JP2011244312A - Node device, optimal path determination method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a processing load for determining an optimal path between node devices in a mesh network.SOLUTION: Network path information acquisition means 131 of an interrupted link determination section 13 acquires a link RTT and the number of routers through which a link is routed based on results of executing a ping program or a traceroute program. It also acquires how many times a link is routed through an AS and router as well as cost based on results of analyzing a BGP or OSPF route control protocol. Interrupted link determination means 132 excludes candidate links which are expected to have poor transmission performance from measurement based on factors such as link RTT and deals with the candidate links as interrupted links when determining an optimal path. This makes it possible to reduce the number of candidate links and the total amount of transmitted probe packets. The amount of calculation for determining the optimal path can also be reduced.

Description

  The present invention relates to a node device, an optimum path determination method, and a program for measuring an available bandwidth of a link between nodes in a mesh network and dynamically determining an optimum transmission path (optimum path) from the measurement result.

  A mesh network refers to a transmission path in which three or more nodes are connected to each other and configured in a mesh shape. In a mesh network, the transmission path between two nodes includes not only the shortest path that directly connects the two nodes, but also a detour path that connects via other nodes. For this reason, even when a failure occurs in the transmission path between two nodes, transmission can be continued by a detour path that passes through another node. In this mesh network, the usable bandwidth of the detour path may be wider than the shortest path due to local congestion of links between nodes.

  Hereinafter, “link” refers to a route that directly connects two (overlay) nodes, and “path” refers to a route that generally connects two (overlay) nodes (including routes that pass through other nodes in the middle). . In addition, in a mesh type network system that realizes material video transmission by an operator, all nodes constituting the mesh type network are managed by an administrator (addresses are known), and nodes frequently participate or leave. Shall not do.

  Conventionally, a method for determining an optimum path between nodes in a network is known (see, for example, Patent Document 1). In the method of Patent Document 1, in consideration of reduction of processing load of the entire network, node grouping is performed based on load information of an inter-node transmission path, and traffic information (available bandwidth) is determined based on received data. It measures and determines the optimal path based on traffic information.

For example, a packet pair method is known as a method for measuring the available bandwidth. FIG. 14 is a diagram illustrating a method for measuring an available bandwidth by the packet pair method. A method for measuring the bandwidth (available bandwidth) _1-2 of the link _1-2 between the node 101 and the node 102 will be briefly described with reference to FIG. Assume that a link between the node 101 and the node 102 has a bottleneck of the bandwidth W. The starting node 101 continuously transmits probe packets having a packet length L to the terminal node 102 at a sufficiently short time interval T. When not affected by other traffic on any path in the link _1-2 , the node 102 at the end point receives the probe packet transmitted from the node 101 at the time interval T ′ = L / W. . Therefore, the node 102 can measure the bottleneck bandwidth (available bandwidth) W by calculating the time interval between the received probe packets. In practice, the available bandwidth is estimated by eliminating the influence of other traffic by statistically processing the results of repeated measurements.

  FIG. 13 is a diagram showing a configuration of a probe packet used in the packet pair method shown in FIG. As shown in FIG. 13, the probe packet is composed of a header such as Version (version) and Header Length (header length), and a payload storing dummy data. In the packet pair method, if the probe packet length is long, the measurement accuracy is improved. Therefore, the probe packet length is often fixed to 1500 bytes, which is generally used as an MTU (Maximum Transmission Unit) of the IP network. . For this reason, the probe packet is composed of dummy data excluding the head IP header portion.

FIG. 15 is a schematic diagram showing a configuration of a mesh network including a conventional node. The mesh network 100 is configured in a mesh pattern by a plurality of nodes 101 to 104 connected to each other. The node 101 transmits the probe packet to the nodes 102 to 104, and the nodes 102 to 104 also transmit the probe packet to the other nodes 101 to 104. When the node 101 receives the probe packet from each of the nodes 102 to 104, the usable bandwidth of the adjacent link (the bandwidth _2-1 of the link _2-1 between the node 102 and the node 101, and between the node 103 and the node 101) band _3-1 of links _3-1, the band _4-1) links _4-1 between the node 104 to node 101, is measured each by the above-described packet-pair technique, and stores the result in the packet node 102 To 104. Upon receiving the probe packet, each of the nodes 102 to 104 also measures the available bandwidth of the adjacent link, stores it in the result packet, and transmits it to the other nodes 101 to 104.

Then, the nodes 101 to 104 receive the result packet in which the usable bandwidth of the adjacent link measured in the other nodes 101 to 104 is stored, and acquire the usable bandwidth of all the links. Then, the optimum path is determined based on the acquired available bandwidth of all links. As shown in FIG. 15, the node 103 configures the path from the node 101 to the node 103 when determining the optimum path from the node 101 to the node 103 based on the available bandwidth of all links. A combination of links to be obtained is obtained, and for each combination, a combination of links having the largest link band minimum value is determined as the optimum path. For example, links _1-3 , links _1-2 , _2-3 , links _1-4 , _4-3 , links _1-4 , _4-2 , _2-3 , and links _{1- 2,2-4,4-3} is present, the bandwidth of each of the link, (bands _1-2 <bands _{2-3, 2-4} bands, bands _4-3), (bands _1-4 <band _{2 -3} , band _4-2 , band _4-3 ) and (band _1-2 <band _1-4 <band _1-3 ), the link _1-3 is determined as the optimum path.

JP 2008-153978 A

  However, the mesh network 100 including the conventional nodes 101 to 104 shown in FIG. 15 has the following problems (problems (1) and (2)).

[Problem (1)]
In the conventional mesh network 100, when there are n nodes, the total number of links to be measured (hereinafter referred to as candidate links) for measuring the available bandwidth is n (n-1), and as n increases. , N ² in order. The increase in the number of candidate links leads to an increase in the transmission amount of the result packet for exchanging the measurement result with the transmission amount of the probe packet, and the load on the mesh network 100 is increased. In addition, when there are a large number of candidate links, the amount of calculation processing for determining the optimum path from the candidate links (for example, calculation and comparison of available bandwidth of all links by the brute force method, and optimum path determination processing by the Dijkstra method) Will also increase.

[Problem (2) / Additional problems]
Further, in the conventional mesh network 100, bandwidth measurement for measuring the available bandwidth of the adjacent link is performed, and in order to exchange measurement results, separate packets (probe packets and measurement results for bandwidth measurement) are used. When a packet is exchanged, a result packet) is transmitted and received, so that the amount of data transmitted to the mesh network 100 increases. Further, as described above, in order to improve the measurement accuracy, the probe packet is often set to a fixed length substantially equal to the MTU, and the payload portion of the probe packet is large even though the load on the mesh network 100 is large. Is composed only of dummy data and is not used effectively.

  Accordingly, the present invention has been made to solve the above-described problem, and an object of the present invention is to determine a node device that can reduce the processing load for determining an optimum path between node devices and an optimum path determination in a mesh network. It is to provide a method and a program.

  The present inventors have intensively studied to achieve the above object. As a result, the path information of the mesh network is analyzed in each node device, and the analysis result (for example, RTT (Round Trip Time: round trip time) obtained by executing a ping program or traceroute program) Or, based on the number of transit routers, the number of transit ASs / the number of transit routers or costs obtained by analyzing messages sent and received using a routing protocol such as BGP (Border Gateway Protocol) or OSPF (Open Shortest Path First). Candidate links that are expected to be inferior in performance are excluded from the measurement target, and the candidate links are treated as disconnected links when determining the optimal path. I found the door.

  As a result, candidate links that are expected to have inferior transmission performance cannot be links included in the optimum path, and thus the number of candidate links that can be measured for the available bandwidth can be reduced. The total amount of probe packets used for measuring the available bandwidth can be reduced, and the load on the network can be reduced. In addition, the amount of calculation for determining the optimum path can be reduced. Therefore, the problem (1) can be solved.

  Further, the present inventors have found that in each node device, the measured available bandwidth of the adjacent link is stored in a probe packet used for bandwidth measurement and transmitted.

  Thereby, each node device does not need to transmit the available bandwidth of the measurement result separately from the probe packet, and the bandwidth measurement and the exchange of the measurement result can be simultaneously realized by the probe packet. The node device that determines the optimum path can measure the available bandwidth of the adjacent link by receiving the probe packet sent from another node device, and at the same time, the available bandwidth stored in the probe packet. Can be obtained. In other words, a packet that is received and transmitted in a mesh network by receiving a probe packet and simultaneously measuring the available bandwidth of the adjacent link in the local node device and acquiring the available bandwidth of the adjacent link in another node device. Network load can be further reduced. Therefore, the problem (2) can be solved.

  That is, a node device according to the present invention is a node device that determines an optimal path between node devices based on an available bandwidth of an adjacent link under a mesh network composed of a plurality of node devices. Network path information acquisition means for acquiring network path information used for determining transmission performance between the node and another node device, and based on the network path information, a link having inferior transmission performance is determined, and the link is blocked. A non-connection link determining unit having a non-connection link determination means for determining as a link and a plurality of candidate links indicating a route between the node device and another node device are excluded from the non-connection link, and the non-connection link in the node device A bandwidth measuring unit that measures the usable bandwidth of the candidate link excluding The available bandwidth of the candidate link excluding the disconnected link is stored in a result packet, transmitted to another node device, and the candidate link excluding the disconnected link in the other node device is used from the other node device. The result packet storing the available bandwidth is received, and the result packet processing unit that acquires the usable bandwidth of the candidate link excluding the non-communication link in the other node device from the result packet, and measured by the bandwidth measuring unit The optimum path based on the usable bandwidth of the candidate link excluding the disconnected link in the node device and the available bandwidth of the candidate link excluding the disconnected link in the other node device acquired by the result packet processing unit. And an optimum path determination unit for determining

  Further, in the node device according to the present invention, the network route information acquisition means of the disconnected link determination unit executes a ping program or traceroute program used for managing the network, and based on the execution result Then, the number of routers or RTT (Round Trip Time) between the node device and another node device is acquired as network route information, and the network link information acquired by the disconnected link determining unit is acquired by the network route information acquiring unit. The information is compared with a predetermined threshold value, and a link between the node device and the other node device for the network path information is determined as a non-connection link.

  In the node device according to the present invention, the network route information acquisition unit of the disconnected link determination unit sets an AS (Autonomous System) -PATH attribute of a BGP message used for BGP (Border Gateway Protocol) for controlling a network route. Based on the included AS number, the BGP message transmitted to the AS that includes the other node device and transmitted to the AS that includes the node device is selected, and the AS-PATH attribute of the selected BGP message is selected. The AS number between the node and another node is acquired as network path information from the included AS number, and the non-connection link determination unit is configured to perform predetermined processing with the network path information acquired by the network path information acquisition unit. Compare with threshold And determining a link between the node device and another node device for the network path information as a disconnected link.

  Further, in the node device according to the present invention, the message is transmitted based on the advertisement message used in the OSPF (Open Shortest Path First) for controlling the network route by the network route information obtaining unit of the non-communication link determining unit. The network address assigned to the interface of the router and the cost information of the link between the routers are acquired, and the number of routers or the cost information between the node device and other node devices are obtained from the network address and the cost information. Information, and the disconnected link determination means compares the network route information acquired by the network route information acquisition means with a predetermined threshold value, and the node device and other node devices for the network route information. And determining a link between the disconnected link.

  In addition, the node device according to the present invention includes a probe packet processing unit instead of the result packet processing unit, and the probe packet processing unit provides other probe packets for measuring an available bandwidth of an adjacent link in the node device. Candidate link usable bandwidth obtained by excluding a non-conforming link in the node device measured by the bandwidth measuring unit in a probe packet received from the other node device and used to measure the usable bandwidth of the adjacent link in another node device And the probe packet is transmitted to another node device.

  Furthermore, an optimal path determination method according to the present invention is a method for determining an optimal path between node devices based on an available bandwidth of an adjacent link under a mesh network composed of a plurality of node devices. Acquiring network route information used for determining transmission performance between the device and another node device, determining a link having inferior transmission performance based on the network route information, and inferior transmission performance Candidates for determining the determined link as a disconnected link, and excluding the disconnected link from a plurality of candidate links indicating a route between the node device and another node device, and excluding the disconnected link in the node device A step of measuring a usable bandwidth of a link, and the measured non-communication link in the node device The usable bandwidth of the removed candidate link is stored in a result packet and transmitted to another node device, and the usable bandwidth of the candidate link excluding the non-communication link in the other node device is stored from the other node device Receiving the obtained result packet, obtaining from the result packet the usable bandwidth of the candidate link excluding the disconnected link in the other node device, and the available bandwidth of the candidate link excluding the disconnected link in the node device And determining the optimum path based on the available bandwidth of the candidate link excluding the non-communication link in the other node device.

  An optimum path determination program according to the present invention causes a computer to function as the node device.

  As described above, according to the present invention, it is possible to reduce a processing load for determining an optimum path between node devices in a mesh network.

1 is a schematic diagram illustrating a configuration of a mesh network including a node according to Embodiment 1. FIG. 3 is a flowchart illustrating an outline of processing of a node in the first embodiment. FIG. 3 is a block diagram illustrating a configuration of a node in the first embodiment. It is a figure which shows the example of an execution result of a ping program. It is a figure which shows the example of an execution result of a traceroute program. It is a figure which shows the example of a BGP message. It is a figure which shows the example of the route map (AS map) produced based on the BGP message. It is a figure which shows the example of router map information produced based on LSA of OSPF. FIG. 10 is a schematic diagram illustrating a configuration of a mesh network including nodes according to the fourth embodiment. 14 is a flowchart illustrating an outline of processing of a node in the fourth embodiment. FIG. 10 is a block diagram illustrating a configuration of a node according to a fourth embodiment. It is a figure which shows the structural example of the probe packet in Example 4,5. It is a figure which shows the structure of the conventional probe packet. It is a figure explaining the measuring method of the usable band by the packet pair method. It is the schematic which shows the structure of the mesh type network containing the conventional node.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is characterized in that, in a mesh network, candidate links are reduced when determining an optimum path between nodes (node devices). The first embodiment is an example in which the network route information is acquired using the execution result of the ping program or the traceroute program for IP network management, and the candidate links are reduced. The second embodiment is an example in which a message used for BGP for route control is analyzed to acquire network route information, and candidate links are reduced. Example 3 is an example in which a message used for OSPF for route control is analyzed to acquire network route information, and candidate links are reduced. In the fourth embodiment, in addition to any of the first to third embodiments, an available bandwidth of an adjacent link is stored in a probe packet and transmitted to reduce the total packet transmission amount of the network. The fifth embodiment is an extension example of the fourth embodiment, and is an example in which the attribute of the usable bandwidth of the adjacent link is also stored in the probe packet and transmitted to reduce the total packet transmission amount of the network. The first to third embodiments can solve the problem (1). In addition, the fourth and fifth embodiments can solve the problem (2) in addition to the problem (1). Here, the network route information is information used when determining the transmission performance of the route.

  First, Example 1 will be described. As described above, the first embodiment is an example in which the network path information is acquired using the execution result of the IP network management ping program or traceroute program, and the candidate links are reduced. The first embodiment is applicable when an overlay transmission network is constructed on an IP network.

  FIG. 1 is a schematic diagram illustrating a configuration of a mesh network including nodes according to the first embodiment. The mesh network 100 is, for example, the Internet, and is configured in a mesh shape by a plurality of nodes 1 to 4 connected to each other. The same applies to Examples 2 and 3 described later.

[Node Processing Overview / Example 1]
FIG. 2 is a flowchart showing an outline of processing of the node 1 shown in FIG. Nodes 2 to 4 perform the same processing as node 1. In this process, for example, when transmitting and receiving video data between the nodes 1 to 4, an available bandwidth is measured, an optimal path is determined, and video data is transmitted and received through the determined optimal path. The same applies to Examples 2 and 3 described later.

  When the node 1 determines the probe packet transmission timing (step S21: Y), the node 1 transmits to the nodes 2 to 4 a probe packet for measuring the available bandwidth in the nodes 2 to 4 (step S201). The transmission timing is, for example, a predetermined time interval, and the probe packet is periodically transmitted to cope with a change in the state of the mesh network 100.

When the node 1 receives probe packets from the nodes 2 to 4 (step S22: Y), as shown in FIG. 14, by calculating the reception interval of the probe packets, the available bandwidth (node link between the band _2-1 links _2-1 between from 2 to node 1, the band _3-1 links _3-1 between the node 3 to node 1, from node 4 to node 1 _{4-1 4-1} ) is measured (step S202). Adjacent links that measure available bandwidth are candidate links. In this case, the node 1 periodically receives probe packets transmitted from the nodes 2 to 4.

When the node 1 determines the update timing of the disconnected link (step S23: Y), the node 1 executes the ping program or the traceroute program. From the execution result, the number of routers between the own node 1 and the partner nodes 2 to 4 and the own node Network route information indicating RTT from 1 to the partner nodes 2 to 4 is acquired (step S203). The update timing is, for example, a predetermined time interval. Then, the node 1 determines the disconnected link based on the network route information (step S204), and excludes the disconnected link from the candidate links (links _{2-1, 3-1 and 4-1} ) (step S205). As illustrated in FIG. 1, for example, the node 1 determines that the link _2-1 is a disconnected link based on the network route information, and excludes the disconnected link _2-1 from the candidate links.

When the node 1 determines the transmission timing of the result packet (step S24: Y), in the above example, the usable bandwidth (band _3-1 ) of the candidate links _{3-1 and 4-1} excluding the disconnected link _{2-1. , 4-1} ) is stored in the result packet, and the result packet is transmitted to the nodes 2 to 4 (step S206). The transmission timing is, for example, a predetermined time interval. As a result, the nodes 2 to 4 can receive the result packet and acquire the usable bandwidth of the candidate link from which the non-communication link in the node 1 is excluded from the result packet.

  When the node 1 receives the result packet from each of the nodes 2 to 4 (step S25: Y), the node 1 acquires the usable bandwidth of the candidate link excluding the non-connection link in the other nodes 2 to 4 from the received result packet ( Step S207).

  When the node 1 determines the timing for determining the optimum path (step S26: Y), the usable bandwidth of the candidate link from which the disconnected link is excluded in the own node 1, and the candidate link from which the disconnected link is excluded in the other nodes 2 to 4 Based on the available bandwidth, for example, the optimum path is determined by the method described above (step S208).

As illustrated in FIG. 1, the node 2 determines that the link _1-2 is a disconnected link, and the node 4 determines that the link _3-4 is a disconnected link. In this case, for example, the node 3 receives the result packet storing the usable bandwidth of the candidate link excluding the disconnected link from the nodes 1, 2, and 4, and acquires the usable bandwidth of the candidate link excluding the disconnected link. To do. Then, the node 3 is a candidate link _{1-3, 2-3} , _4-3 , 3 excluding the disconnected links _2-1 , _1-2 , _1-4 , _2-4 , _3-4 among all the links. _The optimum path is determined based on _-1,4-1 , _4-2, and _3-2 .

[Node Configuration / Example 1]
Next, the configuration of the node 1 shown in FIG. 1 will be described. FIG. 3 is a block diagram illustrating the configuration of the node 1. The node 1 includes a communication unit 11, a probe packet processing unit 12, a disconnected link determination unit 13, a bandwidth measurement unit 14, a result packet processing unit 15, an optimum path determination unit 16, and a storage unit 17.

  The communication unit 11 of the node 1 transmits and receives probe packets and result packets to and from the mesh network 100. In addition, various messages are transmitted and received in accordance with execution of a ping program and a traceroute program described later.

  The probe packet processing unit 12 generates a probe packet for measuring the available bandwidth at the nodes 2 to 4 at the probe packet transmission timing, and transmits the probe packet to the nodes 2 to 4 via the communication unit 11. To do. The probe packet processing unit 12 receives probe packets from the nodes 2 to 4 via the communication unit 11, calculates the probe packet reception interval, and uses the information such as the reception interval as the probe packet reception information as a bandwidth measurement unit. 14 for output. Further, the probe packet processing unit 12 inputs the non-connection link information from the non-connection link determination unit 13 and stops the transmission of the probe packet to the partner node of the non-connection link. The probe packet processing unit 12 reads out the own node bandwidth information that is the usable bandwidth of the candidate link excluding the unavailable link from the storage unit 17 to be described later, identifies the unavailable link based on this own node bandwidth information, You may make it stop transmission of the probe packet with respect to the other node of a disconnected link. In this case, no data is stored in the available bandwidth of the disconnected link.

  The disconnected link determination unit 13 includes a network route information acquisition unit 131 and a disconnected link determination unit 132. The network route information acquisition unit 131 reads and executes a ping program from a memory (not shown), transmits and receives messages via the communication unit 11, and exists between the partner nodes 2 to 4 as a program execution result. The number of routers to perform and the RTTs of the partner nodes 2 to 4 are acquired. Alternatively, the network path information acquisition unit 131 reads and executes the traceroute program from the memory, transmits and receives messages via the communication unit 11, and as a result of the program execution, the routers existing between the other nodes 2 to 4 The RTT to the IP address and the router (including the partner nodes 2 to 4) is acquired, the number of routers is calculated from the number of IP addresses of the router, and the RTT to the partner nodes 2 to 4 is acquired. The network route information acquisition unit 131 outputs the number of routers and the RTT to the disconnected link determination unit 132 as network route information.

  The ping program is generally used for managing an IP network, and is a program for diagnosing a TCP / IP network such as the Internet or an intranet. By specifying the IP address of the counterpart node, a predetermined amount of data is transmitted using ICMP (Internet Control Message Protocol), and whether there is a reply from the counterpart node, depending on the reply time, etc. Diagnose the network. With this program, the number of routers between the own node and the partner node and the RTT from the own node to the partner node can be acquired. The network route information acquisition unit 131 executes the ping program by designating the IP address of the counterpart node, and acquires the number of routers and RTT as the execution result.

  FIG. 4 is a diagram illustrating an execution result example of the ping program. (Note that FIG. 4 shows IP addresses that are not actually used.) As shown in FIG. 4, the network route information acquisition unit 131 uses the IP address “192.168.0.1” of the partner node. As a result of executing the ping program specifying "", the result of the first sequence (icmp_seq = 0) is that the number of routers is 18 (because ttl (time to live) = 237, 255-237 = 18), RTT Is 9.954 ms (time = 9.954 ms), and the results of the second to eleventh sequences are combined, and the minimum value, average value, maximum value, and average deviation value of RTT (7.369 / 8.707 /. ..Ms) is acquired. As described above, the network route information acquisition unit 131 determines the number of routers between the own node and the partner node (17 in the case of FIG. 4) and the RTT from the own node to the partner node (in the case of FIG. 4, the average value). 8.707 ms).

  On the other hand, the traceroute program is also generally used for managing the IP network, and is a program for listing routers to the target host. With this program, it is possible to acquire the IP address of the router existing between the own node and the partner node and the RTT from the own node to each router (including the partner node). The network route information acquisition unit 131 executes the traceroute program by designating the IP address of the counterpart node, and acquires the IP address of the router and the RTT up to each router (including the counterpart node) as the execution result.

  FIG. 5 is a diagram illustrating an example of the execution result of the traceroute program. (Note that FIG. 5 shows an IP address that is not actually used.) As shown in FIG. 5, the network route information acquisition unit 131 uses the IP address “192.168.0.1” of the counterpart node. As a result of executing the traceroute program by designating "", the number of each router (2 to 18) existing with the other node, the IP address of each router (172.31.254.254, ...), each RTT (0.508 ms, ..., 7.284 ms) to the router (including the partner node) is acquired. In FIG. 5, information on each line from “2” to “18” on the left end is information on each router, information on “1” is information on the own node, and information on “19” is information on the partner node. is there. As described above, the network route information acquisition unit 131 includes the IP address of the router (the IP address of 17 routers 172.31.25254,...) Existing between the own node and the partner node, and the own node. RTT (0.508 ms, ..., 7.284 ms) from the node to each router (including the partner node) is acquired. Then, the network route information acquisition unit 131 calculates the number of routers (17 in the case of FIG. 5) between the own node and the partner node from the number of IP addresses of the router, and RTT (for example, The average values of 7.657 ms, 7.463 ms, and 7.284 ms in the information “19” are calculated.

  Note that the number of routers and RTT acquired by the ping program and the traceroute program change over the long term. Therefore, the network route information acquisition unit 131 repeatedly executes the ping program or the traceroute program as appropriate at a predetermined cycle.

  The disconnected link determining unit 132 inputs the network route information (the number of routers between the own node 1 and the partner nodes 2 to 4 and the RTT from the own node 1 to the partner nodes 2 to 4) from the network route information acquisition unit 131. Then, based on the network route information, a candidate link with inferior transmission performance is determined by a comparison operation with a predetermined threshold value, and the determined candidate link is specified as a disconnected link.

  For example, the disconnected link determining unit 132 compares the number of routers up to the partner node with a predetermined threshold value, and determines that the number of routers is greater than the predetermined threshold value, This link is determined to be a candidate link with poor transmission performance. Alternatively, when the RTT up to the partner node is compared with a predetermined threshold and it is determined that the RTT is greater than the predetermined threshold, the link with the partner node is a candidate link with poor transmission performance. Is determined. This is because links that go through a large number of routers and links with a large RTT tend to have a narrow usable bandwidth and poor transmission performance. The disconnected link determining unit 132 may calculate the average number of routers or RTT including the number of routers or RTTs of other links, and may make a determination based on the magnitude relationship thereof, or may be periodically determined by the network route information acquiring unit 131. The network route information acquired in the network is sequentially input, and the number of routers or the variation in RTT is compared with a predetermined threshold value. A link with a large variation is determined to be unstable, and is determined to be a candidate link with inferior transmission performance. You may make it do.

  Then, the disconnected link determining unit 132 outputs information regarding the disconnected link (disconnected link information) to the probe packet processing unit 12 and the bandwidth measuring unit 14. Thereby, the probe packet processing unit 12 can stop the transmission of the probe packet to the partner node of the disconnected link, and the partner node can be prevented from measuring the available bandwidth of the adjacent link. Therefore, the load on the network and the processing load for determining the optimum path can be reduced.

The bandwidth measuring unit 14 inputs the probe packet reception information (such as the reception interval of the probe packets transmitted from the nodes 2 to 4) from the probe packet processing unit 12 and the non-connection link information from the non-connection link determination unit 13. As described above, the bandwidth measuring unit 14 determines the adjacent links (candidate links _{2-1, 3-1, 4-1} ) between the nodes 2 to 4 based on information such as the reception interval in the probe packet reception information. Measure available bandwidth. Further, the bandwidth measuring unit 14 excludes the disconnected link from the candidate links _{2-1, 3-1} and _4-1 , and stores the available bandwidth of the candidate link from which the disconnected link is excluded in the storage unit 17 as its own node bandwidth information. To do. The bandwidth measuring unit 14 stores the measured available bandwidth of the adjacent link (candidate link) in the storage unit 17 and deletes the available bandwidth of the disconnected link indicated by the input disconnected link information from the storage unit 17. May be.

  The result packet processing unit 15 reads out its own node bandwidth information (available bandwidth of the candidate link excluding the non-transmission link in the own node 1) from the storage unit 17 and stores it in the result packet. To the nodes 2-4. In addition, the result packet processing unit 15 receives the result packet from the nodes 2 to 4 via the communication unit 11, and acquires the usable bandwidth of the candidate link excluding the disconnected links in the nodes 2 to 4 from the result packet. . Then, the result packet processing unit 15 stores the usable bandwidth of the candidate link excluding the disconnected links in the nodes 2 to 4 in the storage unit 17 as other node bandwidth information. As a result, the storage unit 17 has the own node bandwidth information, which is the usable bandwidth of the candidate link excluding the disconnected link in the own node 1, and the available bandwidth of the candidate link excluding the disconnected links in the nodes 2 to 4. Other node bandwidth information is stored.

  The optimal path determination unit 16 includes the own node bandwidth information and other node bandwidth information (the usable bandwidth of the candidate link excluding the disconnected link in the own node 1 and the candidate link excluding the disconnected links in the nodes 2 to 4 from the storage unit 17. Available bandwidth) and the optimum path is determined as described above.

As described above, according to the node 1 of the first embodiment, the network route information acquisition unit 131 of the non-communication link determination unit 13 executes the ping program or the traceroute program so that the own node 1 to the partner nodes 2 to 4 The network route information indicating the number of routers between them and the RTT from the own node 1 to the partner nodes 2 to 4 is acquired, and the disconnected link determining means 132 is based on the network route information and has a large number of routers or a large RTT. The link is determined to be a broken link with poor transmission performance. Then, the bandwidth measuring unit 14 excludes the disconnected link from the candidate links _{2-1, 3-1} and _4-1 , and the probe packet processing unit 12 stops the transmission of the probe packet to the partner node of the disconnected link. The path determination unit 16 determines the optimum path based on the available bandwidth of the candidate link excluding the disconnected link in the own node 1 and the available bandwidth of the candidate link excluding the disconnected link in the other nodes 2 to 4. I made it.

  Thereby, since the optimal path is determined from the candidate links excluding the disconnected link, the number of candidate links to be measured can be reduced. The total amount of probe packets used for measuring the available bandwidth can be reduced, and the load on the network can be reduced. In addition, the amount of calculation for determining the optimum path can be reduced. Accordingly, the problem (1) can be solved, and the processing load for determining the optimum path between nodes in the mesh network 100 can be reduced.

  Next, Example 2 will be described. As described above, the second embodiment is an example in which a message used for BGP for route control is analyzed to acquire network route information and candidate links are reduced. The second embodiment is applicable when an overlay transmission network is constructed between nodes arranged on the Internet.

[Node Processing Overview / Example 2]
The configuration of the mesh network including the node of the second embodiment is the same as the configuration illustrated in FIG. Further, the node 1 of the second embodiment performs the same processing as steps S21 to S26, step S201, step S202, and steps S204 to S208 of the first embodiment shown in FIG. 2, and performs processing different from that of step S203. . The description of step S21 to step S26, step S201, step S202, and step S204 to step S208 is omitted.

  The node 1 receives and analyzes the message used for BGP instead of step S203 of the first embodiment shown in FIG. 2, and from the analysis result, the AS existing between the own node 1 and the partner nodes 2 to 4 is analyzed. Network route information indicating the number of (Autonomous System: autonomous system) is acquired (step S203).

[Configuration of Node / Example 2]
Next, the configuration of the node 1 in the second embodiment will be described. The configuration of the node 1 in the second embodiment is the same as the configuration of the first embodiment illustrated in FIG. 3, but the disconnected link determining unit 13 of the node 1 in the second embodiment is different from the disconnected link determining unit 13 of the first embodiment. Differ in that they perform different processing. Descriptions of the communication unit 11, the probe packet processing unit 12, the bandwidth measurement unit 14, the result packet processing unit 15, the optimum path determination unit 16, and the storage unit 17 are omitted.

  The disconnected link determination unit 13 includes a network route information acquisition unit 131 and a disconnected link determination unit 132. The network route information acquisition unit 131 receives a message used for BGP via the communication unit 11, analyzes the received message, and acquires the AS number between the partner nodes 2 to 4 as an analysis result. The network route information acquisition unit 131 outputs the AS number to the non-communication link determination unit 132 as network route information.

  BGP is a route control protocol for exchanging messages for route control between BGP routers between ISP (Internet Service Provider) networks constituting the Internet. In BGP, each ISP network is called an AS, and a unique number (AS number) is assigned to each AS. The BGP router of each AS transmits a BGP message including the network address included in the AS and its AS number to the BGP router of the connection destination AS. Upon receiving this BGP message, the connection destination BGP router appends its own AS number to the head of the received BGP message (this is referred to as an AS-PATH attribute), and transmits it to the BGP router of another connection destination AS. . For details of BGP, please refer to Chapter 7 of "R. Halhotra, Shimizu Shuji, Introductory IP Routing, O'Reilly Japan, 2002/8".

  Here, the node 1 can obtain the BGP message including the AS-PATH attribute by receiving it from the BGP router of the AS that includes the node 1. In general, if an IP address of a node constituting an overlay transmission network existing on the Internet is known, an AS number including the node can be acquired by a program described later. That is, the node 1 can acquire the AS number of the AS that includes the own node and the AS number of the AS that includes the partner node.

  Therefore, the network route information acquisition unit 131 executes the predetermined program by designating the IP addresses of the own node 1 and the partner nodes 2 to 4, and sets the AS number of each AS including the nodes 1 to 4 as the execution result. get. For example, a service of “RADd, MERIT NETWORK INC., ROUTING ASSSETS DATABASE, [April 22, 2010 search], Internet <URL: http://www.radb.net/>” is used as a predetermined program. be able to. Then, the network route information acquisition unit 131 receives the BGP message arriving at the AS containing the node 1 and acquires the AS-PATH attribute from the BGP message, and the AS-PATH attribute indicates the AS containing the partner node. When it is determined that the number starts with the number, the AS existing between the own node 1 and the partner node is identified based on the AS number included in the AS-PATH attribute acquired from the BGP message, and the number of AS is acquired. .

  FIG. 6 is a diagram illustrating an example of a BGP message. The BGP message is composed of the date and time when the message was generated (DATE & TIME), the type of the message (TYPE), the AS number next to the local node (SOURCE_AS), the AS network address (PREFIX), and the AS-PATH attribute (AS_PATH). Is done. In the type, B indicates a route list at a certain time, A indicates addition / update of the route, and W indicates deletion of the route. (In the actual BGP message, a number from 0 to 65535 is described as the AS number. Here, the AS number is described as #X.) The BGP message shown in FIG. AS- # R for the purpose of obtaining the number of ASs existing between the own node included in the network and the partner node (network address www.xx.y.z / 16) included in AS- # S. 7 is a list of BGP messages whose AS-PATH attribute starts with AS- # S from the BGP messages observed in FIG. That is, the BGP message shown in FIG. 6 has an AS-PATH attribute from AS- # S among the BGP messages received by the network route information acquisition unit 131 in the disconnected link determination unit 13 of the node 1 via the communication unit 11. This is a list of extracted BGP messages.

  FIG. 7 is a diagram showing a route map (AS map) generated from the AS-PATH attribute shown in FIG. The network route information acquisition unit 131 analyzes the BGP message (the BGP message whose AS-PATH attribute starts from AS- # S) shown in FIG. 6, and the own node 1 included in the AS- # R and the AS- # S. As shown in FIG. 7, an AS map (AS map) existing with the partner node included in the is generated. As shown in FIG. 7, between the own node 1 and the partner node, a first route via AS- # B, #C, #D, a second route via AS- # T, #A, There are a total of four routes, the third route via AS- # E, #T, #A and the fourth route via AS- # F, #G, #H. Based on the AS map generated from the AS-PATH attribute included in the BGP message, the network route information acquisition unit 131 uses the first route via AS number 3, the second route AS number 2, and the third route. The number of ASs 3 and the number of ASs 3 of the fourth route are acquired, and the minimum AS number is output to the non-connection link determination unit 132 as network route information. This is because in the route control by BGP, the route with the smallest number of via ASs is usually adopted as the actual packet transfer route.

  Note that the AS map may change due to a change in connection between ISPs. Accordingly, the network route information acquisition unit 131 analyzes the received BGP message and creates an AS map by repeating it appropriately at a predetermined cycle. In addition, the AS map generated by analyzing the BGP message may not necessarily reflect the actual route of the mesh network 100. Therefore, even for candidate links that have once been excluded from the measurement target by analysis of the AS map, appropriate measurement is performed to verify the validity.

  The non-communication link determining unit 132 inputs the network route information (the number of ASs in each link between the own node 1 and the partner nodes 2 to 4) from the network route information acquiring unit 131, and based on the network route information, a predetermined route is determined. A candidate link with inferior transmission performance is determined by a comparison operation with a threshold or the like, and the determined candidate link is specified as a non-communication link.

  For example, the disconnected link determining unit 132 compares the number of ASs in the link with the partner node and a predetermined threshold value, and determines that the AS number is larger than the predetermined threshold value. It is determined that the link between the two is a candidate link with poor transmission performance. This is because a link that passes through a large number of ASs has a large number of routers that pass through it, the available bandwidth is narrow, and transmission performance tends to be inferior. The disconnected link determination unit 132 may calculate an average AS number including the AS number of other links, and may make a determination based on the magnitude relationship thereof, or may be periodically acquired by the network route information acquisition unit 131. The network path information may be sequentially input, and the variation in the number of ASs may be compared with a predetermined threshold to determine that a link with a large variation is unstable and a candidate link with poor transmission performance. .

  Then, the disconnected link determining unit 132 outputs information regarding the disconnected link (disconnected link information) to the probe packet processing unit 12 and the bandwidth measuring unit 14. Thereby, the probe packet processing unit 12 can stop the transmission of the probe packet to the partner node of the disconnected link, and the partner node can be prevented from measuring the available bandwidth of the adjacent link. Therefore, the processing load for determining the optimum path can be reduced.

  As described above, according to the node 1 of the second embodiment, the network route information acquisition unit 131 of the disconnected link determination unit 13 receives the BGP message, and includes the partner node from the AS-PATH attribute included in the BGP message. By identifying the BGP message starting from the AS number and analyzing the AS-PATH attribute included in the BGP message, an AS map between the own node 1 and the partner nodes 2 to 4 is generated, and based on the AS map. Thus, network route information indicating the number of ASs in each link between the own node 1 and the partner nodes 2 to 4 is acquired, and the disconnected link determination unit 132 transmits a link having a large number of ASs based on the network route information. Judged as a broken link with poor performance. Then, the bandwidth measuring unit 14 excludes the disconnected link from the candidate links, the probe packet processing unit 12 stops the transmission of the probe packet to the partner node of the disconnected link, and the optimum path determining unit 16 disconnects the local node 1. The optimum path is determined based on the available bandwidth of the candidate link excluding the link and the available bandwidth of the candidate link excluding the disconnected links in the other nodes 2 to 4.

  Thereby, the number of candidate links to be measured can be reduced as in the first embodiment. The total amount of probe packets used for measuring the available bandwidth can be reduced, and the load on the network can be reduced. In addition, the amount of calculation for determining the optimum path can be reduced. Therefore, the problem (1) can be solved, and the processing load for determining the optimum path between nodes can be reduced in the mesh network.

  In the second embodiment, other methods described below can be used. For example, in the mesh network 100 shown in FIG. 1 and the AS map shown in FIG. 7, by executing the above-described “RADd” program, node 1 becomes AS- # R and node 2 becomes AS- # C. Assume that node 3 is included in AS- # S and node 4 is included in AS- # T. At this time, the direct transmission path to the node 1 → 3 and the detour transmission path to the node 1 → 4 → 3 are the same path (AS- # R → # T → # A → # S) on the AS map. It becomes. For this reason, it is predicted that the measurement results of the usable bandwidth of both paths will be similar.

  Therefore, when the non-communication link determination unit 132 receives AS map information from the network route information acquisition unit 131 and determines that there are a plurality of candidate links passing through the same or similar route based on the AS map information. Then, a part of the plurality of candidate links is determined as a discontinuous link. In the case of the above example, the disconnected link determining unit 132 determines, for example, the latter path among the direct transmission path to the node 1 → 3 and the detour transmission path of the node 1 → 4 → 3 as the disconnected link. Thereby, the processing load of the node 1 and the load of the mesh type network 100 can be reduced.

  Further, for example, in the mesh network 100 shown in FIG. 1 and the AS map shown in FIG. 7, the node 1 is AS- # R, the node 2 is AS- # C, and the node 3 is AS in the same manner as described above. -Assume that node 4 is included in AS- # T in #S. In this case, the direct transmission path (AS- # R → # T → # A → # S) to the node 1 → 3 and the detour transmission path (AS- # R → # B →) of the node 1 → 2 → 3. (# C → # D → # S) does not share a route on the AS map, and therefore, direct transmission to node 1 → 3 and detour transmission of node 1 → 2 → 3 are expected to have little mutual interference. Is done.

Therefore, the non-communication link determination unit 132 inputs AS map information from the network route information acquisition unit 131, and based on the AS map information, only constituent links of paths that do not share a route are set as candidate links, and other links. Are determined to be inferior transmission performance and are determined to be non-communication links. In the case of the above example, it is determined that all the links other than the constituent links of both paths (in this case, the link _1-3 , the link _1-2, and the link _2-3 ) are inferior in transmission performance and are determined as non-communication links. The paths used for transmission are limited to these two paths. Thereby, the processing load of the node 1 and the load of the mesh type network 100 can be reduced. For the transmission application executed in the node 1, both paths of the node 1 → 3 and the node 1 → 2 → 3 are presented as the optimum paths, and the transmission application simultaneously transmits both paths so that both Transmission performance can be improved by combining the available bandwidth of the path.

  In the second embodiment, the description has been given assuming that the nodes 1 to 4 receive the BGP message from the BGP router of the AS including each of the nodes 1 to 4. Instead of receiving the BGP message from the BGP router, the nodes 1 to 4 extract (receive) the BGP message including the AS number of the own node and the partner node in the AS-PATH attribute from the BGP message observed by another AS. ), An AS map may be created from these messages. In the example shown in FIG. 7, the BGP message observed by AS- # R when acquiring the network route information of the link connecting the node included in AS- # T and the node included in AS- # S. The AS message may be extracted by extracting the BGP message including the AS number of the own node and the partner node in the AS-PATH attribute. In this case, the nodes 1 to 4 acquire the observation data of the BGP message by executing a predetermined program. For example, as a predetermined program, “routeviews project, [searched on April 22, 2010], Internet <URL: http://www.routeviews.org/>” “routing information service project, [April 22, 2010 [Search by day], Internet <URL: http://www.ripe.net/projects/ris/index.html "Using a service that stores and publishes BGP messages observed at various locations on the Internet The observation data of the BGP message can be acquired.

  Next, Example 3 will be described. As described above, the third embodiment is an example in which the message used for the OSPF for route control is analyzed to acquire network route information, and candidate links are reduced. The third embodiment is applicable to the case where an overlay transmission network is constructed in an ISP internal network, a dedicated network of a company, or the like.

[Node Processing Overview / Example 3]
The configuration of the mesh network including the node of the third embodiment is the same as the configuration illustrated in FIG. Further, the node 1 of the third embodiment performs the same process as steps S21 to S26, step S201, step S202, and step S204 to step S208 of the first embodiment illustrated in FIG. 2, and performs a process different from that of step S203. . The description of step S21 to step S26, step S201, step S202, and step S204 to step S208 is omitted.

  The node 1 receives and analyzes the message used for OSPF instead of step S203 of the first embodiment shown in FIG. 2, and from the analysis result, the number of routers between the own node 1 and the partner nodes 2 to 4 or Network route information indicating the cost (for example, line speed) is acquired (step S203).

[Node Configuration / Example 3]
Next, the configuration of the node 1 in the third embodiment will be described. The configuration of the node 1 in the third embodiment is the same as the configuration of the first embodiment illustrated in FIG. 3, but the disconnected link determining unit 13 of the node 1 in the third embodiment is different from the disconnected link determining unit 13 of the first embodiment. Differ in that they perform different processing. Descriptions of the communication unit 11, the probe packet processing unit 12, the bandwidth measurement unit 14, the result packet processing unit 15, the optimum path determination unit 16, and the storage unit 17 are omitted.

  The disconnected link determination unit 13 includes a network route information acquisition unit 131 and a disconnected link determination unit 132. The network route information acquisition unit 131 receives a message used for OSPF via the communication unit 11, analyzes the received message, and calculates the number of routers or the cost between the partner nodes 2 to 4 as an analysis result. . The network route information acquisition unit 131 outputs the number of routers or the cost as the network route information to the disconnected link determination unit 132.

  OSPF is a route control protocol for exchanging messages for route control between routers constituting a small IP network. In OSPF, a unique number (router ID) is assigned to each router. Each router broadcasts an advertisement message (LSA: Link State Advertisement) including the network address, cost information, and its router ID assigned to its interface from all network interfaces. The router that has received the LSA broadcasts the received LSA again from all network interfaces except the network interface that has received the LSA. Each router receives the LSA broadcast by other routers, so that the router location on the network, the network address assigned to the router interface, and the cost information of the link between routers (eg, line speed) Is obtained, router map information reflecting these is generated, and an actual packet transfer path is determined based on the generated router map information.

FIG. 8 is a diagram illustrating an example of router map information generated based on the OSPF LSA. From the router map information, for example, a route from the network 172.16.10.0/24 to the network 172.16.30.0/24 is a route via the router 1 → 3 (ID1 → ID3) (the cost is Cost _1-3 ) and a route passing through router 1 → 2 → 3 (ID1 → ID2 → ID3) (the cost is the sum of cost _1-2 and cost _2-3 ). Recognize. Since the IP address of the node is known, the network address that contains the node is also known, so the number of routers and the cost between the two nodes can be known from the router map information. For details of OSPF, please refer to Chapter 6 of “R. Halhotra, Shoshi Shimizu, Introductory IP Routing, O'Reilly Japan, 2002/8”.

  The network route information acquisition unit 131 of the disconnected link determination unit 13 in the node 1 receives the LSA broadcast by the router via the communication unit 11, thereby acquiring the router arrangement, network address, and cost information. Router map information equivalent to the OSPF compatible router can be generated. In this case, the network route information acquisition unit 131 of the node 1 may acquire the router map information by providing an OSPF compatible router with a function of transmitting the generated router map information to the node.

  This router map information corresponds to the AS map of the second embodiment shown in FIG. 7, and the router of the third embodiment corresponds to the AS of the second embodiment. That is, the network route information acquisition unit 131 according to the third embodiment performs the same processing as the network route information acquisition unit 131 according to the second embodiment.

  The disconnected link determining unit 132 inputs the network route information (the number of routers and the cost between the own node 1 and the partner nodes 2 to 4) from the network route information acquiring unit 131, and performs predetermined processing based on the network route information. A candidate link with inferior transmission performance is determined by a comparison operation with a threshold value or the like, and the determined candidate link is specified as a disconnected link.

  For example, the disconnected link determining means 132 compares the number of routers in the link with the partner node and a predetermined threshold value, and determines that the number of routers is greater than the predetermined threshold value, It is determined that the link between the two is a candidate link with poor transmission performance. Further, the disconnected link determining unit 132 compares the line speed, which is the cost of the link with the partner node, with a predetermined threshold value, and determines that the line speed is lower than the predetermined threshold value. The link with the counterpart node is determined to be a candidate link with inferior transmission performance. The disconnected link determining means 132 may calculate the average number of routers or costs including the number of routers or costs of other links, and may make a judgment based on the magnitude relationship thereof, or may be periodically determined by the network route information acquiring means 131. The network route information acquired in order is input sequentially, the number of routers or the variation in cost is compared with a predetermined threshold, and the link with a large variation is determined to be unstable and determined to be a candidate link with inferior transmission performance. You may make it do.

  Then, the disconnected link determining unit 132 outputs information regarding the disconnected link (disconnected link information) to the probe packet processing unit 12 and the bandwidth measuring unit 14. Thereby, the probe packet processing unit 12 can stop the transmission of the probe packet to the partner node of the disconnected link, and the partner node can be prevented from measuring the available bandwidth of the adjacent link. Therefore, the processing load for determining the optimum path can be reduced.

  As described above, according to the node 1 of the third embodiment, the network path information acquisition unit 131 of the disconnected link determination unit 13 uses the LSA used for OSPF to arrange the router and the network address assigned to the router interface. And the cost information of the link between the routers is generated to generate router map information, or the router map information is acquired from the router and the router map information is analyzed. Network path information indicating the number of routers or the cost between them, and the non-communication link determining means 132 is able to transmit a link with a large number of routers or a link with a high cost (low line speed) based on the network path information. Judged to be an inferior disconnect link. Then, the bandwidth measuring unit 14 excludes the disconnected link from the candidate links, the probe packet processing unit 12 stops the transmission of the probe packet to the partner node of the disconnected link, and the optimum path determining unit 16 disconnects the local node 1. The optimum path is determined based on the available bandwidth of the candidate link excluding the link and the available bandwidth of the candidate link excluding the disconnected links in the other nodes 2 to 4.

  Thereby, similarly to the first and second embodiments, the number of candidate links to be measured can be reduced. Then, it is possible to reduce the total amount of probe packets that are used for measuring the available bandwidth, and to reduce the addition of networks. In addition, the amount of calculation for determining the optimum path can be reduced. Therefore, the problem (1) can be solved, and the processing load for determining the optimum path between nodes can be reduced in the mesh network.

  In the third embodiment, another method described in the second embodiment can be used. The disconnected link determining unit 132 in the disconnected link determining unit 13 of the node 1 determines, based on the router map information, that there are a plurality of candidate links passing through the same or similar route, as in the other method of the second embodiment. In such a case, a part of the plurality of candidate links is determined as a discontinuous link. Thereby, the processing load of the node 1 and the load of the mesh type network 100 can be reduced. Similarly to the other method of the second embodiment, the non-communication link determination unit 132 sets only the configuration link of the path that does not share the route as the candidate link based on the router map information, and the other links have poor transmission performance. Is determined to be a disconnected link. Thereby, the processing load of the node 1 and the load of the mesh type network 100 can be reduced. Also, for the transmission application, for example, both paths of node 1 → 3 and node 1 → 2 → 3 are presented as optimum paths, and both paths can be used by transmitting to the transmission application using both paths simultaneously. The transmission performance can be improved by combining the bands.

  In the above-described first to third embodiments, all the nodes 1 to 4 of the mesh network 100 measure the available bandwidth of the candidate link excluding the disconnected link, store it in the result packet, and transmit it to the other nodes 1 to 4 By doing so, the measurement results were exchanged with each other, and the optimum path was determined for each. On the other hand, not all of the nodes 1 to 4 may determine the optimum path, but the predetermined path calculation node may determine the optimum path. For example, each of the nodes 1 to 4 measures the available bandwidth of the adjacent link, stores the measurement result in a result packet, and transmits it to the route calculation node. The route calculation node receives the result packet, performs a process similar to that of the disconnected link determination unit 13 of the first to third embodiments to determine a disconnected link, and performs a process similar to that of the optimal path determination unit 16 to determine an optimal path. decide. Each of the nodes 1 to 4 inquires about the broken link and the optimum path to the route calculation node.

  Next, Example 4 will be described. In the fourth embodiment, as described above, in addition to any of the first to third embodiments, the available bandwidth of the adjacent link is stored in the probe packet and transmitted to reduce the total packet transmission amount of the network.

  FIG. 9 is a schematic diagram illustrating a configuration of a mesh network including nodes according to the fourth embodiment. The mesh network 100 is configured in a mesh shape by a plurality of nodes 21 to 24 and the like connected to each other. The same applies to the fifth embodiment.

[Node Processing Overview / Example 4]
FIG. 10 is a flowchart showing an outline of processing of the node 21 shown in FIG. The nodes 22 to 24 perform the same processing as the node 21. The same applies to the fifth embodiment.

When the node 21 receives the probe packet from each of the nodes 22 to 24 (step S91: Y), the node 21 measures the available bandwidth (bands _{2-1, 3-1, 4-1} ) of the adjacent link (step S901). ). Adjacent links that measure available bandwidth are candidate links.

When the node 21 determines the update timing of the disconnected link (step S92: Y), the node 21 acquires network route information according to any one of the first to third embodiments (step S902). The update timing is, for example, a predetermined time interval. Then, the node 21 determines a disconnected link based on the network route information (step S903), and excludes the disconnected link from the candidate links (links _{2-1, 3-1, 4-1} ) (step S904). The example of FIG. 9 shows a case where there is no disconnected link.

  When the node 21 determines the transmission timing of the probe packet (step S93: Y), the probe packet for measuring the available bandwidth in the nodes 22 to 24 is used as the probe packet with the available bandwidth of the candidate link excluding the disconnected link. (Step S905), and transmits the probe packet to the nodes 22 to 24 (step S906). The transmission timing is, for example, a predetermined time interval.

  When the node 21 determines the timing for determining the optimum path (step S94: Y), the usable bandwidth of the candidate link excluding the disconnected link in the own node 21 and the candidate link excluding the disconnected link in the other nodes 22-24. The optimum path is determined based on the available bandwidth (step S907).

[Node Configuration / Embodiment 4]
Next, the configuration of the node 21 shown in FIG. 9 will be described. FIG. 11 is a block diagram showing the configuration of the node 21. The node 21 includes a communication unit 11, a probe packet processing unit 31, a disconnected link determination unit 13, a bandwidth measurement unit 14, an optimum path determination unit 16, and a storage unit 17. 11, parts common to the configuration of the node 1 shown in FIG. 3 are denoted by the same reference numerals as those in FIG. Comparing the node 1 shown in FIG. 3 with this node 21, the nodes 1 and 21 include the communication unit 11, the disconnected link determination unit 13, the bandwidth measurement unit 14, the optimum path determination unit 16, and the storage unit 17. Although the point is the same, the node 21 is different in that it does not include the result packet processing unit 15 and includes a probe packet processing unit 31 different from the probe packet processing unit 12 of the node 1.

  The probe packet processing unit 31 generates a probe packet for measuring the available bandwidth in the nodes 22 to 24 at the probe packet transmission timing, and also transmits its own node bandwidth information (disconnected link in the own node 21 from the storage unit 17). Usable bandwidth of the excluded candidate link) is read out, the own node bandwidth information is stored in the probe packet, and the probe packet is transmitted to the nodes 22 to 24 via the communication unit 11. The probe packet processing unit 31 receives probe packets from the nodes 22 to 24 via the communication unit 11, calculates the reception interval of the probe packets, and uses the information such as the reception interval as probe packet reception information as a bandwidth measurement unit. 14 for output. Then, the available bandwidth of the candidate link excluding the disconnected links in the other nodes 22 to 24 is acquired from the received probe packet, and stored in the storage unit 17 as other node bandwidth information. Further, the probe packet processing unit 31 inputs the non-connection link information from the non-connection link determination unit 13 and stops the transmission of the probe packet to the partner node of the non-connection link.

  As described above, according to the node 21 of the fourth embodiment, the probe packet processing unit 31 transmits the probe packet storing the available bandwidth of the candidate link excluding the disconnected link in the own node 21, and the other nodes 22- The probe packet storing the usable bandwidth of the candidate link excluding the non-conducting link in 24 is received.

  As a result, the bandwidth measurement is performed without separately transmitting and receiving the probe packet for measuring the available bandwidth of the adjacent link and the result packet including the available bandwidth of the candidate link excluding the disconnected link, and the measurement result. Only the probe packet for exchanging is transmitted / received. Therefore, the total amount of packets sent to the network can be reduced while simultaneously performing bandwidth measurement and measurement result exchange. Therefore, in addition to the effect of the first embodiment, the problem (2) can be solved.

  Note that the probe packet processing unit 31 of the node 21 can use the usable bandwidth of the candidate link (specifically, a link identifier (for example, a unique identifier assigned to each link in advance, The identifier (a pair of IP addresses of nodes at both ends of the link) and the measurement result of the usable bandwidth of the link) are stored in the probe packet. However, the storage format is not limited.

  Next, Example 5 will be described. As described above, the fifth embodiment is an extended example of the fourth embodiment, in which the attribute of the usable bandwidth of the adjacent link is stored in the probe packet and transmitted to reduce the total packet transmission amount of the network.

[Node Processing Overview / Example 5]
The configuration of the mesh network including the node of the fifth embodiment is the same as the configuration illustrated in FIG. In addition to the processing of the fourth embodiment illustrated in FIG. 10, that is, the processing of steps S91 to S94 and steps S901 to S907, the node 21 of the fifth embodiment is adjacent between step S905 and step S906. An attribute of the usable bandwidth of the link is generated, and the attribute is stored in the probe packet. Description of steps S91 to S94 and steps S901 to S907 is omitted.

[Node Configuration / Embodiment 5]
Next, the configuration of the node 21 in the fifth embodiment will be described. The configuration of the node 21 in the fifth embodiment is the same as the configuration of the fourth embodiment illustrated in FIG. 11, but the probe packet processing unit 31 and the optimum path determination unit 16 of the node 21 in the fifth embodiment are the same as those in the fourth embodiment. The probe packet processing unit 31 and the optimum path determination unit 16 are different in that they perform different processing. Description of the communication unit 11, the disconnected link determination unit 13, the bandwidth measurement unit 14, and the storage unit 17 is omitted.

  In addition to the processing shown in the fourth embodiment, the probe packet processing unit 31 reads out its own node bandwidth information from the storage unit 17 and performs statistical processing every time it reads out its own node bandwidth information that is a measurement result of measuring the available bandwidth. The reliability of the measurement result (for example, information indicating whether the variation in the measurement result is large or small obtained by comparing with the threshold value) or the stability (for example, by comparing with the threshold value) , Information indicating whether the measurement result shows almost the same value in the long term) is generated as an attribute. Then, the probe packet processing unit 31 stores the generated attribute in the probe packet in addition to the usable bandwidth of the candidate link excluding the disconnected link in the own node 21 and transmits it to the nodes 22 to 24. Further, the probe packet processing unit 31 receives the probe packets transmitted from the nodes 22 to 24, acquires attributes from the probe packets, and outputs them to the optimum path determination unit 16.

  The optimum path determination unit 16 stores the own node bandwidth information and other node bandwidth information (the usable bandwidth of the candidate link excluding the disconnection link in the node 21 and the candidate link excluding the disconnection links in the nodes 22 to 24 from the storage unit 17. Available bandwidth), attributes (reliability or stability of measurement results) are input from the probe packet processing unit 31, and the optimum path is determined based on the available bandwidth and attributes of candidate links excluding the non-communication link. . That is, a link with high reliability or stability is preferentially handled, and the optimum path is determined. For example, when there are a plurality of links having the same available bandwidth, the link with higher reliability or stability is handled so as to be the link with the optimum path.

  The attribute may include the time when the measurement result is obtained (measurement time). In this case, the optimum path determination unit 16 preferentially handles a link with a new measurement time and determines an optimum path. For example, when there are a plurality of links having the same usable bandwidth, the link with the new measurement time is handled so as to be the link of the optimum path. Further, the attribute may include information such as transmission delay, and such information is used in determining the optimum path.

  FIG. 12 is a diagram illustrating a configuration example of a probe packet in the fourth and fifth embodiments. As shown in FIG. 13, the conventional probe packet is composed of dummy data except for the head header portion. On the other hand, the probe packet in the fourth and fifth embodiments shown in FIG. 12 has the same header as the conventional probe packet, the IP address of the partner node of the adjacent link held by the node 21 that transmits the probe packet, and the bandwidth measurement result. And an available bandwidth and a payload including attributes. Dummy data is stored in the remaining payload portion. In FIG. 12, for each adjacent link, the IP address of the link partner node as the link identifier (IP address that can uniquely identify the link together with the Source Address of the IP header), and the bandwidth measurement result of the link The available bandwidth and link attributes are grouped. Here, the usable bandwidth as the link bandwidth measurement result and the data length of the link attribute are 8 bytes. When the number of adjacent links is small, dummy data is stored in the remaining portion, and when the number of adjacent links is large, information on the payload portion is stored in a plurality of probe packets. In the fourth embodiment, the IP address of the partner node of the adjacent link held by the node 21 and the available bandwidth that is the bandwidth measurement result are stored in the payload portion of the probe packet shown in FIG. The IP address of the partner node of the adjacent link held by the node 21, the available bandwidth as a bandwidth measurement result, and the attribute are stored.

  As described above, according to the node 21 of the fifth embodiment, the probe packet processing unit 31 adds the attribute (for example, measured availability) in addition to the available bandwidth of the candidate link excluding the disconnected link in the own node 21. Information that digitizes the reliability or stability of the bandwidth) is also stored and transmitted in the probe packet, and the probe packet storing the available bandwidth and attributes of the candidate links excluding the non-communication links in the other nodes 2 to 4 is received. I tried to do it. Then, the optimal path determination unit 16 determines the optimal path with reference to the attribute.

  This increases the possibility that a path having a link with high link reliability or stability is determined as the optimum path. Therefore, in addition to the effect of the fourth embodiment, the accuracy of the determined optimum path is increased.

  Although the present invention has been described with reference to the first to fifth embodiments, the present invention is not limited to the first to fifth embodiments, and various modifications can be made without departing from the technical idea thereof. For example, the first to fifth embodiments have been described on the assumption that the mesh network 100 is used. However, the mesh network 100 includes a logical network using an overlay technique. In the first to fifth embodiments, the description has been made on the assumption that the available bandwidth is measured using the packet pair method. However, the present invention is applicable to a general measurement method using a probe packet. It is not limited.

  In addition, a normal computer can be used as the hardware configuration of the nodes 1 to 4 and 21 to 24 according to the first to fifth embodiments of the present invention. The nodes 1 to 4 and 21 to 24 are configured by a computer including a volatile storage medium such as a CPU and a RAM, a nonvolatile storage medium such as a ROM, an interface, and the like. The communication unit 11, the probe packet processing unit 12, the disconnected link determination unit 13, the bandwidth measurement unit 14, the result packet processing unit 15, the optimum path determination unit 16, and the storage unit 17 included in the nodes 1 to 4 of the first to third embodiments. Each function is realized by causing a CPU to execute a program describing these functions. The functions of the communication unit 11, the probe packet processing unit 31, the disconnected link determination unit 13, the bandwidth measurement unit 14, the optimum path determination unit 16, and the storage unit 17 included in the nodes 21 to 24 of the fourth and fifth embodiments are also provided. These are realized by causing the CPU to execute programs describing these functions. These programs can be stored and distributed in a storage medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, or the like.

1 to 4, 21 to 24, 101 to 104 Node 11 Communication unit 12 Probe packet processing unit 13 Disconnected link determination unit 14 Bandwidth measurement unit 15 Result packet processing unit 16 Optimal path determination unit 17 Storage unit 31 Probe packet processing unit 100 Mesh type Network 131 Network route information acquisition means 132 Non-connection link determination means

Claims (7)

In a node device that determines an optimum path between node devices based on an available bandwidth of an adjacent link under a mesh network composed of a plurality of node devices,
Network path information acquisition means for acquiring network path information used for determining transmission performance between the node device and another node device, and based on the network path information, determine a link with inferior transmission performance, A disabling link determination unit having a disabling link determination means for determining a link as a disabling link;
A bandwidth measuring unit that excludes the disconnected link from a plurality of candidate links indicating a route between the node device and another node device, and measures an available bandwidth of the candidate link that excludes the disconnected link in the node device; ,
The available bandwidth of the candidate link excluding the disconnected link measured by the bandwidth measuring unit is stored in a result packet, transmitted to another node device, and the disconnected link in the other node device is transmitted from the other node device. A result packet processor that receives the result packet storing the usable bandwidth of the excluded candidate link, and obtains the usable bandwidth of the candidate link from which the non-communication link is excluded from the result packet;
The usable bandwidth of the candidate link excluding the disconnected link in the node device measured by the bandwidth measuring unit, and the usable bandwidth of the candidate link excluding the disconnected link in the other node device acquired by the result packet processing unit And an optimal path determination unit that determines the optimal path based on
A node device comprising: The node device according to claim 1,
The network path information acquisition means of the disconnected link determination unit executes a ping program or a traceroute program used for managing the network, and based on the execution result, the node device and other nodes Obtain the number of routers or RTT (Round Trip Time) from the device as network route information,
The disconnected link determining means compares the network route information acquired by the network route information acquiring means with a predetermined threshold value, and links between the node device and other node devices for the network route information. Is determined as a non-communication link. The node device according to claim 1,
The network link information acquisition unit of the non-communication link determination unit is configured based on an AS number included in an AS (Autonomous System) -PATH attribute of a BGP message used for BGP (Border Gateway Protocol) for controlling a network path. The BGP message transmitted to the AS that includes the node device is transmitted to the AS that includes the node device, and the AS number included in the AS-PATH attribute of the selected BGP message is Obtain the AS number with other nodes as network route information,
The disconnected link determining means compares the network route information acquired by the network route information acquiring means with a predetermined threshold value, and links between the node device and other node devices for the network route information. Is determined as a non-communication link. The node device according to claim 1,
The network route information acquisition means of the non-communication link determination unit is based on an advertisement message used for OSPF (Open Shortest Path First) for controlling the network route, and is attached to the interface of the router to which the message is transmitted Obtaining the address and cost information of the link between routers, obtaining the number of routers or cost information between the node device and other node devices as network path information from the network address and cost information,
The disconnected link determining means compares the network route information acquired by the network route information acquiring means with a predetermined threshold value, and links between the node device and other node devices for the network route information. Is determined as a non-communication link. In the node apparatus as described in any one of Claim 1 to 4,
A probe packet processing unit is provided instead of the result packet processing unit,
The probe packet processing unit receives a probe packet for measuring the available bandwidth of the adjacent link in the node device from another node device, and causes the other node device to measure the available bandwidth of the adjacent link A node device characterized in that, in a packet, an available bandwidth of a candidate link excluding a non-communication link measured by the bandwidth measuring unit is stored, and the probe packet is transmitted to another node device. In a method for determining an optimum path between node devices based on an available bandwidth of an adjacent link under a mesh network composed of a plurality of node devices,
Obtaining network path information used for determining transmission performance between the node device and another node device;
Determining a link with inferior transmission performance based on the network path information;
Determining a link determined to have inferior transmission performance as a discontinuous link;
Measuring the available bandwidth of the candidate link excluding the non-performing link from the plurality of candidate links indicating the path between the node device and another node device; and
Storing the measured available bandwidth of the candidate link excluding the disconnected link in the node device in a result packet, and transmitting to the other node device;
A result packet storing the usable bandwidth of the candidate link excluding the non-conducting link in the other node device is received from another node device, and the candidate link excluding the non-conducting link in the other node device is received from the result packet. Obtaining available bandwidth; and
Determining the optimum path based on the available bandwidth of the candidate link excluding the disconnected link in the node device and the available bandwidth of the candidate link excluding the disconnected link in another node device;
An optimal path determination method comprising:   The optimal path determination program for functioning a computer as a node apparatus as described in any one of Claim 1-5.

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