JPH08213991A - Network system - Google Patents

Abstract

PURPOSE: To reduce the scale of a master station and to easily increase the number of slave stations without changing the scale by transmitting copied information from a slave station, which receives information transmitted from the master station to another slave station. CONSTITUTION: Each of plural slave stations 22 to 25 is provided with a reception means 10 which receives information from a transmission line 20, a copy means 11 which copies information received by the reception means 10, and a transmission means 12 which transmits information copied by the copy means 11 to another preliminarily installed slave station. That is, when the slave station 22 receives cells from the master station 21, it uses the copy part 11 to copy the cells and uses cells of the copy original in its own device and uses the transmission part 12 to transmit copied cells to the slave station 23. Consequently, cells transmitted from the master station 21 are transmitted to slave stations 22, 23, 24, and 25 in order by chaining.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system in which a master station and a plurality of slave stations are connected via a transmission line, and in particular, it is possible to increase the number of slave stations without changing the scale of the master station. Regarding

[0002]

2. Description of the Related Art Conventionally, there is generally known a network system in which a master station and a plurality of slave stations are connected by wire to perform broadcast communication.

[0003] For example, a cable TV called CATV (Cable TV) is used as a measure for preventing hearing loss in an area where radio wave interference occurs, such as in a valley of a building or in a mountainous area, and is a slave station from a main broadcasting station. Television images are transmitted to each subscribing household.

Recently, this CATV is an urban type C installed mainly in a business zone in the center of a large city.
It has become widespread as an ATV, and the number of its subscribers is also increasing.

Therefore, in such a network system, it is an important issue to increase the number of slave stations as subscribers.

However, in the case of constructing such a network system, since a communication path is usually set between the master station and each slave station, the master station becomes large in scale and the number of connectable slave stations is limited. The problem arises.

That is, when the number of slave stations connected to the master station increases, not only the number of communication paths required for connection increase, but also it becomes necessary to provide a transmitter for each communication path in the master station. For this reason, as the number of slave stations increases and the network scale increases, the scale of the master station increases accordingly.

In other words, the number of slave stations connectable to the master station is limited by the scale of the master station and the number of obtainable communication paths.

[0009]

As described above, in a conventional network system in which a master station and a plurality of slave stations are connected by wire, a network is set up because a communication path is set between the master station and each slave station. When it became large, the size of the master station became huge, and there was a problem that the number of slave stations was limited.

Therefore, the present invention solves the above problems,
An object of the present invention is to provide a network system capable of reducing the size of a master station and easily increasing the number of slave stations without changing the size of the master station.

[0011]

In order to achieve the above object, a first aspect of the present invention is that a plurality of slave stations are sequentially connected in a chain from a master station using a transmission line, and information held by the master station is stored in In a network system for transmitting to a plurality of slave stations, the plurality of slave stations includes a receiving means for receiving the information from the transmission path, a copying means for copying the information received by the receiving means, and information copied by the copying means. Is transmitted to another preset slave station.

In the second invention, the master station receives the information transmitted from the slave station connected to the end of the chain, the information transmitted by the transmitting means, and the information received by the receiving means. The slave station connected to the end of the chain further comprises second transmitting means for transmitting the information copied by the copying means to the master station. Characterize.

Further, in the third invention, the slave station requests the detecting means for detecting predetermined information from the information copied by the copying means, and the information requested for the information detected by the detecting means. It is characterized by further comprising an adding means for adding data.

[0014]

According to the first aspect of the invention, a plurality of slave stations are sequentially connected in a chain from the master station, and the slave station receiving the information transmitted from the master station copies the information by using the copying means. The information is used in its own station and the information copied by the copying means is transmitted to another slave station.

According to the second invention, the slave station connected to the end of the chain and the master station are connected by a transmission line,
When the master station receives the information from the slave station connected to the end of the chain, the collating means collates the information held in the master station with the received information.

According to the third aspect of the invention, in the slave station, predetermined information is detected from the information copied by the copying means, and the information requested by adding the data to the information is transmitted using the transmitting means. To do.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings.

FIG. 2 is a diagram showing the overall configuration of the network system used in this embodiment.

In this embodiment, as shown in FIG.
A network configuration is used in which terminal devices 21 to 25 are connected to a ring-type B-ISDN network 20 (hereinafter referred to as "transmission line 20") based on the technology.

Therefore, according to this network, it is possible to set the transmission destination and the reception destination separately, and by changing the route information included in the cells exchanged between the terminals, the destination can be changed. It is possible to change.

In the following, a case will be described in which the terminal device 21 is a master station (hereinafter referred to as "master station 21") and the terminal devices 22 to 25 are slave stations (hereinafter referred to as "slave stations 22 to 25"). In practice, the terminal device that transmits information will be the master station each time, and the terminal device that receives the information will be the slave station each time.

FIG. 1 is a block diagram showing the configuration of the slave station 22 shown in FIG.

As shown in FIG. 1, the slave station 22 includes a receiving unit 1
0, a copy unit 11, and a transmission unit 12.

The receiving unit 10 receives the cells transmitted from the main station 21 via the transmission line 20, and outputs the received cells to the copying unit 11. In addition, according to the present embodiment, all cells transmitted from the master station 21 are addressed to the slave station 22.

The copy unit 11 copies the cell received from the receiving unit 10, outputs the copied cell to the transmitting unit 12, and outputs the received cell itself to internal processing. Although not shown, this internal processing is used for display output by the display unit and the like.

The transmitting unit 12 outputs the cell copied by the copying unit 11 to the slave station 23 via the transmission line 20. That is, the destinations of the cells transmitted from the transmission unit 12 are all the slave stations 23. In this way, the destination is specified because the slave stations are connected in a chain.
Therefore, the VPI / VCI contained in the cell copied in the slave station 22 is corrected and output to the transmission path 20.

In this way, when the slave station 22 receives a cell from the master station 21, it copies the cell using the copy section 11, the copy source cell is used inside itself, and the copied cell is used. Uses the transmitter 22 to send the slave station 23
Send to.

Although the configuration of the slave station 22 has been described above, the slave stations 23 to 25 have the same configuration. Then, the cells transmitted from the master station 21 are sequentially transmitted in chain in the order of the slave station 22, the slave station 23, the slave station 24, and the slave station 25.

FIG. 3 is a diagram showing a chained connection form of the slave stations 22 to 25.

As shown in FIG. 3, the terminal device 2 which is the main station.
The cell transmitted from 1 is first received by the terminal device 22 which is the first slave station, and a copy of the cell is transmitted to the terminal device 23 which is the second slave station. And so on
The cell transmitted from the master station is copied by each slave station and transmitted to other slave stations in a chain. At this time, each slave station changes the VPI / VCI of the copied cell to change the cell destination or the like.

Here, the terminal devices 22 to 24 are slave stations, and the terminal device 25 is not included in the slave stations. In this way, in addition to broadcasting all terminal devices as slave stations,
It is possible to select a terminal device to be broadcast in advance and perform cell transmission.

FIG. 4 shows each of the terminal devices 21 to 24 shown in FIG.
It is a figure which shows the connection form at the time of connecting in a loop shape.

As shown in FIG. 4, if the slave station 24 located at the end of the chain transmits a cell to the terminal device 21 which is the master station, the chain is formed in a loop. Therefore, by configuring the master station 21 to collate the cell transmitted to the slave station 22 with the cell received from the slave station 25, it is possible to confirm whether or not the cell has been transmitted to each of the slave stations 22 to 25 without error. Is possible.

In order to confirm the legitimacy of the cell by forming the chain in a loop, a receiving unit for receiving the cell transmitted from the slave station 25 is provided in the terminal device 21 which is the master station.
It is necessary to provide a storage unit for storing cells to be transmitted to the slave station 22 and a collation unit for collating the cells held in the storage unit and the cells received from the reception unit.

As described above, the cells copied in the slave stations 22 to 25 are sequentially transmitted in a chained manner, so that the number of slave stations can be increased without changing the scale of the master station 21.

In the above embodiment, the case where the slave stations 22 to 25 simply copy a cell is shown, but the slave stations 22 to 2 respectively.
It is also possible to perform some processing on the cell received by 5.

Therefore, a second embodiment will be described below in the case of processing a cell in each slave station.

FIG. 5 is a block diagram showing the configuration of the terminal device 22 which is a slave station in the second embodiment.

As shown in FIG. 5, in this case, the terminal device 22 includes the detecting unit 51, the processing unit 52, the receiving unit 10, the copying unit 11, and the transmitting unit 12 shown in the embodiment shown in FIG.
And an insertion portion 53 are added.

Upon receiving the cell copied by the copying section 11, the detecting section 51 detects a cell to be processed among the cells and outputs it to the processing section 52. In this embodiment, BI
Since SDN is used, VPI / VCI in the cell is set in advance.
To the cell to be processed, the main station 21 gives that value. Then, when the detection unit 51 detects a cell having that value, it determines that the cell is a cell to be processed and outputs it to the processing unit 52.

The detector 51 is provided not only when processing all the received information but also when processing only the specific information.

The processing section 52 performs processing on the cell detected by the detection section 51, and the processing content is set as follows.

The inserting unit 53 inserts the processing result of the processing unit 51 into the information stream output from the copying unit 11 to the transmitting unit 12.

Next, the case where the specific information transmitted from the master station is the "status request of each slave station" will be described in detail as an example.

First, in the terminal device 22, the receiving unit 11 receives the cell indicating the “status request of each slave station” transmitted from the master station 21.
When the cell is received by the terminal device 2, the copy unit 11 copies the cell and one of the cells is transmitted via the transmitter 12 to the terminal device 2.
3 and outputs the other cell to the detection unit 51.

Then, the detecting section 51 confirms a specific value in the VPI / VCI contained in the cell, detects a cell indicating "status request of each slave station", and outputs it to the processing section 52.

The processing unit 52 which has received the cell inserts the state information of the terminal device 22 into the cell, and inserts the cell containing the response information into the transmission line 20 via the inserting unit 53 and the transmitting unit 12.
Output to.

If this network is configured in a loop, the cell including the response information is the terminal device 23 ...
25 is transmitted in a chain and can be grasped by the terminal device 21 which is the main station.

The terminal devices 23 to 25 are replaced by the terminal device 2
With the configuration similar to that of 2, the master station 21 can grasp the states of the slave stations 22 to 25.

Next, the case where the slave stations 22 to 25 join or leave the network will be described.

When a new slave station is to join the network, it is necessary to request the master station to join. This joining request can be made not only when it is sent using the transmission line of this network, but also when it is made by using another transmission line or communication means.

Then, the master station that has received the join request instructs the slave stations located at the end of the chain to set the slave station that has made the join request as the connection destination. Then, when the slave station receiving this instruction changes the connection destination, the terminal device can join as a slave station. Note that specifically, the slave station located at the end of the chain is the VP included in the cell.
The I / VCI will be changed to the terminal device that newly joins.

As described above, when a new slave station joins, the master station instructs the slave station located at the end of the chain to change the connection destination so that the new slave station joins at the end of the chain. You can

Further, considering the geographical position of the newly joining slave station, it is possible to join a slave station in the middle of the chain instead of at the end of the chain. Therefore, in this case, FIG.
Will be explained.

FIG. 6 is a diagram showing a case where a new terminal device is added as a slave station 65 to a network system composed of a master station 61 and slave stations 62 to 64. Here, it is assumed that the newly added slave station 65 is located between the slave stations 63 and 64.

In this case, the new slave station 65 is the master station 61.
In order to facilitate the judgment of the main station 61 when requesting to join, the geographical position of the own station is notified. Then, the master station 61 that has received this notification determines the insertion position of the new slave station 65.

Here, the main station 61 shows a case where the transmission path is the shortest if a new slave station 65 is inserted between the slave station 63 and the slave station 64.

Then, the master station 61, which has made this determination, instructs the slave station 63 to change the connection destination and informs the new slave station 65 that the connection destination is the slave station 64. .

In this way, it is possible to construct a network system in which cells transmitted from the master station 61 can be transmitted in a chain in the order of the slave station 61, the slave station 62, the slave station 63, the slave station 65, and the slave station 64.

Next, the slave station 65 joining the network.
However, the case of leaving the network will be described.

When the master station 61 receives the leave request from the slave station 65, the master station 61 instructs the slave station 65 to disconnect, and instructs the slave station 63, which is the higher slave station, to change the connection destination. As a result, the slave station 63 changes the connection destination from the slave station 65 to the slave station 64, and the disconnection is completed.

As described above, when a new slave station joins or leaves the network system, the master station that receives the join / leave request changes the connection destination to the adjacent slave station that has issued the join / leave request. By giving instructions, you can easily join or leave.

In other words, as slave stations join and leave,
It can be seen that the configuration scale of the main station does not change.

As described above, in the present embodiment, the master station and the plurality of slave stations are connected in a chain using the transmission line, and the plurality of slave stations are provided with the copy units.
If the master station has at least one transmitter, it is possible to transmit cells to each slave station.

Further, since the cell is transmitted from the slave station at the end of the slave stations connected in a chain to the master station and the cell is collated by the master station, the accuracy of the cell can be confirmed at the master station. You can

Further, since the predetermined cell is detected from the cells copied by the slave station and the data corresponding to the cell is added to the cell and transmitted, the cell added by the slave station is transmitted to the master station. Can be sent.

Further, when the slave station joins / leaves, the transmission destination of the adjacent slave station is changed according to the instruction of the master station, so that the slave station can be joined / leaved without changing the scale of the master station.

In the present embodiment, the present invention will be described in B-
Although the case where it is applied to ISDN is shown, the present invention is not limited to this.

[0069]

As described above, according to the first aspect of the invention, the master station and the plurality of slave stations are connected in a chain using a transmission line, and the plurality of slave stations are provided with copying means. ,
It is possible to reduce the size of the main station.

Further, according to the second aspect of the invention, since the slave station located at the end of the slave stations connected in a chain form transmits the information to the master station and the master station collates the information, The accuracy of information can be confirmed at the station.

Further, since the slave station detects predetermined information from the copied information and adds the corresponding data to the information to transmit, the slave station transmits the added information to the master station. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a terminal device shown in FIG.

FIG. 2 is a block diagram showing the overall configuration of a network system according to the present invention.

FIG. 3 is a block diagram showing a chained connection state of the terminal devices shown in FIG.

4 is a diagram showing a state where the terminal devices shown in FIG. 2 are connected in a loop.

5 is a block diagram showing another configuration of the terminal device shown in FIG.

FIG. 6 is a diagram used for explaining joining / leaving of the terminal device shown in FIG. 2;

[Explanation of symbols]

 10 receiver 11 copy unit 12 transmitter 20 transmission line 21 terminal device (master station) 22, 23, 24, 25 terminal device (slave station)

Claims (3)

[Claims] 1. A network system in which a plurality of slave stations are connected in sequence from a master station using a transmission line, and information held by the master station is transmitted to the plurality of slave stations, wherein the plurality of slave stations are: It comprises a receiving means for receiving the information from the transmission path, a copying means for copying the information received by the receiving means, and a transmitting means for transmitting the information copied by the copying means to another preset slave station. A network system characterized by the above. 2. The master station collates the receiving means for receiving the information transmitted from the slave station connected to the end of the chain, the information transmitted by the transmitting means, and the information received by the receiving means. The slave station connected to the end of the chain further comprises collating means, and further comprises second transmitting means for transmitting the information copied by the copying means to the master station. The described network system. 3. The slave station includes a detection means for detecting predetermined information from the information copied by the copying means, and an addition means for adding data required by the information to the information detected by the detection means. The network system according to claim 2, further comprising: