KR100249730B1 - Method for interfacing user network in atm lan system - Google Patents

Abstract

The present invention designates a specific port for transmitting / receiving ATM cells by using extra bits of virtual channel identification information in an ATM LAN system having a plurality of transmission / reception ports, and restores the corresponding virtual channel identification information to an original signal when transmitting an ATM cell. The present invention relates to a user network interface scheme in an ATM LAN system. To this end, the present invention is to multiplex each L Mbps ATM cell input through each port in a receiving ATM terminal to an N Mbps ATM cell, Synchronizing with the start signal of each cell, inserting VPI into the header information of each multiplexed ATM cell and inserting N bits of port recognition information for output port designation, respectively, and transmitting the VPI to the transmitting ATM terminal through the ATM switch; Demultiplex an ATM cell multiplexed at N Mbps into each ATM cell of L Mbps, extract N-bit port recognition information inserted in a predetermined section in the header information of each demultiplexed ATM cell, and extract the extracted port recognition information into each extracted port recognition information. Designating a port for transmission of a corresponding ATM cell among a plurality of ports connected to a transmitting ATM terminal according to the present invention; By removing each port recognition information respectively inserted in the header information of each ATM cell, the header information is restored to the original signal, and each of the restored header information is transmitted to the corresponding terminal through each designated port through each of the restored header information. The user network interface between each ATM terminal each having a transmit / receive port can be effectively performed.

Description

User Network Interface Method in ATM LAN System

The present invention relates to a user network interface method in an asynchronous transfer mode (ATM), and more particularly, to interface between each terminal connected to each port and an ATM switch in an ATM LAN system having a plurality of transmit and receive ports. The present invention relates to a method suitable for a user network interface.

In general, ATM is a communication scheme for implementing a Broadband Integrated Service Digital Network (BISDN), and is a special type of packet message transmission scheme using Asynchronous Time Division Multiplex (ATDM).

Meanwhile, in BISDN, information is transmitted between terminals by a continuous flow of packets having a constant size. The packets of fixed size are called ATM cells. More specifically, the ATM cell is information obtained by dividing a plurality of inputted service information into short cells of fixed length and packetizing each cell with 5 bytes of header information. 53 bytes (paid load information 48 + header information 5), and each of these ATM cells is multiplexed and transmitted to a target terminal through a transmission channel.

In addition, as described above, the ATM cell is a connectivity method, and establishes a virtual channel to transmit service information. Whenever the virtual channel is established, an identification number for connection is given and the identification number is released when the connection is released. .

Therefore, in the ATM exchanger employing the asynchronous scheme as described above, only the interface between one physical layer and the ATM layer is performed.

On the other hand, in recent years, it is considered to employ ATM in a LAN system that is a private network. In this case, an ATM LAN system requires a user network interface that interfaces between each terminal connected to each port and an ATM switch. There is a need for an interface between an ATM switch and terminals with different transmission rates.

For example, assuming that 25 Mbps terminals are connected to respective ports of a user network interface (UNI), and that one ATM switch interface has a speed of 155 Mbps, the user network interface is an ATM cell of these ports. In this case, ATM cells transmitted at 155Mbps from the ATM switch and 155Mbps from the ATM switch should be demultiplexed at 25Mbps to transmit ATM cells to terminals connected to each port.

However, at present, no technique for a user network interface in such an ATM LAN system has been proposed.

That is, in the structure of the user network interface as described above, since no method for designating a terminal location to which ATM cells authorized from an ATM switch are transmitted, that is, a corresponding port of the user network interface, is not proposed, an ATM cell to the corresponding terminal is proposed. Transmission was inevitable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and in an ATM LAN system having a plurality of transmission / reception ports, a specific port for transmitting / receiving an ATM cell is designated by using extra bits of virtual channel identification information, and corresponding to transmission of an ATM cell. It is an object of the present invention to provide a user network interface method in an ATM LAN system capable of restoring virtual channel identification information to an original signal.

In order to achieve the above object, the present invention provides a method for performing a user network interface in an ATM LAN system for performing an interface between ATM terminals connected to a plurality of ports having different data rates through an ATM switch having a predetermined data rate, A first step of multiplexing each L Mbps ATM cell input through each port in a receiving ATM terminal to an N Mbps ATM cell; Synchronizing with a start signal of each cell, inserting N-bit port identification information for output port designation into a predetermined section of header information of each of the multiplexed ATM cells, and transmitting the N-bit port identification information to a transmitting ATM terminal through the ATM switch; 2 courses; Demultiplexing the ATM cells multiplexed at N Mbps into respective ATM cells at L Mbps; N-bit port recognition information inserted in the VPI section in the header information of each demultiplexed ATM cell is extracted, and the corresponding ATM cell of the plurality of ports connected to the transmitting ATM terminal is extracted based on the extracted port identification information. A fourth step of respectively designating a port for transmission; And removing each port recognition information respectively inserted into the header information of each ATM cell, restoring each header information to the original signal, and transmitting each restored header information to the corresponding terminal through each designated port. A user network interface method in an ATM LAN system having a fifth process is provided.

1 is a data format showing a data configuration for a typical ATM cell used in asynchronous transmission mode,

2 is a block diagram of a user network interface device in an ATM LAN system suitable for applying a user network interface method according to the present invention;

3 is a data format illustrating an example of header information in an ATM cell in a user network interface.

<Explanation of symbols for main parts of drawing>

10: ATM switch 20,30: user network interface block

22,32: Multiplexer 24,34: Switch Interface

26,36: Demultiplexer

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a data format showing a data configuration for a typical ATM cell used in asynchronous transmission mode.

As shown in the figure, an ATM cell consists of 5 bytes of header information and 48 bytes of payload information. The main function of 5 bytes of cell header information in a user network interface (UNI) is asynchronous time division modulation. It is to identify cells belonging to the same virtual channel among ATM cells existing in the AT (ATDM) information flow.

Referring to FIG. 1, a 4-bit GFC section performs a media access control function, and an 8-bit virtual path identifier (VPI) section and a 16-bit virtual channel identifier (VCI) section have the same connection. It is a section indicating the identification number of the virtual path and the virtual channel to distinguish the cells belonging to. Here, the virtual channel refers to a logical unidirectional coupling between link ends carrying an ATM cell, and the virtual path refers to a logical combination of virtual channels sharing a certain path.

In addition, the 3-bit PT (Payload Type) section is used to indicate user information, and the 1-bit CLP (Cell Loss Priority) section indicates cell discard priority information indicating whether a corresponding cell is abandoned when a communication jam occurs. The 8-bit HEC (Header Error Control) section is a cyclic redundancy check byte for error checking of the cell header section. This information is used to detect and correct an error of the cell and to detect the cell header.

On the other hand, in the cell header information as described above, the actual number of bits used for the VPI interval and the VCI interval for routing can be determined by negotiation between the user and the network. The lower number of bits is determined, and the VPI and VCI intervals are continuous and filled from the least significant bit (LSB).

On the other hand, considering that the ATM LAN system has a limited number of terminals due to its system characteristics, since 12 bits are already allocated to the VCI, it is not necessary to use all of the 8 bits previously allocated to the VPI. That is, in the case of an ATM LAN system, even if only 3 to 4 bits are used in the allocated 8-bit VPI period, all terminals can be sufficiently accommodated.

As an example, assuming that 4 bits of information are used as the VPI, as shown in FIG. 3A as an example, 4 bits of the actually used VPI interval (ie, 4 bits sequentially following the least significant bit (LSB)) are selected. All remaining bits, ie, the four bits that follow sequentially from the most significant bit (MSB), will be filled with “0”.

Accordingly, the present invention designates a port to transmit an ATM cell among a plurality of ports by using an extra bit present in the VPI interval, that is, an extra bit of the most significant bit side filled with “0” which is not actually used. That is, the port recognition information for designating each port is inserted into the extra bits existing in the VPI section, the corresponding port is designated based on the inserted port recognition information, and the port recognition information is inserted when the ATM cell is transmitted. Restore the VPI section information to the original signal.

2 is a block diagram of a user network interface device in an ATM LAN system suitable for applying a user network interface method according to the present invention using a VPI information interval.

As shown in the figure, the user network interface device includes an ATM switch 10, and user network interface blocks 20 and 30 on the transmitting and receiving side for interfacing the ATM switch 10 with the ATM cell. Here, the ATM switch 10 performs a function such as, for example, a router, that is, routes an ATM cell between two switch interfaces 24 and 34.

Here, the ATM switch 10 has an interface speed of 155 Mbps for convenience of explanation and for better understanding, and the ATM cell through each port (P10-P13 and P00-P03) in each user network interface block (20, 30). It is assumed that the transmission speed of is 25Mbps. In addition, it is assumed that four ports are connected to each of the user network interface blocks 20 and 30. Therefore, when four ports are connected to each of the user network interface blocks 20 and 30, the port recognition information for designating the corresponding port for delivery of the ATM cell may be allocated 2 bits.

On the other hand, each user network interface block (20, 30) is composed of the same component to perform substantially the same function, ATM switch by multiplexing the ATM cells provided from each port (P10-P13 or P00-P03) In step 10, as an example, a 25 Mbps ATM cell generated at each ATM network interface card and input through each port (P10-P13 or P00-P03) is multiplexed and transferred to the ATM switch 10, and the ATM switch ( 10) demultiplex the multiplexed ATM cells provided from 10) to each corresponding port (P00-P03 or P10-P13), for example, demultiplex the cells multiplexed at 155 Mbps to ATM cells of 25 Mbps P00-P03 or P10-P13).

On the other hand, the multiplexer 22 and the demultiplexer 36 have preset port recognition information (e.g., port recognition information of each two bits) for each port P00-P03 on the user network interface block 30 side. In the multiplexer 32 and the demultiplexer 26, preset port recognition information (for example, each 2-bit port recognition information) for each port P10 to P13 on the user network interface block 20 side is stored. ) Is already stored.

At this time, for example, if the port recognition information is "00", the designation of the port P10 or the port P00 is designated. If "01", the designation of the port P11 or the port P01 is designated. Alternatively, the designation of the port P02 may be assigned to mean the designation of the port P13 or the port P03, respectively.

Therefore, in each of the multiplexers 22 and 32, as shown in Fig. 3B, as shown in Fig. 3B, when multiplexing ATM cells inputted through each port (multiplexing 25 Mbps ATM cells to 155 Mbps), the header information of the ATM cell is included. Port recognition information of N bits (for example, 2 bits) for the corresponding port to which the ATM cell is to be transmitted is inserted into a predetermined portion of the VPI information interval (ie, from the most significant bit (MSB)).

In addition, each demultiplexer (26, 36) detects the inserted port recognition information of the VPI information interval in the header information of the ATM cell when demultiplexing the ATM cells multiplexed at 155Mbps, and based on the detected port recognition information It designates the corresponding port to transmit each ATM cell, and also restores the VPI information in the header information to the original signal, that is, removes the port recognition information inserted in the VPI information section and restores the original signal to the original signal.

Next, a process of designating a port for transmitting an ATM cell using a VPI information section and restoring VPI information to an original signal according to the present invention will be described.

First, the present embodiment will be described as an example of providing an ATM cell multiplexed in the user network interface block 20 to the user network interface block 30 through the ATM switch 10.

First, the multiplexer 22 of the user network interface block 20 multiplexes 25 Mbps ATM cells input through each port (P10-P13) to 155 Mbps, which is synchronized with a start of cell (SOC) signal. As an example, as shown in FIG. 3B, the port recognition information of the corresponding port (P00, P01, P02 or P03) to which the ATM cell is to be transmitted in the upper 2 bits of the VPI section of 8 bits of the header information in each ATM cell. In this way, the port recognition information is inserted and thus multiplexed ATM cells are transferred to the ATM switch 10 through the switch interface 24.

For example, when the multiplexer 22 wants to transmit the corresponding ATM cell to the port P00, the multiplexer 22 inserts the recognition information of “00” into the upper two bits of the VPI information interval and transmits the corresponding ATM cell to the port P01. If you want to insert the recognition information of "01" into the upper 2 bits of the VPI information interval, if you want to transmit the corresponding ATM cell to the port (P02), the recognition information of "10" is inserted into the upper 2 bits of the VPI information interval. When the ATM cell is to be transmitted to the port P03, recognition information of "11" is inserted into the upper two bits of the VPI information section.

Next, when the multiplexed ATM cells are input through the ATM switch 10 and the switch interface 34, the demultiplexer 36 in the user network interface block 30 receives 155 Mbps for delivery to each port (P00-P03). The multiplexed ATM cells are demultiplexed and decoded in synchronization with a cell start signal (SOC). For example, as shown in FIG. 3B, a port recognition inserted into the upper two bits of the VPI interval of 8 bits of header information in each ATM cell. Information is extracted, and a port for forwarding each of the demultiplexed ATM cells is specified based on the extracted port recognition information.

That is, in the demultiplexer 36, if the port recognition information extracted from the VPI information section in the header information of the demultiplexed corresponding ATM cell is “00”, the port P00 is designated as the transmission port of the corresponding ATM cell, and extracted from the VPI information section. If the port recognition information is "01", the port P01 is designated as the transport port of the corresponding ATM cell. If the port recognition information extracted from the VPI information interval is "10", the port P02 is designated as the transport port of the ATM cell. If the port recognition information extracted from the VPI information interval is "11", the port P03 will be designated as a transmission port of the corresponding ATM cell.

In addition, the demultiplexer 36 designates a port for delivery of each ATM cell based on the extracted port recognition information, and removes the port recognition information inserted in the header information of each ATM cell before transmitting the ATM cell to each designated port. That is, the VPI information is restored to the original signal by mapping all values of the upper N bits into which the port recognition information is inserted in the VPI information section in each ATM cell header information to a value of "0".

Therefore, each designated 25Mbps ATM cells through each port will be transmitted to each terminal not shown.

As described above, according to the present invention, an ATM LAN system in which a plurality of ports for ATM cell transmission are connected to each other for transmission of ATM cells by using an extra bit of a VPI information interval when transmitting an ATM cell through a specific port. By effectively designating the port and restoring the VPI information to the original signal before transmitting the ATM cell, the user network interface between the ATM terminals can be effectively performed.

Claims (4)

A method of performing a user network interface in an ATM LAN system that performs an interface between ATM terminals connected to a plurality of ports having different data rates through an ATM switch having a predetermined data rate, A first step of multiplexing each L Mbps ATM cell input through each port in a receiving ATM terminal to an N Mbps ATM cell; Synchronizing with a start signal of each cell, inserting N-bit port identification information for output port designation into a predetermined section of header information of each of the multiplexed ATM cells, and transmitting the N-bit port identification information to a transmitting ATM terminal through the ATM switch; 2 courses; Demultiplexing the ATM cells multiplexed at N Mbps into respective ATM cells at L Mbps; N-bit port identification information inserted in a predetermined section of header information of each demultiplexed ATM cell is extracted, and the corresponding ATM cell is selected from among a plurality of ports connected to the transmitting ATM terminal based on the extracted port identification information. A fourth step of respectively designating a port for transmission; And Removing each port recognition information respectively inserted in the header information of each ATM cell, restoring each header information to an original signal, and transmitting an ATM cell having each of the restored header information to a corresponding terminal through each designated port; User Network Interface Method in ATM LAN System with 5 Processes. The method of claim 1, The N-bit port identification information is inserted in an extra bit section of the virtual channel identification information in the header information. The method of claim 2, And the bit identification information is determined based on the number of ports connected to the receiving ATM terminal and the transmitting ATM terminal, respectively. The method of claim 1, The fifth process includes mapping each port identification information to "0" and restoring the header information to the original signal.

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