JP5703154B2 - Switching hub connection stage detection method and apparatus - Google Patents

Description

  The present invention relates to a communication control technique, and more particularly to a switching hub connection stage detection technique for detecting the number of connection stages of switching hubs connected on a communication path connecting nodes.

  In a monitoring control system that monitors and controls building facilities and plant facilities, communication devices having various functions such as an information collection function and a control function are connected as nodes via a communication network such as Ethernet (registered trademark). Based on this information, the central monitoring device monitors and controls each facility. In such a monitoring control system, in order to connect many nodes to a communication network, a communication network in which a plurality of switching hubs are connected in multiple stages is instrumented.

  In such a communication network to which many nodes are connected, in order to check the configuration of the communication network when the network configuration is changed or maintained, several switching hubs are connected on the communication path connecting any nodes. That is, a means for efficiently detecting the switching hub connection stage number is required. Personal computers and node devices capable of performing communication with IP addresses can be easily confirmed, but inexpensive non-intelligent switching hubs cannot be easily confirmed.

  Conventionally, as a technology for recognizing the connection configuration of hubs constituting a communication network, a higher level hub sequentially transmits a stage number signal for confirming the number of connection stages using frequency division from the lower level hub to the lower level hub. Some hubs recognize the connection configuration of hubs by installing a function that sequentially transmits a configuration recognition signal that notifies the number of connection stages between the lower hub and itself from the hub to the upper hub. It has been proposed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 08-084158

  However, in such a conventional technique, it is necessary to use a switching hub constituting a communication network having a special function of transmitting / receiving a specific stage number signal or a configuration recognition signal to / from another switching hub. Therefore, for a communication network that uses an inexpensive non-intelligent switching hub that does not have such a function, the connection configuration of the switching hub cannot be detected. It is necessary to unify with a switching hub having a special function. For this reason, there is a problem that it is difficult to apply to communication networks such as building instrumentation and field instrumentation using various switching hubs.

  The present invention is to solve such problems, and a switching hub capable of easily detecting the number of connection stages of switching hubs connected on a communication path without being unified with a switching hub having a special function. The object is to provide a connection stage number detection technique.

  In order to achieve such an object, a switching hub connection stage number detection method according to the present invention includes a first terminal connected to one end of a communication path in which a plurality of switching hubs are connected in multiple stages, and the communication path. A required time counting step for measuring a required time from transmission to reception of a message in the first terminal by reciprocating the message with the second terminal connected to the other end; A message delay processing step for calculating a communication delay time related to a communication path by subtracting a message reply processing time required from the reception of the message to the reply from the required time, and for transferring the communication delay time and the message in the switching hub. By comparing the message transfer processing time required, the number of connection stages of the switching hubs that make up the communication path can be determined. And a connection number specifying step constant to.

  At this time, the required time is measured multiple times in the required time counting step to measure multiple required times, and the communication delay time calculated for each required time in the communication delay time calculating step is the minimum communication. The delay time may be selected, and the number of connection stages of the switching hub may be specified based on the communication delay time in the connection stage number specifying step.

  In the connection stage number specifying step, the message reply processing time may be corrected based on the message length, and the switching hub connection stage number may be specified based on the corrected message reply processing time.

  Further, in the connection stage number specifying step, the connection stage number of the switching hub corresponding to the communication delay time may be specified based on the correspondence relationship between the preset communication delay time range and the switching hub connection stage number. .

  The switching hub connection stage number detecting device according to the present invention is connected to one end of a communication path in which a plurality of switching hubs are connected in multiple stages, and connected to the other apparatus connected to the other end of the communication path. A switching hub connection stage detection device that detects the number of connected switching hubs, and measures the required time from transmission to reception of the message by reciprocating the message with the partner device. A communication delay time calculating unit that calculates a communication delay time related to a communication path by subtracting a message reply processing time required from the reception of the message at the partner device to a reply from the required time, and a communication delay time and a switching By comparing the message transfer processing time required for message transfer at the hub, And a connection number identifying unit that identifies the number of connection stages of the switching hub that constitutes the.

  According to the present invention, the number of connection stages of switching hubs connected on the communication path can be easily detected based on the round-trip required time of a message obtained by measurement without being unified with a switching hub having a special function. It becomes possible to do.

It is a block diagram which shows the structure of the switching hub connection stage number detection apparatus concerning 1st Embodiment. It is explanatory drawing which shows the switching hub connection stage number specific method. It is explanatory drawing which shows the relationship between communication delay time and the number of switching hub connection stages. It is a flowchart which shows the switching hub connection stage number detection process concerning 1st Embodiment. It is a flowchart which shows the switching hub connection stage number detection process concerning 2nd Embodiment.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a switching hub connection stage number detection apparatus 10 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a switching hub connection stage number detecting apparatus according to the first embodiment.

  This switching hub connection stage number detection device 10 is connected to one end of a communication path L in which a plurality of switching hubs H1 to Hn (n is an integer of 2 or more) are connected in multiple stages, and is connected to the other end of the communication path L. This is a device that detects the number of connection stages of the switching hubs H1 to Hn connected to the other device 20.

  In the present embodiment, a message is reciprocated between the switching hub connection stage detection device (first terminal) 10 and the counterpart device (second terminal) 20, so that the switching hub connection stage detection device 10 The time required from message transmission to reception is counted, and the message reply processing time required from message transmission to reception at the partner device 20 is subtracted from the time required to calculate the communication delay time for the communication path L. By comparing this communication delay time with the message transfer processing time required for message transfer in the switching hubs H1 to Hn, the number of connection stages of the switching hubs H1 to Hn constituting the communication path L is specified. is there.

  The switching hub connection stage number detection device 10 includes a communication I / F unit 11, a storage unit 12, a required time measuring unit 13, a communication delay time calculation unit 14, and a connection stage number specifying unit 15 as main functional units. Yes.

The communication I / F unit 11 includes a general data communication circuit, and has a function of transmitting / receiving a message to / from a terminal device such as the counterpart device 20 connected via the communication path L.
The storage unit 12 includes a storage device such as a semiconductor memory, and has a function of storing processing data processed by each functional unit.

  The required time measuring unit 13 reciprocates a message between the switching hub connection stage number detection device 10 and the counterpart device 20 via the communication I / F unit 11, thereby transmitting a message in the switching hub connection stage number detection device 10. It has a function to measure the time required from reception to reception. For the message transmission / reception time, for example, a timer provided in the CPU may be used.

  The communication delay time calculation unit 14 subtracts the message reply processing time required from message transmission to reception at the counterpart device 20 from the required time measured by the required time measurement unit 13 to thereby determine the communication delay time related to the communication path L. It has a function to calculate

  The connection stage number identification unit 15 compares the communication delay time calculated by the communication delay time calculation unit 14 with the message transfer processing time required for message transfer in the switching hubs H1 to Hn, thereby determining the switching hubs constituting the communication path. It has a function to specify the number of connection stages.

Further, the counterpart apparatus 20 is provided with a communication I / F unit 21 and a message reply unit 22 as main functions.
The communication I / F unit 21 includes a general data communication circuit, and has a function of transmitting / receiving a message to / from a terminal device such as the switching hub connection stage number detecting device 10 connected via the communication path L. Yes.
The message reply unit 22 has a function of replying a message from the switching hub connection stage number detection device 10 received by the communication I / F unit 21.

[Switching hub connection stage identification method]
Next, with reference to FIG. 2, a method for specifying the switching hub connection stage number according to the present embodiment will be described. FIG. 2 is an explanatory diagram showing a method for specifying the switching hub connection stage number.
When a request message is transmitted from the switching hub connection stage number detection device 10 at time T1, a request message transfer process is executed by the first switching hub H1. At this time, in the message transfer process in the switching hub H1, a message transfer process time TH is generated by an amount corresponding to the length of the message, that is, the amount of data. For example, when a message is 1500 bytes on a communication path of 100baseT, a message transfer processing time TH of 120.96 [μsec] occurs in a general switching hub.

  Therefore, the request message is delayed by the message transfer processing time TH in the switching hub H1. This message transfer processing time TH is substantially common to the switching hubs H1 to Hn. For this reason, when n switching hubs H1 to Hn are connected in multiple stages, the delay in these switching hubs H1 to Hn is TH × n.

On the other hand, when a response message is returned from the counterpart device 20 in response to the reception of the request message, a message reply processing time TB also occurs in the message reply process.
Further, for this response message, a delay of TH × n is generated by the amount corresponding to the message transfer processing of the switching hubs H1 to Hn, similarly to the request message.

  Therefore, when the response message is received by the switching hub connection stage number detection device 10 at time T2, if the required time required for the round trip of the message from time T1 to time T2 is TA (= T2-T1), the switching hub H1 The communication delay time TD at ˜Hn is TD = TA−TB≈2 × TH × n.

Here, as described above, when the message is 1500 bytes on the communication path of 100baseT, 2 × TH is 2 × 120.96 [μsec] = 241.92 [μsec]. The message reply processing time TB is almost constant and can be timed in advance. Further, the delay time in the communication cable is extremely small and can be ignored.
For this reason, the connection stage number n of the switching hubs H1 to Hn can be specified based on the communication delay time TD.

FIG. 3 is an explanatory diagram showing the relationship between the communication delay time and the number of switching hub connection stages.
As described above, the message transfer processing time TH in one switching hub is 120.96 [μsec] when the message is 1500 bytes on the communication path of 100baseT. For this reason, every time one switching hub is added on the communication path L, the communication delay time TD increases by 2 × TH.

For this reason, as shown in FIG. 3, the number of connection stages of the switching hub can be made to correspond to the range of the communication delay time TD having 2 × TH as a threshold value.
For example, when the communication delay time TD is less than 241.92 (= 2 × TH) [μsec], the switching hub connection stage number n = 0, and the range is more than 241.92 [μsec] and less than 483.84 [μsec]. Then, the switching hub connection stage number n = 1, and in the range of 483.84 [μsec] or more and less than 725.76 [μsec], the switching hub connection stage number n = 2.

[Operation of First Embodiment]
Next, the operation of the switching hub connection stage number detection apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart illustrating the switching hub connection stage number detection process according to the first embodiment.

First, the required time measuring unit 13 of the switching hub connection stage number detecting device 10 transmits a request message from the communication I / F unit 11 to the communication path L (step 100), and is returned from the partner device 20 accordingly. Waiting to receive a response message (step 101).
When the response message is received (step 101: YES), the required time measuring unit 13 determines the required time TA (= T2-T1) from the time T1 when the request message is transmitted and the time T2 when the response message is received. ) Is calculated (step 102).

Subsequently, the communication delay time calculation unit 14 subtracts the message reply processing time TB in the counterpart device 20 set in advance in the storage unit 12 from the required time TA, thereby causing communication delays in the switching hubs H1 to Hn. Time TD (= TA-TB) is calculated (step 103).
Thereafter, the connection stage number specifying unit 15 compares the communication delay time TD and the message transfer processing time TH in the switching hub set in the storage unit 12 in advance to determine the connection stage number n of the switching hubs H1 to Hn. Specify (step 104), and the series of processing ends.

  When comparing the communication delay time TD and the message transfer processing time TH, for example, a table showing the relationship between the communication delay time and the switching hub connection stage shown in FIG. With reference to the table, the switching hub connection stage number n may be specified. Alternatively, the communication delay time TD may be divided by 2 × TH, and the integer part may be specified as the switching hub connection stage number n.

  On the other hand, the required time measuring unit 13 monitors the reception timeout of the request message while waiting for the response message to be received (step 105), and the response message cannot be received within the specified time from the transmission of the request message. When it becomes (step 105: YES), it is determined as a measurement error (step 106), and a series of processing is terminated.

[Effect of the first embodiment]
As described above, in the present embodiment, a message is reciprocated between the switching hub connection stage number detecting device 10 and the counterpart apparatus 20, so that the required time measuring unit 13 can transmit the message in the switching hub connection stage number detecting device 10. By measuring the required time TA from transmission to reception, the communication delay time calculation unit 14 subtracts the message reply processing time TB required from message transmission to reception at the counterpart device 20 from the required time TA. The communication delay time TD related to the path L is calculated, and the connection stage number specifying unit 15 compares the communication delay time TD with the message transfer processing time TH required for message transfer in the switching hubs H1 to Hn, thereby determining the communication path L The number n of connection stages of the switching hubs H1 to Hn configuring the above is specified.

  This makes it easy to detect the number n of switching hubs connected on the communication path L based on the round-trip required time TA of the message obtained by measurement, without having to unify the switching hubs with special functions. It becomes possible to do.

  In the present embodiment, the connection stage number specifying unit 15 determines the switching hub corresponding to the communication delay time TD based on the correspondence relationship between the preset range of the communication delay time TD and the switching hub connection stage number n. Since the connection stage number n is specified, the connection stage number n of the switching hub can be specified by an extremely simple process of referring to the table.

  Further, in the present embodiment, when the required time TA is measured by the required time measuring unit 13, the case where the required time TA is calculated from the time difference T2-T1 of the message transmission / reception time has been described as an example. The present invention is not limited, and a timer may be started when a request message is transmitted, and the timer may be stopped when a response message is received, and the required time TA may be calculated from the count value of the timer.

Further, in the present embodiment, a case where the required time measuring unit 13, the communication delay time calculating unit 14, and the connection stage number specifying unit 15 are mounted on the switching hub connection stage number detecting device 10 separate from the node N1 will be described as an example. However, the present invention is not limited to this, and may be mounted on the node N1.
Further, in the present embodiment, the case has been described as an example in which the partner device 20 separate from the node N2 returns a message from the switching hub connection stage number detection device 10, but the present invention is not limited to this. The message reply unit 22 may be mounted on N2.

[Second Embodiment]
Next, the switching hub connection stage number detection apparatus 10 according to the second exemplary embodiment of the present invention will be described. In the present embodiment, the required time counting unit 13 counts a plurality of required times TA by executing a round trip of the message a plurality of times, and the communication delay time calculating unit 14 determines the communication delay times TD of these required times TA. The connection hub number specifying unit 15 specifies the switching hub connection stage number n based on the minimum communication delay time TDmin selected from these communication delay times TD.

  The communication delay time TD varies slightly depending on the operating state of each switching hub. This fluctuation fluctuates in a direction in which the message transfer process in the switching hub is delayed, and does not fluctuate in a direction that advances. For this reason, if the smallest one of the communication delay times TD is selected, a communication delay time TD without fluctuation in each switching hub can be obtained.

[Operation of Second Embodiment]
Next, the operation of the switching hub connection stage number detection apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart illustrating the switching hub connection stage number detection process according to the second embodiment.

First, the required time measuring unit 13 of the switching hub connection stage number detecting device 10 transmits a request message from the communication I / F unit 11 to the communication path L (step 200), and is returned from the partner device 20 accordingly. A response message is waited for (step 201).
Here, when the response message is received (step 201: YES), the required time measuring unit 13 calculates the required time TA (= T2-T1) from the time T1 at which the request message is transmitted and the time T2 at which the response message is received. ) Is calculated (step 202).

Subsequently, the communication delay time calculation unit 14 subtracts the message reply processing time TB in the counterpart device 20 set in advance in the storage unit 12 from the required time TA, thereby causing communication delays in the switching hubs H1 to Hn. Time TD (= TA-TB) is calculated (step 203).
On the other hand, the required time measuring unit 13 monitors the reception timeout of the request message while waiting to receive the response message (step 204), and the response message cannot be received within the specified time from the transmission of the request message. When it becomes (step 204: YES), the communication delay time calculation unit 14 sets a maximum value set in advance as the communication delay time TD (step 205).

  Subsequently, the communication delay time calculation unit 14 compares the obtained communication delay time TD with the minimum value TDmin of the communication delay time TD held in the storage unit 12 (step 206), and the communication delay time TD is If it is smaller than the minimum value TDmin (step 206: YES), the minimum value TDmin is updated with the communication delay time TD (step 207).

Thereafter, the communication delay time calculation unit 14 confirms whether the communication delay time has been calculated by repeating the communication delay time a predetermined number of times (step 208), and if the predetermined number of times has not been reached (step 208: NO), returns to step 200. .
On the other hand, when the specified number of times has been reached (step 208: YES), the connection stage number specifying unit 15 compares the communication delay time TD with the message transfer processing time TH in the switching hub set in the storage unit 12 in advance. Thus, the number n of connection stages of the switching hubs H1 to Hn is specified (step 209), and the series of processing ends.

[Effect of the second embodiment]
As described above, in the present embodiment, the required time counting unit 13 counts a plurality of required times TA by executing a round trip of the message a plurality of times, and the communication delay time calculating unit 14 determines each required time TA. The minimum communication delay time TDmin is selected from the calculated communication delay times TD, and the connection stage number specifying unit 15 specifies the switching hub connection stage number n based on the minimum communication delay time TDmin. A small communication delay time TDmin can be calculated, and the switching hub connection stage number n can be specified more accurately.

[Third Embodiment]
Next, a switching hub connection stage number detection apparatus 10 according to a third embodiment of the present invention will be described. In the present embodiment, the connection stage number specifying unit 15 corrects the message transfer processing time TH based on the message length, and specifies the connection stage number of the switching hub based on the corrected message transfer processing time TH ′. It is what I did.

  The message transfer processing time TH required for message transfer in the switching hub varies depending on the message length, that is, the data amount. Therefore, a correspondence value between the message length and the message transfer processing time TH is calculated in advance by calculating or calculating a correction value for a specified message length such as a 1500-byte length in the storage unit 12 by actual measurement or calculation. Based on this correspondence, the unit 14 specifies the number of connection stages of the switching hub using the message transfer processing time TH ′ corrected with the correction value corresponding to the message length.

  In this case, when the lengths of the request message and the response message are different, the message transfer processing time TH for one way is corrected according to the message length, and the total of these message transfer processing times TH is connected to the switching hub. What is necessary is just to use as a threshold value at the time of specifying a stage number.

[Effect of the third embodiment]
Thus, in the present embodiment, the connection stage number specifying step corrects the message reply processing time based on the message length, and specifies the connection stage number of the switching hub based on the corrected message reply processing time. Since it did in this way, the number of connection stages of a switching hub can be specified very accurately.

[Extended embodiment]
The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. In addition, each embodiment can be implemented in any combination within a consistent range.

  DESCRIPTION OF SYMBOLS 10 ... Switching hub connection stage number detection apparatus, 11 ... Communication I / F part, 12 ... Memory | storage part, 13 ... Required time measuring part, 14 ... Communication delay time calculation part, 15 ... Connection stage number specific | specification part, 20 ... Counterpart apparatus, H1 ˜Hn—switching hub, N1, N2—node, L—communication path, TA—required time, TB—message reply processing time, TD—communication delay time, TH—message transfer processing time.

Claims (4)

By reciprocating a message between a first terminal connected to one end of a communication path in which a plurality of hubs are connected in multiple stages and a second terminal connected to the other end of the communication path, A required time measuring step of measuring a required time from transmission to reception of the message in the first terminal;
A communication delay time calculating step of calculating a communication delay time related to the communication path by subtracting a message reply processing time required from the reception of the message to the reply at the second terminal from the required time;
A connection stage number specifying step for specifying the connection stage number of the hub constituting the communication path , corresponding to the communication delay time, based on a correspondence relationship between a preset communication delay time range and the hub connection stage number ; A hub connection stage number detection method comprising: In the hub stage number detection method according to claim 1,
The required time counting step measures a plurality of required times by executing a round trip of the message a plurality of times,
The communication delay time calculating step selects the minimum communication delay time from the communication delay times calculated for each required time,
The hub connection stage number detecting method, wherein the connection stage number specifying step specifies the hub connection stage number based on the communication delay time. In the hub stage number detection method according to claim 1 or 2,
The connection stage number specifying step is based on an integer part obtained by dividing the communication delay time by a value obtained by doubling the message transfer processing time required for transferring the message in the hub instead of the correspondence relationship. A method for detecting the number of connected hub stages, wherein the number of connected stages is specified . Hub connection stage number detection for detecting the number of hub connection stages connected to one end of a communication path in which a plurality of hubs are connected in multiple stages and connected to the other device connected to the other end of the communication path. A device,
A required time measuring unit for measuring a required time from transmission to reception of the message by reciprocating the message with the counterpart device;
A communication delay time calculation unit that calculates a communication delay time related to the communication path by subtracting a message reply processing time required from the reception of the message to the reply at the counterpart device from the required time;
A connection stage number specifying unit for specifying the connection stage number of the hub constituting the communication path , corresponding to the communication delay time, based on a correspondence relationship between a preset communication delay time range and the hub connection stage number ; A hub connection stage number detection device comprising:

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