JPH06276219A - I interface device - Google Patents

Abstract

PURPOSE:To attain an asynchronous transfer mode(ATM) of a subscriber exchange main body by performing the asynchronous transfer mode adaptation layer (AAL) processing for an ISDN subscriber through a subscriber exchange and in response to a subscriber circuit. CONSTITUTION:An LAPB circuit 6 and an LAPD circuit 8 are provided as the access means for a B and/or D channels, an AAL type-1 processing circuit 5 for the B channel which assemble the B and/or D channel signals into an ATM cell and also disassemble the ATM cell into the B and or D channel signals, an AAL processing circuit 7 for B channel packet, and a processing circuit 10 for the D channel. Meanwhile an ATM layer processing interface circuit 11 transmits and receives the cells to and from an ATM exchange. Then a subscriber exchange carries out the AAL processing in response to each subscriber circuit. Thus it is possible to turn the subscriber exchange main body into an ATM and to construct an ATM integrating network with no change of an ISDN terminal.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used in digital communications. The present invention is used for ATM (asynchronous transfer mode) communication. The present invention was developed to extend the subscriber terminals of ATM communication to subscribers using ISDN.

[0002]

2. Description of the Related Art Asynchronous transfer mode (hereinafter referred to as ATM) is a method for transmitting and exchanging all information in units of packets called cells, and is effective for communication in which various speeds or variable speeds and various media are mixed. B-ISDN (Broadband) is a method that can be realized at high speed.
ISDN: It is a basic technology for building a broadband ISDN.

In constructing such an ATM B-ISDN, an existing STM (Synchronous Transfer) is used.
Mode: Synchronous transfer mode) Interconnection with network or STM
It is necessary to have a function of directly connecting an existing terminal of the system or an existing subscriber line to the ATM network.

In particular, it is an indispensable function in the process of efficiently and optimally winding an existing network into an ATM integrated network. Possible methods of converting the existing network to ATM include connecting the STM network and the ATM network by an inter-network adapter, adding a cell assembling / disassembling function to the relay output line of the STM switch, and the multiple output line of the subscriber switch. Alternatively, a cell conversion function is provided for the subscriber line, and the AT is sent from the subscriber line.
It is possible to classify into a rough method such as M conversion, installing an ATM adapter on the terminal side and accommodating an existing terminal directly into an ATM network, but none has been realized so far.

[0005]

In any case, the STM
In order to accommodate the line in the ATM network, a function of assembling or disassembling into ATM cells, that is, an ATM adaptation layer (hereinafter referred to as AAL) process is required.

The existing network and AT are connected by the above-mentioned inter-network adapter.
In the method such as connecting to the M network and adding a cell assembling / disassembling function to the relay output line of the STM switch, the STM line is accommodated by the conventional STM switch, and the AAL function is provided at the entrance / exit to the multiple trunk line. Therefore, this method is relatively easy to introduce, but even if ATM is advanced, the STM switch will eventually remain and it cannot be said to be an ATM integrated network. Further, in this method, local calls are not made into ATM, so that the advantages of making ATM into local calls cannot be utilized.

From another point of view, normally, in order to construct an ATM network, an optical fiber subscriber line is supplied to an ATM subscriber equipped with an ATM terminal, assuming a large capacity digital communication. Done. However, not only large-capacity subscribers but also small-capacity subscribers or those with low communication frequency exist as subscribers who can be ATM subscribers. It would not be appropriate in terms of cost and time to supply optical fiber subscriber lines to these small subscribers each time. At present, a subscriber having an ISDN terminal cannot connect to an ATM network with the equipment as it is.

The present invention has been made against such a background, and makes it possible to convert the main body of the subscriber exchange into ATM by performing AAL processing for the ISDN subscriber in the subscriber exchange corresponding to the subscriber line. An object is to provide an I interface device.

[0009]

The first aspect of the present invention is to:
I equipped with an intra-station line termination circuit to which an ISDN terminal is connected
It is an interface device.

Here, the feature of the present invention is that B
A link access means for the channel and / or the D channel, and a B channel signal and / or a D channel signal
Means for assembling into TM cells or disassembling ATM cells into B channel signals and / or D channel signals;
The M switch has means for transmitting and receiving cells.

A second aspect of the present invention is an ATM exchange equipped with the I interface device.

[0012]

The basic idea of the present invention is an I interface (an interface connecting an ISDN user and a network).
Currently, an intra-station line terminating device is installed for each line, and an AAL function is added to the function of the intra-station line terminating device.

Considering the I interface of the basic group, B
Two channels (64Kb / s) and D channel (16K
b / s) and one are multiplexed and separated into channels by the intra-station line termination circuit. D channel data includes signals for call control and D channel packets, and LAPD
(Link Access Procedure on the D-channel) Terminates the processing and sets the appropriate layer 2
AAL processing including processing is performed. 64 kb for B channel
/ S 2 lines or 128 kb / s AAL type 1
Cell processing and LAPB (Lin
k Access Procedure-Balanced: AAL processing including termination of balanced link access procedure and appropriate layer 2 processing is performed. For example, the call setup signal of the D channel is made into a cell and AT
It is sent to the main body of the M switch and the call processing is performed. An ATM layer header or the like is set by the call processing and a call is placed. After that, the B channel data is appropriately made into cells according to the call setting information, and the call state is realized.

Alternatively, all the information is cellized as a fixed bit string with type 1 (a signal structure consisting of a 47-octet information area following an 8-bit header information area). Type 1 is the easiest to implement in AAL processing. In addition, in type 1, layer 2 such as LAPD and LAPB
Since it does not require the processing and complicated control, it can be realized relatively easily. Also, the interface can be unified with ATM cells. By providing such an AAL means in each I interface, it is possible to make an ATM corresponding to the subscriber line. Considering the I interface of the basic group, two B channels (64 Kb / s) and D channels (16 Kb / s)
/ S) and one are multiplexed and separated into channels by the intra-station line termination circuit. The D channel data includes signals such as call control and D channel packets, but the identification and the cell formation in LAPD frame units are not performed.
Assemble a fixed speed train of kb / s into cells by AAL type 1. The B channel information may also be circuit-switched data and packets, both of which are similarly cellized as a fixed rate sequence type 1. The B channel and the D channel cells are identified by setting a virtual channel, for example, and all the cells are interfaced with the ATM switch body.
A subscriber line signaling device for processing D channel signals is provided in the main body of the ATM switch, and layer 1 processing by AAL type 1 and layer 2 processing by LAPD are performed, and layer 2 processing is performed.
It also sorts signals or packets. If it is a signal, it interfaces with the control device, and if it is a packet, it interfaces with the frame multiplex processing circuit. As for the routing between the subscriber circuit and the subscriber line signaling device, for example, one method is considered in which a fixed connection is established for each subscriber circuit. By doing so, the signal of each subscriber line can always be monitored by the exchange main body. By executing the signal processing, a call is set up, that is, a virtual channel of the B channel is set up and a call is made.

As a result, it is possible to realize an efficient and economical means for accommodating the ISDN terminal in the ATM switch with the same interface as the conventional one.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of a first embodiment device of the present invention.

The present invention is an I interface device 13 having an intra-station line terminating unit 2 to which an ISDN terminal is connected.

Here, the feature of the present invention is that D
LAPD circuit 8 as link access means for channel
And assemble D channel signal into ATM cell or AT
An AAL processing circuit 10 for the D channel as a means for disassembling the M cells into a D channel signal, a LAPB circuit 6 for a packet as a link access means for the B channel, and a B channel signal assembled into an ATM cell or an ATM cell. A for B channel as a means to decompose the
AL type 1 processing circuit 5 and A for B channel packet
It is provided with an AL processing circuit 7 and an ATM layer processing interface circuit 11 as means for transmitting / receiving cells to / from an ATM exchange.

Next, the operation of the first embodiment of the present invention will be described. The intra-station line terminating unit 2 terminates the line according to the transmission method of the I interface. As a transmission method, there are a ping-pong transmission method and an echo canceller method, and processing according to each is performed. The terminated signal is separated into two B channels (64 kb / s or 128 kb / s) and one D channel. Conversely, the B channel and D channel data can be sent to the I interface line according to the above method.

The B channel internal line 3 is an A for B channel.
It is connected to the AL type 1 processing circuit 5 and performs cellization processing for two lines of 64 kb / s fixed speed data or one line of 128 kb / s. LAPB for B channel packets
Circuit 6 and AAL processing circuit 7 for B channel packet
In the case of a B channel packet, the LAPB circuit 6 terminates the layer 2, and the AAL processing circuit 7 for B channel packet performs appropriate AAL processing on the frame data in frame units. The D channel AAL processing circuit 10 is
It complies with the AAL specifications for signals and includes layer 2 equivalent functions. Therefore, the LAPD circuit 8, the control circuit 9, and the D-channel AAL processing circuit 10 convert the D-channel signal into layers 1 and 2 to form cells.
The ATM layer processing interface circuit 11 sends a cell with the set cell header added and cell multiplexing to the main body of the ATM switch 16 and, on the contrary, receives the cell and
B channel AAL type 1 processing circuit 5 or B channel packet AAL processing circuit 7 according to the TM header
Sort into.

Next, the ATM switch 16 to which the I interface ATM subscriber circuit 13 of the first embodiment of the present invention is applied will be described with reference to FIG. FIG. 2 shows an ATM switch 1.
It is a figure which shows the 1st Example apparatus of this invention mounted in 6.
All the input / output information of the circuit of the I-interface ATM subscriber circuit 13 is connected to the ATM switch 14 by ATM cells and appropriately routed by the ATM switch 14. For example, the D channel information from the I interface subscriber line 1 is made into cells and switched to the subscriber line signaling device 19 by the ATM switch 14. AAL processing including layer 2 is performed in the subscriber line signaling device 19, the original D channel information sequence is sent to the control device 15, and the control device 15 processes according to the contents. Further, in response to a request, a signal message to another relay node is sent from the control device 15, the message processing device 17 performs AAL processing, and the ATM switch 14 passes through the ATM switch 14.
6 is output to the relay line 30. I of the first embodiment of the present invention
If the interface device 13 is used, no special function is required for the ATM switch 16.

Next, the flow of processing will be described. First, a D channel signal such as a call is received by the intra-office line terminating unit 2 via the I interface subscriber line 1. The LAPD circuit 8 terminates the layer 2 between the terminals. Under the control of the control circuit 9, the received signal information is processed by the D-channel AAL processing circuit 10
HDLC (High-level Data Link Control) framing (Convergence Sublayer) and segmentation into cells (Segmentation and Reassembly Sublayer)
And the ATM layer processing interface circuit 11
A TM header is added and sent to the main body of the ATM exchange 16. The virtual channel setting procedure at this time is as follows: fixed connection between each line and the main body of the ATM switch 16 (PVC: P
An ermanent virtual circuit) method can be considered.
In accordance with this, the calling signal and the dial information are transmitted and received between the I interface subscriber line 1 and the main body of the ATM switch 16 to set the call. A virtual channel (VC: Virtual Channel) of the U plane (collection surface of User functions) is supplied from the subscriber line signaling device 19 to the I interface device 13 in the form of a cell.
And the information is received by the control circuit 9 to the ATM.
Header is set. After that, 64 kb / s fixed speed (C
BR: Constant Bit Rate) In the case of column communication, the AAL type 1 processing circuit 5 for the B channel converts the cells into cells with the AAL type 1, and the call is performed.

Next, the overall construction of the first embodiment of the present invention is shown in FIG.
Will be described with reference to. FIG. 3 is an overall configuration diagram of the first embodiment of the present invention. The ISDN network 22 and the ATM network 24 are in the office 2
It is connected at 6. Such ISDN network 22 and ATM
The connection with the network 24 is realized by the I interface device 13 and the ATM switch 16 which accommodates the I interface device 13.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram of the apparatus of the second embodiment of the present invention. The second embodiment of the present invention is characterized in that the I interface device 13 performs only AAL type 1 processing. Subscriber line signaling device 1 of ATM switch 16
9, AAL type 1 processing circuit 20, AAL type 3 ~
5 processing circuit 21 and LAPD circuit 22 are included.

Next, the processing flow of the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram showing a second embodiment device of the present invention mounted on an ATM exchange. First ISDN
When a call is made from the subscriber, D that contains the information
Channel signal is only 16k in AAL type 1 processing circuit 5
The data is formed into cells as a b / s fixed speed data string and is routed to the subscriber line signaling device 19 'of the ATM switch 16. This is the I interface subscriber line 1 and ATM
A fixed connection is provided between the exchange 16 and the fixed channel connection for all D channel information. The D channel signal is decellized by the AAL type 1 processing circuit 20 and the LAPD circuit 22 terminates the layer 2. Here, it is discriminated whether it is a signal or a packet, and if it is a signal, the information is transferred to the control device 15, and the call processing is performed there. In response to the request, the signal of the other node is converted into cells by AAL type 3 or 4 or type 5 by the message processing device 17 and transmitted. U of this subscriber line due to call processing
A plane virtual channel is provided and a call is established.
For example, in the case of 64 kb / s call communication, the B channel signal of the B channel internal circuit 3 is made into cells by the AAL type 1 processing circuit 25, and the ATM header set by the ATM layer processing interface circuit 11 is added and sent to the ATM switch 16. To do. The ATM switch 14 routes appropriately according to the header. If it is a D-channel packet, it is first connected to the subscriber line signaling device 19 'in the same manner as the D-channel signal, and then there is type 1 decellization, LA.
PD is terminated and appropriate AAL processing (including layer 2 equivalent functions in AAL3 to 5) is performed as a packet.
The cell is transmitted on the virtual channel set by the call processing. Further, the B-channel packet frame multiplexing circuit 18 can also multiplex and transmit the B-channel packet in response to a request.

As described above, in the second embodiment of the present invention, the hardware configuration can be simplified because all of the cells are AAL type 1 cells. Further, since various signal processing circuits are not provided for each I interface device 13, the amount of hardware and equipment cost can be reduced.

In the first and second embodiments of the present invention, two B-channel lines and a D-channel are described as being coupled to an ATM network. However, one or two B-channel lines or D-channels are used.
It is also possible to adopt a configuration in which only the channel is connected to the ATM network.

[0028]

As described above, according to the present invention, the subscriber exchange main body can be made into ATM by performing ALL processing for each subscriber line in the subscriber exchange. An ATM integrated network can be constructed without changing the ISDN terminal. AT for small subscribers without preparing an ATM terminal
Can be economically incorporated into the M network.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a first embodiment device of the present invention mounted on an ATM exchange.

FIG. 3 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 4 is a block configuration diagram of a second embodiment device of the present invention.

FIG. 5 is a diagram showing a second embodiment device of the present invention mounted on an ATM exchange.

[Explanation of symbols]

 1 I Interface Subscriber Line 2 Intra-Station Line Termination 3 B Channel Internal Line 4 D Channel Internal Line 5 B Channel AAL Type 1 Processing Circuit 6 LAPB Circuit 7 B Channel Packet AAL Processing Circuit 8, 22 LAPD Circuit 9 Control Circuit 10 D Channel AAL processing circuit 11 ATM layer processing interface circuit 12 Intra-station wiring 13 I interface device 14 ATM switch 15 Control device 16 ATM switch 17 Message processing device 18 B channel packet frame multiplexing circuit 19, 19 'Subscriber line signaling device 20, 25 AAL type 1 processing circuit 21 AAL type 3 to 5 processing circuit 22 ISDN network 24 ATM network 26 In-station 30 Relay line

Claims (2)

[Claims] 1. In an I interface device having an intra-station line terminating circuit to which an ISDN terminal is connected, link access means for B channel and / or D channel, and B channel signal and / or D channel signal are assembled into an ATM cell. Alternatively, the I interface device is provided with means for decomposing an ATM cell into a B channel signal and / or a D channel signal, and means for transmitting / receiving the cell to / from an ATM exchange. 2. An ATM exchange equipped with the I interface device according to claim 1.