KR19990059285A - Subscriber terminal access device in ATM network - Google Patents

Abstract

The present invention relates to a subscriber station access device, and more particularly, to a subscriber station access device in an ATM network configured to identify data of a corresponding subscriber station by pre-allocating a virtual path identifier value of an ATM cell delivered to one subscriber station.

Conventionally, a complicated procedure for establishing and releasing a connection of an ATM network in a tap, which is a subscriber terminal access device, has to be processed. Although it should be confirmed, according to the present invention, a VPI value unique to the subscriber station is assigned to a register and the VPI value of the ATM cell stored in the buffer from the corresponding line receiving interface in the comparator by the cell start signal applied from the line receiving interface. By comparing the unique VPI value, the corresponding ATM cell is transmitted to the next subscriber station access device through the line transmission interface or transmitted to the corresponding subscriber station, so that the subscriber station is connected to the ATM network without having to maintain all the connection information in a simple configuration. It is suitable for ATM network of bus structure.

Description

Subscriber terminal access device in ATM network

The present invention relates to a subscriber station access device, and more particularly, to a subscriber station access device in an ATM network configured to identify data of a corresponding subscriber station by pre-allocating a virtual path identifier value of an ATM cell delivered to one subscriber station.

Since the subscriber link speed of a typical ATM network is based on 155 (Mbit) per second, that is, 10 ⁶ (bit) per second, at least one terminal is generally connected at the end of the ATM network. Although the bus structure of the connected method is relatively simple, the connection device to which the terminal is connected has a complicated configuration.

As shown in FIG. 1, a configuration of a general bus structure between an ATM network and a point shift device is provided when an ATM switch 11 and a subscriber station 12-1 to 12 -N in an ATM network are connected to a bus. Taps 13-1 to 13-N are formed between the bus and the subscriber stations 12-1 to 12-N, respectively.

Since the bus is a transmission medium shared by several subscriber stations 12-1 to 12-N, the ATM switch 11 transmits data, that is, an ATM cell, to one of the plurality of subscriber stations 12-1 to 12-N. In this case, a method called 'broadcasting' is used, and the corresponding ATM cell is received from a plurality of taps 13-1 to 13-N connecting the plurality of subscriber stations 12-1 to 12-N to the corresponding bus. It determines whether it is an ATM cell transmitted to itself, and processes only if it is an ATM cell delivered to the corresponding person.

Since the ATM uses optical fiber for high-speed data transmission, the plurality of taps 13-1 to 13-N convert the optical signal into an electrical signal and a virtual path identifier (eg, VPI) of the converted ATM cell. And VCI) to be applied to the corresponding subscriber station 12-1 to 12-N only in the case of the ATM cell corresponding to itself, and otherwise connected to the next subscriber station 12-1 to 12-N. Switch to the tap (13-1 ~ 13-N).

Therefore, the plurality of tabs 13-1 to 13-N had to have information related to the ATM connection and had to retrieve information related to the ATM connection each time the corresponding ATM cell was delivered.

Then, referring to the configuration of the conventional subscriber station access device, as shown in Figure 2, the line receiving interface 14 for converting the ATM cell applied from the ATM switch or the previous tap into an electrical signal, and the corresponding line A connection table 16 having a buffer 15 for storing the ATM cell converted in the reception interface 14 and connection information for determining whether the ATM cell stored in the buffer 15 will be delivered to its subscriber station. And a switch 17 for switching the corresponding ATM cell to the corresponding subscriber station according to the selection information of the connection table 16, and converting the ATM cell applied through the switch 17 into an optical signal to the next tap. And a line transmission interface 18 to be applied.

Referring to the operation of the subscriber station access device configured as described above, first, the line receiving interface 14 receives an ATM cell from an ATM switch or a previous tap, and since the authorized ATM cell is an optical signal, The signal is converted into an electrical signal and applied to the buffer 15.

Accordingly, the buffer 15 stores the ATM cell converted into an electrical signal applied from the corresponding line receiving interface 14 and stored in the buffer 15 for identification of the cell in the connection table 16. It checks whether it is its own cell by checking the VPI and VCI fields in the header of the ATM cell converted into the electrical signal.

If it is its own cell, the connection table 16 connects the switch 17 to its own subscriber station and transmits the corresponding ATM cell. If the cell is not its own cell, the connection table 16 is the switch. (17) is connected to the line transmission interface 18 to apply the ATM cell.

Accordingly, the line transmission interface 18 converts an ATM cell applied through the switch 17 into an optical signal and transmits it to the next tap.

As such, when the corresponding connection table 16 is used to determine whether the corresponding ATM cell is to be delivered to its subscriber station or not, the corresponding tab must manage all connection information.

I.e. fields other words, identifying a cell from the ATM cell, so each 8 (bit) and 16 (bit) at the interface between the user to the VPI and VCI terminal and the ATM network, the number of connections in all cases, `2 ⁸ × 2 ¹⁶ That's about 1678 million.

Since the connection setting for data communication must be reflected in the connection table of the tab, the configuration of the tab, which is a subscriber access device, becomes complicated, that is, the subscriber access to the complicated procedure for establishing and releasing the connection of the ATM network. The role of the device, the tab, is required. The VPI and VCI values of the established or released connection must be registered and released in the connection table.

The signaling function of such a tap has a problem in that its configuration becomes complicated because the tap must serve as an element of an ATM network beyond a simple access device.

As described above, in the related art, a complicated procedure for establishing and releasing a connection of an ATM network is required in a tap, which is a subscriber station access device, and the VPI and VCI values of the established or released connection are registered and released in the connection table. There is a problem in that the configuration of the tab is complicated because it must be confirmed that the ATM cell.

In order to solve the problems as described above, the present invention by assigning the virtual path identifier value of the ATM cell delivered to one subscriber station in advance to identify the data of the subscriber station, the subscriber station to the ATM network with a simple configuration It is intended to be suitable for ATM networks of bus structures by connecting them.

1 is a block diagram showing a configuration between a conventional ATM network and a point speed device.

Figure 2 is a block diagram showing a subscriber station access device in a conventional ATM network.

3 is a block diagram illustrating a subscriber station access device in an ATM network according to an embodiment of the present invention.

FIG. 4 is a circuit diagram of FIG. 3 in a specific hardware configuration. FIG.

Explanation of symbols on the main parts of the drawings

21: line receiving interface 22: buffer

23: register 24: comparator

25 switch 26 line transmission interface

XOR: Exclusive OAGATE NAND: NANDGATE

In order to achieve the above object, the present invention provides a buffer for receiving and storing a converted ATM cell, a line transmission interface for reconverting the converted ATM cell into an optical signal, and transmitting the converted ATM cell to a next subscriber station access device, and a selection control signal. In a subscriber station access device in an ATM network having a switch for switching a converted ATM cell applied from a corresponding buffer to its own subscriber station or a corresponding line transmission interface, an ATM applied from an ATM switch or a previous subscriber station access device A line receiving interface for converting a cell into an electrical signal to apply the converted ATM cell to the buffer and to generate a cell start signal; A register for storing a unique VPI value; And a comparator configured to receive the cell start signal from the line interface and compare the VPI value of the converted ATM cell stored in the buffer with the unique VPI value stored in the register to generate the selection control signal.

The present invention simplifies the structure of a subscriber network access device having a bus structure by allocating and fixing a VPI field value having a length of 8 (bit) in an ATM cell transmitted to one subscriber station, with reference to the accompanying drawings as follows. Explain.

3 is a block diagram illustrating a subscriber station access device in an ATM network according to an embodiment of the present invention, and FIG. 4 is a circuit diagram showing FIG. 3 in a specific hardware configuration.

In the ATM network according to an embodiment of the present invention, as shown in FIG. 3, a subscriber station access device stores a VPI value of 8 (bit) length of an ATM cell transmitted to a connected subscriber station without maintaining all connection information. When it is matched with the VPI value of the input ATM cell, it is switched to the connected subscriber station when it is matched and transferred to the next subscriber station access device in another case. The line receiving interface 21 and the buffer 22 And a register 23, a comparator 24, a switch 25, and a line transmission interface 26.

The line receiving interface 21 converts an ATM cell applied from an ATM exchanger or a previous subscriber station access device into an electrical signal and applies the converted ATM cell to the buffer 22, and at the same time, A cell start signal SOC indicating a bit start is generated and the generated cell start signal SOC is applied to the comparator 24.

The buffer 22 stores a converted ATM cell applied from the line receiving interface 21 and outputs the converted ATM cell to the switch 25.

The register 23 sets in advance the VPI value of the ATM cell to be delivered to the subscriber station connected to the subscriber station access device and stores the set unique VPI value.

The comparator 24 receives a cell start signal SOC from the line interface 21 and performs an operation. The comparator 24 receives a VPI value of a converted ATM cell stored in the buffer 22 and is stored in the register 23. The unique VPI values are applied to each other, and when the comparison result is the same, a selection control signal SCS of a high level is generated and a selection control signal SCS of a low level is generated. To the switch 25.

The switch 25 selects an output port to its subscriber station by a 'high' level selection control signal (SCS) applied from the comparator 24, and selects the converted ATM cell applied from the buffer 22. A switching ATM applied from the buffer 22 by switching to a subscriber station of the terminal and selecting an output port toward the line transmission interface 26 by a 'low' level selection control signal (SCS) applied from the comparator 24. Switch the cell to the line transmission interface 26.

The line transmission interface 26 reconverts a converted ATM cell applied through the switch 25 into an optical signal and transmits the converted ATM cell to a next subscriber station access device.

On the other hand, the specific hardware configuration of the subscriber station access device in the ATM network according to an embodiment of the present invention, as shown in Figure 4, a plurality of exclusive or gate (XOR) and one NAND gate (NAND) in the comparator 24 )

In the ATM network according to an embodiment of the present invention, the subscriber station access device performs the following operation.

First, referring to FIG. 3, when the ATM cell or the previous subscriber station access device applies the ATM cell to the corresponding subscriber station access device, the corresponding line receiving interface 21 performs the corresponding ATM switch or the previous call. Converts the ATM cell, which is an optical signal applied from the subscriber station access device, into an electrical signal, applies the converted ATM cell to the buffer 22, and generates a cell start signal (SOC) for controlling the operation of the comparator. The generated cell start signal SOC is applied to the comparator 24.

Therefore, the buffer 22 delays until the determination of whether to transfer the converted ATM cell applied from the line receiving interface 21 to the subscriber station connected to the subscriber station access device is completed.

Meanwhile, the VPI value of the ATM cell to be transmitted to the subscriber station is set in advance, and the set unique VPI value is stored in the register 23.

In addition, the comparator 24 receives a cell start signal SOC from the line interface 21 to perform an operation, and receives the VPI value of the converted ATM cell from the buffer 22 and receives the register 23. After receiving the unique VPI value stored in), the input VPI value and the unique VPI value are compared with each other.

If the result of the comparison is the same, the comparator 24 generates a selection control signal SCS of a 'high' level and applies it to the switch 25, and the switch 25 is provided from the comparator 24. The output port is selected to the subscriber station by the 'high' level selection control signal (SCS) to switch the converted ATM cell applied from the buffer 22 to the subscriber station.

On the contrary, when the comparison result is different, the comparator 24 generates a selection control signal SCS of a 'low' level and applies it to the switch 25, and the switch 25 is the comparator 24. The output port is selected to the line transmission interface 26 by the 'low' level selection control signal (SCS) applied from the switch to switch the converted ATM cell applied from the buffer 22 to the corresponding line transmission interface 26. .

Accordingly, the line transmission interface 26 reconverts the converted ATM cell applied through the switch 25 into an optical signal and transmits the converted ATM cell to the next subscriber station access device.

Secondly, referring to FIG. 4, for example, to perform the operation of the present invention, the register 23 has a data value of 8 (bit) and has an ATM through the line receiving interface 21. The cells are in turn stored in the 8 (bit) buffer 22.

However, the buffer 22 is implemented as a shifter, and the comparator 24 compares two data of the register 23 and the buffer 22 by using the cell start signal SOC. If the values of the fields match, the value of the exclusive OR gate is '0', and if the value of all the exclusive OR gates is '0', the value of the NAND gate is '1'. Is applied to the switch 25 and the switch 25 transmits the corresponding ATM cell to the subscriber terminal side. Otherwise, the switch 25 transfers the corresponding ATM cell via the line transmission interface 26. Is transmitted to the subscriber terminal access device.

That is, since the ATM cell transmitted from one subscriber station access device to the connected subscriber station can be distinguished by the VPI field of 16 (Bit), one subscriber station can identify data for up to 65,535 connections. Each subscriber station access device is identified by a unique VPI of 8 (bit), so the number of subscriber stations that can be connected to one ATM switch can be limited to 255, but the number of subscriber stations connected to one bus This is not a problem since it is up to several dozen.

As described above, the present invention simplifies the subscriber station access device in the subscriber network of the bus structure, since all connections of the subscriber network use a virtual channel identified by a fixed VPI value between the ATM switch and one subscriber station. Since it can be configured with simple hardware of the same level as the existing local area network access device, the call access control of the ATM network can be made irrelevant to the subscriber station access device.

On the other hand, according to the related art, when establishing a connection in a subscriber station connected to one bus, there was a restriction to have different VPI and VCI values, for example, the VPI and VCI values were set to 100 and 200 in the first terminal. If you do, the value is not available in the second terminal. If the same VPI and VCI value are used, the ATM switch cannot distinguish between the cell transmitted from the corresponding first terminal and the cell transmitted from the second terminal.

However, according to the present invention, even when the UE transmits a cell to the ATM switch, even if the UE establishes a connection with an arbitrary VCI value, the access device assigns a different VPI value, so it is possible to use the same VPI and VCI values. This simplifies the process of assigning VPI and VCI values to establish the connection.

As described above, according to the present invention, the VPI value of the subscriber station is allocated to the register and the VPI value of the ATM cell stored in the buffer from the corresponding line receiving interface in the comparator by the cell start signal applied from the line receiving interface. By comparing the unique VPI value, the corresponding ATM cell is transmitted to the next subscriber station access device through the line transmission interface or transmitted to the corresponding subscriber station, so that the subscriber station is connected to the ATM network without having to maintain all the connection information in a simple configuration. It is suitable for ATM network of bus structure.

Claims (1)

A buffer 22 for receiving and storing a converted ATM cell, a line transmission interface 26 for reconverting the converted ATM cell into an optical signal and transmitting the same to a next subscriber station access device, and a selection control signal (SCS). In a subscriber station access device in an ATM network including a switch 25 for switching a converted ATM cell applied from the buffer 22 to its own subscriber station or the corresponding line transmission interface 26, A line receiving interface 21 for converting an ATM cell applied from an ATM switch or a previous subscriber station access device into an electrical signal to apply the converted ATM cell to the buffer 22 and to generate a cell start signal (SOC); ; A register 23 that stores a unique VPI value; The cell start signal SOC is applied from the line interface 21 to compare the VPI value of the converted ATM cell stored in the buffer 22 with the unique VPI value stored in the register 23 to control the selection control signal SCS. Apparatus for accessing a subscriber station in an ATM network, comprising: a comparator (24) for generating a comparator.