JPH08307424A - Atm exchange - Google Patents

Abstract

PURPOSE: To provide an ATM exchange which can effectively treat information that is balanced in both directions and also a large quantity of information that is unbalanced in both directions. CONSTITUTION: The program selection information 100 on the VOD service which is sent to a VOD service terminal 11 of a transmission line 16 and the information 102 such as the call setting information and the call information to be sent to a general terminal 13 are supplied to a line unit 15. The information on the terminal 13 is sent to the terminal 13 of a transmission line 23 via a path 17, a bidirectional balanced ATM switch 18, and a line unit 22. On the other hand, the information 100 is sent to a server 12 via the switch 18 and a trunk line unit 21. The video information 101 on the VOD service which is received from the server 12 is sent to the terminal 11 via the unit 21, a unidirectional ATM switch 19 and the path 17. The terminals 13 of the visual or digital telephones of both lines 16 and 23 perform the bidirectional communication via the switch 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asynchronous transfer mode (ATM) switch which is suitable for two-way image communication such as a digital telephone and a videophone and which transfers video information having a large amount of information.

[0002]

2. Description of the Related Art ATM exchanges have traditionally been used for digital telephones,
It is an exchange that transfers bidirectional image communication such as videophone to an ATM network and performs exchange in asynchronous transfer mode. Generally, an ATM switch is designed so that the input and output terminals corresponding to the upstream and the downstream of the switch have the same capacity. The traffic is designed to be average in the input direction and the output direction for each input / output terminal. In other words, the traffic applied to the input / output terminals of the ATM switch connected to the transmission line uses a switch designed on the assumption that the two-way traffic volume is equal, and this is called a bidirectional balanced switch here.

The video-on-demand (VOD) service is a service for distributing video programs such as moving image information at the request of subscribers, and is scheduled to be provided on the ATM network. The VOD system includes, as communication equipment, a server device that provides a video program in response to a request from a subscriber and an image terminal in the home of a general subscriber. The subscriber is
By operating the terminal device, program selection information is sent to the server device through the ATM network in the form of a control signal, and the image and audio signals of the video program sent from the server device are received by the terminal device and the video program is reproduced. The control signal sent to the upstream by the subscriber's program selection operation is several 100K.
It is a burst signal of bps, and the video signal sent from the server device to the down line has an information amount of about 6 Mbps. Thus VO
The amount of information transmitted by the D service depends on the video telephone signal rate of 50.
It is more than 10 times 0 Kbps, and is biased to the down line.

[0004]

On the other hand, the conventional ATM switch is a bidirectional balanced type designed assuming bidirectional communication of digital telephones, videophones, etc. and assuming that the traffic volumes of the input and output terminals are equal. Use a switch. ATM that arrives at any input terminal of such a bidirectional balanced switch
Once the cell is stored in the ATM cell storage buffer,
It is routed by the ATM cell header in the ATM switch element and output to the target port. The bidirectional balanced switch is designed on the assumption that cells are not concentrated on a specific output port at this time.

ATM switches typically house a number of common subscriber terminals. VOD services like this
When accommodated in the M-switch network to provide the video information distribution service, a significantly unbalanced traffic occurs between the server device and the subscriber terminal device. When providing such a service to a subscriber terminal, if the server device of the ATM switch and the subscriber terminal are connected by a transmission line having a band necessary for the distribution of moving image information, the subscriber terminal and the server device are connected. In the meantime, although a wide bandwidth for moving images is always secured through the exchange, the transmission bandwidth from the subscriber terminal to the exchange is hardly used. That is, the amount of traffic at the input / output terminals is extremely smaller than that in the case of going down, and becomes extremely unbalanced. Therefore, the line accommodation efficiency is low when viewed from the entire exchange. Also, the use of an ATM switch with a large amount of traffic per terminal has the drawback of making the configuration redundant.

It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide an ATM switch which efficiently accommodates communication equipment in which the transmission information amount in the vertical direction is biased.

[0007]

In order to solve the above-mentioned problems, an ATM switch according to the present invention has a cell as a first transmission line.
And a first ATM switch means for bidirectional transfer and routing in the second direction and a second ATM switch means for bidirectional transfer and routing of cells in the second direction of the transmission line It is connected between the first and second ATM switch means and the first input / output port at which the certain first information is transmitted and the second information having a remarkably large flow rate in the second direction arrives, and the first and second ATM switch means are connected. Of the cells of information arriving at the input / output port, the first information and the second information are identified, the first information is sent to the first ATM switch means, and the second information is sent to the second AT.
First interface circuit means for transferring to the M switch means and outputting the information received from the first and second ATM switch means to the first input / output port, and for sending the first and second information Is connected between the second input / output port and the first and second ATM switch means to which the information of
A second which transfers the information arriving at the second input / output port to the first ATM switching means and outputs the information output from the first and second ATM switching means to the second input / output port
Interface circuit means.

Also according to the invention, the ATM switch has a cell in which the cell is in a first direction and in a second direction opposite to the first direction.
ATM to transfer and route in both directions
The switch means and the first information cell having a flow rate in both directions are transferred in both the first and second directions of the transmission path, and the second information cell having a significantly large flow rate in the second direction is transferred. The second ATM switch means for transferring and routing in the second direction and the input / output terminal on the front side in the first direction of the first ATM switch means are connected to the second stage in the first direction of the second ATM switch means. The first connection path means connected to the input / output terminal on the side, and the input / output terminal on the front side in the first direction of the second ATM switch means on the rear side in the first direction of the first ATM switch means. A second connection path means for connecting to the input / output terminal, wherein the second ATM switch means has an input terminal for receiving the second information on the preceding stage side in the second direction,
Further, the output terminal for outputting the second information is accommodated on the rear side,
The second ATM switch means, when receiving the cell of the first information from the first direction, transfers this cell to the first connecting path means, and when receiving the cell of information from the second direction, this cell The first information and the second information are identified, and the cells of the first information are transferred to the second connecting path means, and the cells of the second information are transferred to the output terminal.

[0009]

According to the present invention, the first ATM switch means is
Transfer and route cells in both directions, first and second directions. The second ATM switch means transfers and routes the cell in the second direction of the transmission path. The first interface circuit means discriminates between the first information and the second information when a cell of information arrives at the first input / output port,
The first information is transferred to the first ATM switch means and the second information is transferred to the second ATM switch means. When receiving information from the first and second ATM switching means, the first
Output to the input / output port of. The second interface circuit means, when information arrives at the second input / output port, the first interface circuit means
Information is output to the second input / output port from the first and second ATM switch means.

Also according to the invention, the first ATM switching means routes the cells bidirectionally in the first and second directions of the transmission line. The second ATM switch means is the first
Cell of information is transferred bidirectionally in the first and second directions and the second cell of information is routed in the second direction. The second ATM switch means, when receiving the cell of the first information from the first direction, transfers this cell to the first connecting path means, and when receiving the cell of information from the second direction, this cell The first information and the second information are identified, and the cells of the first information are transferred to the second connecting path means, and the cells of the second information are transferred to the output terminal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An ATM switch according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the embodiment of FIG. 1, the ATM exchange 10 is an exchange that divides information into fixed length cells and accommodates them, adds a destination label to the cells and transfers the cells to an ATM network. In general, the amount of information flow in such an ATM switch depends on the number of cell transfers per unit time. The ATM exchange 10 accommodates a large number of VOD service terminals 11, a terminal device 13 such as a videophone terminal and a digital telephone terminal, and a trunk line (not shown). Although many of these terminals 11 and 13 are actually accommodated, only two terminals 11 and 13 are shown in the figure for the sake of explanation.

This embodiment also includes video-on-demand.
(VOD) It includes a service function, and for this purpose, the server 12 for the VOD service is also housed. The VOD service sends program selection information in the form of a control signal to the server 12 through the ATM switch 10 by operating the VOD service terminal 11, and in response to this, sends the video and image signals of the video program sent from the server 12 to the VOD. This is an image / sound distribution service in which the service terminal 11 receives and reproduces a video program on the terminal 11. Server 12
Receives the program selection information from the VOD service terminal 11,
It is a service device that delivers an image and / or audio signal of a video program in response to a request from a subscriber with this selection information. The video image from the server 12 is 6M in this example.
Has a bandwidth of bps. In this embodiment, the VOD service terminal 11 installed in the subscriber's home sends control information 100 for program selection in the form of a burst signal of several 100 Kbps to the server 12,
Further, the video information 101 of the video image is received from the server 12. Therefore, the information sent to and from the VOD service terminal 11 is mostly downlink information.

The ATM switch 10 also houses a general voice and / or video terminal 13. When the general terminal 13 is a videophone terminal, bidirectional balanced information 102 of, for example, 500 Kbps is transmitted and received, and when it is a digital telephone terminal, bidirectional balanced information 102 of, for example, 64 Kbps is transmitted and received. The information signals to and from these terminals 13 are presumed to be bidirectional and balanced, but the amount of information is significantly smaller than that of the VOD service terminal 11.

In this embodiment, the ATM switch 10 has two ATMs.
It has switches 18 and 19. The VOD service terminal 11 is housed in the line unit (VLU) 15. The line unit 15 assembles the uplink information 100 from the VOD service terminal 11 and the uplink / downlink information 102 for the general terminal 13 into a cell from the subscriber transmission line 16, transfers this to the ATM switch 18 on one side via the route 17, and It is the video information 101 from the server 12.
Downlink information to the VOD service terminal 11 is the other ATM switch
It is an interface circuit which is input from 19 and transfers it to the transmission line 16. A header is added to each cell, and the header includes a flag indicating the communication or control information 100 or 102. The line unit 19 also has a function of disassembling the cell. FIG. 3 shows a configuration example of the line unit 19
Shown in As you can see, the line unit 15
It has a multiplexing circuit (MUX) 201 which multiplexes the signals coming from the two ATM switches 18 and 19 and sends them to the transmission line 16 to the VOD service terminal 11.

The server 12 is a trunk line unit (TLU)
It is housed in 21. The trunk line unit 21 separates the downlink information 101, which is the video information output from the server 12, from the communication and control information 102 of a small flow rate and assembles them into a cell. The former is one ATM switch 19 and the latter is the other ATM.
It is an interface circuit that sends to the switch 18, and sends the upstream information 100 from the other ATM switch 18 to the server 12. A header is added to each cell, and this header includes a flag indicating whether it is video information 101 or communication or control information 102. The trunk line unit 21 also has a function of disassembling the cell. The trunk line unit 21 has, for example, the configuration shown in FIG. As can be seen from the figure, the trunk line unit 21 is a server
Two ATM switches by demultiplexing the signals coming from 12
It has a demultiplexing circuit (DEMUX) 202 that distributes to 18 and 19.

On the other hand, the ATM switch 19 is a one-way type switch having a structure as shown in FIG. The one-way ATM switch 19 has a large-capacity ATM cell storage buffers 191 and 192 corresponding to the video information 101 having a large amount of information.
M switch element 193 is connected to input port 203 and output port 204, respectively. The ATM switch element 193 is a one-way type switch that adds a label to an input cell coming from the buffer 191 on the input side, causes the label to be routed in the switch 193, and transfers the label to the buffer 192 on the output side. I / O ports 203 and 204 are
Although many are actually accommodated, only four ports are shown in the figure for the sake of explanation.

The other ATM switch 18 is the same bidirectional balanced type ATM switch as the conventional one. The bidirectional balanced ATM switch 18 is a terminal such as a video telephone terminal or a digital telephone terminal which is connected through a subscriber transmission line 23 from a line unit (LU) 22 which is an interface circuit with the general terminal 13.
This is a balanced ATM switch that transfers upstream and downstream information 102 to and from the VOD service terminal 11 to the server 12. The ATM switch 18 is an ATM switch element, as shown in FIG.
181 and a bidirectional ATM cell store buffer 182 connected to its input port 205 and output port 206. ATM cells that arrive at any input terminal are temporarily
The data is accumulated in the accumulation buffer 182, then routed according to the ATM cell header in the ATM switch element, accumulated in the accumulation buffer 182 from the target output port 206, and output to the output terminal. At this time, cells are designed not to concentrate on a specific output port 206. Although a large number of input / output ports 205 and 206 are actually accommodated, only four ports are shown in the figure for the sake of explanation.

A conventional ATM switching network is a one-way AT.
It does not have a switch corresponding to the M switch 31, but has only the bidirectional balanced ATM switch 18. Therefore, when the VOD service provided by the server 12 to the VOD service terminal 11 is to be accommodated, while the ATM switch 18 secures a large-capacity input / output terminal in both directions,
A large amount of information is transferred only in the direction from 12 to the VOD service terminal 11. As a result, the number of terminals that can be accommodated in the ATM switch 18 is reduced, and the line accommodation efficiency is low when viewed from the entire exchange. Further, the amount of traffic at the input / output terminals is extremely smaller than that in the case of going down, and becomes extremely unbalanced.

In the operating state, the line unit 15
It receives various information 100 and 102 from the VOD service terminal 11 on the transmission line 16. The line unit 15 uses the VOD service program selection information 100 sent by the VOD service terminal 11.
And information such as call settings and call information for general terminal 10
2 receives them, identifies them, and distributes the information 102 of the telephone terminal 13 to the route 17, and this information 102 is a balanced type.
Transmission line 23 from line unit 22 through ATM switch 18
To the telephone terminal 13 of. Also, from the VOD service terminal 11
The VOD service selection information 100 is also transferred to the balanced ATM switch 18, which passes from the trunk line unit 21 to the server 12 through the balanced ATM switch 18. On the other hand, the trunk line unit 21 is more VOD than the server 12.
When the video information 101 of the service is received, it is identified and distributed to the one-way ATM switch 19, and the one-way ATM switch 19 routes it to the line unit 15. Via the VOD service terminal 11. In addition, the general terminal 13 such as a videophone or a digital telephone of the subscriber transmission line 23 is a balanced ATM.
Bidirectional communication is performed via the switch 18.

As described above, in this embodiment, the one-way ATM switch 19 is introduced, and the switching from the server 12 to the VOD service terminal 11 is centralized in this switch 19. ATM
The input / output terminal of the switch 19 in the direction from the server 12 to the VOD service terminal 11 secures the capacity required for transmitting moving image information, and the input / output terminal from the VOD service terminal 11 to the server 12 has a control signal. The I / O terminals are set to have the capacity necessary for the transmission of. In this way, the required capacity can be set for each of the upstream and downstream input / output terminals, so that efficient operation can be achieved.

FIG. 2 illustrates an ATM switch 30 according to another embodiment of the present invention. Like reference numerals in FIG. 1 denote like elements. The ATM switch 30 of this embodiment is largely different from the embodiment of FIG. 1 in that it has a bidirectional unbalanced ATM switch 31 in place of the one-way ATM switch 19 of the embodiment shown in FIG. The bidirectional unbalanced ATM switch 31
The line unit 32 accommodates the VOD service terminal 11 via the transmission line 16, and is connected to the server 12 via the trunk line unit 33. The line unit 32 has a function of assembling information from the transmission line 16 into a cell, adding a header to the cell, and disassembling the cell. The trunk line unit 33 has a function of assembling information from the server 12 into a cell, adding a header corresponding to the information type to the cell, and disassembling the cell. ATM switch 31 also
It is also connected to the bidirectional balanced ATM switch 18 through the pavement paths 34 and 35, and is connected to the general terminal 13 such as a videophone or a digital telephone via the latter.

The unbalanced ATM switch 31, which is a bidirectional switch, is an unbalanced switch in which a large amount of traffic flow is set in the downstream direction. This ATM switch 31
The input / output terminal of has a capacity necessary for transmitting moving image information and control information in the direction from the server 12 to the subscriber terminal 11 when setting up a call between the VOD service terminal 11 and the server 12. . This capacity is available from the subscriber terminal 11 to the server.
It is larger than the capacity of the input / output terminal for the information sent from the subscriber to the balanced ATM switch 18, such as the control information sent to 12.
The ATM switch 31 has a function of switching the moving image information sent from the server 12 to the VOD service terminal 11, and a function of separating the control signal and the moving image information. Whether it is a control signal or moving picture information is displayed as an identification flag in the header of the cell. The unbalanced ATM switch 31 switches the separated control information to the path 34 to the balanced ATM switch 18 according to the header.

More specifically, as shown in FIG. 6, the unbalanced ATM switch 31 has an ATM switch element 317, and the switch element 317 has a large input / output capacity 220 and a large input / output capacity. It has an output port 221. Cell buffers 313 and 314 are connected to the input port 220 and the output port 221, respectively. One of the cell buffers 313 is an input / output terminal that is directly connected to the trunk line unit 33.
311 is accommodated, and the other cell buffer 314 accommodates an input / output terminal 312 connected so as to directly enter and leave the line unit 32. The input / output terminal 311 is an unbalanced input / output terminal including a signal line 311a having a large input / output capacity indicated by a thick line and a signal line 311b having a small capacity indicated by a thin line in FIG. Similarly, the other input / output terminal 312 is an unbalanced input / output terminal including a signal line 312a having a large input / output capacity and a signal line 312b having a small input / output capacity.

Input port of ATM switch element 317
Some of the 220 have a multiplexer (MUX) 315
Of the cell buffers 314 and 318 is connected to the input of the multiplexer 315. Multiplexer 315 multiplexes the low-capacity signals from cell buffers 314 and 318 to multiplex the input port of ATM switch element 317.
It has a signal multiplexing function to output to 222. Also, one of the output ports 221 of the ATM switch element 317 is connected to the input 223 of the demultiplexing circuit (DEMUX) 316, the output of which is a signal line with a small output capacity to the cell buffers 313 and 318. It is connected. Demultiplexing circuit 31
6 has a demultiplexing function of demultiplexing the multiplexed signal of the output port 223 of the switch element 317 and distributing it to the cell buffers 313 and 318. The cell buffer 318 is a buffer to which the connection lines 34 and 35 to the bidirectionally balanced ATM switch 18 are connected and which temporarily stores information exchanged with the ATM switch 18.

VO with a large amount of information flow transmitted from the server 12
The cell containing the video information 101 of the D service is the input / output terminal 31.
It is input to the cell buffer 313 from 1a and enters the switch element 317 having a large flow capacity. This video information 101
The signal is routed by the switch element 317, enters the cell buffer 314 from the output terminal 221 thereof, and is output to the input / output terminal 312 having a large flow rate from here. On the other hand, VOD
Information 100 for program selection from the service terminal 11 and information 102 such as call setting and call information for the general terminal 13 such as a videophone and a digital telephone have a small amount of information flow, and these are from the line unit 32 to the cell buffer 314. Is input to the input port 222 of the switch element 317. In addition, the information of the switch connection line such as NO.7 method, which also has a small information flow rate, is also input to the cell buffer 318, and the multiplexer
It is multiplexed into this at 315. These information 100 and
The 102 cells are routed at switch element 317 and switched to the corresponding output ports 221 and 223. Output port 223 of switch element 317
Information output from low-flow information 100 and 102
Is demultiplexed by the demultiplexing circuit 316 and distributed to the cell buffers 313 and 318, respectively, and output to the output terminals 311b and 34 having a small information flow rate.

Returning to FIG. 2, when the VOD service terminal 11 sends the program selection information 100 of the VOD service and the information 102 such as the call setting and call information of the general terminal 13 from the subscriber transmission line 16, the line unit 32 , Receives it, assembles it into a cell, and inputs it to the ATM switch 31. ATM switch 31
Routes it towards route 34 according to its header. The information 100 or 102 input to the ATM switch 18 from the route 34 is transmitted from the ATM switch 18 to the telephone information 10
2 is routed to the line unit 22 and sent from the transmission line 23 to the general terminal 13. Further, the program selection information 100 of the VOD service is routed from the ATM switch 18 to the route 35 and is input to the unbalanced ATM switch 31 again. The unbalanced ATM switch 31 routes the cell of control information 100 to the trunk line unit 33, which causes the control information 100 to reach the server 12. On the other hand, the video information 101 of the VOD service from the server 12 is assembled into a cell by the trunk line unit 33 and is then input to the ATM switch 31. The ATM switch 31 routes this according to its header to the line unit 32. As a result, the video information 101 reaches the VOD service terminal 11. A general terminal 13 such as a videophone or a digital telephone on the subscriber transmission line 23 performs bidirectional communication via the balanced ATM switch 18. This is similar to the embodiment shown in FIG.

In the embodiment described with reference to FIG. 2, the moving image information and the control information are separated in the bidirectional unbalanced switch 31. Therefore, the line interface part
It is not necessary to provide the information separation function in 32 and 33. This has the effect of more effectively using existing equipment as compared to the embodiment described with reference to FIG.

[0028]

As described above, according to the present invention, it is possible to cope with a mixture of heterogeneous communication such as a conventional telephone in which bidirectional information flow is balanced and a VOD service in which one-way information flow is extremely large. A bidirectional balanced switch with a small cell transfer amount per output terminal and a unidirectional or bidirectional unbalanced switch with a large cell transfer amount are combined. As a result, the redundancy of various elements such as buffers and switch elements in the ATM switch configuration can be minimized, and the ATM switch can be efficiently configured.

When introducing a VOD service into a conventional balanced ATM switch that handles videophones and digital telephones, it is possible to add a unidirectional or bidirectional unbalanced switch to the conventional bidirectional balanced switch. .

[Brief description of drawings]

FIG. 1 is a relay system diagram of an embodiment of an ATM exchange according to the present invention.

FIG. 2 is a relay system diagram of another embodiment of the ATM switch according to the present invention.

FIG. 3 is a diagram showing a configuration example of a line unit in the embodiment shown in FIG.

FIG. 4 is a diagram showing a configuration example of a trunk line unit in the embodiment.

5 is a block diagram showing a configuration example of a one-way type ATM switch in the embodiment shown in FIG.

FIG. 6 is a bidirectional unbalanced AT in the embodiment shown in FIG.
FIG. 3 is a block diagram showing a configuration example of an M switch.

FIG. 7 is a block diagram of a balanced ATM switch in these examples.

[Explanation of symbols]

 10,30 ATM switch 11 VOD service terminal 12 Server 13 General terminal 15, 22, 32 Line unit 16, 23 Subscriber transmission line 18 Bidirectional balanced ATM switch 19 Unidirectional ATM switch 21, 33 Trunk line unit 31 Bidirectional Unbalanced ATM switch

Front page continued (72) Inventor Hiroyasu Mizuno 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (5)

[Claims] 1. A first ATM switch means for transferring and routing a cell bidirectionally in first and second directions of a transmission path, and a first ATM switching means for transferring and routing a cell in a second direction of a transmission path. 2 ATM switch means, 1st input / output port and 1st and 2nd ATM which send out 1st information which has flow volume bidirectionally, and 2nd information whose flow volume is remarkably large arrives in 2nd direction Of the cells of information that are connected between the switch means and arrive at the first input / output port,
The first information and the second information are identified, and the first information is converted into the first information.
First ATM switch means and second information to the second ATM switch means, and outputs the information received from the first and second ATM switch means to the first input / output port.
Connected between the first and second ATM switch means and the second input / output port for transmitting the first and second information and arriving at the first information. The information arriving at the output port is transferred to the first ATM switch means, and the first and second ATM switch means are transferred.
An ATM switch comprising: second interface circuit means for outputting information output from the ATM switch means to a second input / output port. 2. A first ATM switch means for transferring and routing cells bidirectionally in a first direction of a transmission line and a second direction opposite to the first direction and bidirectionally flowable. The cells of the first information are transferred bidirectionally in the first and second directions of the transmission path, and the cells of the second information having a significantly high flow rate in the second direction are transferred and routed in the second direction. A first ATM switch means and a first input / output terminal of the first ATM switch means in the first direction connected to the input / output terminal of the second ATM switch means on the rear side in the first direction. And a second connection for connecting the input / output terminal of the second ATM switch means on the front side in the first direction to the output terminal of the first ATM switch means on the rear side in the first direction. A second ATM switch means in a second direction Kicking second input terminal receiving a second information in the preceding stage and the subsequent stage
The second ATM switch means receives the cell of the first information from the first direction, transfers the cell to the first connection path means, and outputs the second terminal of the second ATM switch means. When a cell of information is received from a direction, the first information and the second information of the cells are identified, the cell of the first information is sent to the second connection path means, and the cell of the second information is sent. An ATM switch which transfers data to the output terminal. 3. The ATM switch according to claim 2, wherein the first ATM switch means receives cells from the first connecting path means to the second connecting path means, and the second connecting path means. An ATM switch characterized in that the cells received from are transferred to the first connecting path means. 4. The ATM switch according to claim 1, wherein the first information includes a signal requesting a video program distribution service, and the second information is a video distributed in response to the signal. An ATM exchange characterized by including image information of a program distribution service. 5. The ATM exchange according to claim 1 or 2, wherein the exchange accommodates a terminal that handles first information, and the first information is provided between the terminal and the first ATM switching means. An ATM switch characterized in that it includes a third interface means for transferring a packet.