KR20000046385A - Operation, administration and maintenance cell processing apparatus in atm based communication system - Google Patents

Abstract

PURPOSE: An OAM(Operation, Administration and Maintenance) cell processing apparatus in an ATM(Asynchronous Transfer Mode) based communication system is provided to generate and transfer OAM cells or to carry out an associated process after detecting OAM cells received. CONSTITUTION: An OAM cell receiving part(310) and an OAM cell transmitting part(320) respectively are comprised of an OAM cell extraction part(311), an available cell inspection part(312) and an OAM cell processing/generating part(313). The OAM cell extraction part(311) extracts OAM cells in the flow of ATM cells and passes user cells as they are. Inspecting the OAM cells extracted from the OAM cell extraction part(311), the available cell inspection part(312) outputs available cells only. Inspecting the OAM cells outputted from the available cell inspection part(312), the OAM cell processing/generating part(313) outputs OAM information about AIS(Alarm Indication Signal) cells, RDI(Remote Defect Indication) cells or loop back cells and generates the AIS cells, the RDI cells or the loop back cells by a required OAM cell generation command.

Description

A unit of handling Operation, Administration and Maintenance cells in communication systems based on Asynchronous Transfer Mode

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cell processing apparatus for operation maintenance in a communication apparatus based on an asynchronous transmission mode. In particular, the present invention relates to an asynchronous transmission such as a demand-intensive optical subscriber transmitter (FLC-C). Create and transmit an OAM Cell (Operation, Administration, and Maintenance Cell) used for maintenance, management, and maintenance in communication devices based on ATM (Asynchronous Transfer Mode). An apparatus for detecting an OAM cell and performing a corresponding process.

In recent years, with the rapid growth of the multimedia field, a communication network for digitally transmitting a wideband signal such as a video signal has been required, and thus, B-ISDN (Broadband-Integrated Services Digital Network) has emerged. With the advent of broadband ISDN, it is possible to meet various service needs of users, and in particular, it is possible to transmit moving images, thereby becoming a foundation for realizing the dream of the future information society.

The B-ISDN requires an ATM technology, which transmits a fixed length (53 bytes) information block called an ATM cell using the ATDM scheme.

As shown in FIG. 1, the ATM cell is divided into a 5-byte header section and a 48-byte user information section, and the 5-byte header is a header at a user network interface (UNI). The structure is divided into the header structure at the NNI (Network Node Interface), and the header structure at the user network interface (UNI) is the first byte of 4 bits of Generic Flow Control (GFC) and 4 A virtual path identifier (VPI) of bits, and the second byte consists of a 4-bit virtual path identifier (VPI) and a 4-bit virtual channel identifier (VCI), and a third byte Is composed of 8 bits of virtual channel identifier (VCI), 4th byte is 4 bits of virtual channel identifier (VCI), 3 bits of payload type (PT) and 1 bit of cell abandonment ranking (CLP: Cell Loss Priority), and the fifth byte is 8 bits It consists of: (Header Error Control HEC) header error control.

On the other hand, in the ATM technology, an operation maintenance cell (OAM cell) is used separately from the user cell as described above. The format and function of the OAM cell are defined in detail in ITU-T I.610. The structure of the cell is shown in FIG. 2.

The OAM cell 200 has a total size of 53 bytes, like a user cell, a 5-octet header 210, a 4-bit OAM type 220, a 4-bit function type 230, It consists of a 45 octet Function Specific Field (240), a 6-bit preservation interval 250 that is reserved for future use, and a 10-bit CRC-10 information 260.

The header 210 is a section including a virtual channel identifier (VCI), and is a value of the virtual path identifier of the header 210. The header 210 is an OAM cell for a segment or an OAM cell for an end to end. Distinguish cognition. That is, if the value of the virtual path identifier is 3, it is a segment OAM cell. If the value of the virtual path identifier is 4, it is an end-to-end OAM cell.

The OAM type 220 indicates the type of management function that the OAM cell performs, and the function type 230 indicates the function that is actually performed within the management type indicated by the OAM type 220. At this time, the functional classification according to the OAM type 220 and the function type 230 is defined as shown in Table 1 below.

OAM type Coding Function type Coding Fault management 0001 AIS 0000 RDI 0001 Continuity Check 0100 Loopback 1000 Performance Management 0010 Forward monitoring 0000 Backward reporting 0001 Active / Deactive 1000 Continuity Check 0001 System administration 1111 Undefined Undefined

In addition, the 6-bit reserved save period 250 is all set to '0' as a default value, and the CRC-10 information 260 means an error detection code (EDC), except for the CRC-10 information section. Cyclic redundency check (CRC) -10 error detection coding information for an OAM cell.

On the other hand, the structure of the function specific field 240 of 45 octets is different for each OAM type. First, the function specific field 240 for an Alarm Indication Signal (AIS) cell and a Remote Defect Indication (RDI) cell among error management cells. ) Is shown in Table 2 below.

Failure type (1 octet) Fault location (16 octets) Unused octets (28 octets)

In Table 2 above, the failure type interval and the failure location interval are used as options, and in the continuity check (CC) cell, the hexadecimal 6A must be coded in an unused octet.

The structure of the function specific field 240 for the loopback (LB: LoopBack) cell is shown in Table 3 below.

Loopback indication (1 octet) Correlation Tag (4 octets) Loopback position (16 octets) Source ID (16 octets) Unused (8 octets)

In Table 3 above, the loopback display section of one octet uses only the least significant bit 1 bit and fills the remaining 7 bits with '0'.

In addition, the structure of the function specific field 240 of the active / deactive cell is shown in Table 4 below.

Message ID (6 bit) Direction of operation (2 bits) CorrelationTag (8 bit) PM block size A-B (4-bit) PM block size B-A (4-bit) Unused (336 bits)

At this time, the value of the message ID is shown in Table 5 below.

message Command / response Coding Active Command 000001 Activation confirmation answer 000010 Reject activation request answer 000011 Disabled Command 000101 Confirm deactivation answer 000110 Deny request to deactivate answer 000111

The PM block size is shown in Table 6 below.

Message type PM block size Coding etc unused 0000 Activation and activation confirmation for performance monitoring 1024 0001 512 0010 256 0100 128 1000

Meanwhile, an ATM-based communication device requires an apparatus for generating an OAM cell having such a function and structure, or detecting an OAM cell among received ATM cells to perform a corresponding process.

In addition, the OAM cell processing apparatus conventionally used for this purpose does not easily perform bidirectional processing by performing only one-way processing that only detects the OAM cell in the receiving direction and generates the OAM cell in the transmitting direction. There was a problem.

Accordingly, the present invention has been made to solve the above problems, and is based on an apparatus capable of generating / detecting the OAM cell 200 in both a transmission direction and a reception direction, that is, in both directions, that is, based on an asynchronous transmission mode. It is an object of the present invention to provide a cell processing device for operation maintenance in a communication device.

In order to achieve the above object, the cell processing apparatus for operation maintenance in a communication device based on the asynchronous transmission mode according to the present invention is a microprocessor in a communication device based on the asynchronous transmission mode (ATM) An operation maintenance cell processing apparatus for performing an operation maintenance (OAM) process on a flow of an asynchronous transmission mode cell (ATM cell) transmitted and received under control, wherein the operation maintenance cell (OAM) is flowed in the flow of the ATM cell. OAM cell extraction unit for extracting the cell, and passes the user cell as it is; A valid cell inspecting unit for inspecting an operation maintenance cell extracted by the OAM cell extracting unit and outputting a valid cell and discarding an invalid cell; And inspecting operation maintenance cells output from the valid cell inspection unit, and operating and maintaining an alarm display signal cell (AIS cell), a remote failure display cell (RDI cell), a continuity test cell (CC cell), or a loopback cell. Generates and outputs alarm display signal cell (AIS cell), remote fault display cell (RDI cell), continuity check cell (CC cell), or loopback cell by the function of outputting information and the command of creating cell for operation maintenance. An OAM receiver and an OAM transmitter comprising an OAM cell processing / generation unit configured to perform an operation; A memory for storing the operation maintenance information output from the OAM receiver or the OAM transmitter; A memory controller which controls the memory and interfaces the OAM receiver and the OAM transmitter with the memory; And a microprocessor interface unit for interfacing between the microprocessor and the memory controller.

At this time, when the OAM cell processing / generation unit is a component of the OAM receiving unit, if the operation maintenance cell is a loopback cell, the position identifier of the loopback cell is changed to '1', and then the function is sent to the OAM transmitting unit. In addition, in the case of a component of the OAM transmitter, it is possible to implement it more preferably by changing the value of the loopback display interval of the loopback cell to " 00h "

1 is a format diagram of an ATM cell;

2 is a format diagram of an OAM cell;

3 is a block diagram of an OAM cell processing apparatus according to the present invention,

4 is a flowchart illustrating an OAM cell detection and processing procedure;

5 is a flowchart illustrating a process of generating and processing an OAM cell.

* Explanation of symbols for main parts of the drawings

300: OAM cell processing unit 310: OAM cell receiving unit

311: OAM cell extraction unit 312: Effective cell inspection unit

313: OAM cell processing / generation unit 320: OAM cell transmitter

330: memory 340: memory control unit

350: microprocessor interface unit

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

3 is a block diagram of an OAM cell processing apparatus 300 according to the present invention, which includes an OAM cell receiver 310, an OAM cell transmitter 320, a memory 330, a memory controller 340, and a microprocessor interface. The OAM cell receiver 310 and the OAM cell transmitter 320 include an OAM cell extractor 311, an effective cell inspector 312, and an OAM cell processor / generator 313. .

4 is a flowchart illustrating a process of detecting and processing an OAM cell, and FIG. 5 is a flowchart illustrating a process of generating an OAM cell.

First, the ATM cells received by the OAM cell processing apparatus 300 of the present invention are input to the OAM cell receiver 310 or the OAM cell extractor 311 of the OAM cell transmitter 320, and the OAM cell extractor 311. Investigates the value of the virtual channel identifier (VCI) of the corresponding ATM cell, and when the value of the VCI is 3 or 4, it considers it as an OAM cell, extracts the cell, and sends it to the valid cell checker 312.

However, if the VCI value of the corresponding cell is not 3 or 4, the cell is a user cell and thus passed through. This process is the cell extraction process (P410) shown in FIG.

The valid cell inspecting unit 312 determines whether the OAM cell sent from the OAM cell extracting unit 311 as the OAM cell is a normal cell, and discards the cell if it is not a normal cell. That is, the CRC-10 check is performed on the CRC-10 information 260 of all OAM cells sent from the OAM cell extracting unit 311 to check whether the corresponding cell is a valid cell, and discards the invalid cell.

However, the normal cell is sent to the OAM cell processing / generation unit 313, which is the valid cell inspection process P420 shown in FIG.

The OAM cell processing / generation unit 313 determines whether the OAM cell received from the valid cell inspecting unit 312 is an AIS cell, an RDI cell, a CC cell, or an LB (LoopBack) cell, and determines the determined matter. The data is stored in the memory 330 in a predetermined format through the 340.

The OAM related information stored in the memory 330 is read by the microprocessor 400 at a predetermined time point, and then the processing thereof is performed. Since the processing in the microprocessor 400 for the OAM related information is not related to the present invention, a detailed description thereof will be omitted.

In addition, the OAM cell processing / generation unit 313 creates an OAM cell (AIS cell, RDI cell, CC cell, etc.) having a cell abandon priority (CLP) value of '0', and generates a CRC-10 value in the created OAM cell. Perform the function of attaching.

At this time, the OAM cell processing / generation unit 313 of the OAM cell receiver 310 detects an end-to-end or segment loopback cell whose value of the loopback display section is 01H and transmits it to the OAM cell transmitter 320. The OAM cell processing / generation unit 313 of the OAM cell transmitter 320 converts the loopback display interval of the loopback cell received from the OAM cell receiver 310 to 00H and transmits the signal. Do it.

Now, the detection / processing operation of the OAM cell processing / generation unit 313 will be described in detail with reference to the OAM cell detection / processing process P430 of FIG. 4.

First, it is checked whether the VCI value of the OAM cell received by the OAM cell processing / generation unit 313 through the OAM cell extracting unit 311 and the valid cell inspecting unit 312 is 3 or 4. In this case, a VCI value of 3 indicates that the cell is a segment OAM cell, and a VCI value of 4 indicates that the cell is an end-to-end OAM cell.

If the VCI value is 3, it is determined whether the value of the OAM type 220 is "1" to determine whether it is a cell related to fault management (FM) or a cell related to active / deactive. do.

As a result of examining the OAM type 220, if the cell is related to activation / deactivation, it is checked whether the value of the OAM type 220 is "1000". If the value is not "1000", the cell is discarded and the OAM cell is detected / processed. After the process P430 is terminated, and in the case of "1000", the process proceeds to the OAM generation process after the OAM cell detection / processing process P430 is finished.

However, in the case of a cell related to error management, it is determined whether the value of the function type 230 is "0", and in the case of "0", the data indicating that the AIS cell is received is output to the memory controller 340 in a predetermined format. And store the data in the memory 330, and then terminate the OAM cell detection / processing process P430. If the value of the function type 230 is not “0”, the value of the function type 230 is “1”. Judge.

At this time, when the value of the function type 230 is "1", the data indicating that the RDI cell has been received is output to the memory controller 340 in a predetermined format, stored in the memory 330, and then detected / processed by the OAM cell. The process P430 ends.

However, if the value of the function type 230 is not "1" or the VCI value is 4, it is determined whether the value of the function type 230 is "100".

As a result of the determination, when the value of the function type 230 is "100", data indicating that the CC cell has been received is output to the memory controller 340 in a predetermined format, stored in the memory 330, and then OAM cell. If the value of the function type 230 is not "100", the detection / processing process (P430) is terminated. If the value of the function type 230 is not "1000", the corresponding cell is checked. Discard.

On the other hand, if the value of the function type 230 is "1000", and the OAM cell detection / processing process P430 currently in progress is being performed by the OAM receiver 310, this OAM cell is a loopback cell, and thus the corresponding OAM After changing the cell's location ID to '1', the cell transmits the cell to the OAM transmitter 320.

The OAM cell generation / processing process P500 of the OAM cell processing / generation unit 313 of the OAM cell receiver 310 and the OAM transmitter 320 will now be described in detail with reference to FIG. 5.

When the OAM cell processing / generation unit 313 of the OAM receiver 310 or the OAM transmitter 320 receives a command to create an OAM cell (S510), it determines whether the cell to be created is an error management cell or an activation / deactivation cell. (S520).

If the OAM cell to be created is an active / deactivated cell, the function of setting "1000" to the OAM type 220 of the corresponding OAM cell, the function of setting the message ID, the function of setting the direction of operation, and the setting of the correlation tag The OAM cell is generated and transmitted by sequentially performing a function of setting a PM block size, a function of setting unused octets, and calculating and coding a CRC-10.

However, if the OAM cell to be created is an error management (FM) cell, then set "1" to OAM type 220.

If the OAM cell to be created is a loopback cell, a function of generating a loopback cell, a function of setting the function type 230 to "1000", a function of setting a loopback display section to "1", and a function of setting a correlation tag To generate and transmit loopback cells by performing the function of setting loopback location ID to FFH, setting source ID to 6AH, setting unused octets to 6AH, and calculating and coding CRC-10. .

However, if the OAM cell to be created is an AIS cell, an RDI cell, or a CC cell, the corresponding OAM cell is generated, respectively, and then "0" (for an AIS cell) or "1" in the function type 230 of the generated OAM cell. "(In case of RDI cell) or" 100 "(in case of CC cell) is set.

In addition, the following process is commonly performed during the generation of the AIS cell, the RDI cell, or the CC cell.

That is, the function specific field 240 is set to 6AH, the retention interval 250 is set to 00H, and the CRC-10 value is calculated and coded to generate and transmit an OAM cell.

On the other hand, the memory 330 is a component used to store information about the OAM cell detected or generated by the OAM receiver 310 or the OAM transmitter 320, and is a microprocessor interface through the memory controller 340. Data is exchanged with the unit 350, the OAM receiver 310, and the OAM transmitter 320.

In addition, the microprocessor interface unit 350 is an apparatus for performing an interface function between the predetermined microprocessor 400 and the OAM cell processing apparatus 300 of the present invention. The processor 400 may transmit or transmit instructions from the microprocessor 400 to the OAM cell processing apparatus 300.

The microprocessor 400 is a predetermined central processing unit (CPU) that generally controls the processing of the OAM cell outside the OAM cell processing apparatus 300.

As described above, the present invention can be used in a communication device based on ATM, so that the OAM cell can be generated / detected in both a transmission direction and a reception direction, that is, in both directions, thereby processing the OAM cell more effectively.

Claims (2)

In a communication device based on an asynchronous transmission mode (ATM), an operation maintenance cell processing apparatus for performing an operation maintenance (OAM) process for the flow of an asynchronous transmission mode cell (ATM cell) transmitted and received under the control of a microprocessor. An OAM cell extraction unit for extracting an operation maintenance cell (OAM cell) in the flow of the ATM cell and allowing a user cell to pass through it; A valid cell inspecting unit for inspecting an operation maintenance cell extracted by the OAM cell extracting unit and outputting a valid cell and discarding an invalid cell; And Operation maintenance information about the alarm display signal cell (AIS cell), remote failure display cell (RDI cell), continuity test cell (CC cell), or loopback cell by inspecting the operation maintenance cell output from the valid cell inspection unit. Function to generate alarm output signal cell (AIS cell), remote failure display cell (RDI cell), continuity check cell (CC cell), or loopback cell according to the operation maintenance cell creation command. An OAM receiver and an OAM transmitter comprising an OAM cell processing / generation unit to perform; A memory for storing the operation maintenance information output from the OAM receiver or the OAM transmitter; A memory controller which controls the memory and interfaces the OAM receiver and the OAM transmitter with the memory; And And a microprocessor interface unit for interfacing between the microprocessor and the memory control unit. The method of claim 1, wherein when the OAM cell processing / generation unit is a component of the OAM receiver, if the operation maintenance cell is a loopback cell, the position identifier of the loopback cell is changed to '1', and then the OAM cell is transmitted to the OAM transmitter. Has additional sending capability, In the case of a component of the OAM transmitter, a communication device based on the asynchronous transmission mode is configured to further include a function of directly changing the value of the loopback display interval of the loopback cell to "00h". Cell processing unit for operation maintenance.