JP5190498B2 - Relay device, relay system, and relay program - Google Patents

Description

  Embodiments described herein relate generally to a relay device, a relay system, and a relay program.

  Relay devices (eg, routers, gateways) that connect a plurality of communication media having different characteristics and mediate communication between communication devices (nodes) that can communicate via each communication medium are widely used in information communication systems. It is used. In particular, by improving the technical and economic quality of the relay device, a broadband and low-cost communication network is built not only in LAN (Local Area Network) but also in WAN (Wide Area Network), and development of industry and culture It contributes to.

  On the other hand, a communication network used in a control system (BAS: Building Automation System) for monitoring and controlling the state of electrical equipment installed in a building is the one built when the building is built. Often used for many years. This is because high costs are often required for updating the communication network, such as the fact that originally broadband communication is not necessary, and communication media and communication devices are embedded in the wall surface.

  In recent years, in order to save resources, reduce costs, and prevent global warming, it is required to reduce energy consumed in buildings. For this reason, data such as energy consumption of electrical facilities are visualized (visualized) for residents through a LAN, and efforts are made to promote energy saving activities of residents. In order to transmit electrical facility data to a communication network (LAN) used by residents, the communication network of the control system in the building and the communication network such as the LAN in the building are connected via a relay device. Need to be connected.

  However, the communication network of the control system in the building has a narrow band, whereas the communication network such as a LAN in the building often has a wide band. For this reason, there is often a large difference in the characteristics of the communication medium to which the relay device is connected, and the conventional relay device may cause a problem in performance.

  For example, an access node (information processing device such as a personal computer connected to a LAN) connected to a first broadband network is connected to a data output node (for example, a data output node connected to the second narrow-band network via a relay device). Consider the case of acquiring sensor node data in electrical equipment.

  The communication input device provided in the access node and the communication software operating in the access node are often optimized for communication via a broadband network. It is often designed with the assumption. On the other hand, the response speed of the data output node connected to the second network is often designed assuming a narrow bandwidth of the second network and a communication delay typical of the second network.

  For this reason, when the access node connected to the first network transmits a data acquisition request to the data output node connected to the second network with high frequency, the data output node There has been a problem that it is difficult to respond to a data acquisition request and congestion easily occurs.

  In addition, when congestion occurs on the second network, there is a problem that the queue of data to be transmitted to the second network becomes longer in the relay device, and the possibility of congestion occurring increases.

  As described above, when the relay device performs a relay process between a wideband network and a narrowband network, there is a problem that congestion easily occurs in the relay device and on the narrowband network.

  In a conventional relay device, a technique called RED (Random Early Detection) is used in which packets are stochastically discarded before congestion occurs in order to reduce the congestion state. However, this method has a problem in that a packet that is to be discarded cannot be discarded or a process that should not be discarded is discarded because the packet is discarded at random.

  In addition, there is a known technique for reducing data discard by increasing the buffer capacity when the occurrence rate of data discard due to buffer overflow increases. However, since the buffer is increased when the burst occurs, the discard of processing is reduced, but the processing waiting time increases, and there is a problem that the occurrence of the congestion state cannot be prevented. In particular, since the equipment in the building has a slow response, there is a possibility that the number of requests staying correspondingly increases and the buffer becomes enlarged.

  In this way, with the method of reducing the occurrence of congestion by discarding packets stochastically or the method of reducing discard by increasing the buffer capacity, only unnecessary processing, that is, wasteful processing, can be discarded. There wasn't.

Japanese Patent No. 3623712

Floyd, S., and Jacobson, V., “Random Early Detection gateways for Congestion Aviation”, V. 1 N. 4, August 1993, pp. 397-413

  An object of the present invention is to provide a relay device, a relay system, and a relay program that discard only unnecessary processes (unnecessary processes) and reduce the occurrence of congestion.

According to the present embodiment, the relay device receives a request from the first node via the first network, analyzes the request, and data based on the request from the second node via the second network. A first storage unit that stores a first time required to acquire the second time, a second storage unit that stores a second time in which the first node waits for a response to the request, the first time, and the second time And a determination unit that determines that the request is discarded when the first time is longer than the second time, and that determines that the request is executed when the first time is equal to or less than the second time. And when the determination unit determines to execute the request, transmits a data acquisition message to the second node via the second network, and An acquisition unit for receiving a response message containing the data based on the request from the node, and a response unit that transmits the data via the first network to the first node, wherein from the receiving unit accepts the request A first calculation unit that calculates a third time required for the response unit to transmit the data, wherein the first calculation unit receives the data and the third time When the time is longer than the second time or when the first node does not receive the data and the third time is shorter than the second time, the third time is used to store the data in the second storage unit. The stored second time is updated .

1 is a schematic configuration diagram of a relay system according to an embodiment of the present invention. It is a sequence diagram showing an example of the operation of the relay system according to the embodiment. It is a schematic block diagram of the relay apparatus which concerns on the same embodiment. It is a flowchart explaining the request reception process which concerns on the same embodiment. It is a flowchart explaining the request discard determination processing according to the embodiment. It is a flowchart explaining the data acquisition process and data acquisition time calculation process which concern on the embodiment. It is a flowchart explaining the request response process and timeout time calculation process which concern on the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a relay system according to an embodiment of the present invention. The relay system includes a relay device 100 connected to a plurality of networks having different characteristics, a plurality of access nodes 11 and 12 that can communicate with the relay device 100 via the first network 10, and a relay via the second network 20. A plurality of data output nodes 21 and 22 capable of communicating with the apparatus 100 are provided. The first network 10 and the second network 20 have different bands, for example, the first network 10 has a wide band, and the second network 20 has a narrow band.

  The access nodes 11 and 12 exchange data with the data output nodes 21 and 22 by communicating with the relay device 100. The data output nodes 21 and 22 exchange data with the access nodes 11 and 12 by communicating with the relay device 100.

  For example, the access nodes 11 and 12 are PCs, the first network 10 is a LAN, and the data output nodes 21 and 22 are data of facility equipment (data such as air conditioning set temperature and lighting on / off). The sensor node, the second network 20 is a communication network for the control system in the building.

  In FIG. 1, an example in which the relay system includes two access nodes 11 and 12 is shown, but one or three or more may be used. Similarly, the relay system may have one data output node or three or more data output nodes.

  FIG. 2 shows an operation when the access node 11 acquires the observation data of the data output node 21 via the relay device 100 as an example of the operation of the relay system according to the present embodiment.

  First, the access node 11 transmits a request message 201 for acquiring observation data of the data output node 21 to the relay device 100. The request message 201 includes an identifier indicating data observed by the data output node 21.

  The relay apparatus 100 analyzes the request message 201 and transmits a data acquisition message 202 for acquiring corresponding data to the data output node 21.

  The data output node 21 analyzes the data acquisition message 202 from the relay device 100 and transmits a response message 203 including the corresponding data to the relay device 100.

  The relay device 100 analyzes the response message 203 from the data output node 21 and transmits a request response message 204 including the corresponding data to the access node 11.

  Through such a series of operations, the access node 11 can acquire observation data from the data output node 21.

  Note that the relay device 100 measures the time T1 required from receiving the request message 201 from the access node 11 to transmitting the request response message 204 to the access node 11. Further, the relay device 100 measures a time T2 required for the data acquisition process from the transmission of the data acquisition message 202 to the data output node 21 until the reception of the message 203 from the data output node 21. In the following description, this time T2 is referred to as data acquisition time.

  FIG. 3 shows a schematic configuration of the relay device 100. The relay device 100 includes a request reception unit 111, a request discard determination unit 112, a data acquisition unit 113, a data acquisition time calculation unit 114, a request response unit 115, a timeout time calculation unit 116, a request queue 121, a request response queue 122, a data acquisition A time storage unit 123 and a timeout time storage unit 124 are provided.

  The request reception unit 111 receives requests (request messages 201) from the access nodes 11 and 12 via the first network 10.

  The request discard determination unit 112 determines whether to discard the request received by the request reception unit 111. The determination process will be described later.

  In the request queue 121, the data acquisition processing content of a request that the request discard determination unit 112 determines not to discard among the requests received by the request reception unit 111 is registered.

  The data acquisition unit 113 outputs a data acquisition message to the data output nodes 21 and 22 via the second network 20 based on the data acquisition processing content registered in the request queue 121. The data acquisition unit 113 also receives response messages from the data output nodes 21 and 22 and registers data included in the response messages in the request response queue 122.

  The data acquisition time calculation unit 114 calculates the data acquisition time from when the data acquisition unit 113 outputs the data acquisition message to the data output nodes 21 and 22 until the response message is received, and stores the data acquisition time in the data acquisition time storage unit 123. To do.

  The data acquisition time storage unit 123 stores a data acquisition time for each data acquisition destination and acquisition data.

  The request response unit 115 outputs a request response message including data registered in the request response queue 122 to the access nodes 11 and 12 via the first network 10. Further, the request response unit 115 detects whether or not the access nodes 11 and 12 have received the output request response message. The access nodes 11 and 12 wait for a request response message from the relay device 100 for a predetermined time after outputting a request to the relay device 100, and do not receive the request response message when the predetermined time is exceeded. This predetermined time is called a timeout time.

  The timeout time storage unit 124 stores the timeout time (time estimated as the timeout time) of the access nodes 11 and 12.

  The timeout time calculation unit 116 calculates the time required from when the request reception unit 111 receives a request until the request response unit 115 outputs a request response message. Then, the timeout time calculation unit 116 updates the timeout time stored in the timeout time storage unit 124 based on the calculated time and whether the access nodes 11 and 12 have received the request response message.

  Next, details of processing of each unit of the relay device 100 will be described using a flowchart.

  First, the processing in the request reception unit 111 will be described using the flowchart shown in FIG.

  (Step S401) The request reception unit 111 receives a request from the access node 11 (or 12). At this time, the timeout time calculation unit 116 starts measuring the time required from receiving the request to responding to the request.

  (Step S402) The request reception unit 111 analyzes the request.

  (Step S403) The request reception unit 111 requests the request discard determination unit 112 to determine whether or not to discard the request.

  (Step S404) If the request discard determination unit 112 determines not to discard the request, the process proceeds to step S405. If it is determined to discard, the process proceeds to step S406.

  (Step S405) The request reception unit 111 registers the data acquisition processing content of the request in the request queue 121. The type or format of information when registering in the request queue 121 is arbitrary. For example, all of the data acquisition processing contents included in the request may be registered, the data acquisition destination (node, point, identifier) included in the request and the data to be acquired (type, identifier, data-dependent attributes) It may be stored in a format associated with, and may be registered together with the order and time when the request is received and the registered order and time. Further, when requests having the same data acquisition destination identifier or data-dependent attribute are duplicated, they may be appropriately aggregated and registered.

  (Step S406) The request reception unit 111 discards the request.

  Next, the processing in the request discard determination unit 112 will be described using the flowchart shown in FIG.

  (Step S <b> 501) The request discard determination unit 112 acquires the time T <b> 3 required for this data acquisition process from the data acquisition time storage unit 123 based on the data acquisition process content of the request received by the request reception unit 111. The data acquisition process includes the data acquisition destination and the data to be acquired, and the request discard determination unit 112 acquires the time T3 required for the data acquisition process from the data acquisition time storage unit 123 based on the information. To do.

  (Step S502) The request discard determination unit 112 acquires the timeout time T4 of the access node 11 (or 12) that has output the request from the timeout time storage unit 124. Note that the processing order of steps S501 and S502 is arbitrary.

  (Step S503) The request discard determination unit 112 compares the time T3 acquired in step S501 with the time T4 acquired in step S502. If the time T3 is greater than the time T4, the process proceeds to step S504. If the time T3 is equal to or less than the time T4, the process proceeds to step S505.

  (Step S504) The request discard determination unit 112 determines to discard the request. This is because the data acquisition time is longer than the timeout time, so even if the data acquisition process is executed and data is acquired from the data output nodes 21 and 22, the access nodes 11 and 12 do not receive the request response message. This is because it is wasted.

  (Step S505) The request discard determination unit 112 determines not to discard (execute) the request. This is because the data acquisition time is equal to or less than the timeout time, and the request response message output to the access nodes 11 and 12 by executing the data acquisition process is received by the access nodes 11 and 12 so that the data acquisition process is not wasted. It is.

  Next, processing in the data acquisition unit 113 and the data acquisition time calculation unit 114 will be described using the flowchart shown in FIG.

  (Step S <b> 601) The data acquisition unit 113 acquires the data acquisition processing content related to the request from the request queue 121.

  (Step S602) The data acquisition unit 113 creates a data acquisition message to be transmitted to the data output node 21 (or 22).

  (Step S603) The data acquisition unit 113 transmits a data acquisition message. At this time, the data acquisition time calculation unit 114 starts measuring the data acquisition time.

  (Step S604) The data acquisition unit 113 receives a response message from the data output node 21 (or 22). At this time, the data acquisition time calculation unit 114 stops measuring the data acquisition time.

  (Step S605) The data acquisition unit 313 registers the acquired data in the request response queue 122. The type or format of information when registering in the request queue response 122 is arbitrary. For example, only the data included in the acquired data may be registered, or the data acquisition destination (node, point, identifier) and information about the acquired data (type, identifier, data-dependent attribute) ) May be stored in a format associated with (), or may be registered together with the order and time of data reception and the order and time of registration. In addition, when data having the same data acquisition destination identifier or data-dependent attribute are duplicated, they may be appropriately aggregated and registered.

  (Step S606) The data acquisition time calculation unit 114 stores the measured data acquisition time (corresponding to the time T2 in FIG. 2) in the data acquisition time storage unit 123. At this time, it may be stored in a format associated with information (node, point, identifier, type, identifier, data-dependent attribute) regarding the acquired data. Further, the data acquisition time may be saved every measurement, or may be saved only when different from the data acquisition time measured in the past. Further, a value subjected to statistical processing such as an average value, a variance value, and a moving average value may be stored from a history of data acquisition times measured in the past.

  In addition, although the example in which the data acquisition time calculation unit 114 measures the data acquisition time is shown here, the data acquisition unit 113 may measure the data acquisition time. If the time required for data acquisition is known, this time may be stored in advance in a storage area inside the apparatus or outside the apparatus.

  Next, processing in the request response unit 115 and the timeout time calculation unit 116 will be described using the flowchart shown in FIG.

  (Step S701) The request response unit 115 acquires data registered in the request response queue 122.

  (Step S702) The request response unit 115 transmits a request response message including the acquired data to the access node 11 (or 12). At this time, the timeout time calculation unit 116 stops measuring the time required from the request reception (started in step S401 in FIG. 4) to the request response.

  (Step S703) If the access node 11 (or 12) receives the request response message, the process proceeds to step S704. If not received, the process proceeds to step S705.

  There are various methods for confirming whether or not the access node 11 (or 12) has received the request response message. For example, whether there is an abnormality when the request response message is transmitted to the access node, the request response message It can be confirmed whether or not a confirmation response message indicating that a request response message has been received from the access node has been returned. Furthermore, when the request message from the access node is repeatedly retransmitted, it can be estimated whether or not the access node is ready to receive the request response message depending on whether or not the retransmission continues. Good.

  (Step S704) The time-out time calculation unit 116 compares the time T5 (corresponding to the time T1 in FIG. 2) measured from step S401 to step S702 and the time-out time T4 stored in the time-out time storage unit 124. If the measurement time T5 is longer than the timeout time T4, the process proceeds to step S706.

  (Step S705) The time-out time calculation unit 116 compares the time T5 measured from step S401 to step S702 with the time-out time T4 stored in the time-out time storage unit 124. If the measurement time T5 is shorter than the timeout time T4, the process proceeds to step S706.

  (Step S706) The timeout time calculation unit 116 stores the measurement time T5 in the timeout time storage unit 124, and updates the timeout time of the access node 11 (or 12).

  When the access node 11 (or 12) receives the request response message (step S703-Yes) and the measurement time T5 is longer than the timeout time T4 (step S704-Yes), the access node 11 grasped by the relay device 100 The actual timeout time of the access node 11 (or 12) is longer than the timeout time of (or 12). Therefore, more request responses can be transmitted to the access node 11 (or 12) by updating the timeout time stored in the timeout time storage unit 124 (replaced with the measurement time T5).

  If the access node 11 (or 12) does not receive the request response message (step S703-No) and the measurement time T5 is shorter than the timeout time T4 (step S705-Yes), the access node grasped by the relay device 100 The actual timeout time of the access node 11 (or 12) is shorter than the timeout time of 11 (or 12). Therefore, by updating the timeout time stored in the timeout time storage unit 124 (replaced with the measurement time T5), the number of requests determined to be discarded by the request discard determination unit 112 increases, and unnecessary (wasted) data. Execution of the acquisition process can be prevented.

  When the measured time T5 is stored in the timeout time storage unit 124, it is associated with information about the request from the access node or the request response to the access node (the identifier of the access node, the type of data included in the request, and the data-dependent attribute) You may save it in another format. Further, the time T5 may be saved every time it is measured, or may be saved only when there is a change in the value of the time T5 measured in the past, or the average from the history of the time T5 measured in the past. Values subjected to statistical processing such as values, variance values, and moving average values may be stored.

  The request reception unit 111 and the request response unit 115 may measure the timeout time of the access nodes 11 and 12. For example, when the timeout times of the access nodes 11 and 12 are known, the time may be stored in advance in a storage area inside the device or outside the device. Further, the access nodes 11 and 12 and the relay device 100 are provided with means for explicitly transmitting the timeout time of the access nodes 11 and 12 from the access nodes 11 and 12 to the relay device 100. The timeout times of the access nodes 11 and 12 may be acquired using the means and stored in the timeout time storage unit 124.

  As described above, according to the relay device 100 according to the present embodiment, the time required for the data acquisition process is longer than the timeout time of the access node, and only requests that do not need to be executed (data acquisition process is wasted) are discarded. The occurrence of congestion can be reduced.

  In the above embodiment, when the request discard determination unit 112 determines to discard the request (data acquisition process), the request response unit 115 notifies the access nodes 11 and 12 of the determination content and the determination reason. Good.

  Thereby, since the access nodes 11 and 12 can know that the request transmitted to the relay device 100 has been discarded by the relay device 100, the access node can retransmit the request or acquire data. 11 and 12 can execute exception processing. Further, by displaying that the data could not be acquired on the display device included in the access nodes 11 and 12, information can be provided to the users of the access nodes 11 and 12.

  In addition, when the data acquisition unit 113 detects an abnormality in the data output nodes 21 and 22, the request response unit 115 may notify the access nodes 11 and 12 of the detection information. The abnormality of the data output nodes 21 and 22 is, for example, a state where the power is turned off. Furthermore, when the request response unit 115 detects that the data output nodes 21 and 22 have returned to normal, the request response unit 115 may notify the access nodes 11 and 12 of the detection information. The fact that the data output nodes 21 and 22 return to normal means, for example, that the power is turned on.

  Thereby, the access nodes 11 and 12 can grasp the state of the data output nodes 21 and 22 and execute an appropriate process.

  At least a part of the relay devices described in the above-described embodiments may be configured by hardware or software. When configured by software, a program for realizing at least a part of the functions of the relay device may be stored in a recording medium such as a flexible disk or a CD-ROM, and read and executed by a computer. The recording medium is not limited to a removable medium such as a magnetic disk or an optical disk, but may be a fixed recording medium such as a hard disk device or a memory.

  Further, a program that realizes at least a part of the functions of the relay device may be distributed via a communication line (including wireless communication) such as the Internet. Further, the program may be distributed in a state where the program is encrypted, modulated or compressed, and stored in a recording medium via a wired line such as the Internet or a wireless line.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 1st network 11 and 12 Access node 20 2nd network 21 and 22 Data output node 100 Relay apparatus 111 Request reception part 112 Request discard determination part 113 Data acquisition part 114 Data acquisition time calculation part 115 Request response part 116 Timeout time calculation part 121 Request Queue 122 Request Response Queue 123 Data Acquisition Time Storage Unit 124 Timeout Time Storage Unit

Claims (6)

Receiving a request from the first node via the first network and analyzing the request;
A first storage unit for storing a first time required to acquire data based on the request from the second node via the second network;
A second storage unit for storing a second time for the first node to wait for a response to the request;
Comparing the first time with the second time, determining that the request is to be discarded if the first time is longer than the second time, and if the first time is less than or equal to the second time, A determination unit that determines to execute the request;
When the determination unit determines to execute the request, it transmits a data acquisition message to the second node via the second network, and receives a response message including data based on the request from the second node. An acquisition unit to
A response unit for transmitting the data to the first node via the first network;
A first calculation unit that calculates a third time required from when the reception unit receives the request until the response unit transmits the data;
With
The first calculation unit is configured such that the first node receives the data and the third time is longer than the second time, or the first node does not receive the data and the third When the time is shorter than the second time, the relay device updates the second time stored in the second storage unit using the third time . A second calculation unit that calculates a time from when the acquisition unit transmits the data acquisition message to when the response message is received, and stores the calculated time as the first time in the first storage unit; The relay apparatus according to claim 1. The response unit, the relay device according to claim 1 or 2, characterized in that notifying that the determination unit determines that discarding the request to the first node. The acquisition unit detects whether the second node is in an abnormal state or a normal state, and the response unit notifies the first node of information detected by the acquisition unit. Item 4. The relay device according to any one of Items 1 to 3 . A relay device connected to the first network and the second network;
A first node that communicates with the relay device via the first network;
A second node that communicates with the relay device via the second network;
A relay system comprising:
The relay device is
Receiving a request from the first node via the first network and analyzing the request;
A first storage unit for storing a first time required to acquire data based on the request from the second node via the second network;
A second storage unit for storing a second time for the first node to wait for a response to the request;
Comparing the first time with the second time, determining that the request is to be discarded if the first time is longer than the second time, and if the first time is less than or equal to the second time, A determination unit that determines to execute the request;
An acquisition unit that acquires data based on the request from the second node via the second network when the determination unit determines to execute the request;
A response unit that transmits the data acquired by the acquisition unit to the first node via the first network;
A calculation unit that calculates a third time required from when the reception unit receives the request until the response unit transmits the data;
With
When the first node receives the data and the third time is longer than the second time, or when the first node does not receive the data and the third time When the time is shorter than the second time, the second time stored in the second storage unit is updated using the third time . Receiving a request from the first node via the first network;
Analyzing the request;
Retrieving from the first storage unit a first time required to acquire data based on the request from the second node via the second network;
Retrieving from the second storage unit a second time for the first node to wait for a response to the request;
Determining to discard the request if the first time is longer than the second time;
Obtaining the data based on the request from the second node when the first time is less than or equal to the second time;
Transmitting the data acquired from the second node to the first node;
Calculating a third time required from receiving the request to transmitting the data;
When the first node receives the data and the third time is longer than the second time, or the first node does not receive the data and the third time is greater than the second time If shorter, updating the second time stored in the second storage using the third time; and
A relay program that causes a computer to execute

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