JPH09186700A - Atm private branch exchange system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform ATM(asynchronous transfer mode) extension communication without performing a header conversion. SOLUTION: Unique VPI(virtual path identification data) and the VCI(virtual channel identification data) are preliminarily assigned to terminals 100 to 102. The terminal 100 sets the VPI and VCI assigned to a communicating party to the header of cells and turns on an EX(extension bit) in the case of an extension and sets the VPI and VCI assigned to a self-terminal to the header of the cells and turns off the EX in the case of a line wire. A switch part 106 receiving the cells from the terminal 100 via a line correspondence part 103 performs the routing to the route that the VPI and VCI show for the cells when the EX is turned on and transmits these cells to a header conversion part 107 without referring to the VPI and VCI when the EX is turned off. The header conversion part 107 converts the VPI and VCI of the header by referring to a table 108, makes the form of the header in conformity with the call setting procedure of an exchange for station and transmits the cells to a trunk line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM private branch exchange system which is composed of an ATM private branch exchange and a plurality of ATM terminals accommodated in the ATM private branch exchange, and which exchanges extension communication between the ATM terminals in an asynchronous transfer mode. .

[0002]

2. Description of the Related Art In recent years, a high-speed and flexible communication system compatible with multimedia has been desired, and an ATM (asynchronous transfer mode) communication system has attracted attention.

FIG. 2 shows an A comprising a conventional ATM private branch exchange and ATM terminal compatible with such an ATM communication system.
The structure of the TM private branch exchange system is shown in FIG.
The M private branch exchange 214 includes a plurality (three in the drawing) of line corresponding units 203 to 205, a plurality of (three in the drawing) header conversion units 206 to 208, and a plurality of (three in the drawing) tables 209 to 209. 211 and a switch unit 212, the line corresponding units 203 to 205 accommodate the terminals 200 to 202, respectively, and are connected from the switch unit 212 to the central office switch 213 via a central line.

The terminals 200 to 202 are devices capable of transmitting or receiving information such as voice and video, and more specifically, telephones, facsimile devices, workstations, personal computers, or ATM routers (relay devices).
It is a communication terminal compatible with ATM communication system such as
Each is connected to the line corresponding units 203 to 205 and transmits or receives ATM cells (hereinafter referred to as cells).

The line corresponding units 203 to 205 are provided for each terminal 20.
An interface for accommodating 0 to 202, which monitors the capacity of the cell input from each terminal and performs maintenance and operation. Each of the line corresponding units 203 to 205 can accommodate a plurality of terminals (one in the figure).

The header conversion units 206 to 208 have tables 209 to 211, respectively.
To 211, the line interface unit 20 is referred to.
3 to 205 or VPI (virtual path identifier) and VCI of the header part of the cell sent via the switch unit 212.
The value of (virtual channel identifier) is converted (assigned).

Tables 209 to 211 are storage devices that store information for header conversion, and are referred to by the header conversion units 209 to 211.

The switch section 212 includes a header conversion section 206.
˜208, receives the cell, decodes the header portion of the cell and decodes the route (each terminal 200 to 202 accommodated in the ATM private branch exchange 214 or the central office exchange 2 via the central office line).
The cell is output to 13).

The central office exchange 213 is an exchange compatible with the ATM system, and is used when communication is performed from the terminals 200 to 202 accommodated in the ATM private branch exchange 214 to the outside of the ATM private branch exchange 214 or outside the ATM private branch exchange 214. To terminals 20 to 20 accommodated in the ATM private branch exchange 214
2 is connected when communicating.

With such a configuration, the ATM private branch exchange 21
The operation when the first terminal 200 accommodated in No. 4 communicates with the second terminal 201 accommodated in the same ATM private branch exchange 214 will be described below.

First, the first terminal 200 is the second terminal 20.
Establishes a connection with 1. After the connection is established, the cell transmitted from the first terminal 200 passes through the first line interface 203 to the first header converter 2
06, the first header conversion unit 206 refers to the first table 209, and the VPI and VC of the header portion of the cell are sent.
I is converted.

After that, the cell sent from the first header conversion unit 206 to the switch unit 212 is routed by the header portion and sent to the second header conversion unit 207.

The second header conversion unit 207 refers to the second table 210 and refers to the VPI and V of the header portion of the cell.
The CI is converted, and the cell obtained by converting the VPI and the VCI is sent to the second terminal 201 via the second line interface 204.

FIG. 3 shows how the header conversion units 206 to 208 convert the headers. In FIG. 3, the physical lines and the VPs (virtual paths) are made to correspond one to one.

In FIG. 3, cells having header information of VPI = 2 and VCI = 1 are converted to VPI = 3 and VCI = 2 by header conversion units 206 to 208.

[0016]

However, in the conventional ATM private branch exchange system, since the VCI is uniquely assigned in the VPI, it is necessary to perform the header conversion even in the communication by the extension in the same ATM private branch exchange. However, there is a problem that the communication speed decreases due to the header conversion.

Further, since it is necessary to provide the same number of header conversion units as the line corresponding units, the hardware configuration becomes complicated and the manufacturing cost is high.

[0018]

The invention according to claim 1 is an AT
An ATM private branch exchange system configured by an M private branch exchange and a plurality of ATM terminals accommodated in the ATM private branch exchange to exchange extension communication between ATM terminals in an asynchronous transfer mode, comprising the following means. Characterize.

That is, the ATM private branch exchange is an ATM
An ATM switch unit that routes the ATM cell according to the virtual path identifier and the virtual channel identifier in the cell is provided, and the virtual path identifier and the virtual channel identifier are uniquely assigned in advance to each accommodating ATM terminal. , When performing extension communication, the virtual path identifier and virtual channel identifier assigned to the destination ATM terminal are set in the header of the ATM cell to be transmitted, and A
The TM switch unit routes the ATM cell by the virtual path identifier and virtual channel identifier set by the originating ATM terminal.

According to the invention of claim 1, the virtual path identifier and the virtual channel identifier are uniquely assigned in advance to each of the ATM terminals to be accommodated so that the header conversion is not required. The virtual path identifier and virtual channel identifier assigned to the destination ATM terminal are set in the header of the ATM cell to be transmitted during communication, and the ATM switch unit sets the source ATM terminal to the ATM cell. By the virtual path identifier and virtual channel identifier (assigned to the destination ATM terminal)
The ATM cell is routed to the route of the destination ATM terminal, that is, extension communication is not accompanied by header conversion.

In the invention of claim 1, the ATM private branch exchange receives the virtual path identifier and the virtual channel identifier set in the ATM cell received from the switch unit from the AT.
The AT received from the outside line after being converted into a virtual path identifier and a virtual channel identifier between the M private branch exchange and the outside line
A header conversion unit for converting the virtual path identifier and the virtual channel identifier set in the M cell into the virtual path identifier and the virtual channel identifier pre-assigned to the destination ATM terminal is further provided between the switch unit and the outside line, and the extension communication When performing the call, the originating ATM terminal sets the virtual path identifier and virtual channel identifier assigned to the destination ATM terminal in the header of the ATM cell to be transmitted, and an extension indicating that the extension is an extension. When the identifier is sent and transmitted to the outside line, the originating ATM terminal sets the virtual path identifier and the virtual channel identifier assigned to the own ATM terminal in the header of the ATM cell to be transmitted, and then the outside line The ATM switch section sends out an external line identifier indicating that the virtual line is set by the ATM terminal on the sending side when the extension line identifier is received. The ATM cell is routed by the identifier and the virtual channel identifier, the ATM cell is routed to the header conversion unit when the outside line identifier is received, and is set by the header conversion unit when the ATM cell is received from the header conversion unit. It is preferable to route the ATM cell by the virtual path identifier and the virtual channel identifier.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an ATM private branch exchange system according to the present invention will be described below in detail with reference to the drawings.

FIG. 4 shows the structure of a cell used for extension communication in the ATM private branch exchange system according to the present embodiment. It has a header (5 × 8 bits) and an information field (48 × 8 bits). And the header is G
FC (4 bits), VPI (8 bits), VCI (15
Bit), EX (1 bit), PT (3 bits), and CLP (1 bit) and HEC (8 bits).

GFC (Generic Flow Co)
(control, general flow control) is a field for performing flow control between the ATM terminal and the network. PT (Payload Type, Payload Type) is a field in which an information field of 48 × 8 bits indicates a user information cell, an OAM cell, or a resource cell. CLP (Cell Loss P
Priority, cell loss priority display) is a field indicating the priority of the cell, and indicates that CLP = 1 is easily discarded and CLP = 0 is difficult to be discarded. HEC
(Header Error Control, header error control) is a field for recording a cyclic redundancy code, and has a role of protecting information in other parts of the header. These fields are the same as before.

The fields of VPI and VCI are also the same as in the conventional case, but 16 bits of VCI are conventionally reserved, whereas only 15 bits are reserved in the present embodiment, and the remaining 1 Bits are assigned to EX fields described later.

EX (extension bit) is a field for identifying whether the call is an extension or an outside line,
Whether or not it is an extension is determined by the switch unit 106.

The information field is a user information cell, O
Although it can be used for various purposes such as an AM cell and a resource cell, in the case of a user information cell, information such as voice and video which is the object of communication is divided into 48 × 8 bits and set.

FIG. 1 shows the configuration of the ATM private branch exchange system of this embodiment. The ATM private branch exchange 110 includes a plurality of (three in the figure) line corresponding units 103 to 105, a switch unit 106, a header conversion unit 107, and a table 108.
The line corresponding units 103 to 105 accommodate the terminals 100 to 102, respectively, and the switch unit 106 to the header conversion unit 107 and the central office switch 109 via the central line.
It is connected to the.

The terminals 100 to 102 basically function in the same manner as the conventional one, but the method of setting the cell header is different from the conventional one. The terminals 100 to 102 set the VPI and VCI assigned to their own terminals in the ATM private branch exchange, and output the cells to the corresponding line corresponding units 103 to 105. At this time, the terminals 100 to 102 communicate with the terminals 100 to 102 in the same ATM private branch exchange (extension).
In case of, EX is turned on, and in other cases, EX is set to off.

The line corresponding units 103 to 105 function in the same manner as the conventional ones, but unlike the conventional ones, they are directly connected to the switch unit 106.

The header converting section 107 basically functions in the same manner as the conventional one, but the position and the number in the ATM private branch exchange are different from the conventional ones, and the switch section 106 and the central office exchange 109 are different.
In the conventional ATM private branch exchange, only one is provided between the switch section 106 and the switch section 106. It is for converting the VPI and VCI values of the header part of the cell sent from the central office switch 109. That is, the header conversion unit 107 converts the VPI, VCI assigned in the ATM private branch exchange to the VPI, VCI assigned between the ATM private branch exchange and the central office switch, or between the ATM private branch exchange and the central office switch. The assigned VPI and VCI are converted into the assigned VPI and VCI in the ATM private branch exchange. AT
VPI assigned between the M private branch exchange and the central office exchange,
VCI is the VPI assigned in the ATM private branch exchange,
When converting to VCI, the switch unit 106 simultaneously turns on EX (extension bit).

The table 107 is a storage device that stores information for header conversion, and functions in the same manner as the conventional one, but the position and the number in the ATM private branch exchange are different from the conventional one, and the switch unit 106 and the local station are different from each other. It is referred to by the header conversion unit 107 located between the private branch exchange 109 and the conventional private branch exchange 109, and three are conventionally provided.
Only one is provided.

The switch section 106 includes the line corresponding section 103 ...
When the cell is received from 105, the header portion of the cell is decoded, and when EX is turned on, it is determined that the cell is an extension in the ATM private branch exchange, and the cell corresponding to the corresponding cell corresponding to the cell 103-1.
Output to 05. When EX is off, the switch unit 106 determines that the line is an outside line and outputs the cell to the header conversion unit 107. Further, in the case of an incoming call from an outside line, the switch unit 106 causes the corresponding line corresponding unit 103 to
Output to 105.

It should be noted that in the present embodiment, in order to perform exchange without performing header conversion during extension communication, A
Terminals 100 to 102 accommodated in the TM private branch exchange 110
Unique VPI and VCI are assigned to each. The number of terminals accommodated in the ATM private branch exchange is usually several thousand to tens of thousands, and 23 bits are reserved for VPI + VCI in the present embodiment. Therefore, a unique VPI + VCI should be allocated to the terminal accommodated in the ATM private branch exchange. Is possible.

The operation of the ATM private branch exchange system in this embodiment will be described below.

First, the operation when the first terminal 100 communicates with the second terminal 101 will be described.

The first terminal 100 establishes a connection with the second terminal 101. After the connection is established, the first terminal 100 sets the header part of the cell, and further sets information for communication such as voice and video in the information field, and sets the first line interface unit. The cell is transmitted to 103. At this time, VPI, V in the header of the cell
For the CI, the VPI and VCI assigned to the terminal (second terminal 101) of the other party trying to communicate are set,
EX (extension bit) is turned on to indicate the extension communication.

Upon receiving the cell sent from the first terminal 100, the first line interface 103 performs processing such as cell flow monitoring and maintenance, and sends the cell to the switch 106.

The switch unit 106 is the first line interface unit 1.
03 decodes the cell header sent from
Since X is on, VP and VC indicated by VPI and VCI
The cell is routed to and the cell is sent to the second line interface 104.

The second line interface 104, which has received the cell (downlink cell) sent from the switch 106,
Performs processing such as cell flow rate monitoring and maintenance to make the cell the second
Then, the second terminal 101 extracts the information field from the cell and performs the desired processing.

As described above, in the case of communication between extensions, the communication can be performed without converting the header.

Next, the first terminal 100 switches the central office switch 1
The operation when communicating with another terminal outside the ATM private branch exchange 110 via 09 will be described.

The first terminal 100 has a central office switch 109.
To establish a connection with another terminal outside the ATM private branch exchange 110. After the connection is established, the first terminal 100 sets the header part of the cell, and further sets information for communication such as voice and video in the information field, and sets the first line interface unit. The cell is transmitted to 103. At this time, VPI and VC in the header of the cell
For I, V assigned to the self terminal (first terminal 100)
PI and VCI are set, and EX (extension bit) is turned off to indicate external line communication.

Upon receiving the cell sent from the first terminal 100, the first line interface 103 performs processing such as cell flow monitoring and maintenance, and sends the cell to the switch 106.

The switch unit 106 is the first line interface unit 1.
03 decodes the cell header sent from
Since X is off, the cell is sent to the header conversion unit 107 without referring to VPI and VCI.

The header conversion unit 107 is a VPI, VCI of the header portion of the cell (those assigned to the first terminal).
ATM private branch exchange 11 stored in table 108
0 to VPI and VCI between the central office switch 109, the format of the cell header conforms to the call setting procedure of the central office switch (EX is not set), and the cell is connected via the central office line. To the central office switch 109.

As described above, in the case of the call to the outside line, the call to the outside line is made by converting the header structure according to the call setting procedure of the central office switch 109 immediately before sending the cell from the ATM private branch exchange 110. Will also be possible.

Finally, the ATM private branch exchange 11 (not shown)
0 from other terminals to the first in the ATM private branch exchange 110
The operation when performing communication with the terminal 100 will be described.

In the case of an incoming call from the outside line to the first terminal 100, a connection is first established, and then the cells sent from another terminal outside the ATM private branch exchange 110 are transferred to the central office switch 109 and the central line. ATM private branch exchange 11
The header conversion unit 107 in 0 receives it, and the header conversion unit 1
07 is VPI, VCI of the header portion of the cell (VPI, VC between the ATM private branch exchange 110 and the central office exchange 109).
I) is converted into VPI and VCI assigned to the first terminal based on the information stored in the table 108, and at the same time, EX (extension bit) is turned on, and the cell concerned is switched to the switch unit 106. Send out.

The switch section 106 is a header conversion section 106.
The header part of the cell sent from is decoded, and since EX is on, the cell is routed to VP and VC indicated by VPI and VCI, and the cell is sent to the first line interface 103. .

Upon receiving the cell sent from the switch unit 106, the first line interface unit 103 performs processing such as cell flow monitoring and maintenance, sends the cell to the first terminal 101, and The terminal 101 of No. 1 extracts the information field from the cell and performs desired processing.

As described above, in the case of the call to the outside line, the cell from the office line is transferred to the ATM private branch exchange 1 by the header conversion unit 107.
An incoming call from an outside line can be accepted by converting the header structure in 10.

As described above, according to the above embodiment,
Uniquely assigning VPI + VCI to each terminal beforehand, and performing extension communication, the VPI and VCI assigned to the receiving terminal in the header of the cell to which the transmitting terminal transmits
Is set to ON, the EX (extension bit) is turned on, and when EX is turned on, the switch terminal sets the cell to the destination terminal by the VPI and VCI set in the cell by the calling terminal. Since I tried to route it, the same A
Communication between terminals accommodated in the TM private branch exchange (extension communication)
Since it is not necessary to perform the header conversion when performing the above, the structure of the ATM private branch exchange system can be simplified.

Further, when a call is made to an outside line, the calling terminal sets the VPI and VCI assigned to the own terminal, and turns off EX, and the switch section switches the cell concerned when EX is off. The header is sent to the header conversion unit, and the header conversion unit refers to the table and sends the header of the cell to the AT.
VPI assigned between M private branch exchange and central office exchange
Since it is converted to VCI, it is possible to communicate with the central office switch having a different header configuration.

The present invention is not limited to the above-mentioned embodiment, but allows various modifications.

In the above embodiment, one bit of the field normally used as VCI is used as EX (extension bit), but one of the fields used as other fields or information field in the header is used.
The part may be used as EX. Note that EX does not have to be 1 bit, and may have any length.

Further, in the above embodiment, the central office switch is connected to the central office switch, but the present invention is also applicable to the case where the private line is used to connect to another ATM private branch exchange. .

Further, in the above embodiment, the terminal and V
PI + VCI was made to correspond one to one, but VPI, V
A few bits in the CI field may be excluded from the routing of the switch unit 106, and a plurality of channels may be assigned to one terminal.

In the above embodiment, only the connection type communication is explained, but the ATM private branch exchange system of the present invention can be applied to the connectionless type communication.

[0060]

As described above, according to the present invention, it is possible to uniquely assign a virtual path identifier and a virtual channel identifier in advance to each ATM terminal to be accommodated without performing header conversion. The ATM terminal sets the virtual path identifier and the virtual channel identifier assigned to the destination ATM terminal in the header of the ATM cell to be transmitted when performing the extension communication, and the ATM switch unit causes the source ATM terminal to transmit. Uses the virtual path identifier and the virtual channel identifier set in the ATM cell to route the ATM cell to the route of the destination ATM terminal. Therefore, the terminals accommodated in the same ATM private branch exchange can communicate with each other. Since it is not necessary to perform the header conversion when performing the conversion, the structure of the ATM private branch exchange system can be simplified, and the communication speed due to the header conversion is low. It is possible to suppress.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ATM private branch exchange system according to an embodiment.

FIG. 2 is a block diagram showing a configuration of a conventional ATM private branch exchange system.

FIG. 3 is a conceptual diagram showing the principle of header conversion in a conventional ATM private branch exchange system.

FIG. 4 is a block diagram showing a configuration of a cell used as an extension in the ATM private branch exchange system according to the embodiment.

[Explanation of symbols]

 100-102 Terminals 103-105 Line-corresponding section 106 Switch section 107 Header conversion section 108 Table 109 Office switch 110 ATM private branch exchange

Claims (3)

[Claims] 1. An ATM private branch exchange and a plurality of ATM terminals accommodated in the ATM private branch exchange,
ATM for exchanging extension communication between terminals in asynchronous transfer mode
A private branch exchange system, wherein the ATM private branch exchange includes an ATM switch unit for routing the ATM cell according to a virtual path identifier and a virtual channel identifier in the ATM cell, and each ATM terminal to be housed has a virtual path identifier and a virtual channel in advance. Uniquely assigning an identifier, the originating ATM terminal sets the virtual path identifier and virtual channel identifier assigned to the destination ATM terminal in the header of the ATM cell to be transmitted when performing extension communication. The ATM switch unit uses the virtual path identifier and the virtual channel identifier set by the originating ATM terminal for the AT.
ATM private branch exchange system characterized by routing M cells. 2. The ATM private branch exchange converts a virtual path identifier and a virtual channel identifier set in an ATM cell received from the switch section into a virtual path identifier and a virtual channel identifier between the ATM private branch exchange and an external line. In addition, the virtual path identifier and virtual channel identifier set in the ATM cell received from the outside line are used as the destination ATM.
An ATM cell to be transmitted by the originating ATM terminal during extension communication is further provided between the switch section and the outside line, further comprising a header conversion unit for converting into a virtual path identifier and a virtual channel identifier previously assigned to the terminal. The virtual path identifier and virtual channel identifier assigned to the destination ATM terminal are set in the header of
Furthermore, when transmitting an extension identifier indicating that it is an extension and transmitting it to an outside line, the originating ATM terminal uses the virtual path identifier and virtual channel identifier assigned to its own ATM terminal in the header of the ATM cell to be transmitted. And further sends an outside line identifier indicating that the line is an outside line, and the ATM switch section uses the virtual path identifier and the virtual channel identifier set by the calling ATM terminal when the extension line identifier is received. When the ATM cell is routed and the outside line identifier is received, the ATM cell is routed to the header conversion unit, and when the ATM cell is received from the header conversion unit, the virtual path identifier set by the header conversion unit is used. The ATM cell is routed by a virtual channel identifier. ATM private branch exchange system as claimed. 3. The ATM switch unit accommodates an ATM to be accommodated by not referencing a part of the virtual path identifier and / or the virtual channel identifier when routing the ATM cell by the virtual path identifier and the virtual channel identifier. The ATM private branch exchange system according to claim 1 or 2, wherein a plurality of channels are provided to any of the terminals.