KR20000020254A - Method for testing operation administration and maintenance cell in atm local switch - Google Patents

Abstract

PURPOSE: An OAM(Operation Administration and Maintenance Cell) test in an ATM(Asynchronous Transfer Mode) layer is provided to understand a cell location in which an error has occurred, and to observe, detect the cell having the error, and to observe the efficiency of the cell. CONSTITUTION: An OAM(Operation Administration and Maintenance Cell) test in an ALS(ATM(Asynchronous transfer Mode) Local Switch) comprises the steps of: generating an OAM cell, by analyzing an OAM cell processing request of an operation terminal in a cell path test device; confirming whether malfunction is generated, by checking an EDC(Error Detect Code) bit after receiving the OAM cell from the ALS; performing an OAM cell processing function, by analyzing the corresponding cell when the malfunction for the OAM cell is not generated; informing to the operation terminal by transmitting the result to the cell path test device.

Description

How to test OEM cell in ATM exchange

The present invention relates to an OAM cell test (Operation Administration and Maintenance Cell Test) in the ATM layer, and in particular, in the ATM switch that allows the cell path test apparatus to perform OAM cell processing function by performing the OAM cell path test by the call processing equipment. OAM cell test method.

The ATM cell path test using the existing ACTA board has the function of checking for abnormal cell flow to the switch port through the cell, that is, the firmware in the ATM Cell Test Assembly Board. Since only the function of checking the flow of cells to the switches and subscribers in the exchange was not able to determine the position and state of the cells when an error of the corresponding cell itself occurred.

In order to solve the problems as described above, the present invention performs a function for monitoring the location of the error cell and the monitoring, detection, performance monitoring of the error cell as a test function using the OAM cell with ATM exchange operation maintenance software It is intended to be.

1 is a block diagram illustrating a system for OAM cell test in an ATM switch in accordance with an embodiment of the present invention.

FIG. 2 is a diagram illustrating a message format of an OAM cell in FIG. 1. FIG.

3 is a flowchart illustrating an OAM cell test method in an ATM switch according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: cell path test device

20: ALS (ATM Local Switch)

The present invention for achieving the above object is a first step of generating an OAM cell by analyzing the OAM cell processing function request of the HMI operator terminal in the cell path test apparatus; A second step of receiving the OAM cell from the ALS and checking an EDC bit to confirm whether there is an error; A third step of performing an OAM cell processing function by analyzing a corresponding OAM cell when there is no abnormality in the received OAM cell in the second step; And a fourth process of transmitting the result of performing the OAM cell processing function to the cell path test apparatus and informing the HMI operator terminal.

In addition, the fifth step of the OAM cell retransmission request to the cell path test apparatus when there is an error in the received OAM cell in the second step; And a sixth step of re-analyzing the OAM cell processing function request by receiving the OAM cell retransmission request and regenerating the OAM cell.

The present invention enables OAM cell path testing by the ADTEC call processing equipment to allow firmware in a cell path test apparatus, which is a test board in an exchange, to perform OAM cell processing functions, so that the VP (Virtual Path) and VC (Virtual Channel) segments ( Segment, end-to-end OAM cell test and loopback test function. Cell detection and cell monitoring functions such as an alarm indication signal (AIS) and a remote detect indication (RDI) for locating an error cell are performed.

In addition, the present invention allows the cell path test apparatus to perform not only a test cell but also a test of an OAM cell.

Hereinafter, with reference to the accompanying drawings will be described as follows.

1 is a block diagram illustrating a system for testing OAM cells in an ATM switch according to an embodiment of the present invention, FIG. 2 is a diagram illustrating a message format of an OAM cell in FIG. 1, and FIG. 3 is an embodiment of the present invention. This is a flowchart illustrating an OAM cell test method in an ATM switch according to an example.

As shown in FIG. 1, a system for testing an OAM cell in an ATM switch according to an embodiment of the present invention includes a cell path test apparatus 10 and an ALS (ATM Local Switch) 20.

The cell path test apparatus 10 receives an OAM cell test request and an OAM loopback test request from a Human Interface (HMI) operator terminal to generate an OAM cell and apply the generated OAM cell to the ALS 20. The test result is received from 20) and informed to HMI operator terminal.

The ALS 20 includes an interface module such as a low speed interface module, a medium speed interface module, and a high speed interface module. The ALS 20 receives an OAM cell from the cell path test apparatus 10 and checks for cell abnormality. After performing the OAM cell processing function through each interface module, a test result is reported to the cell path test apparatus 10.

According to the present invention, in addition to the switch path test function performed by the cell path test apparatus, the OAM function of the ATM layer can be processed as well as the flow of the cell through the transmission and reception of OAM cells for each segment section corresponding to the VP and VC using the OAM cell. Make sure

First, the message format of the OAM cell is as shown in FIG. 2, wherein a header of 5 octets, a 4-bit OAM form, a 4-bit function form, a 45-octet function-only field, and a 6-bit spare field are provided. And 10 bits of Error Detect Code (EDC).

The header is described in detail in ITU-T Recommendation I.361, and two virtual channel identifiers (VCIs) pre-assigned for F4 information flow classification are used for the OAM cell for the Virtual Path Connetion (VPC) and the VPC segment. Used for classification, two Payload Type Indentifiers (PTIs), which are pre-allocated to distinguish the F5 information flow, are used to distinguish the OAM cells for the VCC (Virtual Channel Connetion) and the VCC segment.

The OAM cell type represents a type of management function performed by the OAM cell, that is, failure management, performance management, activation / deactivation, and system management.

The OAM function type represents the actual function performed by the OAM cell in the management mode indicated by the OAM cell type.

The preliminary fields are all encoded with a value of '0', and the availability of the corresponding field indicates the OAM protocol version.

The EDC represents an error detection code calculated for information fields of all OAM cells, and is the remainder obtained by multiplying the OAM cell information area by X ¹⁰ and dividing by the generation polynomial.

In addition, the OAM function of the ATM layer includes an AIS function, an RDI function, a continuity check function, a loopback function, a forward performance monitoring function, a reverse performance monitoring function, and an activation / deactivation function. Represents the identifier of.

OAM form sign Function mode sign Fault Management One AIS 0 RDI One Continuity check 100 Loopback 1000 Performance management 10 Forward performance monitoring 0 Reverse performance watchdog One Activation / deactivation 1000 Performance monitoring 0 Continuity check One System administration 1111 - -

Here, the 'AIS function' is a function for indicating a defect state in the forward direction, the 'RDI function' is a function for indicating a remote defect state in the reverse direction, and the 'continuity check function' is a continuous monitoring of continuity. The 'loopback function' is a function for monitoring connectivity and fault isolation on demand and continuity check before service provision, and the 'forward performance monitoring function' is a function for predicting performance, and the corresponding 'reverse direction' 'Performance Monitoring' is a function for reporting backward performance prediction, and 'Activation / Deactivation' is for enabling or disabling performance monitoring and continuity check.

In addition, the OAM function of the ATM layer has a function of generating and transmitting an OAM cell in a call processing device, for example, a call processing device, and the OAM processing function registration and result can be processed in an ATM switch. In addition, by generating the OAM cell generated by the call processing equipment in the firmware in the cell path test apparatus, the processing result is reported from each subscriber and notified to an upper application program to further process the OAM cell processing function in the exchange. It can be processed efficiently.

Then, the OAM cell test method in the ATM switch according to the embodiment of the present invention will be described with reference to the flowchart of FIG. 3.

First, when an OAM cell test request and an OAM loopback test request are made from the operator terminal to the cell path test apparatus 10 side (step S1), the corresponding cell path test apparatus 10 receives the OAM cell test request and OAM authorized from the operator terminal. Analyze the loopback test request, i.e., determine which OAM and function type the test request requires (step S2), and generate the OAM cell as shown in the message format of FIG. The generated OAM cell is transmitted to the ALS 20 side (step S4).

Accordingly, the subscriber board in the ALS 20 receives the OAM cell from the cell path test apparatus 10 (step S5) and checks the EDC bit of the received OAM cell, that is, whether there is an abnormality of the received OAM cell. Check (step S6).

At this time, if there is an error in the received OAM cell in the sixth step S6, the ALS 20 requests to retransmit the OAM cell to the cell path test apparatus 10 (step S7). The cell path test apparatus 10 checks whether the OAM cell retransmission request is applied from the ALS 20, analyzes the test request of the second step S2 again, and generates and transmits the OAM cell again (step S8). ).

On the contrary, if there is no abnormality in the received OAM cell in the sixth step S6, the ALS 20 analyzes the received OAM cell to know what the OAM cell processing function is, that is, the AIS function of failure management. Whether it is a request to perform RDI, continuity checking, and loopback functions, or is a request to perform forward and reverse performance monitoring for performance management, or a performance monitoring and continuity checking function for activation / deactivation, or system management. (Step S9).

Accordingly, the ALS 20 performs the identified OAM cell processing function through each interface module such as a low speed interface module, a medium speed interface module, and a high speed interface module (step S10), and performs the corresponding OAM cell processing function. The test result, which is a later result, is transmitted to the cell path test apparatus 10 (step S11).

Then, the cell path test apparatus 10 receives a test result from the ALS 20 (step S12) and informs the operator terminal of the corresponding test result (step S13).

In the present invention, the fault management of the AIS function, the RDI function, the continuity check function and the loopback function, the performance management of the forward performance monitoring function and the reverse performance monitoring function, the activation / deactivation of the performance monitoring and the continuity checking function, and the system management Let's take a closer look at the specific fields for the cell corresponding to.

First, looking at a specific field for a fault management cell, one of the specific fields for that fault management cell has a defect type of 1 octet, a defect location of 16 octets, and no use of 28 octets. This includes fields. The type of fault indicates the type of fault reported, such as no fault, a fault in the VP / VC layer, a fault in the layer that supports the layer through which the OAM information flow is being sent, and whether the fault is still in service or stopped. The division, detailed defect information, and corresponding defect type area are shown. The defect location indicates information on a failure location, which indicates a location where an AIS cell is generated for an AIS cell, and includes location classification information received by a corresponding AIS cell for an RDI cell.

The continuity check failure management cell of a specific field for the corresponding failure management cell is encoded as '6AH' without a specific field.

In addition, the loopback cell of the specific field for the fault management cell has a 4-octet for loopback indication of one octet indicating whether the cell has already looped back and a correlation between the transmitted OAM cell and the received OAM cell. It consists of a correlation indication, a 16-octet loopback position identifier that identifies the virtual point on which the loopback occurs, or a connection point on the segment, and a 16-octet information source identification number that identifies the source from which the loopback cell originates. It further includes a portion encoded by '6AH' of the tet, an unused portion of 7 bits, and 1 bit.

Second, looking at specific fields for the forward supervisor and reverse report performance management cells, the 8-bit supervisor cell sequence number representing the value of the modular 256 counter indicating the forward supervisor and reverse report OAM cell order, and the forward supervisor cell are inserted. Total number of user cells related to a 16-bit user cell flow representing the counter's value associated with the total number of user cells transmitted at the time of transmission, and the even parity calculated for the information field of the user cell block transmitted since the previous supervisory cell. A 16-bit block error detection code representing an error detection code, a total number of 16-bit user cells associated with a user cell whose number of user cells transmitted is '0', and a 32-bit representation of the time at which a performance monitoring OAM cell is inserted. The total number of received cells of 16 bits representing the timestamp, the value of the counter associated with the total number of receiving user cells, and the number of received user cells It includes a total number of 16-bit received cells associated with a user cell of '0' and an 8-bit block error result indicating the number of parity bits in which an error detected by the code of the forward monitoring OAM cell occurs.

Third, a specific field for the activation / deactivation cell contains a six-bit message identification number representing the message identification number for enabling or disabling a specific VPC / VCC OAM feature, and each message to allow nodes to associate commands and responses. An 8-bit correlation tag generated for, a 2-bit operating direction indicating the direction of transmission for enabling / disabling the OAM function, and 8 indicating the block size selection supported by the activator for PM block size or performance monitoring. It includes the PM block size of the bit.

As described above, the present invention is suitable for performing functions for monitoring the location of an error cell and monitoring, detecting, and monitoring performance of the error cell as a test function by an ATM switching operation maintenance software and a cell path test apparatus. Do.

Claims (3)

Analyzing the OAM cell processing function requirement of the operator terminal in the cell path test apparatus to generate an OAM cell; Receiving the OAM cell in ALS and checking an EDC bit to confirm whether there is an error; Performing an OAM cell processing function by analyzing a corresponding OAM cell when there is no abnormality in the received OAM cell; And transmitting a result of performing the OAM cell processing function to the cell path test apparatus and informing the operator terminal of the result of the OAM cell processing. The method of claim 1, Making an OAM cell retransmission request to the cell path test apparatus when there is an error in the received OAM cell; And receiving the OAM cell retransmission request and re-analyzing the OAM cell processing function request to regenerate the OAM cell. The method according to claim 1 or 2, The message format of the OAM cell includes a header, an OAM type, a function type, a function-only field, a reserved field, and an EDC.