KR100763706B1 - Loop-back test of cells in UTOPIA interface - Google Patents

Abstract

The present invention is to enable a physical path test for a subscriber line in service by looping back a desired test cell and normal user cell during a system service in a UTOPIA interface. ; Comparing the physical address of the cell received by the receiver of the physical layer with the address of the physical layer under test; If the physical address of the cell received by the receiver and the address of the physical layer under test match, looping the received cell back to the transmitter; If the physical address of the cell received from the receiver and the address of the physical layer to be tested do not match, the received cell is received and processed according to the utopia interface, and the internal cell path of the ATM system is periodically tested even during service. As a result, it is easy to find a path failure and increase the reliability of the service.

Description

Loop-back test of cells in UTOPIA interface

1 is a block diagram of a general utopia interface device.

2 is a flowchart of a cell loopback test method at a utopia interface according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

110: master 120: slave

111, 121: transmitter 112, 122: receiver

The present invention relates to a subscriber line test of a communication system. More specifically, a desired test cell is looped back during system service in a Utopia (Universal Test and Operations Physical Interface for ATM, or UTOPIA) interface, and a general user cell is processed normally. An apparatus and method for selective loopback testing of an asynchronous transmission mode cell enabling the testing of a subscriber line in service.                         

Utopia interface applied to communication system has the function to selectively loop back only a specific Asynchronous Transfer Mode (or ATM) cell designated by CPU (Central Processing Unit), and between ATM layer and physical layer in ATM forum. This is an international standard for the interface of devices. It is used for all chips in ATM and physical layer.

The path test in the conventional ATM system is performed by generating a cell in a processor having a segment and reassembly (SAR) function capable of inserting / extracting test cells, and comparing the cell returned with a loopback from a framer, etc., of a physical layer. do. Typically, a framer that supports loopback or a Very Large-Scale Integration (VLSI) chip that performs utopian matching is configured to loop back all cells received at the interface.

1 is a block diagram of a general utopia interface device.

According to FIG. 1, a utopia interface is implemented between a master 110 chip of an ATM layer and a slave 120 chip of a physical layer. In general, the master 110 interfaces with a plurality of slaves 120. Data is exchanged via the transmitters 111 and 121 and the receivers 112 and 122, and the clocks (TxClk, RxClk), 8-bit data (TxData [7: 0], RxData [7: 0]), sockets (TxSoc, RxSoc), transmit and receive activation signals (TxEnb, RxEnb), and cell transmit and receive enable signals (TxClav, RxClav) are exchanged.

The loopback function of the conventional subscriber board is simply a transmitter TX on the master 110 side to a receiver RX on the slave 120 side and a receiver RX on the master 110 side in a chip performing utopia matching. Are connected to the transmitting unit TX on the slave 120 side to loop back the entire interface. Therefore, all the cells including the service cell received at the interface are looped back and the service is disconnected during the path test.

Although these Utopia interface devices provide the ability to loop back paths, all cells loop back so that they cannot be used during service and cannot perform online automatic path testing. This is a serious limitation of the system, and even if the path is disconnected due to a hardware / software failure that the system cannot detect, it may not be recognized.

On the other hand, ATM has OAM (Operations, Administration & Maintenance) function, but there is a method to test online, but only when requested by the operator, the online test is performed, and even if the failure is detected by the OAM function, There is a problem that can not easily determine the location of. As such, the conventional loopback function does not provide a function of testing a physical path at regular intervals during service.

The present invention was created to solve the above-mentioned conventional problems, and an object of the present invention is to loop back a desired test cell during a system service in a UTOPIA interface and to handle a normal user cell normally to a subscriber line in service. An object of the present invention is to provide an apparatus and method for selective loopback testing of an asynchronous transmission mode cell that enables physical path testing.

Cell loopback test method in the utopia interface of the present invention for achieving the above object comprises the steps of setting a physical layer to be tested; Comparing the physical address of the cell received by the receiver of the physical layer with the address of the physical layer under test; If the physical address of the cell received by the receiver and the address of the physical layer under test match, looping the received cell back to the transmitter; If the physical address of the cell received by the receiving unit and the address of the physical layer to be tested does not match, the received cell is characterized in that it comprises the step of receiving processing according to the utopia interface.

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

This embodiment is applied to the interface between the master 110 of the ATM layer and the slave 120 of the physical layer, as shown in FIG. 1, and includes a specific virtual path identifier / virtual channel identifier (VPI / VCI). The Utopia interface method provides a function of selectively looping back only cells of a virtual channel identifier), and loops back only cells of a specific VPI / VCI designated to a CPU (Central Processing Unit, not shown).

2 is a flowchart of a cell loopback test method at a utopia interface according to an embodiment of the present invention.

Receiving units 112 and 122 on the master or slave 120 side in charge of the utopia interface receive the cell transmitted from the other side. The receiving CPU determines whether the cell is a loopback target when the cell is received. This is because the cell path test loops back only the cell designated as the test cell, rather than looping back all the cells to be transmitted and received (S21 to S22).

In addition, the loopback test may be performed at a predetermined time interval, that is, every set cycle. In addition to setting the loopback function to be activated at regular intervals, the loopback function may be activated at an arbitrary time according to a system operator's selection. The CPU of the master 110 and the slave 120 is in charge of activation and deactivation control of the loopback function.

When the system is initialized or when the master 110 or the slave 120, which is the chip in charge of the utopia interface, is initialized, the loopback function is basically set to inactive and the loopback function is periodically or aperiodically activated by the CPU. do.

The receiving CPU performs loopback only when the received cell is the target of the loopback. The ability to loop back the cell can be easily implemented in a high level hardware design language and does not require much of the gate of the VLSI. Hereinafter, an operation of generating and transmitting a test cell on the master 110 side and looping back the test cell received on the slave 120 side will be described.

First, if the loopback function is inactive, the receiver processes all cells normally according to the utopian interface technique (S27).

When the loopback function is activated, the slave 120 monitors the received cell and checks whether it is a loopback target, processes all non-target cells as normal, and loops back the cell that is the loopback target from the receiver 122 to the transmitter 121. []                     

The cell loopback process will be described in detail. First, when a cell is detected, the receiver 122 temporarily stores the cell in a buffer. The cells stored in the buffer are looped back in such a manner that they are inserted into the transmitter 121 when there is no cell coming into the transmitter 121. As such, the ATM and physical layers loop back in the same way to provide local and remote loops.

The activated loopback feature provides two modes. Such are the 'PHY mode' looping back all the cells of the physical layer and the 'cell mode' looping only for a specific VPI / VCI, the mode can be selected and the loopback control according to each mode is in charge of the CPU (S23).

If the PHY mode is set, the CPU checks the physical address of the currently received cell to determine whether it matches the configured physical layer address. As a result of the determination, all cells whose physical addresses match are looped back. In this case, the address of the physical layer to be tested may be inserted into the test cell transmitted from the master 110 and transmitted to the slave 120 (S24 and S26).

On the other hand, when set to the cell mode, the CPU checks the VPI / VCI of the currently received cell to determine whether the path to test. If the VPI / VCI of the path to be tested is specified, the CPU checks the cell under test by comparing with the VPI / VCI of the received cell. For example, when the master 110 inserts and sends the VPI / VCI of the path to be tested in the test cell, the slave 120 compares the VPI / VCI and confirms that it is a test cell. Loop back to (S25 ~ S26).

To summarize the case where the receiver 122 does not loop back the received cell, when the loopback function is inactive, the loopback function is active and in PHY mode, and the physical address of the received cell is different from the address of the physical layer to be tested. And when the loopback function is active and in cell mode, when the VPI / VCI of the received cell is different from the path to be tested (S27).

After completing the loopback process or the normal process for one cell, the receiver 122 returns to step S21 to detect the next received cell and then repeats the above-described process.

As such, during normal cell processing between the master and the slave that performs the utopia interface, the test cell can generate and send the test cell, and only the test cell can be selectively looped back from the receiver, thereby testing the cell path simultaneously with the service. can do.

The embodiments described above are within the scope of various changes, modifications, and equivalents of the present invention. Therefore, the present invention is not limited to the description of the examples.

According to the cell loopback test method at the utopia interface of the present invention, the internal cell path of the ATM system having the utopia interface can be periodically tested during service. This enables immediate recognition of path failures of all cells, such as hardware and software, and increases service reliability.

In addition, by adding one check point for the path test, it is easier to determine the location of the failure in the event of a system failure.

Claims (3)

Setting a physical layer to be tested; Comparing the physical address of the cell received by the receiver of the physical layer with the address of the physical layer under test; If the physical address of the cell received by the receiver and the address of the physical layer under test match, looping the received cell back to the transmitter; And if the physical address of the cell received by the receiver and the address of the physical layer to be tested do not match, receiving the received cell according to a utopia interface. The method of claim 1, Setting a path to be tested; Comparing the virtual path identifier / virtual channel identifier and the test target path of the cell received by the receiver of the physical layer; If the virtual path identifier / virtual channel identifier and the test target path of the cell received by the receiver match, looping the received cell back to the transmitter; And if the virtual path identifier / virtual channel identifier and the test target path of the cell received by the receiver do not coincide, the received cell is further processed according to a utopia interface. Test Methods. The method according to claim 1 or 2, If the loopback function is not activated, the cell loopback test method for a utopia interface is characterized in that all cells received by the receiver of the physical layer are immediately received.

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