KR100195060B1 - OAM Cell Generation Method for OAM Function Test in ATM Switching System - Google Patents

Abstract

The present invention relates to a method for generating an OAM cell in an ATM switch, comprising: setting a register for a loop if an OAM cell test is required; Displaying an OAM test in an operation terminal; Generating an OAM cell by registering an interrupt service routine for the OAM test and setting the VPI to a predetermined value for the end-to-end test and setting the OAM type to a predetermined value for the AIS test; Generating an OAM cell by setting the VPI to a predetermined value other than the end-to-end test and setting the OAM type to a predetermined other value if the RDI test; And by generating the appropriate OAM cell according to the test requirements, including the step of transmitting the generated OAM cell to the destination, there is an effect that can simply test the OAM function without additional test equipment.

Description

OAM Cell Generation Method for OAM Function Test in ATM Switching System

1 is a block diagram showing an example of an ATM switch to which the present invention is applied.

1 is a flowchart illustrating a method of generating an OAM cell according to the present invention.

(A)-(c) of FIG. 3 is a format diagram of an ATM cell.

* Explanation of symbols for main parts of the drawings

1-0 to 1-7: Subscriber Switching Subsystem (ALS)

2 Central Switching Subsystem (ACS) 3 ISNM

4: NSCM

10-0 to 10-6: Medium and low speed subscriber registration module (MSIM)

11-0 ~ 11-8: Low speed subscriber matching board (LUIA)

12: medium and low speed subscriber registration control board 20: subscriber switching module (ASNM)

21,23: link interface block 22: subscriber switching block

211,212,231,232: Local Link Registration Board (LLIA)

221: switching memory board (SMEA) 222: switching control board (SCTA)

ALS: ATM Local Switching subsystem

ACS: ATM Central Switching Subsystem

ISNM: Interconnection Switching Network Module

NSCM: Network Synchronization Control Module

LUIA: Low speed User Interface board Assembly

ASNM: Acess Switch Network Module

LLIA: Local Link Interface board Assembly

SMEA: Switch Memory board Assembly

SPTA: Switch Processor and Timing board Assembly

SCP: Subscriber Call Processor

The present invention relates to a technique for generating an OAM cell to test OAM functionality in a block for matching low to medium speed subscribers of an ATM exchange.

Recently, with the rapid growth of the multimedia field, the B-ISDN (Broadband Integrated Services Digital Network) has emerged due to the demand for a communication network for digitally transmitting broadband signals such as video signals. 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 exchange technology. The ATM transfers information using a fixed length (53 bytes) information block called a cell using an Asynchronous Time Division Multiplexing (ATDM) scheme. Here, as shown in FIG. 3 of the ATM cell, a 5-byte header section and a 48-byte user information section are provided, and the 5-byte header has a header structure on a user network interface (UNI). The header structure at the user interface (UNI) is divided into 4 bits of Generic Flow Control (GFC) and 4 bits. It consists of a virtual path identifier (VPI: Virtual Path Identifier), the second byte consists of a 4-bit virtual path identifier (VPI) and a 4-bit virtual channel identifier (VCI: Virtual Channel Identifier), 3 bytes are composed of 8 bits of virtual channel identification number (VCI), 4 bytes are 4 bits of virtual channel identification number (VCI), 3 bits of payload type (PT) and 1 bit of cell discard CLS (Cell Loss Priority), and the fifth byte is an 8-bit header error control (HEC: Header Error Control).

Also, when looking at the header structure at the network node interface (NNI), the general flow control (GFC) in the first byte of the user network interface (UNI) described above is used as the virtual path identification number (VCI). It can be seen that the header structure of the user network interface (UNI) is the same.

On the other hand, in ATM technology, the ATM switch generally processes the OAM cell for management separately from the user's cell.

That is, after the OAM cell and the user cell are inputted together through the UNI (User Network Interface) through the low speed subscriber matching board (LUIA), the subscriber matching control board arrives at the subscriber matching control board. Isolate a cell and provide services for it.

However, in order to test whether the subscriber matching control board processing the OAM cell normally processes the OAM cell, an additional OAM cell generator is required to provide the OAM cell, and thus the cost is increased. There is an inconvenient problem because additional work is required.

Accordingly, an object of the present invention is to provide a method for generating an OAM cell for testing an OAM processing function of a medium to low speed subscriber matching block for matching a medium to low speed subscriber in an ATM switch.

In order to achieve the above object, the method of the present invention, in the ATM switch for switching the low-speed subscriber to exchange ATM cells, if the OAM cell test is required, the step of the cell for the register register; Displaying an OAM test in an operation terminal; Generating an OAM cell by registering an interrupt service routine for the OAM test and setting the VPI to a predetermined value for the end-to-end test and setting the OAM type to a predetermined value for the AIS test; Generating an OAM cell by setting the VPI to a predetermined value other than the end-to-end test and setting the OAM type to a predetermined other value if the RDI test; And transmitting the generated OAM cell to a destination.

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

FIG. 1 is a block diagram showing an example of a configuration of an ATM switch to which the present invention is applied. The configuration includes a subscriber switching subsystem (ALS: 1-0 to 1-7) for connecting subscribers and exchanging primary cells. It is largely divided into Central Switching Subsystem (ACS) 2, which performs the interconnection function between ALSs and acts as a distribution device for large systems.

In addition, the subscriber switching subsystem (ALS: 1-0) includes a self routing switch module (ASNM) 20 and includes a plurality of low and low speed subscriber matching modules 10-0 for matching low and low speed subscribers. 10-6), and when the number of subscriber-side links is n and the number of link-side links is m, it has an aggregation function of n: m. In this case, the self-writing means that a routing header is attached before each cell enters the switch network, and the head network uses this head to output the corresponding port by hardware logic.

The central switching subsystem (ACS: 2) is a pure inter-connector without call processing that exchanges information between ALSs, the Inter-connect Switch Network Module (ISNM: 3), and the Network Synchronization Control Module (NSCM). 4) and Operation and Maintenance Control Module (not shown).

The low-speed subscriber matching module (10-0) of the subscriber switching subsystem may include a plurality of low-speed subscriber matching boards (LUIA0 to LUIA8: 11-0 to 11-8) or one medium-speed subscriber matching for connecting low-speed subscribers. Board and a medium and low speed subscriber matching control board 12 for controlling the matching of medium and low speed subscribers, wherein the subscriber switching module 20 is connected to a local link block 21 and a central switching subsystem side for connecting subscribers. It consists of a local link block 23 and a switching block 22 for connection. The switching block 22 is composed of a switching memory board (SMEA) 221 and a switching memory control board (SCTA) 222 that controls the switching memory board 221 according to a command of the SCP.

In addition, although not shown separately in the figure, in the subscriber matching module 10, the receiver of the subscriber module ATM layer classifies a user data cell, a user signal cell, a meta signal cell, and an OAM cell from cells transmitted from a physical layer. Data cell and user signal cell are transmitted to user parameter control unit (UPC) to perform UPC, and VPI / VCI is received so that the cell can be delivered to the destination through the established call path by receiving the cell output from UPC unit. The meta signal cell is recognized by the matching controller 12 and converted into an internal message (IPC) cell and input to the switch network to transfer the signal path to the block for managing the signal path. Is processed by the matching control unit 12. At this time, the IPC message is formed as a PDU in the form of AAL5.

In addition, the subscriber transmitter distinguishes an internal message (IPC) cell, a user data cell, and a user signal cell from the cells transmitted from the switch network, and transmits the user data cell and the user signal cell to the physical layer to be delivered to the subscriber. VPI / VCI conversion is performed and delivered to the physical layer. The internal message (IPC) cell is delivered to the subscriber matching control unit 12 to perform a matching control function such as changing various tables. That is, the subscriber matching control unit 12 generates or receives and processes an internal message cell for communicating with an upper control system (SCP), processes an OAM cell delivered from a physical layer, and performs a virtual path OAM with a subscriber. Create an OAM cell and deliver it to the physical layer.

When the physical layer receiving unit is notified of the presence of an ATM cell from the physical layer, the physical layer reads the system clock from the FIFO with the physical layer and checks the VPI / VCI. The OAM cell and the meta-signal processing cell are transmitted to the OAM processing unit. The user signal cell is transmitted in the UPC block.

The cell writing processing unit is composed of a table for converting VPI / VCI, attaching a routing tag, and converting VPI / VCI of the cell header when a cell is input from the UPC block, and inserting a 3-byte routing tag before the cell header. do. The configuration of the routing table uses an index method that can use all areas of VPI / VCI, and if the cell is entered by configuring with DPRAM, the corresponding routing tag and VPI / VCI are recorded in the index by referring to VPI / VCI in the cell header. It finds and prints out the existing address and the routing table is changed / deleted by the control of management plane.

The header conversion unit is composed of a header change table of a broadcast cell, and performs a VPI / VCI conversion when a broadcast cell is input. The output header conversion table for header conversion of the broadcast cell is composed of DPRAM and puts the VPI / VCI output by inputting BCN as an address into the header of the output cell. The output cell header conversion table is changed and deleted by the control of the management plane.

The physical layer transmitter transfers the user ATM cell transmitted from the header converter, the OAM cell received from the OAM processor, and the meta signal processing cell to the FIFO of the physical layer, and outputs 53 bytes of ATM cells by the system clock.

Here, the subscriber matching control unit 12 generates an internal message (IPC) cell and delivers it to the upper processor (SCP), controls the subscriber module according to the internal message (IPC) cell received from the upper processor, and applies the UPC to the UPC block. Pass the parameter to execute to UPC block. In addition, the subscriber matching control unit 12 manages a routing table in the routing processing unit of the user plane according to a message such as a routing change / delete received from a higher processor, and changes / deletes a header translation table received from a higher processor. Manages header conversion table of user plane according to message.

Subscriber Call Processor (SCP) 30 provides system-level services by mounting application software including call processing on the basis of the processor and the OS. The Signaling Handler Part (SHP), It consists of a Call Process Part (CPP) and a Number Translation Part (NTP). The signal processing unit (SHP) performs the AAL and Layer 2 functions and informs the CPP of the Q.2931 for UNI and the B-ISUP signal for the NNI, and the call processing unit (CPP) signals for Q.2931 and B-ISUP. Performs processing and examines system resources to determine whether to accept a new call (connection admission control). The NTP performs a function of finding a physical output port corresponding to the called party number. The physical output port number is composed of an ALS number and an output link number. The called ALS number is an outgoing ALS. Incoming ALS is to be translated.

On the other hand, the switch structure of the ATM switch is a limited shared memory structure, which is flexible in dealing with the fluctuations in the input traffic compared to other switch structures, is easy to realize a broadcasting function, and has a memory sharing type that can easily solve a conflict at the output stage.

In the subscriber switch module, the switch memory board (SMEA) 221 receives an input through a local link board (LLIA), multiplexes it, stores it in a memory, translates the head of the received input cell, and performs routing to store the stored memory. It performs the function of sending data to the desired output port.

At this time, the structure of the data transferred between the exchanged links is an Inter-Module Interface (IMI) having a size of 64 octets. This IMI is a 53 octet ATM cell, a 3-octet routing head, and 8 for link maintenance. Consists of octets of data.

In addition, the switch memory control board (SPTA: Switch Processor and Timing board Assembly, 222) is implemented as a microprocessor, SRAM, DPRAM and the like to control the unit switch, first receiving the broadcast path information from the broadcast control processor When receiving a broadcast call, it enables broadcasting service, manages the status of FIFO, memory, and I / O ports mounted in Switch Memory board Assembly (221), and reads and maintains error information of input cells detected by SMEA. It performs the function of reporting to the processor. When the input cell exceeds / recovers the threshold by managing the priority control function, the over / recovery information is also reported to the maintenance processor.

Referring to the OAM cell generation method of the present invention based on the understanding of the basic characteristics of the ATM exchange as described above are as follows.

First, an operation management maintenance (OAM) function related to the present invention will be described.

OAM function is to check whether user information cell can be delivered to destination well in ATM network. That is, OAM cells are generated periodically or at the request of an operator between each ATM node or between ATM end to end to check the state of a transmission path or a subscriber board.

The OAM cell used for this purpose includes an Alarm Indication Signal (AIS) cell and a Remote Detect Indication (RDI) cell. The AIS cell is a cell that is sent from the ATM switch that detects a failure to the called terminal. A cell is a terminal that receives an AIS cell and sends a cell to the calling terminal to notify a failure so that the calling party no longer sends the user cell.

The OAM function is performed in the low and low speed subscriber matching block of the ATM switch. When the OAM function is to be tested without any equipment, an appropriate OAM cell is generated and sent to the corresponding destination according to the test requirements.

However, even in the case where a failure condition such as actual line break does not occur, the operator of the ATM exchanger needs to generate an AIS cell or an RDI cell arbitrarily and check whether these cells are normally processed, but the present invention is used in such a case. .

2 is a flowchart illustrating a method for generating an OAM cell according to the present invention, wherein an idle state 100 means a state in which a subscriber matching control board does not perform an OAM function.

In step 101 of determining whether an OAM cell test is required, when the operator of the ATM switch instructs the ATM switch to perform an OAM test through a predetermined operation terminal, the subscriber matching control board of the corresponding ATM switch detects it. .

At this time, the OAM test request message transmitted through the operation terminal includes information on end-to-end test approval, information on whether to perform AIS test in end-to-end test, and RDI test if not. Information about whether it is included is included.

As a result of the determination in step 101, if the test of the OAM cell is not required, the process proceeds to step 100 to continuously monitor whether there is a test request of the OAM cell, but if the OAM cell test is required, the process proceeds to step 102.

Determining whether the release of the OAM cell test (Release) is required (step 102) is a process of monitoring whether the release command to release the OAM cell test is input, if the test of the OAM cell is requested in step 101, If there is a command to release the OAM test, the OAM test procedure is not performed any more, and after releasing a predetermined loop register (103), it returns to the idle state (100).

However, if the OAM test is not released, the loopback register is set (104) to allow loopback in the corresponding UNI, and a message (e.g. OAM LOOP TEST) is sent to the operator terminal indicating that the OAM loop test is in progress. Inform the operator that he is testing (105).

Here, the loopback register means a control register located in the low speed subscriber matching boards 11-0 to 11-8, and the signal inputted from the low speed subscriber matching control board to the low speed subscriber matching board according to the state of the loopback register. It is determined whether to send back to the low-speed subscriber registration board.

In other words, by setting the loopback register to a predetermined value, the operator can receive a predetermined OAM cell and check whether normal OAM function is performed.

In the step 107 of registering an interrupt service routine for the OAM test, the interrupt service routine for the OAM test is performed among the interrupt service routines for the operation of the ATM switch.

Now, it is determined whether the OAM mode indicated by the operator through the operator terminal indicates an end-to-end test (108). In the case of the end-to-end test, the value of the virtual path identification number (VPI) of the generated OAM cell is hexadecimal ' Set to 0x04 '(109). If it is not an end-to-end test, set the value of the virtual path identification number (VPI) to hexadecimal' 0x03 '(112).

This is the discrimination information so that other ATM exchanges or end terminals receiving OAM cells generated and transmitted by the corresponding ATM exchange can be recognized by the ATM terminal.

In the case of the end-to-end test, it is determined whether to instruct the AIS test (110). When the AIS test is to be performed, the OAM type information section of the generated OAM cell is set to hexadecimal '0x10'. In operation 111, the generated OAM cell is transmitted to the destination.

If it is not the end-to-end test, it is determined whether to perform the RDI test (113). If the RDI test is to be performed, the OAM type information interval is set to hexadecimal '0x11' (114), and then the set OAM cell Is transmitted to the corresponding destination (115).

As described above, the VPI is located in the header area of the 53-byte ATM cell, and the oam-type information is carried in the information area of the ATM cell.

The OAM cell thus transmitted is looped back from the UNI side and returned to the low and medium speed subscriber matching control board for processing.

As described above, when testing the OAM function in the low- and medium-speed subscriber control board, according to the present invention generates an appropriate OAM cell according to the test requirements, it is possible to simply test the OAM function without additional test equipment It works.

Claims (1)

11. An ATM switch for exchanging ATM cells by accessing a medium to low speed subscriber, comprising: counting registers for a loop if an OAM cell test is required; Displaying an OAM test in an operation terminal; After registering a predetermined interrupt service routine for the OAM test, if the end-to-end test, the virtual path identification number (VPI) of the corresponding OAM cell is set to a predetermined value, and if it is an AIS test, the OAM type is set to a predetermined value to generate the OAM cell. Doing; Generating an OAM cell by setting a virtual path identification number (VPI) to a predetermined other value if not an end-to-end test and setting the OAM type to a predetermined other value if the RDI test; And transmitting the generated OAM cell to a destination.