KR100600952B1 - Router and its method for provide optimal path within a subnetwork in hierarchical transport network - Google Patents

Abstract

The present invention relates to a routing apparatus and method for providing a shortest path in a subnetwork of a hierarchical communication network, and includes various causes (connection creation, connection deletion, connection modification, failure, and It provides the shortest routing path by reflecting network status change by management status change in real time.

Therefore, when providing a routing service, the network service provider can consider the state of network resources in real time. Therefore, it is possible to provide a routing service in consideration of the state of the entire network, thereby preventing traffic concentration on a specific link or node. Since more connections can be established with network resources, revenue can be expected to increase, and from the subscriber's point of view, selecting the path with the minimum number of hops between any transmitting / receiving nodes minimizes the latency and improves the traffic transmission quality. You can expect.

Real-time shortest path selection router considering network state change

Description

Routing device and method for providing shortest path in subnetwork of hierarchical communication network {Router and its method for provide optimal path within a subnetwork in hierarchical transport network}

1 is a diagram showing the construction of a large-scale asynchronous transmission mode communication network constructed in a conventional hierarchical structure.

2 is a diagram illustrating a conversion rule for converting various types of network shapes applied to an embodiment of the present invention into a routing state from a routing point of view.

3A to 3E are diagrams of routing algorithms for selecting shortest paths in an arbitrary subnetwork applied to an embodiment of the present invention.

4 is a diagram illustrating a routing table constructed according to a routing algorithm employed in an embodiment of the present invention.

5A and 5B are diagrams showing an internal configuration diagram of a router apparatus employed in the embodiment of the present invention.

6 is a flowchart illustrating a routing table reconstruction process according to a network state change employed in an embodiment of the present invention.

7 is a flowchart illustrating a process for providing a routing service for providing the shortest path by the router apparatus.

<Description of Symbols for Main Parts of Drawings>

1: Main Router Module 1a: Main Routing Algorithm

1b: primary routing table 2: secondary router module

2a: secondary routing algorithm 2b: secondary routing table

3: Network shape and state management module 3a: Connection admission control algorithm

3b: network shape and state management information 4: workflow management module

5: asynchronous transfer mode switch

The present invention provides a routing apparatus and method for providing a shortest path in a subnetwork of a hierarchical communication network capable of providing a shortest path in real time by reflecting a network state in any subnetwork of a hierarchically configured communication network according to a management area. It is about.

In general, in a large communication network, the communication network is divided into several management areas in consideration of ease of management and scalability. The divided unit management area is called a subnetwork. In one subnetwork, one to several dozen asynchronous transfer mode switches are assigned and managed.

As an example, FIG. 1 is a schematic diagram showing a division of a large network composed of a combination of asynchronous transfer mode switches and links connecting them into four sub-networks, which are management areas. Referring to FIG. 1, a communication network is divided into four subnetworks, and each divided network manages four asynchronous transmission modes and a link connecting them.

However, in the conventional asynchronous transmission mode, the state of the network changes from time to time as the remaining bandwidth of the link changes as the connection is created, deleted, and modified, and the failed link and switch cannot be used until the failure is recovered due to the failure of the link or switch. It becomes a state. In addition, various states of links and switches are maintained for management purposes, so certain links or switches may not be available depending on these states.

Therefore, from the point of view of network resource management, it is possible to manage and manage the network resource state in various ways. However, from the routing point of view, the time for shortest path selection considers all states as the network configuration becomes complicated. This has to be exponentially increased disadvantages. In other words, in terms of network management, it is easy to manage a plurality of states for links and nodes, but from a routing point of view, as the network shape becomes complicated, when selecting the shortest path between any transmitting / receiving nodes, any one node or link The routing path selection time is increased because all states of the network must be compared.

Accordingly, the present invention has been devised to solve the above-mentioned problems. In order to minimize the routing service providing time, the present invention converts various states representing network resource states into a single routing state that is meaningful in terms of routing, and thus, in the shortest time. Define a network resource state transition method capable of providing a route, define a routing algorithm that can select the shortest path in real time when an arbitrary transmission / reception point is specified according to the defined routing state of the network resource state transition method, and state transition A router device equipped with a method and a routing algorithm is provided to map various states of network resources to one state necessary from a routing point of view, and to select a shortest path with one routing state instead of various resource states when selecting a routing path. Routing route calculation time It is an object of the present invention to provide a routing apparatus and method for providing the shortest path in a subnetwork of a hierarchical communication network so as to be significantly reduced.

In order to achieve the above object, a network shape change method for providing an optimal path in a hierarchical network structure includes: a) collecting the state of network resources, changing the routing state of links and nodes according to translation rules, and storing the routing state; process; b) notifying the changed routing state in step (a) and checking the state of the primary router to determine whether the router is idle; c) reconstructing the routing table by changing the network state according to the main router module when the main router state is in the idle state as determined in step (b); And d) if it is determined in step (b) that the primary router state is not idle, inspecting the idle state of the secondary router and constructing a routing table by changing the network state according to the secondary router module. do.

In addition, in order to achieve the object of the present invention, a routing service method for providing an optimal path in a hierarchical network structure includes: a) determining an idle state of a primary routing module and a secondary routing module when a shortest path selection between arbitrary transmission / reception points is requested; Process of doing; b) requesting routing service to the main lighting module and selecting the shortest path from the main routing table when the state of the main router is idle as determined in step (a); c) providing the routing service by changing the network shape and state and notifying the main router module that it is in an idle management state when it passes by determining whether the connection acceptance control of the shortest path selected in step (b) is passed. process; d) requesting a routing service from the auxiliary routing module and selecting the shortest path from the auxiliary routing table when the state of the auxiliary router is idle as determined in step (a); And e) if it passes the connection acceptance control of the shortest path selected in step (d) and passes, changes the network shape and state and notifies the auxiliary router module that the auxiliary router module is in an idle management state to provide routing services. Characterized in that the process is made to include.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The large-scale communication network divides the communication network into several sub-networks as shown in FIG. 1 according to management areas in consideration of ease of management and scalability. Each segmented network manages network resources consisting of switches and links belonging to its own management domain.

For network resource management, the network resources have management states (UNLOCKED, SHUTTING DOWN, UNLOCKLED), operational states (ENABLED, DISABLED), and available states (NORMAL, FAULT) as shown in FIG. 2, respectively. Maintain state.

In other words, from a network management perspective, the following four types of states are managed, the first being an administrative state with UNLOCKED, SHUTTING DOWN, and LOCKED states. It is set by the operator in terms of management.

Second, Operational State is a state expressing whether a link or a switch can be serviced and is defined as ENABLED or DISABLED, which is set and managed by the network management system without operator intervention. The third is Available Status, which represents the detailed information of the operational status, which is defined as NORMAL and FAULT. Fourth, the residual bandwidth is defined only for the link and is defined as the ratio of the remaining bandwidth to the total bandwidth of the link.

Among the administrative states, UNLOCKED means that a connection can be created, deleted, and modified. SHUTTING DOWN can delete a connection existing in a link / switch, but creates a new connection or creates an existing connection. Means the state that cannot be changed, and LOCKED means that connection creation, deletion and modification are all impossible.

ENABLED represents the state in which traffic can be transmitted through a corresponding link or switch, and DISABLED represents a state in which traffic transmission through a corresponding link or switch is impossible.

The Available Status represents a detailed status of the operational status, and the NORMAL represents a status in which normal traffic transmission / reception through the corresponding link or switch is possible when the operational status is ENABLE. In this case, the fault (FAULT) indicates that the reason for changing the operation state to DISABLE when the operation state is DISABLE is due to a failure.

The various states described above are general states representing the state of a network resource (link or switch). It is not necessary to maintain all of these states from a routing point of view, but it is desirable to convert them to meaningful states from a routing point of view.

In FIG. 2, the states of nodes and links for routing are defined as IN and OUT. NORMAL refers to the state of the link or node to be reflected in the network shape when the shortest path is selected, and OUT refers to the state of the link or node to be excluded from the network shape when the shortest path is selected. Therefore, the link and node declared as OUT are excluded when the routing algorithm is executed, so the time for shortest path selection is significantly reduced.

Methods and rules for converting network resource states (administrative state, operational state, available state and remaining bandwidth) to routing state from a routing point of view are

If the management state of the link or switch is UNLOCKED, the routing state is IN, and if it is SHUTTING DOWN or LOCKED, the routing state is OUT. If the operational state of the link or switch is ENABLED, the routing state is IN and if it is DISABLE, the routing state is OUT.

If the available state of the link or switch is NORMAL, the routing state is IN, and if the fault is FAULT, the routing state is OUT. If the remaining bandwidth of the link does not exceed 20% of the total bandwidth, the routing state of the link is IN, and if it exceeds 20%, the routing state of the link is OUT.

According to the above rules, the management state of the link and node in the network configuration for routing as shown in FIG. 3 is UNLOCKED, the operation state is ENABLED, the available state is NORMAL, and the remaining bandwidth is the total bandwidth. The routing state is defined as IN only if it does not exceed 20%, and in all other cases it is defined as OUT.

In addition, the network shape is defined as a node and a link as shown in FIG. A node corresponds to an asynchronous transfer mode switch managed inside a subnetwork, and a link refers to a link connecting an asynchronous transfer mode switch. Accordingly, FIG. 3 is an exemplary diagram representing a network shape of the subnetwork 1 of FIG. 1.

In FIG. 3, link 6 in the network configuration represents a link in which a failure occurs at present, and thus traffic transmission / reception over this link is impossible. If a link fails, its operational state is DISABLED and its available state is declared as FAULT, so the routing state is declared OUT from the routing point of view, regardless of the state of management or remaining bandwidth. It is excluded from the shortest path selection.

In FIG. 3, when the cause of failure for the failed link 6 is resolved, the operational state of the link 6 is ENABLED and the available state transitions to NORMAL. Accordingly, the routing state of the link 6 is locked. (UNLOCKED) and if the remaining bandwidth remains above 20% of the total bandwidth, the routing state is IN, and if the managed state is not UNLOCKED and the remaining bandwidth remains below 20% of the total bandwidth, Regardless of the transition of state and available state, the routing state for link 6 is set to OUT. When the routing state conversion according to the network resource state (management state, operational state, available state and remaining bandwidth) for nodes and links in the network configuration is completed,

As shown in FIG. 3, an order is defined at each node and a link, the value thereof is set to a maximum value, and the shortest path between any transmitting / receiving nodes designated by the shortest path selection routing algorithm is selected.

When the transmitting / receiving node to select the shortest path in subnetwork 1 is node 1 and node 4, and the routing state of link 6 is OUT, the process of selecting the shortest path between node 1 and node 4 is as follows. .

First, in step 1, the order of the transmitting node 1 is set to 0. In step 2, the order of the transmitting node 1 is set to 0, and then the value of increasing the order of all the links connected to the node 1 to the order of the node 1 is set. If the value set in the link is less than or equal to the value to be newly set, the existing order is maintained without setting a new order. In this example, the order of all links 1, 2, and 3 connected to node 1 is set to 인, which is the maximum value, and the new order is 0 +1 = 1, which is node 1, so link 1 is 1 It is newly set in the order of.

In step 3, when the order setting operation for the neighbor link of node 1 is completed in step 2 of FIG. 3, the order value for node 2, which is the neighbor node of link 1, is set as the link value. The order (Order) of node 2, which is the neighbor node of link 1, sets 1, which is the order of link 2. In this process, if the existing order of Node 2 is smaller than the newly set order, the new order is set to the new order, or the existing order is maintained as it is. The same process is performed for link 2 and link 3 which are neighbor links of node 1.

In step 4, the ordering operation is performed for nodes 2, 3, and 4 that have a new order value. In the case of node 2, the order of link 1, link 4, and link 5, which are neighboring links to node 2, is changed. In this process, the order to be set in the neighbor link is increased by 1 to 1, which is the order of node 2. Set the value (2). In this process, if the new link order is smaller than the preset link order, the new order is set. If the preset order value is smaller than the new order, the existing order is maintained. This process determines the link order for links 4, 5, and 6 in step 4.

In step 5, links 1, 5, and 6 are set to node 4 in order. In this process, if the order value less than the order value of links 1, 5, and 6 is set to the order value of node 4, the existing node 4 order is maintained and the newly set order value is greater than the existing node order value. Only a small number is changed to the new order value.

In the process 2, the order value of the node 5 is set to 1, and in the process 5 of FIG. 3, when the order value of the link 5 is compared with the order value of the node 5 in the process 5 of FIG. Do not change it to 2, the order value of 5. In addition, since the routing state of link 6 is defined as OUT, the value of link 6 is not reflected in node 5 order.

Comparing the order of the nodes and links set in the process 5 of FIG. 3 through the above process, the order of the transmitting node is 0 and the order of the receiving node 5 is 1. The order set in the receiving node means the number of links (hop counts) of the shortest path from the transmitting node to the receiving node. Therefore, when a link having the same order value as that of node 5 is found at receiving node 5, it is link 1. Thus, the shortest path between node 1 and node 5 is "node 1 <-> link 1 <-> node 5" with a hop count of 1.

After the above process, if the order of the receiving nodes is the maximum value, it means that there is no possible routing path between the corresponding transmitting / receiving nodes.

The routing table calculated for the subnetwork 1 of FIG. 1 according to the routing algorithm of FIG. 3 is shown in FIG. 4. In the example of FIG. 4, cost means the number of links (hop counts) present in the shortest path between the transmitting / receiving nodes, and reachability indicates whether a routing path exists between the transmitting / receiving nodes.

In FIG. 3, since the routing state of link 6 is OUT, the hop count of the shortest path between node 2 and node 4 is 2 via link 4 and link 5. If the routing state of link 6 is IN, the shortest path hop count for node 2 and node 4 will be 1.

Meanwhile, a router equipped with a rule for changing the network resource state to the routing state illustrated in FIG. 2 and the routing algorithm of FIG. 3 has the configuration as shown in FIGS. 5A and 5B, and the configuration is the main router module 1 and the secondary router. It comprises a module (2), network and state management module (3), workflow management module (4).

The main router module 1 also includes a main routing algorithm 1a and a main routing table 1b. The secondary router module 2 comprises a main routing algorithm 2a and a main routing table 2b. The network shape and state management module 3 includes a connection acceptance control algorithm 3a and network shape and state management information 3b.

In this case, each module constituting the router performs the following functions when a network state change and a routing service request are made.

First, when changing the network state, the network shape and state management module 3 collects the state (management state, operating state, available state) of the network resource from the switch (100), and thus the routing state of the link and node according to FIG. 2. It changes according to the rules and stores the routing state in the network configuration and management information 3b database (110, A-1).

When the network configuration and state management module 3 notifies the workflow management module that the network management state has changed (120, A-2), the network configuration and state management module 3 checks the states of the primary router module and the secondary router module (A-3-1). , A-3-2). The state of the router is set in the primary router and the secondary router module, respectively. The state of the router represents the current work performed by the primary / secondary router module and is divided into "build routing table", "provide routing service" and "idle" states.

": Building Routing Table" status means that the routing table building operation is being performed. The "Routing Service Provisioning" status means that the shortest path providing request is received by the network management system and is currently providing routing service. " Idle "state means that nothing is currently being done.

The workflow management module that receives the network management status change notification checks the state of the primary / secondary router module and sends a request to rebuild the routing table from the router module that is in the "idle" state (130, 140, A-4-1, A-). 4-2). The primary router module 1 or the secondary router module 2 that has received the routing table reconstruction request is illustrated in FIG. 4 by the method shown in FIG. 3 using the routing algorithm 1a / 2a mounted thereon. A routing table is constructed and stored in the primary routing table 1b or the secondary routing table 2b (131, 141, A-5-1, A-5-2).

After completing the routing table creation, the primary / secondary router module (1/2) sets its status to "idle" and informs the workflow management module that the routing table rebuilding is complete due to the network state change (132, 142). , A-6-1, A-6-2).

If the shortest path selection request between any transmitting / receiving point by the network management system arrives at the workflow management module 4 (200, B-1), the workflow management module is the primary router module 1 and the secondary router module. Inquiry state (2) (210, B-2-1, B-2-2) is requested to provide a routing service to the router module in the " idle " state (B-3-1, B-3-2). . If both the primary router module 1 and the secondary router module 2 are "idle", priority is given to the primary router module 1 (220-a), and the status of both routers is "idle". If not, the router module that is in the "idle" state of the primary / secondary router module is first requested to provide a routing service.

The primary or secondary router module receiving the request for rebuilding the routing table finds the shortest path between the transmission / reception points specified in the primary routing table 1b or the secondary routing table 2b (B-4-1, B-4-2). It requests the network shape and state management module 3 for the connection admission control (B-5-1, B-5-2). The network shape and state management module 3 receiving the connection admission control request determines whether the remaining bandwidth for the link on the routing path selected by the primary / secondary router module according to the connection admission control algorithm 3a can accommodate the requested bandwidth. Determine whether or not (connection admission control).

If the selected link passes the connection admission control, the remaining bandwidth is changed among the network resource states of the link (240-a / 240-b). When the remaining bandwidth is less than 20% of the total bandwidth as a result of the state change of the remaining bandwidth, the routing state existing in the network shape and state management information 3b is changed to OUT (B-6).

The main / second router module notifies the workflow manager of the path that has passed the connection admission control by the connection admission control algorithm 3a of the network configuration and state management module 3 (B-7-1, B-7-). 2). The workflow manager provides the network management system with the shortest path provided by either the primary routing module or the secondary routing module (B-8). Finally, the primary or secondary router module notifies the workflow management module that its management status is "idle", thereby providing the routing service (260).

The present invention defines a state transition rule that converts various kinds of network resource states into one routing state from a routing point of view, thereby minimizing time for selecting the shortest path between any transmitting / receiving points while maintaining various network resource states. In addition, we propose a routing algorithm to provide the shortest path in any subnetwork. In addition, in configuring a router device equipped with a state change rule and a routing algorithm, a primary router module and a secondary router module are provided so that a routing service can be provided in the shortest time when a routing service request is requested.

When providing a routing service according to the above-described method and apparatus, the network provider can consider the state of network resources in real time from the viewpoint of the network provider, and thus, it is possible to provide a routing service considering the state of the entire network, thereby providing traffic to a specific link or node. By avoiding congestion, establishing more connections with the same network resources, we can expect to increase revenue, and by choosing the path with the minimum number of hops between any transmitting / receiving node from the subscriber's point of view By minimizing the delay time, the traffic transmission quality is improved.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications and modifications belong to the following claims You will have to look.

Claims (10)

The network shape change method for providing an optimal path in the hierarchical network structure a) collecting the state of network resources to change the routing state of links and nodes according to translation rules and to store the routing state; b) notifying the changed routing state in step (a) and checking the state of the primary router to determine whether the router is idle; c) reconstructing the routing table by changing the network state according to the main router module when the main router state is in the idle state as determined in step (b); And and d) if the primary router state is not in the idle state as a result of the step (b), checking the idle state of the secondary router and establishing a routing table by changing the network state according to the secondary router module. A routing method for providing the shortest path in a subnetwork of a structured communication network. The method of claim 1, The conversion rule in step (a) is An administrative state which is divided into unlocked, shooting down, and locked and is set by an operator for network management; An operational state indicating whether a link or a switch can be serviced with a state divided into enabled and disabled; An available state expressing detailed information of the network operating state with a state divided into normal and fault; And A routing method for providing the shortest path in a subnetwork of a hierarchical communication network, characterized in that the remaining bandwidth defines a ratio of the remaining bandwidth to the total bandwidth of the link. The method of claim 2, In the management state Unlocked is a state in which a network can be created and deleted, and the shooting down is a state in which a link existing in a link and a switch can be deleted but a new connection can not be created or a basic connection can not be changed. Locked is a routing method for providing the shortest path in the sub-network of a hierarchical communication network, characterized in that the connection creation, deletion, and modification are all impossible. The method of claim 2, In the above operating state Enable (enabled) is a state in which traffic can be transmitted through a corresponding link or switch, and the disabled (disabled) is a subnetwork of a hierarchical communication network, characterized in that it is defined as a state in which traffic can not be transmitted through the link or switch. Routing method to provide the shortest path in the network. The method of claim 2, In the available state, normal is a state where normal traffic can be transmitted / received through a corresponding link or switch when the operational state is enabled, and the fault is disabled when the operational state is disabled. A routing method for providing the shortest path in a subnetwork of a hierarchical communication network, wherein the reason for the change is defined as a failure. The method of claim 1, Step (c) is c1) requesting reconfiguration of the routing table if the primary router state is idle; c2) generating and storing a new main routing table according to the changed routing state after receiving the reconstruction request in step (c1); And c3) the routing method for providing the shortest path in the sub-network of the hierarchical communication network, wherein the step (c2) is set to idle after completing the creation of the main routing table and notifies that the main routing table is rebuilt. . The method of claim 1, (D) process d1) requesting reconfiguration of the routing table when the secondary router state is idle; d2) generating and storing a new main routing table according to the changed routing state after receiving the reconstruction request in step (d1); And d3) The routing method for providing the shortest path in the sub-network of the hierarchical communication network, characterized in that (d2) in the step of setting the idle after completing the creation of the main routing table and notifying that the routing table is rebuilt. Network shape changer to provide optimal path in hierarchical network structure a) means for collecting the state of network resources to change the routing state of links and nodes according to translation rules and to store the routing state; b) means for notifying the changed routing status in the means (a) to check the status of the primary router to determine if it is idle; c) means for rebuilding the routing table by changing the network state according to the main router module when the main router state is idle as determined by the means (b); And d) means for building a routing table by changing the network state according to the secondary router module by checking the idle state of the secondary router when the primary router state is not idle as determined by the means (b). Routing device for providing the shortest path in the subnetwork of the hierarchical network. Routing service method for providing optimal path in hierarchical network structure a) determining an idle state of the primary routing module and the secondary routing module when a shortest path selection between any transmission / reception points is requested; b) requesting routing service to the main lighting module and selecting the shortest path from the main routing table when the state of the main router is idle as determined in step (a); c) providing the routing service by changing the network shape and state and notifying the main router module that it is in an idle management state when it passes by determining whether the connection acceptance control of the shortest path selected in step (b) is passed. process; d) requesting a routing service from the auxiliary routing module and selecting the shortest path from the auxiliary routing table when the state of the auxiliary router is idle as determined in step (a); e) providing the routing service by changing the network shape and state and notifying the auxiliary router module that it is in an idle management state when it passes by determining whether the connection acceptance control of the shortest path selected in step (d) has passed. Routing method for providing the shortest path in the sub-network of the hierarchical communication network, characterized in that the process is included. Routing service device for providing an optimal path in a hierarchical network structure a) means for determining an idle state of the primary routing module and the secondary routing module as a shortest path selection between any transmission / reception points is requested; b) means for requesting a routing service from the main lighting module and selecting the shortest path from the main routing table when the state of the main router is idle as determined by the means (a); c) providing the routing service by changing the network shape and state and notifying the main router module that it is in an idle management state when it passes by determining whether the connection acceptance control of the shortest path selected in the above (b) means passes. Way; d) means for requesting a routing service to the auxiliary routing module and selecting the shortest path from the auxiliary routing table when the state of the auxiliary router is idle as determined by the means (a); And e) When the pass through the connection acceptance control of the shortest path selected in the above (d) means is passed, the network shape and state are changed and the auxiliary router module is notified that the idle management state is provided. Routing device for providing the shortest path in the sub-network of the hierarchical communication network characterized in that it comprises a means.

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