JP4555769B2 - Route setting method and route setting device - Google Patents

Description

  The present invention relates to a route setting method and a route setting device.

  In recent years, ADSL (Asymmetric Digital Subscriber Line), optical access and other access line speed improvements and broadband service subscribers are increasing at a rapid pace. As the access line speed increases, new applications such as large file transfers such as P2P (Peer to Peer) and new data services such as high-throughput communications such as content distribution have increased rapidly, resulting in an increase in backbone traffic. It's getting on.

  In order to efficiently transfer these large volumes of traffic, a TE (Traffic Engineering) function that enables efficient use of resources is required. To achieve efficient use of resources in the backbone network so far, TE using MPLS (Multiprotocol Label Switching) technology, GMPLS (Generalized MPLS) technology, Asynchronous Transfer Mode (ATM) technology, etc. has been widely used. Has been applied.

  In many cases, the traffic flowing in the network changes as time passes (when it becomes dynamic traffic). Even if the path of a path in the network is calculated based on the traffic at a certain time, it may not be compatible at another time. Therefore, the path calculation of the path in the network needs to be performed not only once but also many times reflecting the traffic flowing in the current network.

  The prior art TE can re-calculate the path of the path, thereby improving the network throughput and reducing the congestion. For example, in the Wang method (Non-Patent Document 1), which is a prior art of MPLS-TE, a route of an LSP (Label Switched Path) that is a path in the network is periodically recalculated. However, the Wang method merely calculates a path of a plurality of paths, and the timing of traffic change and path calculation is completely independent, so dynamic traffic is not considered.

In Patent Document 1, a route calculation method is proposed that realizes minimization of network cost in a network from a plurality of routes that can be taken by a path in consideration of dynamic traffic.
Y. Wang, et al., “Explicit Routing Algorithms for Internet Traffic Engineering,” Eight International Conference on Computer Communications and Networks, Oct 1999, pp. 582-588 JP 2002-252639 A

  It is necessary to change the currently active path by recalculating the path route. In changing the path, it is necessary to release a predetermined path and newly set a new path when switching the path of the path. At that time, if the number of paths to be changed is large, an extra burden is placed on the network. The burden is, for example, an increase in a CPU (Central Processing Unit) utilization rate of a node that sets a path in order to process a management message accompanying a path change.

  Furthermore, since the amount of management messages for path change increases in proportion to the number of paths accompanied by path change, a large problem arises when the network is enlarged. Further, in a network that performs bandwidth guarantee, it is necessary to secure network resources in order to realize bandwidth guarantee even after performing path switching. Therefore, when the number of paths accompanied by route changes increases, extra network resources must be secured.

  The technique described in Patent Document 1 is intended to minimize the network cost, but does not consider the number of paths that involve a path change at the time of recalculation. For this reason, in order to minimize the network cost, the number of paths accompanied by a route change tends to increase. That is, the technique described in Patent Document 1 focuses only on the profit (reduction in network cost) associated with the path change. However, when the disadvantage associated with the path change (increase in management message) is greater than the profit associated with the path change (decrease in network cost), it is preferable not to change the path.

  In other words, for each path that accompanies the change calculated by recalculating the path, select the path that has a large profit to change the path as the change target and do not select the path that has a small profit, thereby suppressing the number of paths to be changed. It is necessary to do. As a result, the benefits and disadvantages of changing paths can be enjoyed in a balanced manner.

  Accordingly, an object of the present invention is to reduce the number of paths accompanied by a path change at the time of recalculation while achieving efficient use of network resources.

In order to solve the above-described problems, the present invention provides a route setting method for setting a route of a path connecting edge nodes in the transfer network in a transfer network to which a node accommodating the path is connected. A traffic matrix management procedure in which the computer records the topology and traffic in the transfer network as a traffic matrix in a storage means, and a target link determination procedure in which a link having a high link utilization rate in the network is selected based on the traffic matrix And a target path determination procedure for selecting a path with a large amount of traffic from the paths accommodated in the selected link, and calculating a route of the selected path, and instructing the node to change the route based on the result And a route calculation procedure to be executed.

  This makes it possible to efficiently use network resources and reduce the number of path settings associated with a path change in network path settings.

  In the present invention, the target link determination procedure selects a link having the highest link utilization rate for a network link, and the target path determination procedure selects a path with the highest traffic volume that is accommodated by the selected link. It is characterized by selecting.

  As a result, the number of paths that accompanies a path change is one, so that the amount of management messages for path release and establishment is small.

  In the present invention, the target link determination procedure selects a link having the highest link utilization rate for a network link, and the target path determination procedure is a path accommodated by the selected link, and the traffic amount is equal to or higher than a predetermined order. It is characterized by selecting a path.

  As a result, the number of paths to be selected can be explicitly specified, so that the overhead for changing the path can be kept constant.

  In the present invention, the target link determination procedure selects a link having a link utilization rate of a predetermined order or more for a network link, and the target path determination procedure has the largest traffic volume of the path accommodated in each of the selected links. It is characterized by selecting a high path.

  As a result, the number of paths to be selected can be explicitly specified, so that the overhead for changing the path can be kept constant.

  According to the present invention, the target link determination procedure selects a link having a link utilization rate of a predetermined value or more for a network link, and the target path determination procedure determines a traffic amount of a path to be accommodated in each of the selected links. A path that is higher than the rank is selected.

  As a result, it is possible to achieve efficiency higher than a predetermined level without being affected by the number of paths.

  The present invention is characterized in that the target path determination procedure selects a path whose product of the traffic amount and the number of hops related to the accommodated path is a predetermined rank or more in each selected link.

  As a result, the number of paths to be selected can be explicitly specified, so that the overhead for changing the path can be kept constant.

  The present invention is characterized in that the target path determination procedure selects, for each selected link, a path having a hop count relating to the accommodated path equal to or greater than a predetermined value and a traffic volume equal to or higher than a predetermined rank.

  As a result, it is possible to achieve efficiency higher than a predetermined level without being affected by the number of paths.

The present invention relates to a path setting device for setting a path of a path connecting edge nodes in the transfer network in a transfer network to which a node accommodating a path is connected, the topology in the transfer network and A traffic matrix management unit that records traffic as a traffic matrix in a storage unit, a target link determination unit that selects a link with a high link utilization rate in the network based on the traffic matrix, and a path accommodated in the selected link A target path determination unit that selects a path with a large amount of traffic from the network, and a route calculation unit that performs route calculation of the selected path and instructs a node to change the route based on the result. To do.

  This makes it possible to efficiently use network resources and reduce the number of path settings associated with a path change in network path settings.

  According to the present invention, by selecting a corresponding path based on the link utilization rate in the network, the traffic information of the path, and the path of the path, efficient use of network resources in the network path setting, The number of path settings associated with the route change can be reduced.

  Hereinafter, an embodiment of a route setting system to which the present invention is applied will be described in detail with reference to the drawings.

  The present embodiment is characterized in that the number of paths accompanied by a path change is reduced at the time of recalculation while achieving an efficient network resource. Note that network resource efficiency is the averaging of network resource usage, and specifically, in a network that minimizes the link usage rate (traffic bandwidth / link communication bandwidth) of each link. It is to determine the path of the path. Thereby, the link utilization rate of each link can be made uniform, and the throughput of the entire transfer network can be improved. In addition, by reducing the number of paths that involve route changes, it is possible to efficiently use resources of the entire network, prevent service interruptions due to route changes, and suppress management messages.

  Note that, in order to reduce the number of paths that involve route changes, for example, the paths to be changed are paths that are accommodated in links with a high link utilization rate and that have a large amount of traffic. Such a path to be changed has the effect of changing the path more than other paths because one path has a large influence on the average of link utilization when the link utilization in the network is averaged. Is big.

  FIG. 1 shows an outline of the configuration of a route setting system in the present embodiment. In the packet transfer network 9, an edge node 2 serving as a path end point is arranged. A plurality of relay nodes 3 are arranged between the edge nodes 2 so that transfer packets between the edge nodes 2 are relayed. In the packet transfer network, a path is set in advance between edge nodes, and data communication traffic is transferred on this path. In FIG. 1, there is one path calculation device in the network, but it is also possible to dispersely deploy to each node. The route setting device 1 instructs the edge node 2 and the relay node 3 to set a path.

  The path setting device 1 illustrated in FIG. 2 includes a topology management unit 11, a path management unit 12, a traffic matrix management unit 13, a target link determination unit 14, a target path determination unit 15, and a route calculation unit 16 as functional units. . The path setting device 1 is configured as a computer including at least a memory as a storage unit used when performing arithmetic processing, an arithmetic processing device that performs the arithmetic processing, and an interface for inputting and outputting data. . The memory is constituted by a RAM (Random Access Memory) or the like. Each functional unit that executes arithmetic processing is realized by an arithmetic processing device configured by a CPU (Central Processing Unit) executing a program on a memory. Each functional unit will be specifically described below.

  The topology management unit 11 aggregates the input topology and link utilization rate, and records it in the storage means as the topology of the entire network and the link utilization rate of all links in the network. The path management unit 12 aggregates the traffic amount and path route of the input path and records them in the storage means as the traffic amount and route of all paths in the network.

  The traffic matrix management unit 13 creates a traffic matrix in the network from the traffic amount of the aggregate path and the route of the aggregate path, and records it in the storage means. The traffic matrix is a matrix that gives the amount of traffic from a node in the network to another node, and the vertical axis and the horizontal axis are given by a node number or the like. As a method for creating a traffic matrix, there are a method for obtaining a traffic amount between nodes by measuring a traffic amount of each path, a method for estimating a traffic matrix itself without measuring the traffic amount, and the like. Note that the method for estimating the traffic matrix is realized by employing, for example, a Simple gravity model, a Global gravity model, a Tomo-gravity model, and the like. A method for estimating a traffic matrix and a method for evaluating the effectiveness of TE using the estimated traffic matrix are described in the literature (M. Roughan, et al., “Traffic Engineering with Estimated Traffic Matrices,” ACM Internet Measurement Conference 2003, pp.248-258).

  The target link determination unit 14 selects an arbitrary link in the network based on the traffic matrix. The target path determination unit 15 selects an arbitrary path from the information stored in the target link from the information of the path management unit 12 and the selected link. The route calculation unit 16 performs route calculation of the selected path, and transmits a route switching request for instructing change of the route based on the result.

  The network device changes the path of the path in accordance with the received path path switching request. In order to change the path of the path, it is necessary to stop the currently active path and generate a new path to be changed. Therefore, the order of the current path stop procedure and the change-destination path movable procedure becomes a problem. First, in the method of stopping the current path → moving the destination path, there is a possibility that the service is interrupted because there is a time during which neither the current path nor the destination path is movable.

  Note that the network device can suppress service interruption by adopting a method (make-before-break) in which the moving procedure of the path to be changed is changed to the stopping procedure of the current path. However, in make-before-break, the arrival order of packets is reversed due to the route change. Whether to adopt make-before-break may be set in the network device in advance or may be included in the path switching request.

  The arrows in FIG. 2 indicate information exchanged between the functional units. Hereinafter, specific contents of the information exchanged will be described.

  The topology management unit 11 receives input of topology and link utilization rate. The path management unit 12 receives an input of a path traffic amount and a path route. Information that the topology management unit 11 and the path management unit 12 accept input is collected from a node or the like, or directly collected by the path setting device 1.

  The topology management unit 11 notifies the aggregated topology and link utilization rate to the traffic matrix management unit 13 and the target link determination unit 14. The path management unit 12 notifies the traffic matrix management unit 13 and the target path determination unit 15 of the aggregated traffic volume and path route.

  The traffic matrix management unit 13 notifies the target link determination unit 14 of the traffic matrix. The target link determination unit 14 notifies the target path determination unit 15 of the selected link. The target path determination unit 15 notifies the route calculation unit 16 of the selected path. The route calculation unit 16 notifies the route switching request of the selected path to the network devices (edge node 2 and relay node 3) that set the path.

  Hereinafter, the flowchart of FIG. 3 will be described.

  The topology management unit 11 and the path management unit 12 register network information (topology and link utilization rate, path traffic volume and path route) (S11). The route calculation unit 16 calculates the route of the path based on the traffic matrix (S12). The traffic matrix management unit 13 determines whether or not there is a change in the traffic matrix (S13). Note that a method for detecting a change in the traffic matrix may be based on a dynamic actual measurement value, or a time at which the traffic matrix will change may be statically input in advance. When there is no change (No in S13), the traffic matrix management unit 13 waits until there is a change. Hereinafter, the operation when there is a change (S13, Yes) will be described.

  The target link determination unit 14 selects a link based on the link usage rate (S14). The target path determination unit 15 selects a path based on the traffic volume of the selected link (S15). The route calculation unit 16 calculates the route of the selected path (S16). As a method for calculating the path of the path, there are a method such as a method for solving an optimization problem by a mathematical programming method, a Dijkstra method, and the like. The route calculation unit 16 requests path switching according to the calculated route (S17).

  It should be noted that various methods can be adopted as a combination of the link selection method (S14) and the path selection method (S15). Hereinafter, an example of those combinations is shown.

  In the first method, the link selection method is one link (the link having the highest link utilization rate), and the path selection method is one path (a path accommodated by one link with the largest traffic volume). High pass).

  In the second method, the link selection method is one link (the link having the highest link utilization rate), the path selection method is N paths (the path accommodated by one link, and the traffic amount is predetermined). (Path higher than ranking).

  In the third method, the link selection method is M links (link utilization rate is a link having a predetermined order or more), and the path selection method is M paths (the traffic of the paths accommodated in each of the M links). Path with the highest amount).

  In the fourth method, the link selection method is P links (link utilization rate is a link having a predetermined value or more), and the path selection method is Q paths (the traffic of paths accommodated in each of the P links). The amount of the path is equal to or higher than a predetermined order).

  In the fifth method, the link selection method is R links (selected based on the link utilization rate), and the path selection method is S paths (the amount of traffic related to the paths accommodated in each of the R links). And the product of the number of hops is a predetermined order or more).

  In the sixth method, the link selection method is X links (selected based on the link utilization rate), and the path selection method is Y paths (the number of hops related to the paths accommodated in each of the X links). Is a path with a traffic amount equal to or higher than a predetermined value).

  One path selected by the first method has the largest contribution to the averaging of link utilization in the network. Therefore, performing the path change of the path can achieve substantially the same effect as the optimization of network resource utilization by changing a plurality of paths. In addition, since the number of paths that accompanies a path change is one, the amount of management messages for path release and establishment is small.

  On the other hand, in the second method to the sixth method, the use of network resources can be made more efficient by using a plurality of paths as route change targets. In addition, by using a predetermined value as a path or link selection method, it is possible to achieve efficiency higher than a predetermined level without being affected by the number of paths. On the other hand, since the number of paths to be selected can be explicitly specified by using a predetermined order as a path or link selection method, overhead associated with path changes can be kept constant.

  Hereinafter, the method of this embodiment is evaluated by comparing the method of this embodiment with a comparative example.

  The network topology (Cost 239 model) in FIG. 4 is generally used as a topology benchmark. The Cost 239 model is a physical optical network installed in Europe, and is realized by WDM (Wavelength Division Multiplexing). Further, as a method for giving a traffic matrix in advance, traffic between nodes is determined by a method called a Gravity model. In the Gravity model, the amount of traffic between nodes is proportional to the product of the population of each node and inversely proportional to the square of the distance between the nodes.

  FIG. 5 is a diagram assuming the population of each node for the node numbers in FIG. The population at this time is defined as population A. Moreover, in order to realize the dynamic change of the traffic matrix, the population of each node was changed in this evaluation. The population of each node after the change is also shown in FIG. The population at this time is defined as population B.

First, a traffic matrix for the population A is calculated by the Gravity model, and when this traffic matrix is given, an objective function for minimizing the link utilization rate in the network is set, and a network for realizing the minimum link utilization rate Determine the path of the path inside. Next, using the traffic matrix changed to the population B, the same calculation as described above is performed. In the method of the comparative example calculated in this way, the number of paths changed from the case of the population A in the path of the path existing between the nodes in the network was 37 for the total number of paths of 110. The maximum link utilization rate at this time is C.

  On the other hand, in the second method, when the path with the highest traffic volume accommodated in the top six links, that is, six paths out of 110, is changed, the maximum link utilization value is about 1. It was 06 times, and it was found to have a value almost close to the optimal solution C. In the third method, when the path with the highest 6 traffic volume, that is, 6 out of 110 paths, is changed, the maximum link utilization value is approximately 1.01 times C, which is extremely optimal. A value close to the solution C can be obtained.

It is a block diagram which shows the path | route setting system regarding one Embodiment of this invention. It is a block diagram which shows the route setting apparatus regarding one Embodiment of this invention. It is a flowchart which shows the route setting process regarding one Embodiment of this invention. It is a graph which shows the network topology of the Cost239 model regarding one Embodiment of this invention. It is explanatory drawing which shows the population of each node in the Cost239 model regarding one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Path setting device 2 Edge node 3 Relay node 11 Topology management part 12 Path management part 13 Traffic matrix management part 14 Target link determination part 15 Target path determination part 16 Path calculation part

Claims (8)

In a transfer network to which a node accommodating a path is connected, a route setting method for setting a path of a path connecting edge nodes and edge nodes in the transfer network ,
Computer
A traffic matrix management procedure for recording the topology and traffic in the transport network in a storage means as a traffic matrix;
A target link determination procedure for selecting a link having a high link utilization rate in the network based on the traffic matrix;
A target path determination procedure for selecting a path with a large amount of traffic from the paths accommodated in the selected link;
A route calculation procedure for performing route calculation of the selected path and instructing the node to change the route based on the result;
The route setting method characterized by performing.   The target link determination procedure selects a link with the highest link utilization rate for the network link, and the target path determination procedure selects a path with the highest traffic volume accommodated by the selected link. The route setting method according to claim 1, wherein:   The target link determination procedure selects a link having the highest link utilization rate for the network link, and the target path determination procedure selects a path accommodated by the selected link and having a traffic amount of a predetermined order or more. The route setting method according to claim 1, wherein:   The target link determination procedure selects a link having a link utilization rate of a predetermined order or more for a network link, and the target path determination procedure selects a path having the highest traffic volume of the accommodated path in each of the selected links. The route setting method according to claim 1, wherein:   The target link determination procedure selects a link having a link utilization rate of a predetermined value or more for a network link, and the target path determination procedure includes a path in which the traffic volume of the accommodated path is a predetermined rank or higher for each of the selected links. The route setting method according to claim 1, wherein:   2. The route setting method according to claim 1, wherein the target path determination procedure selects a path whose product of the traffic amount and the number of hops related to the accommodated path is a predetermined rank or more in each of the selected links.   2. The route setting according to claim 1, wherein the target path determination procedure selects, for each of the selected links, a path in which the number of hops related to the accommodated path is a predetermined value or more and a traffic amount is a predetermined order or more. Method. In a transfer network to which a node that accommodates a path is connected, a path setting device that sets a path of a path connecting edge nodes and edge nodes in the transfer network ,
A traffic matrix management unit for recording the topology and traffic in the transport network in a storage means as a traffic matrix;
A target link determination unit that selects a link having a high link utilization rate in the network based on the traffic matrix;
A target path determination unit that selects a path with a large traffic volume from the paths accommodated in the selected link;
A route calculation unit that performs route calculation of the selected path and instructs the node to change the route based on the result;
A path setting device comprising:

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