cost from the C port of the C port to the port c for connection to the E port and the port cost from the C port of the C port to the a port of the E port The link cost (6) is added to the path cost from the existing A node to the C node to update the path cost.

Accordingly, the path cost from the node A to the node E can be updated to 18. The path cost may be updated at the E-node.

Next, since the path cost calculation for the C node has been completed, the path calculation device 100 performs the path cost calculation for the B node.

The path cost to the B node is set to 7. Next, the path cost from the B-node to the D-node is calculated as the inter-port cost to the B-port of the B-node from the a-port of the B-node to the D- The link cost (2) is added to 5, and the path cost 7 to the existing B node is added up to update 12.

The path calculation device 100 may then update the path cost to the neighbor nodes for the D node.

For example, E-node and F-node are detected as neighbor nodes of D-node. The cost of the path from the D node to the E node depends on the path cost from the D node to the E node to the path cost to the D node (the port cost from the a port of the D node to the c port of the D node to the E node, And the link cost (3) between the c port of the D node and the b port of the E node).

The path cost to the E node via the C node is 18, and the minimum cost to the D node is updated to 17 since the path cost to the E node via the B node and the D node is 17, which is smaller.

Then, the path calculation device 100 calculates the path cost to the F-node via the D-node. For example, the path calculation device 100 calculates the path cost from the D node to the F node to the path cost to the D node (the inter-port path cost from the a port of the D node to the b port of the D node to go to the F node, The path cost is calculated as 18 by summing the link cost of the node (2), the port b of the node D, and the port a of the node F. The path calculation apparatus 100 can set the path cost of the node F to 18.

Then, the path calculation device 100 calculates the path cost for the path via the E-node. The path cost of the F node to the path through the E-node is the cost of the path from the E-node to the E-node to the c-port of the E-node for connection to the F-node from the a-port of the E-node (5) The link cost (1) from the port c to the port b of the F node can be calculated. In this case, the path cost to the F node is 24 when it passes through the E node, and is not updated because it is larger than the path cost of the previous F node.

Therefore, the path calculation device 100 can select the path from the A node to the F node to the A node => B node => D node => F node as the minimum cost path.

As described above, the path calculation apparatus 100 can select the path with the minimum total cost as the optimal path by using the port cost from the ingress port to the egress port in each node and the link cost to the neighbor node adjacent to each node have.

5 illustrates a pseudo code according to the first embodiment.

6 is a diagram for explaining a path calculation method in a multi-domain structure according to the second embodiment.

According to the second embodiment, the network may include multiple layered domains. That is, one domain may include at least one layered sub-domain, and the parent domain and the sub-domain may calculate respective paths individually.

Also, a node in the topology may look like a single router or switch, but it may be an independent network consisting of several switches or routers internally. However, only the node for the external network and the connection part is displayed as a link, and the internal connection node is not disclosed, and the configuration or state of the node for the internal network is hidden.

Accordingly, some of the nodes connected to the external network (upper domain) of the lower domain may be selected, and some selected nodes may be designated as internal ports of the nodes of the upper domain to be used for route calculation. Here, the nodes connected to the external network may be external connection nodes that are exposed to the external network.

As described above, some of the external connection nodes disclosed in the external network (upper domain) of the lower domain are designated as the internal ports of the upper layer node and used for the route calculation, thereby reducing the complexity of the route calculation .

Describing in more detail with reference to FIG. 6, it can be seen that node C in FIG. 6 includes a sub-domain. In this case, the sub-domain may include nodes that are exposed to external networks such as a node, s node, b node, c node, e node, and f node. At this time, the path calculation device 100 can receive information on a plurality of nodes disclosed to the outside from the sub-domain, and selects a, b, and c nodes among a plurality of nodes disclosed in the external network, It can be specified as the internal port of the C node of the domain.

In addition, the lower domain and the upper domain each include a path calculation device that is independent of each other, and each of the path calculation devices can independently perform the path calculation independently for the lower and upper domains.

In the multi-domain structure as shown in FIG. 6, the upper level domain can calculate the path having the lowest cost in the upper level domain using the cost to the external connection node (i.e., external connection port) for the lower level domain abstracted by the lower level domain.

As described above, the path calculation of the upper domain is proportional to the number of the external connection ports connected to the upper domain, not the number of nodes of the lower domain, which is advantageous in that the complexity does not increase compared to the conventional method.

Also, in the case of the lower domain, there is an advantage that the traffic for information exchange does not increase greatly because the node or traffic information updated at any time is abstracted into port information of the virtual node of the upper domain and transmitted to the upper domain.

However, in the second embodiment, it is assumed that a certain node of the upper domain includes a transmitting / receiving node managed / set separately by the administrator.

7 is a block diagram schematically showing the internal configuration of the path calculation apparatus according to the first embodiment.

7, the path calculation apparatus 100 according to the first embodiment includes an initialization unit 710, a path calculation unit 715, a topology configuration unit 720, a memory 725, and a processor 730 .

The initialization unit 710 initializes the path cost for each node in the topology. The initialization unit 710 may allocate the port cost and the inter-node link cost for each node constituting the topology.

The path calculation unit 715 calculates the path by reflecting the port cost of each node and the inter-node link cost. This is the same as that described above with reference to FIG. 1, so that a duplicate description will be omitted.

The topology configuration unit 720 functions to configure the topology.

At this time, in the case of a multi-domain structure, the topology configuration unit 720 can abstract the topology to a node (virtual node) in the upper domain for the lower domain.

The topology configuration unit 720 may receive information on an external connection node connected from a lower domain to a higher-level domain, select a part of the external connection node, and configure the topology by designating the internal connection port as an internal port of the corresponding virtual node.

Accordingly, the topology configuration unit 720 includes a selection unit for selecting some of the external connection nodes connected to the external domain among the nodes of the subdomain, and a port for designating a selected node as an internal port of the virtual node corresponding to the subdomain And a designation unit.

The detailed description thereof is the same as that described with reference to FIG. 6, so that redundant description will be omitted.

The memory 725 stores various algorithms necessary for performing a path calculation method reflecting the port cost and the inter-node link cost in the node according to the first embodiment, various data derived from the process, and the like.

The processor 730 is connected to the internal components (e.g., the initialization unit 710, the path calculation unit 715, the topology configuration unit 720, the memory 725, and the like) of the path calculation apparatus 100 according to the first embodiment ).

8 is a block diagram schematically showing an internal configuration of an apparatus for generating an abstracted node according to the first embodiment.

Referring to FIG. 8, an apparatus () for generating an abstracted node according to the first embodiment includes a port selection unit 810 and a node abstraction unit 815.

The port selection unit 810 selects a part of external public nodes included in the lower domain and designates the port as a port when each node is connected to a lower domain in a multi-domain environment.

The node abstraction unit 815 generates an abstracted node having the external public node as the port for the lower domain and abstracts the inter-node path cost in the lower domain as the inter-port cost of the abstracted node, And performs a function of generating node information. In addition, the node abstraction unit 815 may perform the function of transmitting the abstracted node information to the upper domain. The abstracted node information can be transmitted to the upper domain through the routing protocol.

Meanwhile, in a multi-domain structure according to an embodiment of the present invention, a method of abstracting a subdomain to a virtual node to construct a topology, calculating a path using a port cost of each node in the topology and a link cost between nodes, May be implemented in the form of program instructions that may be executed through a means for processing information and recorded on a storage medium. The storage medium may include program instructions, data files, data structures, and the like, alone or in combination.

Examples of program instructions include machine language code such as those produced by a compiler, as well as devices for processing information electronically using an interpreter or the like, for example, a high-level language code that can be executed by a computer.

The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

100: Path calculation device
710:
715: Path calculation unit
720:
725: Memory
730: Processor

Claims (24)

In a method for a path calculating device to calculate a path,
Setting a port cost and a link cost for each node; And
Calculating a path reflecting the port cost within the node and the link cost between the nodes,
Wherein the calculating the path comprises:
Wherein the path cost to the target node and the calculated path cost from the target node to the neighboring node adjacent to the target node are summed and updated as the path cost for the path to the neighboring node. The method according to claim 1,
Wherein the calculating the path comprises:
And calculating a path cost for the path to the neighboring node using the port cost in the target node and the link cost to the neighboring node adjacent to the target node. The method according to claim 1,
Wherein the port cost is a cost between an incoming port to the node and an outgoing port for connection to the neighboring node from the node. 3. The method of claim 2,
Wherein the calculating the path comprises:
After calculating the path cost,
Further comprising selecting a neighboring node having the minimum path cost among the path costs for each path to the neighboring node as the target node,
Calculating a path cost according to the selection of the target node until there is no remaining node in the topology. 5. The method of claim 4,
Wherein the step of selecting the target node comprises:
When a plurality of neighboring nodes having a minimum path cost is selected as a target node, a neighboring node having the minimum path cost is sequentially selected as a target node,
And calculating a path cost for each successively selected target node. delete The method according to claim 1,
Wherein the route cost for the route to the neighboring node is not updated if the calculated route cost for the route to the neighboring node is greater than the previously set route cost. The method according to claim 1,
Prior to calculating the path cost,
Setting a port cost of each node and a link cost for a link between the nodes. The method according to claim 1,
Before the step of calculating the path,
If each of the nodes is connected to a lower domain, each of the nodes selects a part of the external connection nodes included in the lower domain and designates the internal connection port as an internal port of each of the nodes. In a method for a path calculating device to calculate a path,
Selecting a part of external connection nodes of a sub-domain connected to an external domain; And
Abstracting the sub-domain into a virtual node on the external domain, and designating the selected selected node as an internal port of the virtual node. 11. The method of claim 10,
Wherein the external domain is a parent domain having a hierarchical structure with the child domain. 11. The method of claim 10,
Wherein the lower domain is a communication network provided by a communication company different from the external domain. 11. The method of claim 10,
After the step of designating the internal port,
Wherein the external domain and the sub-domain independently calculate paths separately reflecting the port cost of each node and the inter-node link cost. 14. The method of claim 13,
Wherein the port cost is a cost between an incoming port to the node and a port to each outgoing port for connection from the incoming port to the neighboring node. A computer readable recording medium on which program codes for carrying out the method according to any one of claims 1 to 5 and 7 to 14 are recorded. A selection unit for selecting a part of external connection nodes of a sub domain connected to the external domain; And
And a port designation unit for abstracting the subdomain as a virtual node on the external domain and designating the selected selected node as an internal port of the virtual node. 17. The method of claim 16,
And a path calculation unit for calculating a path reflecting the port cost and the inter-node link cost of each node. An initialization unit for initializing a path cost for each node;
And a path calculation unit for calculating a path reflecting the port cost in the node and the link cost between the nodes,
The path calculation unit may calculate,
Wherein the path cost to the target node and the path cost calculated from the target node to the neighboring node adjacent to the target node are summed and updated as the path cost for the path to the neighboring node. 19. The method of claim 18,
The path calculation unit may calculate,
And a path calculation unit for calculating a path cost for a path to the neighboring node using a port cost in the target node and a link cost to a neighboring node adjacent to the target node. 19. The method of claim 18,
Further comprising a port designation unit for selecting some of the external public nodes included in the lower domain and designating the selected external public nodes as internal ports of the respective nodes when the nodes are connected to the lower domain. A port selection unit selecting a part of external public nodes included in the lower domain when each node is connected to a lower domain in a multi-domain environment; And
And a node abstraction unit for generating an abstracted node having the selected external public node as a port for the lower-level domain and abstracting the inter-node path cost in the lower-level domain as a cost between ports of the abstracted node, / RTI > 22. The method of claim 21,
Wherein the abstracted node information is transmitted via a routing protocol. delete Initializing a path cost for each node;
Selecting a part of external public nodes included in the lower domain when each node is connected to a lower domain in a multi-domain environment;
Generating an abstracted node having the selected external public node as a port for the lower-level domain, abstracting the inter-node path cost in the lower-level domain as a cost between ports of the abstracted node to generate abstracted node information; And
And transmitting the abstracted node information to a parent domain through a routing protocol or a control protocol.

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