JPH07297837A - Virtual channel handler - Google Patents

Abstract

PURPOSE:To realize distributing connection function without adopting a special switch by providing a means, which distributes and outputs ATM cells inputted from circuit input (output) information lines to arbitrary numbers of virtual channels, to flexibly cope with the variance of demand related to distributing connection. CONSTITUTION:A means which distributes and outputs ATM cells inputted from circuit input information lines 41 to 4n correspondingly to arbitrary numbers of virtual channel identifiers in circuit output information lines 51 to 5n and self-routing switch input information lines 61 to 6n and a means which distributes and outputs ATM cells inputted from self-routing switch output information lines 71 to 7n correspondingly to area arbitrary numbers of virtual channel identifiers in circuit output information lines 51 to 5n and self-routing switch input information lines 61 to 6n are provided. Thus, information inputted to line control parts 21 to 2n are distributed and connected to arbitrary numbers of lines in both of the direction of circuit output information lines 51 to 5n and the direction of self-routing switch input information lines 71 to 7n.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an asynchronous transfer mode (A
TM) digital communication technology, and in particular, as a mode of information communication of ATM, in addition to a mode of bidirectional communication between one terminal and another terminal, a plurality of terminals from one information source are used. The present invention relates to an improvement in the configuration method of a virtual channel handler (ATM switch) capable of flexibly providing a service of mainly one-way communication mode for distributing and connecting information.

[0002]

2. Description of the Related Art First, a basic problem in providing a service of mainly one-way communication mode in which information is distributed and connected from one information source to a plurality of terminals will be explained, and then the basic problem will be explained. A configuration technique of a virtual channel handler according to the related art for solving the problem will be described.

FIG. 2 is a diagram showing a general configuration of a general virtual channel handler according to the prior art and a general information flow of bidirectional communication. In FIG.
1 is a self-routing switch, 41, 42-4n are line input information lines, 51, 52-5n are line output information lines,
Reference numerals 61, 62 to 6n are self-routing switch input information lines, 71, 72 to 7n are self-routing switch output information lines, 21, 22 to 2n are line control units corresponding to the respective lines, 81, 82 to 8n and 91, 92 to. Reference numeral 9n is a virtual channel identifier control function unit. The shaded portion in FIG. 2 shows an example of the flow of information in bidirectional communication, and the ATM cell input from the line input information line 42 is
The virtual channel identifier control unit 82 converts the virtual channel identifier and inputs it to the self-routing switch 1 via the self-routing switch input information line 62. In the self-routing switch 1, the virtual channel identifier information attached by the virtual channel identifier controller 82 is identified and connected to the desired self-routing switch output information line 7n. Thereafter, the ATM cell is converted into a new virtual channel identifier by the virtual channel identifier control unit 9n of the line control unit 2n and output to the line output information line 5n.

The flow of information in the reverse direction is also the same. For the ATM cell input from the line input information line 4n, the virtual channel identifier is converted by the virtual channel identifier control unit 8n, and the self-routing switch input information line 6n. Is input to the self-routing switch 1 via. In the self-routing switch 1, the information of the virtual channel identifier attached by the virtual channel identifier controller 8n is identified, and the target self-routing switch output information line 7
Connected to 2. After that, the ATM cell is connected to the line control unit 22.
Is converted to a new virtual channel identifier by the virtual channel identifier control unit 92 and is output to the line output information line 52.

The above is the outline of the information transfer of the bidirectional communication in the information transfer phase. In such connection-type information transfer, there is a call setup phase before the information transfer phase, in which virtual channel identifier control unit 82, 9n, 8n, 92 inputs which virtual channel identifier It is determined whether to correspond to the output of the channel identifier.

FIG. 3 shows a configuration equivalent to the general configuration of the general virtual channel handler shown in FIG. 2, in which the information is distributed and connected from one information source to a plurality of terminals, mainly in one-way communication mode. It is a figure for demonstrating the fundamental problem when providing a service. The configuration of the virtual channel handler in FIG. 3 is exactly the same as that of FIG. 2, but it has been rewritten so that the flow of cells goes from left to right. The hatched portion in FIG. 3 shows an example of the information flow of one-way distribution connection type communication, and the information input from the line input information line 41 is used for all the line output information lines 51 to 5n. Shows an example of output to.

The cell input from the line input information line 41 to the line control unit 21 is copied (that is, distributed connection) to the number of information corresponding to the number n of terminals of the self-routing switch 1 by the virtual channel identifier control unit 81. A virtual channel identifier corresponding to each output is attached and output to the self-routing switch input information line 61. The self-routing switch 1 performs switching for allocating such information to each output terminal, that is, the self-routing switch output information lines 71, 72 to 7n according to the virtual channel identifier. For example, the information arriving at the self-routing switch output information line 71 is copied by the virtual channel identifier control unit 91 to a cell having a plurality of virtual channel identifiers as necessary, and the line output information line 51
Is output to. The same applies to the output parts (72, 92, 52, etc.) of the virtual channel handler other than 71, 91, 51.

The problem here is that since the virtual channel identifier control unit 81 performs distribution connection, the amount of information to be transmitted by the self-routing switch input information line 61 depends on the number of distributions and the speed of information to be distributed. In some cases, the information transfer becomes impossible and the line utilization efficiency of the self-routing switch input information line 61 becomes too large, which hinders the other two-way connection as described in FIG. 2, for example. Is there. The example of connection explained above is an extreme example of distribution connection to all line output information lines, but even if it is not distributed to all line output information lines, the number of information sources to be distributed and the respective information There is a basic problem that the information transfer capability of the self-routing switch input information line is insufficient depending on the speed of the source and the number of distributing each information source.

In the above description, it is assumed that the information distribution connection is performed by the virtual channel identifier controller. The reason is that the virtual channel identifier control unit has the information storage function and the correspondence information of the input / output virtual channel identifiers for the line control unit, so that the distribution connection can be easily realized. This will be described in detail with reference to the configuration example of the line control unit 21 in FIG.

As described with reference to FIGS. 2 and 3, 41 is a line input information line, 61 is a self-routing switch input information line, 71 is a self-routing switch output information line, 5
Reference numeral 1 is a line output information line. Reference numerals 101 and 102 are information storage and output control function units, and reference numerals 103 and 104 are virtual channel identifier correspondence tables. As shown in FIG. 6, when an ATM cell having a virtual channel identifier of a is input from the line input information line 41, the cell is stored in the information storage and output control function unit 101 and corresponds to the virtual channel identifier. After determining that the virtual channel identifier b should be output for the input of the virtual channel identifier a by referring to the table 103, the ATM cell having the virtual channel identifier b is output to the self-routing switch input information 61.

In this manner, in the virtual channel identifier correspondence table, associating a with b corresponds to making a one-to-one connection. In the virtual channel identifier correspondence table, distribution connection can be easily performed by associating one input virtual channel identifier with a plurality of output virtual channel identifiers.

For example, from the self-routing switch output information line 71 to A having a virtual channel identifier i.
Information storage and output control function unit 1 in which TM cells are input
02, the virtual channel identifier correspondence table 10
4, it is determined that two cells of the virtual channel identifiers j and k should be output for the input of the virtual channel identifier i, and the virtual channel identifier j for the same information.
It is possible to output the ATM cell to which is added and the ATM cell to which the virtual channel identifier k is added. Thus, in the virtual channel identifier correspondence table, j for i
Corresponding to and k means making a one-to-two distribution connection.

An arbitrary number of distributions can be realized, and an arbitrary number of output virtual channels can be made to correspond to one input virtual channel by a method called data chaining, for example. Depending on the number of corresponding output virtual channels, 0 means a virtual channel that is not used, 1 means a virtual channel for one-to-one connection, and 2 or more means a distributed connection virtual channel.

In FIG. 6, reference numeral 105 denotes a call connection control function unit, which communicates a call control signal ATM cell with another call connection control function unit via the information lines 106 and 107 in the call setting phase, and an appropriate virtual channel. Control line 1
It has a function of rewriting the contents of the virtual channel identifier correspondence table via 08. The call connection control function unit may be installed individually for each line interface unit or may be shared by a plurality of line interface units.

A conventional problem which avoids the basic problem that the information transfer capability of the self-routing switch input information line may be insufficient when the distribution connection is performed by the virtual channel identifier control function unit as described above There are two methods of technology. One is a system that uses a dedicated line interface for distribution, and the other is a system that uses a self-routing switch capable of distributing and connecting information.

First, a system using a line interface dedicated to distribution will be described with reference to the configuration example of FIG. In FIG. 4, reference numeral 201 denotes a line interface dedicated to distribution. The line-corresponding unit 201 dedicated to distribution is configured so that one line input information line can be distributed and connected to a plurality of self-routing switch input information lines 601, 602, 603 by the virtual channel identifier control unit 801. The other structure is exactly the same as that of FIG. In this method, the basic problem that the information transfer capability of the self-routing switch input information line is insufficient is avoided by increasing the number of self-routing switch input information lines, but a new problem occurs.

The biggest problem is the calculation of the number of facilities. Distribution connection is for connecting image information such as a movie to many terminals, but it is difficult to predict the number of information to be distributed, the speed of information, and the required distribution number of each information, In the example of FIG. 4, three self-routing switch input information lines (601 to 603) are provided in one distribution dedicated line corresponding part, but how many are appropriate and how many distribution dedicated line corresponding parts are installed. The problem is that it is difficult to calculate the number of facilities. In this system, if the demand for distribution connection fluctuates, it is necessary to increase the number of self-routing switch input information lines and the number of line-corresponding sections dedicated to distribution.

If the virtual channel handler is designed with a high degree of freedom for the addition of such equipment, there is a drawback that the cost is increased. Also in this method,
There is also a problem that the scale of the self-routing switch 1 must be increased because the number of self-routing switch input information lines increases. Increasing the scale of the switch substantially reduces the efficiency of use of the switch.

As a method similar to the method of increasing the number of self-routing switch input information lines connected to the self-routing switch from one line corresponding part as described above, for example, the self-routing switch input information lines 61 and 62 in FIG. The information transfer speeds of .about.6n and the information transfer speed of the self-routing switch output information line are set to the line input information lines 41, 42-4n and the line output information line 5.
There is also a method of increasing the speed as compared with the information transfer speed of 1,52 to 5n. This method of speeding up is effective in that it increases the degree of freedom for distribution connection, but it has a limited information transfer rate, and simply increasing the speed will increase the information transfer capability of the self-routing switch input information line. We have not solved the basic problem of shortage.

Another conventional technique, that is, a system using a self-routing switch capable of distributing and connecting information will be described with reference to FIG. 5, the line corresponding parts 21, 22 to 2n, the line input information lines 41, 42 to 4n,
Self-routing switch input information lines 61, 62 to 6
n, self-routing switch output information lines 71, 72
.About.7n and line output information lines 51, 52 to 5n are the same as those in FIG. The difference is that the self-routing switch 2 is a self-routing switch capable of distributed connection.

In this structure, the distribution of information to the self-routing switch output lines 71, 72 to 7n is
Instead of being performed by the virtual channel identifier controller 81,
This is performed by the self-routing switch 2 which can be distributed and connected. In this method, the distribution connection is made within the self-routing switch in this way, thereby avoiding the fundamental problem that the information transfer capability of the self-routing switch input information line is insufficient.

However, in this method, since the distribution connection is made by the self-routing switch, the structure of the self-routing switch becomes complicated and the cost of the switch becomes high. In addition, although a great number of methods of constructing ATM self-routing switches have been proposed at present, there are very few methods of constructing self-routing switches that can be distributed and connected. That is, there is a problem in that most of the other construction methods currently proposed are not applicable and a special construction method must be selected.

Another problem in the system using the self-routing switch which can be distributed and connected is the format of the ATM cell handled by the self-routing switch. According to the international recommendation of the telecommunications standardization sector (ITU-T), which is an international standardization organization for telecommunications, the information payload is 48 bytes + overhead 5 bytes as an ATM cell format. The virtual channel identifier is a part of information in the overhead 5 bytes. Extra information must be added to the 53-byte ATM cell in order to perform the distribution connection by the self-routing switch. It is information about where and where the output terminals are to distribute the respective ATM cells.

Since this information is independent of whether or not to distribute each output of the self-routing switch, at least the same number of bits of information as the number of output terminals is required.
For example, the size of the self-routing switch is 64 inputs ×
For 64 outputs, at least 64 bits = 8 bytes are required, and for a 128-input × 128-output self-routing switch, at least 128 bits = 16 bytes are required. This extra information is used as an overhead for each A
Must be added to the TM cell.

That is, in the method using the self-routing switch capable of distribution connection, the ATM cell format handled by the self-routing switch has a very large overhead as compared with the standard format, and the substantial information transfer capability is deteriorated. There is a problem. Further, since the amount of this overhead depends on the maximum size of the self-routing switch, there is a problem that the format of the ATM cell to be handled must be changed when the design value of the size of the self-routing switch changes.

[0026]

The problems of the prior art are as follows.
As described above, (1) it is difficult to calculate the number of facilities because it is difficult to predict the demand related to the distribution connection, and (2) the self-routing switch has to be large in scale, and the usage efficiency of the switch decreases ( 3) It is necessary to adopt a special self-routing switch dedicated to distribution, (4) It is necessary to adopt a non-standard ATM cell format with a large overhead, and the substantial information transfer capability is reduced, etc. The object of the present invention is to solve these problems, to flexibly respond to demand fluctuations related to distribution connection, and to implement general self-routing for one-to-one connection without adopting a special self-routing switch dedicated to distribution. A switch is adopted to realize the distribution connection function, and further, the use efficiency of the switch and the substantial information transfer capability are reduced. And to provide a virtual channel handler does not lead.

[0027]

According to the present invention, for this purpose, an ATM cell input from a line input information line is made to correspond to a virtual channel identifier and a line output information line and A means for distributing and outputting to an arbitrary number of virtual channels in the self-routing switch input information line, and an ATM cell input from the self-routing switch output information line, in correspondence with the virtual channel identifier, the line output information line and self The above problem is solved by providing means for distributing and outputting to an arbitrary number of virtual channels in the routing switch input information line.

[0028]

According to the present invention, the means for solving the above-mentioned problems allows the information input to the line control unit in the line control unit to be directed to both the direction of the line output information line and the direction of the self-routing switch input information line. It is possible to make distributed connection to any number. As a result, in addition to the one-to-one connection as the virtual channel handler, the multi-stage distribution connection can be performed by using the self-routing switch input information line with low utilization efficiency, so that the flexible distribution connection that can respond to the demand fluctuation related to the distribution connection. Is possible.

[0029]

FIG. 1 shows an embodiment of the present invention, in which 1 is a self-routing switch, 21, 22 to 2n are line corresponding parts, 41, 42 to 4n are line input information lines, and 51, 52 to.
5n is a line output information line, 61, 62-6n is a self-routing switch input information line, 71, 72-7n is a self-routing switch output information line, 31, 32-3n.
Is a virtual channel identifier control unit, which distributes and outputs ATM cells input from the line input information line in association with any number of virtual channel identifiers in the line output information line and the self-routing switch input information line. And AT input from the self-routing switch output information line
Means for distributing and outputting the M cells in correspondence with any number of virtual channel identifiers in the line output information line and the self-routing switch input information line. As a result, it is possible to distribute and connect the information input to the line control unit in any number in both the direction of the line output information line and the direction of the self-routing switch input information line.

FIG. 7 shows an example of the structure of the line interface in the embodiment of the present invention shown in FIG. 1, in which the input information is read in the direction of the line output information line and in the self-routing switch input information line. It is for explaining the means for connecting in an arbitrary number in both directions. In FIG. 7, 41 is a line input information line, 61 is a self-routing switch input information line, 71 is a self-routing switch output information line, and 51 is a line output information line. 11
Reference numeral 1 is an information storage and output control function unit, and 112 is a virtual channel identifier correspondence table.

Virtual channel identifier correspondence table 112
Is the virtual channel identifier correspondence table 1 described in FIG.
What is different from 01 and 102 is that, in addition to the information of the virtual channel identifier, it is a virtual channel in the output (O) direction as viewed from the self-routing switch or a virtual channel in the input (I) direction to the self-routing switch. That is, it has information for identifying whether or not. Figure 6
Compared with the virtual channel identifier correspondence table shown in FIG.
Since the additional information in the virtual channel identifier correspondence table 112 shown in (1) identifies the output direction or the input direction, it is sufficient to add 1-bit information, which can be easily realized.

As shown in FIG. 7, an ATM having a virtual channel identifier of line input information lines 41 to a.
When a cell is input, the information is stored in the information storage and output control function unit 111, the virtual channel identifier correspondence table 112 is referred to, and the virtual channel identifier b is set in the input (I) direction of the virtual channel identifier a. After determining that the self-routing switch should output in the input (I) direction, A having a virtual channel identifier of b
TM cell self-routing switch input information line 61
Output to.

As described in the description of FIG. 6, in the virtual channel identifier correspondence table 112, by making a plurality of output virtual channel identifiers correspond to one input virtual channel identifier, distribution connection can be easily performed. It will be possible. For example, an AT having a virtual channel identifier i from the self-routing switch output information line 71
Information storage and output control function unit 11 to which M cells are input
1 and is stored in the virtual channel identifier correspondence table 112.
2, the two cells of the virtual channel identifiers j and k are output in the output (O) direction when viewed from the self-routing switch with respect to the input of the virtual channel identifier i in the output (O) direction of the self-routing switch. At the same time, it is determined that two cells having virtual channel identifiers s and t should be output in the input (I) direction when viewed from the self-routing switch, and an ATM cell to which the virtual channel identifier j is added to the same information. Virtual channel identifier k
It is possible to output the ATM cell to which the virtual channel identifier s is added and the ATM cell to which the virtual channel identifier t is added to the self-routing switch input information line 61, while outputting the ATM cell to which the virtual channel identifier s is added to the line output information line 51.

As described above, in the virtual channel identifier correspondence table 112, in addition to the information of the virtual channel identifier,
Input from the line input information line by adding information for identifying whether the virtual channel is in the output (O) direction from the viewpoint of the self-routing switch or the virtual channel in the input (I) direction to the self-routing switch. A means for distributing and outputting ATM cells corresponding to an arbitrary number of virtual channel identifiers in the line output information line and the self-routing switch input information line, and line output information for the ATM cells input from the self-routing switch output information line. It is possible to realize means for distributing and outputting corresponding to any number of virtual channel identifiers in the line and the self-routing switch input information line.

In FIG. 7, a call connection control function unit 105 communicates the call control signal ATM cell with another call connection control function unit via the information lines 106 and 107 in the call setting phase, and an appropriate virtual channel. Control line 1
08 via virtual channel identifier correspondence table 112
It has a function to rewrite the contents of. This call connection control function unit is the same as that described in FIG.

The shaded portion in FIG. 1 shows an example of the information flow of the one-way distribution connection communication in the embodiment of the present invention, in which A input from the line input information line 41 is used.
The TM cell is distributed and connected to the line output information line 51 by the virtual channel identifier control unit 31 and also to the self routing switch input information line 61. The ATM cells distributed and connected to the self-routing switch input information line 61 are connected to the self-routing switch output information line 72 by the self-routing switch 1. The ATM cells input from the self-routing switch output information line 72 to the line control unit 22 are distributed and connected by the virtual channel identifier control unit 32 to a plurality of virtual channels corresponding to a plurality of virtual channel identifiers in the line output information line 52. At the same time, it is distributed and connected to the plurality of virtual channels in the self-routing switch input information line 62.

Self-routing switch input information line 6
The ATM cell of one virtual channel among the plurality of virtual channels distributed and connected to the self-routing switch output information line 7 by the self-routing switch 1.
n. AT input from the self-routing switch output information line 7n to the line controller 2n
The M cell is distributed and connected to a plurality of virtual channels corresponding to a plurality of virtual channel identifiers in the line output information line 5n by the virtual channel identifier control unit 3n, and a plurality of virtual channels in the self-routing switch input information line 6n are connected. The channels can be distributed and connected.

As can be seen from the above description of the example of the information flow of the distribution connection in the embodiment of the present invention, in the virtual channel handler of the present invention, since the bidirectional distribution connection in the line control unit can be multistage, Arbitrary distribution connection is possible by avoiding the basic problem that the information transfer capability of the self-routing switch input information line described in the prior art is insufficient. To explain further about the bidirectional distribution connection in the line control unit, if there is a lot of one-way information distribution connection from the line corresponding unit to the line output information line, it will be connected to that line corresponding unit. It means that the line input information line and the self-routing switch input information line have low utilization efficiency, and the distribution connection to the side of the self-routing switch input information line is a connection that effectively uses the information line with low utilization efficiency. I understand.

Note that the line corresponding part of the virtual channel handler according to the present invention receives the self-routing switch output information line and the line input information line as input and outputs the line output information line and the self-routing switch input information line as output 2 × It can also be regarded as equivalent to a virtual channel handler capable of distributed connection of two outputs.

Further, since a dedicated line interface such as the system using the dedicated line interface described in the prior art is not required, it is difficult to predict the demand for distribution connection, and it is difficult to calculate the number of facilities of the dedicated line interface. There is no problem that
Increasing the scale of the self-routing switch does not cause a problem that the efficiency of use of the switch decreases.

Further, unlike the method using the self-routing switch capable of distributing and connecting information described in the prior art, a self-routing switch for general one-to-one connection can be used without using a special self-routing switch capable of distributing and connecting. Since a routing switch can be adopted, there is no problem that a special self-routing switch dedicated to distribution has to be adopted, and there is also a problem that when a non-standard ATM cell format with a large overhead is adopted, substantial information transfer capability is reduced. It has the advantage of not happening.

In the virtual channel handler of the present invention, since the distribution connection is realized by a multi-stage connection, there is a drawback that the delay time of information in the case of the distribution connection increases, but in general, the service for performing the distribution connection. Since, for example, as in a movie program, the call holding time is very long and the connection is mainly one-way connection, a slight increase in the delay time does not cause a significant deterioration in service quality.

The method of increasing the speed of the self-routing switch input / output information line as compared with the speed of the line input / output information line described in the prior art increases the degree of freedom of distribution connection in the present invention. Is also effective.

[0044]

As described above, in the virtual channel handler of the present invention, (1) distribution connection capable of flexibly responding to demand fluctuations related to distribution connection is possible.
(2) The distribution connection function can be realized by adopting a general one-to-one connection self-routing switch without adopting a special self-routing switch dedicated to distribution. There is an advantage that it does not cause a decrease in the information transfer ability, and in addition to the form of bidirectional communication between one terminal and another terminal,
It is possible to economically realize a virtual channel handler capable of flexibly providing a service of mainly one-way communication mode for distributing and connecting information from one information source to a plurality of terminals.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a virtual channel handler according to a conventional technique.

FIG. 3 is a diagram showing a configuration example of a virtual channel handler according to a conventional technique.

FIG. 4 is a diagram showing a configuration example of a virtual channel handler according to a conventional technique.

FIG. 5 is a diagram showing a configuration example of a virtual channel handler according to a conventional technique.

FIG. 6 is a diagram showing a configuration example of a line corresponding unit of a conventional technique.

FIG. 7 is a diagram showing a configuration example of a line interface in the embodiment of FIG.

[Explanation of symbols]

1, 2 self-routing switch 21, 22-2n line corresponding part 31, 32-3n, 81, 82-8n, 91, 92-9
n, 801, 901 Virtual channel identifier control unit 41, 42-4n Line input information line 51, 52-5n Line output information line 61, 62-6n, 601, 602, 603 Self-routing switch input information line 71, 72-7n , 701 Self-routing switch output information line 101, 102, 111 Information storage and output control function unit 103, 104, 112 Virtual channel identifier correspondence table 105 Call connection control function unit 106, 107 Information line 108 Control line

Claims (1)

[Claims] 1. A self-routing switch having a plurality of self-routing switch input information lines and a self-routing switch output information line for outputting an ATM cell to a target self-routing switch output information line, a line-input information line, and a line-output information. In a virtual channel handler including a plurality of line control units arranged between a line and the self-routing switch input / output information line for controlling a virtual channel identifier, the line control unit receives an ATM cell input from the line input information line. , Means for distributing and outputting to any number of virtual channels of the line output information line and the self-routing switch input information line corresponding to the virtual channel identifier, and the ATM input from the self-routing switch output information line
A virtual channel handler, comprising means for distributing a cell to an arbitrary number of virtual channels in a line output information line and a self-routing switch input information line in correspondence with a virtual channel identifier and outputting the cells.