KR20070059924A - Link-state update method and appararus thereof - Google Patents

Abstract

A method and an apparatus for updating link state information are provided to remarkably reduce the overheads due to link state update and the fluctuation of a routing protocol by reducing the number of times link state information is updated. A node, in a network where a plurality of nodes are connected through links, transmits link state information, which indicates the state of its own connected link, to a neighbor node, and constructs a whole network link state table containing link state information of the whole network, based on the transmitted link state information(S110). If a QoS routing request is made, the node configures a QoS routing table, based on the whole network link state table, and establishes a QoS path. The node calculates a value consumed for the resources of each link located on the established QoS path and acquires the present value and average value of the link state information(S120). In case the difference between the present value and average value of the link state information is larger than a threshold, the node transmits the present value to the neighbor node(S130).

Description

Link-state Update Method and Appararus

1 is a method of updating link state information according to an embodiment of the present invention.

2 is a method for updating link state information according to another embodiment of the present invention.

3 is an apparatus for updating link state information according to an embodiment of the present invention.

4 is an apparatus for updating link state information according to another embodiment of the present invention.

5 is a shortest path routing table structure and a routing table structure for a quality guarantee path according to an embodiment of the present invention.

6 is a performance comparison diagram comparing the link state updating method and apparatus according to an embodiment of the present invention with the prior art.

The present invention relates to a method and apparatus for updating link state information, and more particularly, to a method and apparatus for updating link state information for establishing a QoS path.

In order to provide quality assurance services (QoS) on the Internet, QoS routing that satisfies constraints is required. The routing path calculation algorithm and the link state update trigger policy in routing for QoS path establishment satisfying the constraints greatly affect the performance of the routing.

The path calculation algorithm determines the path that satisfies the request when the path setting request occurs. The existing shortest path routing algorithm selects the path having the shortest distance to the destination as the routing path. However, if the routing request includes bandwidth or delay for providing quality assurance services rather than simply the shortest path, the existing shortest path routing cannot be used.

This is because if the shortest path established by the existing shortest path routing algorithm does not satisfy the constraints required for the quality assurance service, the corresponding path cannot be used.

Therefore, while the existing path determination routing algorithm uses only physical topology information to determine only the shortest path, routing for QoS paths must maintain constraint information for QoS on each link and determine the path that satisfies the given constraint based on this. do.

In constraint-based routing for such QoS paths, it is necessary to maintain accurate link state information to calculate a path that satisfies the required constraints. That is, the link state information including the existing physical topology state information and QoS state information should be updated to reflect the changing information from time to time. In addition, the routing path state trigger policy must determine when to update.

If link state updates for routing occur frequently, the most appropriate routing path can be established by reflecting the correct path state, while the overhead of the network due to the link state update increases.

One link state update is reflected in all routing protocols in the autonomous system. This often incurs an overhead in which all routers in the autonomous region must perform route calculation.

On the contrary, when the occurrence of the routing link state update is low, the overhead due to the link state update is reduced, but the immediate link state is not reflected by the path setting and the change, so that the effective path setting due to the incorrect link state information is difficult.

Therefore, the link state update trigger policy for QoS path routing should be determined in consideration of the side of occurrence of overhead due to link state information update and the aspect of efficient QoS path establishment using accurate link state information.

An object of the present invention is to provide a method and apparatus for updating link state information capable of efficiently establishing a QoS path while reducing overhead due to link state update.

An embodiment of the method for updating link state information according to the present invention for achieving the above technical problem is a method for updating link state information for establishing a QoS path on a network in which one or more nodes are connected by a link. Transmitting link state information indicating a state to a neighbor node and constructing a network-wide link state table including network-wide link state information based on the transmitted link state information, and a QoS path based on the network-wide link state table. If there is a setting, calculating a current value and an average value of the link state information by calculating a value consumed by the resources of each link located on the established QoS path, and the difference between the current value and the average value of the link state information is a threshold value. If larger, the step of transmitting the current value of the link state information to the neighbor node. The.

An embodiment of an apparatus for updating link state information according to the present invention for achieving the above technical problem is a device for updating link state information for establishing a QoS path on a network in which one or more nodes are connected by a link, wherein each node of the link is connected to itself. In the case where there is a QoS path setting based on the network-wide link state table and the network-wide link state table including link state information indicating the state to the neighbor node and the network-wide link state information based on the transmitted link state information. If the difference between the current value and the average value of the statistics unit and the link state information to obtain the current value and the average value of the link state information by calculating the consumed value of the resources of each link located on the set QoS path, An update unit transmits a current value of link state information to a neighbor node.

The present invention relates to a method and apparatus for updating adaptive link state information using link statistical information when establishing a path satisfying a constraint for providing a quality of service (QoS).

The quality assurance service requires not only providing the shortest path based on the physical topology in the conventional best-effort service but also establishing a path that satisfies a given constraint.

For such constraint-based routing, it is necessary to maintain accurate constraint information for each link of the entire network in addition to the physical topology information. In order to maintain the link information including the exact constraints of the entire network, the routing protocol updates the link state information according to the link state information trigger policy and reflects it to the routers in the network.

As such, link state information update trigger policy is essential for efficient constraint based QoS path establishment.

To this end, in the present invention, link state update is performed in consideration of the average of the available bandwidth based on link statistical information, thereby achieving both overhead reduction due to link state information update and efficient QoS path setting using accurate link state information. .

That is, the overhead of updating link state information by reducing the number of link state updates by updating QoS related local link state information only when the difference between the available capacity of the current link and the average available link capacity is larger than the threshold determination function. Decreases.

In addition, the link state update method of the present invention has excellent performance in terms of efficiency of QoS routing by generating a smaller number of updates than the conventional update method and showing similar routing success probability as the conventional method.

Therefore, the link state update is not generated whenever the available band information of the link is changed, thereby significantly reducing the overhead and fluctuation of the routing protocol due to frequent link state updates.

In addition, despite the small number of updates, the method of the present invention has a similar probability of QoS routing success as the existing frequent update method, and thus does not cause performance degradation. Therefore, through the method of the present invention, it is possible to provide an efficient and stable QoS path in providing a quality guarantee service, which is a main service of the Internet.

1 is a method of updating link state information according to an embodiment of the present invention. Referring to FIG. 1, each node on a network transmits link state information indicating a state of a link connected to the neighbor node. Each node constructs a network-wide link state table including network-wide link state information based on the transmitted link state information (S110).

That is, it configures the local link state information including QoS information and exchanges the local link state information with the neighbor to form a network-wide link state table.

A current value and an average value of the link state information are obtained by calculating a value consumed by resources of each link located on the set QoS path (S120).

If there is a QoS path establishment request, the QoS path is set based on the network-wide link state table S110.

In the general case, the shortest path routing table is configured based on the network-wide link state table.

However, when there is a QoS routing request requiring a specific bandwidth, a QoS routing table with constraints is configured. When the QoS path setting is completed, the value of the resource consumption of each link is calculated to manage link statistics information including the current value and the average value of the link state information.

When the QoS related link state change event is detected, it is determined whether to update the QoS related local link state according to the link state information update trigger condition. If it is decided to update, it propagates the current local link state to the whole network and reconstructs topology information including QoS link state.

That is, when the difference between the current value and the average value of the link state information is greater than the threshold value, the current value of the link state information is transmitted to the neighbor node (S130). If the difference between the current value and the average value of the link state information is less than or equal to the threshold, the link state information is not updated.

2 is a method for updating link state information according to another embodiment of the present invention. Referring to FIG. 2, all nodes operating the link state routing protocol in the network receive an initial link state value from an operator (S201).

A local link state information table of each node is configured (S202). The local link state information table is configured based on link-specific metric information in a routing protocol considering only the shortest path.

In order to provide a QoS path, the present invention adds QoS-related link state information to link-specific metric information. Since the most important QoS information currently considered is bandwidth information, the maximum capacity and usable capacity of each link are configured as QoS link state information.

The routing protocol configuring the initial link state information forms a neighbor with a neighbor node on which the same routing protocol is being driven (S203).

It exchanges the local link state information it establishes through the formed Naver connection (S204).

Such Naver connection and link state information exchange occurs continuously throughout the network, and eventually, all the link state information is collected from each node from all nodes in the autonomous system, and based on this, the link state table of the entire network is configured (S205). That is, all nodes can know link state information including QoS information.

First, the shortest path for every destination is calculated based on the link state table of the entire network (S206). This is used for general best practices services.

The shortest path routing table is configured using the calculated shortest path (S207). The shortest path routing table includes next hop address information for going to the shortest path calculated according to the destination address of the incoming packet.

When a general service proceeds based on the shortest path routing table and a QoS path setting request for a specific band occurs (S208), the routing protocol calculates a path that satisfies the band of the constraint condition (S209).

A routing table for the QoS path is configured according to the calculated path (S210). The signaling protocol sets up the QoS path based on the routing table (S211).

When the signaling protocol sets up the QoS path, the corresponding link of each node recognizes that the bandwidth of the bandwidth required for the above path is consumed, and thus needs to modify and store statistical information of the corresponding link (S212).

That is, the available capacity of the link is reduced by the bandwidth consumed, and the capacity of the available link is recalculated and stored on average. The modified statistical information is information used for a link state update trigger condition later.

The routing protocol that calculates the shortest path and the routing protocol that calculates the QoS path listen for the local link state change event because the local link state should be recognized and reflected in the link topology of the entire network (S213).

If a link state change event occurs and this is not a QoS related state information but a change of a link metric or a link up / down state change, this immediately updates the local link state information (S215). Local link state information is transmitted to all neighbor nodes of NAVER to reorganize the entire network link state table.

However, if the link state change event is a change in the available bandwidth information related to QoS, the trigger condition for updating the QoS link state information is first checked in order to reduce the overhead caused by immediately reflecting this (S216).

)과 평균적으로 사용 가능한 링크의 용량(

)을 이용한다. 수학식 1을 만족하지 않는 경우에는 로컬 링크 상태 정보를 업데이트 하지 않고 계속 로컬 링크 상태 변경 이벤트 발생 수신에 대기한다(S213).At this time, the available capacity of the current link (

) And average available link capacity (

). If it is not satisfied with Equation 1, without waiting for updating the local link state information, it continues to wait for reception of a local link state change event (S213).

The QoS related local link state information is updated only when Equation 1 is satisfied (S218). All neighbor nodes of NAVER are reconfigured with network-wide link state table including QoS information.

)를 사용할 수 있다.Where the threshold determination function is the standard deviation of the available link capacity (

) Can be used.

3 is an apparatus for updating link state information according to an embodiment of the present invention. Referring to FIG. 3, the link state information updating apparatus 300 includes a network-wide link state table 310, a statistics unit 320, and an update unit 330.

The network-wide link state table 310 transmits link state information indicating a state of a link connected to each node in the network to a neighbor node and configures the link state information based on the transmitted link state information.

 The statistics unit 320 calculates the consumed value of the resource of each link located on the set QoS path when there is a QoS path setting based on the network-wide link state table 310, and provides the current value of the link state information. And an average value.

The updater 330 transmits the current value of the link state information to the neighbor node when the difference between the current value and the average value of the link state information is larger than the threshold.

If the difference between the current value and the average value of the link state information is less than or equal to the threshold, the link state information is not updated.

4 is an apparatus for updating link state information according to another embodiment of the present invention. Referring to FIG. 4, the link state information updating apparatus 400 includes an operator interface unit 401, a QoS path management unit 402, a QoS routing protocol unit 403, a QoS path setting unit 406, and a resource management unit 407. Has

The operator interface unit 401 performs a function of setting link state information by using an operator command.

The operator interface unit 401 provides a command for initially setting and changing the bandwidth for each link and the available bandwidth for each link in addition to the existing link metric information for setting the quality guarantee path.

The operator interface unit 401 transfers the link state information set by the operator to the routing protocol unit 403.

The QoS path manager 402 performs a function of processing a connection and requesting a QoS path connection establishment request in the router system.

The QoS routing protocol unit 403 manages link state information for QoS path calculation and calculates a path that satisfies the constraint.

The QoS routing protocol unit 403 distributes its link state information, collects the link state information of the neighbor, and generates a QoS link state information table 405 including link state information of the entire network.

The QoS routing protocol unit 403 calculates a path using a QoS path calculation algorithm 404 that satisfies a given constraint based on the QoS link state table 405.

The QoS path setting unit 406 sets the actual connection to the calculated QoS path. The QoS path setting unit 406 sets the QoS path using a signaling protocol.

The resource manager 407 manages resource information in the router system. Since the resource management unit 407 changes the resource information on its link when establishing the QoS connection, when the connection setting is completed, the resource management unit 407 corrects the local link resource information and notifies the QoS routing protocol unit 403 of this.

5 is a shortest path routing table structure and a routing table structure for a quality guarantee path according to an embodiment of the present invention.

Referring to FIG. 5, the routing protocol 501 for providing the shortest path for the best service establishes the shortest path routing table 202 considering only the metric among the link state information.

The routing protocol 504 for providing a path that satisfies the constraints for the quality assurance service establishes a QoS routing table 505 that satisfies the constraints considering the QoS related link state information.

The shortest path routing table generates packet forwarding information 503 for all destination nodes.

Constrained route routing tables make inter-edge route establishment 506 that satisfies a given constraint whenever there is a QoS route request.

The QoS routing protocol 504 for providing a quality guaranteed path is implemented as an extension of the existing shortest path routing protocol in an actual implementation, but logically has a structure for forming and managing independent routing tables.

6 is a performance comparison diagram comparing the link state updating method and apparatus according to an embodiment of the present invention with the prior art.

Referring to Figure 6, it shows the link state update frequency according to the traffic load according to the present invention and the prior art.

The prior art link state update is a method for performing an update in all cases where a QoS routing request is successful or blocked. Prior art link state updates result in frequent updates (601).

)를 사용하였다.On the other hand, the link state update method using the link statistics information according to the present invention generates a much smaller number of updates than the existing method by properly considering the traffic characteristics of the network (602). Where the threshold determination function is the standard deviation of the available link capacity (

) Was used.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

As described above, the method and apparatus for updating link state information according to the present invention significantly reduce the overhead of the link state update and fluctuation of the routing protocol by reducing the number of update of the link state information.

In addition, the link state information updating method and apparatus according to the present invention does not cause performance degradation by having a similar QoS routing success probability as that of the conventional update method despite the small number of link state information updates.

As described above, the method and apparatus for updating link state information according to the present invention provide an efficient and stable quality assurance service (providing a QoS path).

Claims (10)

A method of updating link state information for QoS routing on a network in which one or more nodes are linked, (a) each node transmitting link state information indicating a state of a link connected to the node to a neighbor node and constructing a network-wide link state table including network-wide link state information based on the transmitted link state information; ; (b) in the case where there is a QoS path setting based on the network-wide link state table, the current value and the average value of the link state information are obtained by calculating a value at which resources of each link located on the set QoS path are consumed. Doing; And and transmitting the current value of the link state information to the neighbor node when a difference between the current value and the average value of the link state information is greater than a threshold. The method of claim 1, wherein step (a) (a1) obtaining local link state information including state information of at least one link connected to the node; And and (a2) exchanging local link state information with a neighbor node to construct a network-wide link state table including network-wide link state information. The method of claim 1, wherein step (b) (b1) if there is a request for establishing a QoS path, configuring a QoS routing table based on the network-wide link state table and establishing a QoS routing path; And (b2) calculating a consumed value of a resource of each link located on the set QoS path to obtain a current value and an average value of the link state information. The method according to claim 1, 2 or 3, Wherein the link state information is information on a bandwidth between a source node, a destination node, or a source node and a destination node, and the resource of the link is a bandwidth. The method according to claim 1, 2 or 3, And wherein the threshold is a standard deviation value of the link state information. An apparatus for updating link state information for QoS path establishment on a network in which one or more nodes are connected by a link, A network-wide link state table, wherein each node transmits link state information indicating a state of a link connected to the node to the neighbor node and includes network-wide link state information based on the transmitted link state information; A statistics unit for calculating the consumed value of resources of each link located on the set QoS path and obtaining a current value and an average value of the link state information when there is a QoS path setting based on the entire network link state table; And And a updating unit which transmits the current value of the link state information to the neighboring node when the difference between the current value and the average value of the link state information is greater than a threshold value. The method of claim 6, wherein the statistics unit, A QoS routing manager configured to configure a QoS routing table based on the network-wide link state table and to establish a QoS routing path when there is a QoS path establishment request; And And a calculator configured to calculate a consumed value of a resource of each link located on the set QoS path to obtain a current value and an average value of the link state information. The method according to claim 6 or 7, And the link state information is information about a bandwidth between a source node, a destination node, or a source node and a destination node, and the resource of the link is a bandwidth. The method according to claim 6, 7, or 8, And wherein the threshold is a standard deviation value of the link state information. A computer-readable recording medium having recorded thereon a program for executing the method according to any one of claims 1 to 5 on a computer.

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