JP2010141384A - Network system, node, node evaluation method, program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a network system or the like in which each node can more appropriately evaluate the behavior and traffic status of each other.
A rating node 3, 2-hop neighbor node ₇₁ of the measurement probe packets transmitted to the evaluation target nodes 5, ..., rather than to grasp by measuring the transfer status to 7 _J, 2 hops adjacent nodes 7 _1, ..., 7 the packet measurement unit 43 ₁ of the _J, ..., 7 _J by watching the evaluation target node 5 to obtain a reception status of the measurement packet, a 2-hop neighborhood adjacent nodes ₇₁ that information ,..., 7 _J can be shared by each node, and each node can autonomously and appropriately detect a node that does not operate normally.
[Selection] Figure 1

Description

  The present invention relates to a network system, a node, a node evaluation method, a program, and a recording medium, and in particular, two nodes such as a multi-hop wireless network do not relay other nodes or relay other nodes. The present invention relates to a network system that performs communication.

  In a wireless LAN (Local Area Network), a terminal station constructs a LAN by performing wireless communication with an access point (Access Point (AP)) connected to an existing infrastructure network (infrastructure). Currently, a multi-hop wireless network (MWN), which uses wireless LAN communication between APs and relays communication between APs, attracts attention.

  In MWN, the entire network is configured by a wireless network. Since a large number of APs form a network, it can be expected to provide a wide service area. Therefore, in order not to impair the availability of the network, high reliability is required for the AP configuring the network. When the AP cannot operate normally, the reliability of the AP constituting the network is lowered. In such a case, a mechanism for evaluating the operating status of each AP in the network is necessary in order for the network itself to appropriately take appropriate measures such as reconfiguration of the MWN.

  Nodes that adversely affect MWN can be classified into two. One is a malicious node that maliciously affects surrounding nodes. For example, there are various attacks such as a DoS (Denial of Service) attack.

  Another node that has an adverse effect is a selfish node that plans to create a network that greedily meets its requirements. A selfish node is very uncooperative with the network and aims to maximize the data it sends or the throughput of nodes under its control. For example, the packet generated by itself is normally transferred, the packet transmitted from other nodes is not transferred, and the intention to participate in the network is displayed around the weakness of the MAC layer protocol, Actually, it performs activities such as sending only its own information.

  These adversely affecting nodes are currently reported in the Mobile Ad Hoc Network (MANET), and research is being conducted on countermeasures against each attack. For example, countermeasures against selfish nodes can be roughly divided into three. A method based on a currency model, a method based on a game theory, and a method based on reputation (for example, refer to Non-Patent Document 1 and Non-Patent Document 2 for a method based on reputation).

P. Michiardi et al., “CORE: Collaborative Reputation Mechanism to enforce node cooperation in Mobile Ad hoc Networks”, Proc. Of the 6th IFIP Communication and Multimedia Security, 2002 S. Buchegger et al., “Performance analysis of the CONFIDANT protocol”, Proc. Of ACM International Symposium on Mobile Ad hoc Networking and Computing, 2002

  The method based on the currency model is a method in which a currency value is added to a packet flowing to each node, and the reliability of the node is measured based on the currency circulation amount of the node. In this method, in the case of MANET, nodes are mobile, and packets flow uniformly in all nodes, so that there is little bias in the amount of packet distribution with respect to each node. However, in the case of MWN, since the AP that constructs the network does not have mobility, packets may not flow uniformly to all nodes, and variations may occur in each node.

  The technique based on the game theory is a technique for detecting a selfish node by analyzing the operation of each node using the game theory. This method allows complex analysis. However, since the premise for verification and its network model are unrealistic, adaptation in an actual network is difficult.

  The reputation-based method is a method of identifying and dealing with a selfish node by monitoring adjacent nodes of each node and creating a reputation of the adjacent nodes from the monitoring result. Since this method uses a simple method of generating the reputation of adjacent nodes based on the monitoring results, each node can easily identify nodes that are selfish in a distributed manner without performing centralized management.

Reputation-based methods are being researched mainly in the field of MANET. Typical techniques include CORE described in Non-Patent Document 1 and CONFIDANT described in Non-Patent Document 2. These basic approaches, with reference to FIG. 4 (a), the node AP _k will be described as an example the case of transferring the data via the AP k _{+ 1} to the AP k _{+ 2.} First, AP _k transfers data to AP _{k + 1} within a communicable range. AP _{k + 1 transfers} the data received from AP _k to AP _{k + 2} within the radio range of AP _{k + 1} . In this case, since the AP _k has radio wave AP k _{+ 1} exists in the extent possible reached, by a method such as to operate the interface in promiscuous mode, knowing the data transfer status of the AP k + ₁ Can do. Therefore, AP _k can confirm whether or not AP _{k + 1} correctly transfers the data packet transmitted by itself to AP _{k + 2} .

  However, the adjacent node monitoring method in these MANETs is based on the premise that each node can detect the content transmitted by the adjacent node to a further node. However, at present, in order to prevent deterioration of communication quality due to interference of the same radio channel in MWN, for example, studies are being made to maintain a plurality of interfaces for each node. Therefore, when the MANET method is applied to the MWN, it may be difficult for each AP to monitor the operation of the neighboring AP.

The difficulty of AP monitoring in MWN, with reference to FIG. 4 (b), AP _k will be described as an example the case of transferring data through the AP k _{+ 1} to the AP k _{+ 2.} At this time, it is assumed that each AP has two interfaces and uses different channels for the reception interface and the transmission interface. As for the reception interface of each AP, AP _k is set to channel 1, AP _{k + 1} is set to channel 2, and AP _{k + 2} is set to channel 3. AP _k transmits data to the AP k _{+ 1} in channel 2, and transfers the data in AP k _{+ 1} is the channel 3 to the AP k _{+ 2.} In this case, the receiving interface of AP _k because it is set to channel 1, AP k + ₁ can not information that originated in channel 3 AP _k detects. Thus, when the AP has a plurality of interfaces and uses a plurality of radio channels, each AP cannot monitor the data transfer of the neighboring AP.

  Accordingly, an object of the present invention is to propose a network system or the like in which each node can more appropriately evaluate the behavior and traffic status of each other.

  The invention according to claim 1 is a network system including three or more nodes, wherein the two nodes do not relay other nodes or perform communication by relaying other nodes. , Communication is possible without relaying other nodes to the evaluation target node, and the evaluation target node does not relay the evaluation node to two or more forwarding nodes different from the evaluation node. The evaluation node includes probe management means for transmitting a probe to the evaluation target node, and the evaluation target node transfers the received probe to each transfer node, and each transfer node Comprises a packet measurement means for measuring the reception status of the transferred probe, and a measurement result transmission means for transmitting the measurement result of the packet measurement means to the evaluation node. The system includes an integration unit that generates an overall evaluation value by integrating the measurement results received from the transfer nodes, and a determination unit that determines a communication status of the evaluation target node using the evaluation value. .

  The invention according to claim 2 is the network system according to claim 1, wherein the packet measuring means of each forwarding node relays the evaluation target node from the evaluation node in addition to the forwarded probe. And measuring the reception status of the packets transferred to the forwarding node, and the integration means of the evaluation node integrates the measurement results to calculate a local evaluation value, and transmits the measurement result of each forwarding node. The means transmits a local evaluation value for the evaluation target node calculated in the transfer node, in addition to the measurement result indicating the reception status of the transferred probe and the transferred packet. The integration unit integrates the local evaluation value calculated by integrating the measurement results and the local evaluation value in the forwarding node, and thereby combines the total evaluation value. It is intended to be generated.

  The invention according to claim 3 is the network system according to claim 1 or 2, wherein, in the evaluation node, the probe management means transfers to each of the transfer nodes via the evaluation target node. Managing a probe transmission dedicated route table holding route information, transmitting the probe to each forwarding node in the probe transfer route information, and each of the probe management means and the probe transmission dedicated route table is the evaluation The same number exists corresponding to the target node.

  The invention according to claim 4 is the network system according to claim 3, wherein communication in a communication path from the evaluation node to the forwarding node via the evaluation target node is wireless communication, and the evaluation node The evaluation target node and each forwarding node hold a plurality of interfaces, and the evaluation node transmits and receives data other than the probe to other nodes in addition to the probe transmission dedicated route table. A default routing table that holds routing information; routing information management means that manages the default routing table; and path management means that changes information held by the routing information management means to manage the default routing table. It is.

  The invention according to claim 5 is a node in the network system, the probe management means for transmitting a probe to the evaluation target node, and the evaluation target node transfers the probe to two or more different transfer nodes, and Measurement result determination means for evaluating the communication status of the evaluation target node from evaluation values obtained by integrating the probe reception measurement results at each transfer node is provided.

  The invention according to claim 6 is a node evaluation method in a network system including a plurality of nodes, wherein the evaluation node probe management means transmits a probe to the evaluation target node; and The step of transferring the probe to two or more different transfer nodes, and the communication of the evaluation target node from the evaluation value obtained by integrating the measurement result determination unit of the evaluation node with the reception measurement result of the probe in the transfer node Evaluating the situation.

  The invention according to claim 7 is a probe management means for transmitting a probe to the evaluation target node, a computer capable of communicating with the evaluation target node, and the evaluation target node transfers the probe to two or more different transfer nodes. And a program for functioning as a measurement result judging means for evaluating the communication status of the evaluation target node from the evaluation value obtained by integrating the reception measurement results of the probes in the respective transfer nodes.

  The invention according to claim 8 is a computer-readable recording medium for recording the program according to claim 7.

  Note that the evaluation node may include a network control unit that controls the network based on the determination result of the determination unit.

  According to the present invention, the evaluation node does not measure and grasp the transmission status of the evaluation target node, but monitors the evaluation target node by obtaining the reception status of the packet that has reached the forwarding node through the evaluation target node. However, by sharing the information between neighboring nodes, each node can autonomously and appropriately detect a node that does not operate normally. Further, for example, the network can be reconfigured.

  In the invention according to claim 3, the transfer of the probe is managed not by the evaluation target node but by the evaluation node. As a result, it is possible to set a special transfer path for evaluation instead of the transmission path managed by the evaluation target node. Furthermore, by providing the probe transmission means and the probe transmission dedicated management table corresponding to the evaluation target node, it is possible to flexibly cope with the generation / disappearance of the evaluation target node.

  Further, in the invention according to claim 4, the probe transmission dedicated management table is separate from the default management table for managing a normal communication path, and the path management means further includes path information for managing the default management table. Change the management information of the management means. Thereby, there is no fundamental change in the conventional communication information management means, and the evaluation method of the present invention can be realized in an added form.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  First, with reference to FIG. 1, the outline | summary of the evaluation method of a present Example is demonstrated. FIG. 1 is a schematic block diagram showing a network system 1 which is an embodiment of the present invention. In this embodiment, the network system 1 is a multi-hop wireless network system (MWN) in which a plurality of nodes (for example, access points AP) are arranged. FIG. 1 shows only nodes related to the evaluation process by the evaluation nodes (APs) 3, but there are other nodes in the network system 1. In this embodiment, each node has a plurality of wireless interfaces (hereinafter referred to as “multi-I / F”) using a wireless link in the 4.9 GHz-5.2 GHz band (IEEE11a or j) or 2.4 GHz band (IEEE11b or g). ). As described above, the present embodiment considers multi I / F / multi radio.

In the present embodiment, a case where the evaluation target node (AP _t ) 5 that is an adjacent node of the evaluation node 3 is evaluated will be described as an example. The evaluation node 3 cooperates with 2 hop neighboring nodes (2HN-AP: 2 Hop Neighbor Access Point) 7 ₁ ,..., 7 _J which are other nodes adjacent to the evaluation target node 5 to evaluate. This is to cope with the monitoring problem of neighboring APs in multi I / F / multi radio. Further, in this embodiment, in order to improve reliability, the direct report from the evaluation target node 5 is not reliable, and is linked to the indirect nodes 2 hop adjacent nodes 7 ₁ ,..., 7 _J. This evaluates the behavior of the evaluation target node. It is assumed that information flowing between the nodes is not wiretapped / tampered.

2 shows an evaluation processing sequence between 2-hop adjacent nodes (2HN-AP) 7 ₁ ,..., 7 _J when the evaluation node (AP _s ) 3 of FIG. FIG. Hereinafter, with reference to FIG. 1 and FIG. 2, the evaluation method of a present Example is demonstrated concretely.

In the network system 1 of FIG. 1, the evaluation node 3 and the evaluation target node 5 are nodes that can communicate without passing through other nodes (hereinafter referred to as “adjacent nodes”), and are adjacent to the evaluation target node 5 in two hops. Nodes 7 ₁ ,..., 7 _J are also adjacent nodes.

  The evaluation node 3 includes a route information management unit 11 that manages communication paths of general packets (packets excluding at least measurement probe packets described later), a default path table 13 that stores communication paths of general packets, An additional evaluation unit 15 that performs evaluation processing of the evaluation target node 5 is provided. In the following, a case will be described as an example where the route information management unit 11 performs management using OLSR (Optimized Link State Routing protocol, see the Internet <URL: http://www.olsr.org>). The route information management unit 11 is realized by a resident process that performs route calculation according to OLSR called olsrd.

The additional evaluation unit 15 corresponds to the control unit 21 that controls the processing of the additional evaluation unit 15, the topology detection unit 23 that performs the topology detection process, and the node to be evaluated, and the measurement probe is connected to the corresponding node. packet (hereinafter, referred to as. "probe") probe manager 25 ₁ for transmitting, ..., 25 _N and the probe control section 25 _1, respectively, ..., probe transmission dedicated to hold the transmission path of the probe in response to 25 _N route table 27 _1, ..., and 27 _N, probes other node has transferred (hereinafter, referred to as "transfer probe.") and the packet measurement unit 31 for measuring the reception status of packets, including, with respect to the source of the probe The measurement result transmission unit 33 that transmits the measurement result of the packet reception status, the measurement result reception unit 35 that receives the measurement result from another node, and the received measurement result are integrated. Comprising measurement result integration unit 37, and determines the measurement result determination unit 39 an integrated measurement results, the network control unit 40 for controlling the network by the determination of the measurement result determination unit 39.

In this embodiment, it is assumed that the additional evaluation unit 15 is realized as an OLSR plug-in (wirem plug-in in FIG. 1). As described above, the additional evaluation unit 15 can be realized by being added to an existing system. In addition, the topology detection unit 23, probe management units 25 ₁ ,..., 25 _N , transfer probe reception unit 31, measurement result transmission unit 33, measurement result reception unit 35, measurement result integration unit 37, measurement result determination unit 39, and network control Each unit 40 is realized by a separate thread. In each node, thread management is performed as necessary (for example, generation / release of a child thread from the main thread, priority setting of each thread, and the like). ) Is done.

  The control unit 21 sets configuration parameters for the additional evaluation unit 15 (for example, a probe transmission UDP port number and transmission interval, probe reception) from a Config file (hereinafter referred to as “Config”) read by the route information management unit 11 at the time of activation. Result, DV value notification UDP port number and notification interval, weighted average coefficient α for DV value calculation, etc.).

  The topology detection unit 23 acquires the topology information of the route information management unit 11. For example, the topology check is performed at regular intervals using the scheduling function of olsrd. As a means for updating the topology information, the interface information held by the nodes is periodically exchanged at a specified cycle. In this way, the topology information held by the route information management unit 11 is updated.

The topology detection unit 23 discovers the evaluation target node 5 from the acquired topology information, and further discovers 2-hop adjacent nodes 7 ₁ ,..., 7 _J that are adjacent nodes of the evaluation target node 5 other than the evaluation node 3. (Step ST1 in FIG. 2). A set of an adjacent node address and a 2-hop adjacent node address passing through the adjacent node is managed as 2-hop adjacent node information. When the detection / disappearance of the node is recognized, the probe management unit 25 ₁ ,..., 25 _N is notified. At this time, reputation data (DV, GV, etc. described later) retains information.

The topology detection unit 23 activates the probe management units 25 ₁ ,..., 25 _N as child threads corresponding to the nodes to be evaluated. Each of the probe managers 25 ₁ ,..., 25 _N manages a probe transmission dedicated route table 27 ₁ ,..., 27 _N that holds a communication route that reaches a 2-hop adjacent node via the corresponding node to be evaluated. To do. In the following, it is assumed that the evaluation target node 5 corresponds to the probe management unit 25 _n (n is a natural number equal to or less than N).

The probe management unit 25 _n transmits the probe to the IP addresses of the 2-hop adjacent nodes 7 ₁ ,..., 7 _J via the evaluation target node 5 by using the port specified in Config and by specifying the socket option. The probe to be transmitted is a dedicated message and is transmitted using the UDP port number specified in Config.

The probe always passes through the evaluation target node 5. Therefore, an interface device name (such as eth0) with the evaluation target node 5 is required. For this, I / F information managed by olsrd is searched using the IP address of the adjacent node, and the interface device name is acquired. After that, the probe management unit 25 _i creates a UDP socket, specifies the interface device name acquired by specifying the socket option, and transmits it at the probe transmission interval specified by Config. In addition, the probe transmission source OLSR representative address and the evaluation target adjacent node OLSR representative address are set in the UDP data portion of the probe, and the inspection probe from the same node is identified.

  Further, the probe transmission process started by this probe management function continues until the topology detection function recognizes the topology change. When the detection / disappearance of the topology is recognized, the probe transmission start / stop is individually controlled for each node. When the probe transmission to the 2-hop adjacent node is temporarily stopped, the created probe transmission dedicated route table and the transmission rule are cleared. Then, after these changes, the probe transmission processing is performed on the 2-hop adjacent node corresponding to the changed topology information.

Evaluation target node 5, 2-hop neighbor node ₇₁ of the probe, ... are transferred to 7 _J. Transfer probe using UDP reception socket, 2-hop neighbor nodes _71, ..., to arrive at the specified port in Config of 7 _J.

The packet measuring unit 43 _j of the two-hop adjacent node 7 _j (j is a natural number equal to or less than J) has two data packet numbers (for example, the number of receptions, the number of losses, the weight of the data) and the transfer probe. Multiple). Packet measurement unit 43 _j is the number of packets, managing for each evaluation node 3 (2-hop neighbor nodes as seen from the receiving node) (step ST2, ST3 and ST4 in FIG. 2). Since the same node may evaluate different adjacent nodes, information on adjacent nodes held in the transfer probe is also managed.

Evaluation node 3, the evaluation target node 5 each 2-hop neighbor nodes _71, ..., for every packet transferred to 7 _J, 2 hop neighbor 7 _1, ..., measures the number of transfer for each 7 _J. If the predetermined time data path between the evaluation target node and two-hop neighbor node 7 _j is not flowing, evaluation node 3 by sending a probe to the 2-hop neighbor node 7 _j, the number of packet forwarding of the route Let me measure.

Then, the measurement result transmission unit 45 _j of the 2-hop adjacent node 7 _j periodically reports the number of received packets as the measurement result to the evaluation node 3 at a constant cycle interval specified by Config. Further, the measurement result transmitting unit 45 _J transmits the evaluation value DV (Direct Value) of the evaluation target node 5 to the evaluation node 3. DV is an evaluation value obtained by each node from an actual transfer rate, and will be described in detail later. The measurement result transmission unit 45 _j operates at the notification interval specified by Config asynchronously with the packet measurement unit 43 _j, and sequentially performs notification processing for all of the managed probe reception information.

Measurement result receiving unit 35 of the evaluation node 3, 2-hop neighbor nodes _71, ..., receives the like transmitted measurement results from 7 _J. This is performed asynchronously with the probe transmission process.

Measurement result integration unit 37, the evaluation value DV and the two-hop neighbor node ₇₁ is determined from the actual transfer rate in the evaluation node 3, ..., the evaluation value IV for the evaluation target node 5 obtained from 7 _J (Indirect Value), An evaluation value GV (Global Value) of the evaluation target node 5 is obtained. Each evaluation value DV, IV, and GV will be specifically described below.

The DV is created based on the DirectRatio that is the packet transfer rate collected by the evaluation node 3 from each 2-hop adjacent node 7 _j . The measurement result receiving unit 35 compares the number of received packets reported from each 2-hop adjacent node 7 ₁ ,..., 7 _{J with the} number of data packets (actual data and probe) transmitted by itself, and each 2-hop adjacent node The packet transfer rate R _j of 7 _j is obtained. Then, using the transfer rate R _j of each 2-hop adjacent node 7 _j and further from the transfer rate of each 2-hop adjacent node 7 _{j based on} the weighted moving average shown in Equation (1) using the past evaluation, Obtain the evaluation value, DirectRatio. Here, DR _st-j (t) represents the DirectRatio related to the transfer that relays from the evaluation node 3 to the evaluation target node 5 at time t and reaches the 2-hop adjacent node 7 _j , and R _j (t) represents at time t The packet transfer rate is represented, and α represents a weighted average weight.

Then, after obtaining the DirectRatio for each 2-hop adjacent node 7 _j , the measurement result integration unit 37 directly evaluates the local evaluation value of the evaluation target node 5 from these minimum values, as shown in Equation (2). The value DV is determined. Here, DV _st (t) represents the evaluation value DV for the evaluation target node 5 of the evaluation node 3 at time t.

IV indicates not the value obtained by the evaluation node 3 itself but the evaluation value DV _jt for the evaluation target node 5 obtained by each 2-hop adjacent node 7 _j . All nodes create a DV for each adjacent node. Each node transmits a DV for an adjacent node to a 2-hop adjacent node further adjacent to the adjacent node. The evaluation node 3 on the receiving side uses the evaluation value DV _jt of the evaluation target node 5 transmitted from each 2-hop adjacent node 7 _j as an indirect evaluation value IV _st-j for evaluation of the evaluation target node 5.

Each node holds DV and IV of the number of 2-hop adjacent nodes for each adjacent node. The measurement result integration unit 37 obtains the evaluation value GV of the evaluation target node 5 from the minimum values of these DV and IV, as shown in the equation (3). Here, GV _st (t) is the GV of the evaluation target node 5 at the time t of the evaluation node 3, and IV _st-j (t) is the evaluation target node obtained by the evaluation node 3 from the 2-hop adjacent node 7 _{j at the} time t. IV for 5 is represented.

  The measurement result determination unit 39 uses the GV of the evaluation target node as a guideline for its reliability. For example, the network control unit 40 may exclude APs that do not operate normally by cooperating with the evaluation value and the path control mechanism from the network.

  As described above, the measurement result integration unit 37 not only selects and integrates one of DR, DV, and IV to generate a GV, but also selects, for example, two or more values and performs an operation. And GV may be calculated. Further, not only the number of receptions but also an evaluation value obtained by using, for example, the number of losses or the overlapping number may be performed.

  The calculation of DR, DV, or GV may be performed periodically at a periodic interval specified by Config.

  Furthermore, although the evaluation method between 2-hop adjacent nodes was proposed in the present Example, generally evaluation between k-hop adjacent nodes (k is an integer greater than or equal to 2) is good. However, the amount of calculation increases. Therefore, for example, the number of hops may be changed depending on the relationship between the accuracy of evaluation and the amount of calculation.

  Furthermore, the network system may be configured by an end user including a network system 1 and accommodated in each node (AP), a wired network, and the like. At this time, between the nodes of the wireless network system 1 serving as a core network, a MESH type network may be configured using a wireless link. In addition, by arranging a GUI server that displays topology information and evaluation values of each node in such a network system, the network state may be visually recognized. Such a GUI server can be realized using a topology information acquisition plug-in provided by olsrd.

  In this embodiment, an example of specific design and implementation of the present invention will be described with reference to FIG.

FIG. 3A is a diagram showing a design outline of the present embodiment. 3A corresponds to the evaluation node 3 in FIG. 1, and 2HN-AP in FIG. 3A corresponds to the 2-hop adjacent nodes 7 ₁ ,..., 7 _J in FIG. Hereinafter, the mechanism for evaluating adjacent APs in this embodiment is referred to as WiReM (Wireless Reputation Mechanism). In the implementation of this embodiment, OLSR is used as a route control method. This is because OLSR is currently the main route control method in MWN, and each module can be easily incorporated as a plug-in during mounting.

Each module of this embodiment includes a Monitor / Capture unit (corresponding to the topology detection unit 23, the probe management units 25 ₁ ,..., 25 _N and the packet measurement unit 31 of the evaluation node 3 in FIG. 1), which transmits and receives probes. Notification unit that publicizes DV generated by AP to surroundings (corresponding to measurement result transmission unit 33 and measurement result reception unit 35 of evaluation node 3 in FIG. 1), GV is generated from DV and IV, and adjacent AP is determined according to evaluation decision policy Reputation part to be evaluated (corresponding to the measurement result integration part 37 and measurement result determination part 39 in FIG. 1), and PathMGR (Manager) part (corresponding to the network control part 40 in FIG. 1) that cooperates with the link management mechanism of the OLSR It is comprised from these four. In the following, each of these modules will be outlined.

  First, the design of the Monitor / Capture part will be described. The Monitor / Capture unit includes a Monitor unit and a Capture unit.

The Monitor unit detects neighboring APs to be evaluated by WiReM and 2HN-APs to be evaluated in cooperation with the topology information managed by the OLSR. The Monitor unit refers to an LSDB (Link State Data Base) held by the OLSR at a constant cycle, and manages this adjacent AP to be evaluated and 2HN-AP information in pairs. Further, the Monitor unit creates a dedicated measurement probe packet and sets 2HN-AP information at the destination based on the pair information. This probe must pass through the adjacent AP to be evaluated. However, if probe transmission is performed using the default route table managed by OLSR, neighboring APs that cannot be evaluated will appear. To solve this problem, the default path separately neighbor AP probe dedicated route table for respective 2HN-AP and table so as to hold the (probe transmit-only path table 27 ₁ in FIG. 1, ..., corresponding to 27 _N) The probe can be transmitted to an adjacent AP that cannot be routed only by the default route table.

  The Capture unit receives the probe packet transmitted from the 2HN-AP, and manages the number of receptions, the number of losses, and the duplication number for each probe transmission source AP.

  Next, the design of the Notification unit will be described. In the Notification unit, the number of received probes, the number of losses, the overlap number, and the evaluation value DV of the adjacent AP managed by the Capture unit are periodically transmitted to the probe transmission AP. When receiving information from the Notification section of 2HN-AP, the AP receives the probe reception result and the indirect evaluation value IV of the evaluation target AP in 2HN-AP. Then, each AP calculates the transfer rate DR of the adjacent AP for each 2HN-AP from the equation (1) using the received probe information.

  Next, the design of the Reputation unit will be described. In the Reputation unit, first, DV is calculated from Equation (2) using the DR in the adjacent AP calculated for each 2HN-AP calculated by the Notification unit. Then, using the DV calculated here and the IV acquired from 2HN-AP, a comprehensive evaluation value GV is calculated from Equation (3).

  Next, the design of the PathMGR unit will be described. The PathMGR unit provides a function of excluding / returning neighboring APs to be monitored from the network based on the evaluation result of the Reputaion unit. This function includes a link metric operation function, a notification function, a management function, and a route calculation function reflecting the link metric.

  The link metric operation function is a function that intentionally sets the link metric value of the OLSR I / F for the neighboring AP whose evaluation value is lower than the threshold value. By this link metric value operation, the OLSR indirectly recalculates the route and excludes the neighboring AP in the network. When the evaluation value recovers from the threshold value, the target AP can be returned to the network by returning the link metric value set intentionally high.

  The link metric notification and management function advertises to the entire OLSR network that the link metric value of the OLSR I / F for the target neighboring AP has been changed (MPR flooding) or receives the advertised link metric value change message. It is a function to do. By doing so, it becomes possible to synchronize the LSDB in the OLSR of all APs, and the consistency of the routing table can be maintained. In the current OLSR implementation, since there is no mechanism for advertising the link metric value, it was added as MSG type 210 (UDP). This link metric notification message is MPR-flooded when the link metric is changed, but it also provides a function of advertising at regular intervals in consideration of the loss of the UDP message. The OLSR that has received this message reflects the link metric value stored in the notification message in the LSDB held by itself, and recalculates the route only when there is a change. Regarding this route calculation, OLSR adopts the shortest path by Dijkstra algorithm, and the path with the smallest number of hops is selected. This has been expanded so that the route calculation reflecting the metric value for each link is implemented. As a result, even if the path passing through the AP whose evaluation has deteriorated is the shortest path, the calculation is performed in consideration of the link metric value so that it is not selected as the optimum path.

  By performing the above operation, each AP can evaluate neighboring APs, and can exclude / recover neighboring APs from the network based on the evaluation value.

  In addition, as a GUI function, WiReM adds a GUI function for each AP to evaluate neighboring APs and monitor what network topology is configured. In the GUI, it is possible to display the number of APs constituting the network, details of the topology, and evaluation values of each AP in real time. This GUI display does not require a dedicated server and can be displayed on each AP.

  3B, 3C, and 3D are diagrams illustrating an example of specific operations. In order to verify the operation of WiReM, an AP on which WiReM was installed was created using a PC having a plurality of wireless I / Fs, and an MWN was constructed. There are four APs, and each AP is connected by IEEE802.11a. One interface was used for each link, and radio channels were set so that they would not interfere with each other as much as possible. Communication between each AP is connected in an ad hoc mode. It was set to be displayed at a certain AP (hereinafter referred to as “evaluation AP”).

  OLSR and WiReM were executed on all APs in this network environment. The network path is set to arbitrarily set the OLSR initial metric, and always passes through an AP that is an adjacent node of the evaluation AP (hereinafter referred to as “evaluation target AP”). At this time, only the probe was intentionally discarded in the evaluation target AP, and WiReM detected the abnormality of the evaluation target AP and verified the process of excluding it from the network.

  FIG. 3B is a diagram illustrating a screen shot at the time when the probe is not discarded in the evaluation target AP. The display on the left is the WiReM GUI function. The upper left area 1 is a graph of evaluation values of the evaluation target AP (horizontal axis: elapsed time, vertical axis: evaluation value), the lower left area 2 is the network topology state, and the right area 3 is the AP that displays the GUI. 2 shows a graph of throughput flowing through the wireless interface (horizontal axis: elapsed time, vertical axis: throughput). In the area 1, the evaluation value of the specific AP is shown in real time. In this graph, the GV of an adjacent AP (evaluation AP or the like) that is evaluating the evaluation target AP is shown. From FIG. 3B, the evaluation value is stable when no abnormality has occurred in the evaluation target AP, and the throughput of the evaluation AP in the region 3 flows stably with respect to ath0 (via the evaluation target AP). Can be confirmed.

  Next, it was set so that only the probe was intentionally discarded using iptables in the evaluation target AP. FIG. 3C shows a screen shot at this time. From the region 1 in FIG. 3C, it can be confirmed that the probe is discarded in the evaluation target AP, and the evaluation value of the evaluation node for the evaluation target node decreases with time. Also, if this evaluation value falls below the threshold value of 0.5 (which can be set arbitrarily), the throughput flowing from the area 2 to the wireless interface of the evaluation AP is switched from ath0 (via the AP to be evaluated) to ath1 (via another AP). You can confirm that From this result, it was confirmed that the evaluation nodes detected the abnormality of the evaluation target node and avoided the evaluation target AP and used a route passing through another AP.

  Further, the discard setting of the probe packet in the evaluation target AP is erased and set to operate normally. FIG. 3D is a diagram showing a screen shot at this time. From the area of 1, it was confirmed that the evaluation value for the evaluation target AP of the evaluation AP and the like increased with the deletion of the probe discard in the evaluation target AP. When the evaluation value exceeds the threshold value, it can be confirmed that the throughput flowing from the area 3 to the wireless interface of the evaluation AP is switched from ath1 to ath0. This indicates that the evaluation AP et al. Have confirmed that the transfer of the evaluation object AP is normal, and that the path from the other AP has recovered to the path through the evaluation object AP.

  From the above, it was shown that each AP autonomously monitors and evaluates an adjacent AP by using the WiReM implemented this time, so that an AP in which an abnormality has occurred can be detected and appropriately dealt with.

Evaluation node 3 2-hop neighbor node ₇₁ which is an example of embodiment of the present invention, ..., is a block diagram showing an outline of a network system 1 to evaluate the evaluation target node 5 by cooperation with 7 _J. FIG. 2 is a diagram showing an evaluation processing sequence between an evaluation node (AP _s ) 3 in FIG. 1 and 2-hop neighboring nodes (2HN-AP) 7 ₁ ,..., 7 _J in FIG. It is a figure explaining the design and mounting of this invention. It is a figure which shows the method of detecting the malicious node which is background art.

Explanation of symbols

1 network system, 3 evaluation node, 5 evaluation target nodes, 7 _1, ..., 7 _J 2 hop neighbor, 11 route information management unit, 13 a default routing table 15 additional evaluation unit, 25 _1, ..., 25 _N probe Administration 27 ₁ ,..., 27 _n probe transmission dedicated route table, 31 packet measurement unit, 33 measurement result transmission unit, 35 measurement result reception unit, 37 measurement result integration unit, 39 measurement result determination unit, 41 ₁ ,. _J path information management unit, 43 ₁ ,..., 43 _J packet measurement unit, 45 ₁ ,..., 45 _J measurement result transmission unit

Claims (8)

A network system including three or more nodes, wherein the two nodes do not relay other nodes or perform communication by relaying other nodes;
The evaluation node can communicate with the evaluation target node without relaying other nodes,
The evaluation target node can communicate with two or more forwarding nodes different from the evaluation node without relaying the evaluation node;
The evaluation node includes probe management means for transmitting a probe to the evaluation target node,
The node to be evaluated transfers the received probe to each forwarding node,
Each forwarding node is
A packet measuring means for measuring the reception status of the transferred probe;
A measurement result transmitting means for transmitting the measurement result of the packet measuring means to the evaluation node;
The evaluation node is
Integration means for generating a comprehensive evaluation value by integrating the measurement results received from the forwarding nodes;
A network system comprising determination means for determining a communication status of the evaluation target node using the evaluation value. In addition to the forwarded probe, the packet measuring means of each forwarding node measures the reception status of the packet forwarded from the evaluation node to the forwarding node via the evaluation target node,
The integration means of the evaluation node calculates a local evaluation value by integrating the measurement results,
The measurement result transmission means of each forwarding node includes a local evaluation for the evaluation target node calculated in the forwarding node, in addition to the measurement result indicating the reception status of the forwarded probe and the forwarded packet. Send value,
The integration unit of the evaluation node generates the comprehensive evaluation value by integrating the local evaluation value calculated by integrating the measurement results and the local evaluation value in the transfer node.
The network system according to claim 1. In the evaluation node,
The probe management means manages a probe transmission dedicated route table holding probe transfer route information to be transferred to each forwarding node via the evaluation target node, and for each forwarding node in the probe forwarding route information Send the probe,
3. The network system according to claim 1, wherein the probe management unit and the probe transmission dedicated route table are present in the same number corresponding to the evaluation target node. Communication in a communication path that relays the evaluation target node from the evaluation node to each transfer node is wireless communication, and the evaluation node, the evaluation target node, and each transfer node hold a plurality of interfaces,
The evaluation node is
In addition to the probe transmission dedicated route table, a default route table that holds communication route information for transmitting / receiving data other than the probe to other nodes, and
Route information management means for managing the default route table;
4. The network system according to claim 3, further comprising path management means for changing information held by the route information management means for managing the default route table. A node in a network system,
Probe management means for transmitting a probe to an evaluation target node;
The evaluation target node transfers the probe to two or more different transfer nodes, and the measurement result for evaluating the communication status of the evaluation target node from the evaluation value obtained by integrating the reception measurement results of the probe in each transfer node Determination means,
A node comprising A node evaluation method in a network system including a plurality of nodes,
The probe management means of the evaluation node transmits a probe to the evaluation target node; and
The node to be evaluated forwards the probe to two or more different forwarding nodes;
The evaluation node measurement result determination means evaluates the communication status of the evaluation target node from the evaluation value obtained by integrating the reception measurement results of the probe in the forwarding node;
Node evaluation method including A computer that can communicate with the node to be evaluated
Probe management means for transmitting a probe to the node to be evaluated;
The evaluation target node transfers the probe to two or more different transfer nodes, and the measurement result for evaluating the communication status of the evaluation target node from the evaluation value obtained by integrating the reception measurement results of the probe in each transfer node Determination means,
Program to function as.   A computer-readable recording medium for recording the program according to claim 7.