KR100417820B1 - Method for physical fault checking and OAM cell creation in ATM OAM - Google Patents

Abstract

The present invention separates the generation of ATM OAM alarm generation to the EMS according to its own physical alarm occurrence and the generation of ATM OAM cell among physical layer inspection functions that check whether each virtual connection managed by the device has its own alarm according to the ATM OAM function. To provide a method for physical layer inspection and OEM cell generation in asynchronous transmission mode OEM that compensates for the performance degradation of equipment according to the implementation of OAM in software. A physical checking step of checking whether an alarm has occurred on the ATM layer connection and updating each connection state of the state variable unit; It includes OAM cell generation step to generate AIS cell or RDI cell according to the current state of each connection's state variable.In case of implementing OAM function in software because the hardware of ATM equipment does not fully support OAM function This reduces the load on the central processing unit so that an effective OAM function is performed.

Description

Asynchronous transmission mode OAM's physical layer checking and OAM cell creation method {Method for physical fault checking and OAM cell creation in ATM OAM}

The present invention relates to the physical layer (AM) OAM (physical layer) inspection of the OAM (AM) OAM cell generation, and more specifically to the equipment according to the ATM (Asynchronous Transfer Mode) OAM (Operation Administration and Maintenance) function The present invention relates to a physical layer inspection and a method for generating an OEM cell of an asynchronous transmission mode OH that is suitable for a physical layer inspection function for checking whether an occurrence of an own alarm of each virtual connection managed by the.

In general, the ATM layer is set between an asynchronous transmission mode cell and a virtual path (VP) capable of varying bandwidth and a user terminal to carry actual data on a virtual path (VP). Or VC). In ATM, the label multiplexing is performed by a block of fixed lengths (5 byte header and 48 byte information field) called cells, so that the bandwidth of the communication channel can be changed in time by changing the number of communication of the cells.

The virtual path (VP) refers to a logical path provided by the ATM layer, which corresponds to a bundle of VCs, and is exchanged in bundles. The virtual path terminates at the terminal or network node (VC handler) relayed to the corresponding VP handler in the cross-connection, and the VP is identified by the VP identifier (VPI) of the ATM cell header.

ATM network includes VPH (VP Handler, collectively known as ATM Cross Connector) which is responsible for connection and switching of virtual paths, VCH (VC Handler, commonly known as ATM Switcher) relaying communication channel of virtual channel, playback device responsible for data playback, user It is configured to include a terminal and the like.

Here, the connection between the VPHs is called a digital section. As described above, the connection between the VCHs becomes a VP connection, and the connection between user terminals becomes a VC connection.

Maintenance operation in ATM networks is defined in the OAM Principle in Recommendation ITU-T I.610 of the International Telecommunication Union, and it has largely fault management and performance management functions. In detail, ① performance monitoring ② detection of faults or failures And predicting ③ closing and switching of the system in case of failure, ④ providing information on failures and performance, and ⑤ finding faults. Among them, the fault management function detects a physical process on the network, generates an alarm, and transmits information about a failure to another node on the network.

1 shows a hierarchical structure of a general ATM OAM.

According to FIG. 1, an OAM layer is divided into F1 to F5, and F4 of a virtual path connection (VPC) layer and F5 of a virtual channel connection (VCC) layer correspond to an ATM OAM layer.

OAM information generated in the ATM OAM layer is transmitted through alarm indication signal (AIS), remote defect indication (RDI), continuity check (CC), and loopback (LB) cells, and according to the delivery period, segments and It is divided into end-to-end.

Figure 2 is a block diagram showing a physical inspection function of the ATM OAM according to the prior art.

According to FIG. 2, the DSL APU 210 detects an alarm about the connection with the ATM switch 220 through the network interface STM-1 / DS3 in the end-to-end transfer section, and detects the subscriber interface (ACU). Through this, the alarm about the connection with the ATU-R 230 is detected. Among ATMOAM failure management functions, the function to check whether an alarm occurs is to check the occurrence of a physical alarm on the ATM connection managed by the equipment and notify the EMS when an alarm occurs, and accordingly, the alarm occurs by the EMS OAM cell, AIS or RDI cell. It generates and transmits to the OAM delivery point on each connection that occurred.

Since ATM OAM function must manage each node in software, semaphore is used to manage the state information of each node by sharing the state variable part as a critical section so that other tasks can be shared according to the principle of mutual exclusion. Apply the method of using.

The physical alarm checking function takes the ATM OAM alarm to the upper level for the node that generated the alarm through the task of checking the physical alarm on the physical layer every second for every connection that the OAM function is activated at the same time that the device is started. In order to generate the corresponding OAM cell, the state of the connection of the state variable managed by software is changed and the corresponding alarm cell is periodically generated.

However, according to the related art described above, when a small number of nodes are managed in a single device, there is no problem, but as the number of managed nodes increases, all the alarms generated exponentially are inspected and the corresponding functions are performed. This has a hard disadvantage. In other words, more detailed processing is required.

The present invention has been created to solve the above-mentioned conventional problems, the object of the present invention is the physical physical alarm of the physical layer inspection function to check whether the self-alarm of each virtual connection managed by the equipment according to the ATM OAM function By separating ATM OAM alarm generation and generation of ATM OAM cell to EMS according to occurrence, physical layer inspection and OEM cell generation method of asynchronous transmission mode OEM that complements software performance deterioration according to OAM implementation. To provide.

In order to achieve the above object, the physical layer inspection and the OEM cell generation method of the asynchronous transmission mode OEM of the present invention periodically checks whether an alarm occurs on each ATM layer connection when the equipment is activated and the OAM function is activated. A physical checking step of updating each connection state of the state variable unit; And an OAM cell generation step of generating an AIS cell or an RDI cell according to the current state of the state variable of each connection.

1 is a hierarchical structure diagram of a typical ATM OAM.

2 is a block diagram of a physical inspection function of an ATM OAM according to the prior art.

3 is a software module configuration diagram for performing a physical inspection function of the ATM OAM to which an embodiment of the present invention is applied.

4 is a flow chart of a physical layer inspection and OEM cell generation method of the asynchronous transmission mode OEM according to an embodiment of the present invention.

5 is a flowchart of a method of generating an OEM cell of an AMS in accordance with an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

310: OAM API 311: OAM Cell Creation Task

312: state variable unit 313: physical inspection task

313A: Connection State Change Process 313B: Alarm Generation Process

320: physical layer 330: application layer

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

3 is a configuration diagram of a software module for performing a physical inspection function of an ATM OAM to which an embodiment of the present invention is applied, and FIG. 4 is a physical layer inspection and OEM cell generating method of an asynchronous transmission mode OEM according to an embodiment of the present invention. 5 is a flowchart of a method for generating an OEM cell of an asynchronous transmission mode OEM according to an embodiment of the present invention.

This embodiment does not provide hardware support for F4 and F5 levels of ATM OAM physical layer inspection for multiple channels in transmission equipment such as FLC (Fiber Loop Carrier) or DSLAM (Digital Subscriber Line Access Multiplexer). In case of implementation, it is possible to reduce basic computational load such as central processing unit while maintaining basic trouble management function.

As shown in FIG. 3, the software module on the OAM API 310 (Application Program Interface) located between the lower physical layer 320 and the upper application layer 330 periodically generates an alarm on each connection as the device is started. A physical inspection task 313 for checking whether or not, an OAM cell generation task 311 for generating an AIS cell or an RDI cell according to the current state of the state variable of each connection, and a state variable unit 312 protected by a critical section. It is configured to include.

From the point of view of the equipment, as shown in FIG. 2, the DSL APU 210 detects a physical error occurrence of the connection between the ATM switch 220 on the network side and the ATU-R 230 on the subscriber side. In this case, the software module proposed in this embodiment operates in the OAM API 310 which is in charge of the interface with the upper layer, and checks the alarm occurrence of the connection to the lower physical layer 320 and generates the OAM cell accordingly. Report to the parent.

Looking at each function, first, the state variable unit 312 is a portion having a state variable of each node and a list of nodes executing the continuity check, protected by a critical section, and shared by the other two tasks 311 and 313. It is done.

The physical inspection task 313 checks the physical alarm for every connection that the OAM function is activated and made at the same time as the device is started, and transmits the ATM OAM alarm to the upper level for the node where the alarm occurred, and the corresponding OAM cell. The state of the connection of the state variable unit 312 managed by software is changed in order to generate. Functionally separating them, the alarm generation process 313B is driven to deliver the ATM OAM alarms to the upper level, and a connection state change process 313A is provided to change the connection state of the state variable unit 312.

In this case, the initial flag and the physical flag are placed to distinguish the alarm transmission from the generation of the cell, and thus have a next four-step mode. The four phase modes are OAM active boot, OAM inactive boot, transition to OAM active boot and then inactive phase, and transition to OAM inactive boot and to active phase. In addition, when the transition between the OAM active state and the inactive state is passed through the step of initializing the state of each connection to synchronize the alarm information.

The OAM cell generation task 311 generates an alarm cell according to the state of the state variable unit 312 and the normal / AIS / RDI state that is managed by software for every connection at the same time as the device is started. Do it. Also in this case, it is set to operate in different periods according to the above-described modes.

As described above, in this embodiment, each node must be managed in software, so that the semaphore method is used to manage the state information of each node while sharing the three tasks according to the principle of mutual exclusion by setting the state variable unit 312 as a critical section. use.

In more detail, as illustrated in FIG. 4, the physical inspection task 313 may include the state information regarding the connection when the device is initialized or when the switch to the backup mode occurs due to the inability of the CPU. The initial flag is set in consideration of the delay time until the update is completed (hereinafter, referred to as initialization delay time). Here, the initialization delay time set in consideration of the completion of the update of the status information may be appropriately set. Hereinafter, it is assumed that 20 seconds. In addition, the initial flag value is set to '0' at initial booting, and to '1' if only alarm occurs, and to be operated by a physical flag when '2' or more. This initial flag value is checked after the initialization delay time has elapsed, and if the value is '0' or '1', it is increased by '1' (S41 to S45).

If the alarm is set with the connection information already set at the first task start and the alarm cell goes out accordingly, the DSLAM equipment does not cause a problem but the connection is disconnected due to excessive alarm on the ATM switch side. Therefore, when the initial flag value is '0' or '1' during initial task startup, the initial flag value is increased by '1'.

And according to the performance degradation caused by the error of the majority of connection connection, the user sets the physical flag to change the value when the user wants to perform only basic functions among the OAM functions. Divide the steps into actions. The physical flag value is set to '0' for active boot, '1' for inactive boot, '2' for active mode, and '3' for inactive mode.

At this time, the alarm cell setting cycle and the alarm setting cycle are alternated at the first occurrence of the alarm. After setting the alarm, the alarm cell is sent in the next cycle. That is, after the alarm is generated, only the alarm cell needs to be sent periodically until the alarm is released.

Therefore, in the case of OAM active booting, it operates normally after giving an initialization delay time, and OAM inactive booting operates by arranging an alarm setting period and an alarm cell generation period alternately after an initialization delay time. The transition from the OAM active state to the inactive state or from the inactive state to the active state is converted to the normal state which is the current initialization state, and then the same process as in the case of the inactive boot or the active boot is repeated.

The operation according to the four-step mode will be described with reference to the case of checking the alarm generated from the equipment AADU and PMC as follows.

After the initial flag value is set, the unit fail check routine of the AADU is performed. This routine checks whether an alarm occurs due to a failure of the AADU unit, and ends when it is confirmed that the alarm does not occur. On the other hand, when the alarm of the unit occurs, the physical flag value is '0' (active boot) or '2' (active mode) and the initial flag value is '2' (that is, set to be operated by the physical flag). If it is determined that this condition is established, the alarm generation process (313B) is activated to generate an alarm to the upper application layer 330 and generate an alarm OAM cell, and the condition is not established. If it is determined that no, the alarm is generated through the alarm generating process 313B, and if the timer value is '1', the timer is reset to '0' and the alarm OAM cell is generated. The routine OAM cell is terminated without generating (S46 to S52).

Subsequently, it is checked whether the physical flag value is '0' or '1', that is, whether it corresponds to a transient transition state. The transient transitions are transitioning to basic and full mode, in which case all settings must be reinitialized. After this initialization process, alarms are set and cells are generated in basic mode and pull mode again. Therefore, AADU and PMC failure checking routines are performed to synchronize. That is, after performing the AADU unit failure check routine following the process of steps S46 to S52, and performing the PMC Physical Fail Check routine following the process of steps S59 to S65 to be described next, the physical flag value is Check whether it is '1' (disabled booting) (S53 to S56).

If it is determined in step S56 that the physical flag value is not '1', the physical flag value is set to '3'. If the physical flag value is '1', the physical flag value is set to '2' (S57 and S58).

As described above, the operation related to the transition between the OAM active state and the inactive state is changed by the user's command. In the basic mode-> full mode, the flag value is transferred in the order of 3-> 0-> 2. In the full mode-> basic mode, the transition is in the order of 2-> 1-> 3.

If it is determined in step S53 that it does not correspond to the transient transition state, the PMC failure check routine is performed. The routine terminates immediately if no alarm occurs in the PMC, but if the alarm occurs in the PMC, the physical flag value is' 0 '(active boot) or' 2 '(active mode) and the initial flag value is' 2 '(if it is set to be operated by a physical flag), and if it is determined that this condition is satisfied, the alarm generation process 313B is started to generate an alarm to the upper application layer 330 and then alarm. When the OAM cell is generated and it is determined that the condition is not established, the alarm is generated to the upper level through the alarm generation process 313B. If the timer value is '1', the timer is reset to '0' and the alarm OAM cell is reset. If the timer value is not '1', the routine terminates without generating the alarm OAM cell (S59 to S65).

After the PMC failure checking routine is finished, the physical flag value may be changed (S66 to S67).

After performing steps S57 and S58, if the physical flag value is not changed in step S66, or after the physical flag value is changed in step S67, the controller waits for an alarm setting period and returns to step S42 to repeat the subsequent process. . At this time, the alarm setting period is preferably about 1 second (S68).

In the above process, the physical inspection task 313 is performed to detect an alarm occurrence of the physical layer 320 and generate an alarm cell. Next, an alarm cell generation process by the OAM cell generation task 311 will be described.

In the case of generating an alarm cell in the OAM cell generation task 311, the alarm should generate a cell every 1 sec. However, in order to cancel an alarm, the alarm cell should not be received for about 2.5 seconds. It is necessary to maintain the alarm status by creating a one-time operation, and to adjust the incidence rate of AIS and RDI per second through a function (for example, sendOAM) for transmitting an OAM cell so that only basic operation is possible when the OAM is inactive. do.

Referring to FIG. 5, when the OAM cell creation task 311 is activated, it is checked whether the physical flag value is '1' (inactive boot) or '3' (inactive mode) (S510).

So if it is determined that it is not in the inactive boot or inactive mode, the state variables of each connection are taken from the state variable portion 312. Since the state variables are protected in a semaphore method, the operation of obtaining the variable value is possible by acquiring access rights using 'Spend' and the like (S511).

The RDI cell is transmitted only when the AIS state variable of the F4 level is '1' by checking the imported state variable, and the alarm is transmitted to the upper level (S512 to S513).

If the AIS state variable at F4 level is not '1' or the alarm is sent to the upper level, it is checked whether the RDI state variable at F4 level is '1'. If the RDI state variable of the F4 level is '1', the alarm is transmitted to the upper level (S514 to S515).

If the RDI state variable at the F4 level is not '1' after the alarm is delivered to the upper level in step S515, or if the AIS state variable at the F5 level is '1', the RDI cell is transmitted and the alarm is transmitted to the upper level (S516 ~). S517).

If the AIS state variable at the F5 level is not '1' after the alarm is delivered to the upper level in step S517 or if the RDI state variable at the F5 level is '1', the alarm OAM cells are transmitted (S518 to S519).

After performing the operation in the non-inactive boot or non-inactive mode as described above, transfer access to the state variable using 'Spost', etc. according to the semaphore method. After waiting for about 1 second), the process returns to step S510 (S520 to S521).

On the other hand, the operation in the case where it is determined in the inactive boot or inactive mode in step S510 follows the following flow.

First, the RDI cell is transmitted only when the AIS state variable of the F4 level is obtained by taking the state variable (S531 to S533).

When the RDI cell is transmitted in step S533 or when the AIS state variable at the F4 level is not '1', the RDI cell is transmitted only when the AIS state variable at the F5 level is '1' (S534 to S535).

When the RDI cell is transmitted in step S535 or when the AIS state variable at the F5 level is not '1', after the access right of the state variable is transferred, the controller waits for 2 seconds and returns to step S510. That is, in the OAM active state, even if an alarm cell generation cycle for maintaining an alarm state is about 2 seconds, the corresponding alarm is not released (S536 to S537).

Thereafter, the above-described operation is repeated.

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 physical layer inspection and the OEM cell generation method of the asynchronous transmission mode of the present invention, the OAM function in the hardware of the ATM equipment does not fully support the OAM function in the case of implementing the OAM function in software equipment due to excessive load Compared with the prior art, which caused a deterioration in overall performance, the load on the central processing unit can be reduced, and thus the OAM function can be more effectively performed.

Claims (7)

A physical inspection step of periodically checking whether an alarm has occurred on each ATM layer connection when the equipment is started and the OAM function is activated, and updating each connection state of the state variable unit; The OAM cell generation step of generating an AIS cell or an RDI cell in accordance with the current state of the state variable of each connection. The method of claim 1, wherein the state variable unit, It holds the state variable of each connection and the connection list that executes the continuity check, and is protected as a critical section by semaphores so that it can be shared by the physical check task and the OAM cell creation task. Physical Layer Inspection and OEM Cell Generation Method. The method of claim 1, wherein the physical inspection, Inspecting a physical alarm for all connections that the OAM function is activated and established according to a set cycle; Generating an OAM alarm to a higher level for the connection where the physical alarm occurred; The connection state change process is driven to change the state for the corresponding connection of the state variable unit to generate an OAM cell corresponding to the physical alarm. AMC cell generation method. The method of claim 3, Place initial and physical flags to distinguish the top-level forwarding of the alarm and the generation of the OAM cell according to the combination of the flag values so that OAM active boot mode, OAM inactive boot mode, transition to inactive mode after OAM active boot, and OAM inactive The physical layer inspection and OEM cell generation method of the asynchronous transmission mode OS, characterized in that the transition to the active mode after booting. The method of claim 4, wherein When the initial flag value and the physical flag value are determined to correspond to a transient transition between the OAM active state and the OAM inactive state, initializing the state variables for each connection of the state variable unit to synchronize the alarm information. Physical layer inspection of the asynchronous transmission mode OEM and method for generating OMS cell. The method of claim 1, wherein the OAM cell generation, Checking the state of all connections with reference to the state variable according to a set period simultaneously with the start of the equipment; And generating an AIS cell or an RDI cell for alerting according to the normal / AIS / RDI state change of the connection. The method of claim 6, The generation period of the AIS cell and the RDI cell is asynchronously characterized in that it is set in a range that is longer than the alarm cell generation period required by the OAM failure management function and shorter than the time without alarm reception required when the alarm is released. Method of physical layer inspection and mode generation of OEM cell.