KR20030057590A - Automatic protection switching for transmission system - Google Patents

Abstract

PURPOSE: An automatic protect switching processing method of a transmission system is provided to enhance the speed of an optical line and a unit automatic protective switch and performance of a system by using a switching method according to a hardware in a multiplexing period within a transmission equipment. CONSTITUTION: Each task for checking a switching condition generation checks continuously whether an automatic protect switching condition is generated(S51). When the automatic protect switching condition is generated, a Queue Post of ID of the corresponding unit, an event type and the corresponding event is performed to a task for discriminating the priority of the switching condition(S52). Then, the task compares the event and then discriminates whether it is the case that a switching operation must be performed. If a bidirectional switching operation is needed, the switching operation must not be performed(S53). If a switching operation is needed, the task is operated, then management and preparation states of a hardware are changed, a buffer is updated, then a generation of the switching operation and the current management and preparation unit states are notified to an event manager through an event task(S54-S56).

Description

Automatic protection switching for transmission system

The present invention relates to automatic protection switching processing of a transmission system, and more particularly, to implement a software structure for improving optical path and unit automatic protection switching speed and system performance in a multiplexing section in a transmission equipment. The present invention relates to an automatic protection switching processing method of a transmission system that is suitable.

In general, the optical communication system is designed to be switched to the protection line in a short time in the event of a failure in the line operating in a large capacity. For example, a communication system consisting of two operating units and one protection unit will have a 2: 1 switching ratio.

In this switching structure, the operating unit operates in the working mode, and the protection unit operates in the standby mode. Any unit may operate in either the working mode or the reserve mode at a particular point in time.

The main field of application of the switching structure is the optical transmission system. The optical transmission system uses DSG to interface DS multiplexing signals, multiplexes them, forms a frame with a certain format, and transmits them through an optical repeater through an optical transmission path. Demultiplexing to restore the original DS signal. The switching system is applied to the DS interface block in the optical station equipment of the optical transmission system.

Here, the switching structure will be described based on the DS3 interface.

1 is a block diagram of a transfer processing of a general transmission system.

Referring to FIG. 1, a splitter unit 110 for dividing an input signal into two, a plurality of DS3 interface units 120 and 130 for receiving a signal divided from the splitter unit 110 and DS3 interface, and a fault of a specific unit It is configured to include a protection switch (PSW) (140) to perform the switching control function by switching the operation mode of each DS3 interface unit 120, 130 when a certain situation such as occurs.

The splitter unit 110 receives the received signal TRTI # and divides the signal into two signals. The splitter unit 110 integrates the signals applied from the DS3 interface units 120 and 130 and outputs the single signal TTIP #. .

Here, the DS3 interface unit 120 and 130 are provided in plural numbers according to the transfer ratio. At least one unit operates in a standby mode, such as the DS3 interface unit 130 in a standby state. The two split signals from the splitter unit 110 are input to the DS3 interface unit 120 operating in the operation mode and the DS3 interface unit 130 operating in the standby mode, respectively. The DS3 interface unit 130 in the operation mode includes a plurality of units performing the DS3 interface.

When a predetermined condition is achieved in the switching structure operated as described above, the protection switch (PSW) 140 operates to control the switching between units. The hernia or mounting of each unit achieves automatic protective switching conditions. As a typical example, when a unit is detached from the DS3 interface unit 120 in the operation mode, the DS3 interface unit 130 in the standby mode is switched to the operation mode and is in charge of the DS3 interface function of the detached unit. The return transfer operation according to the unit mounting is performed in reverse.

2 shows a software structure related to automatic protection switching processing of a conventional transmission system. The software module includes an interrupt and polling task for storing switching conditions generated in hardware and optical signals in global variables, and an auto-protection switching task for switching redundancy units and updating the transfer status buffer by periodically polling the global variables. 260, and an event task 270 for notifying a working or standby state of the redundant unit when a transfer operation occurs.

The object of transfer is the redundancy unit hardware 210, which is controlled by the device driver 220. A plurality of automatic protection transfer tasks (APS TASK) 260 is driven by the polling process of the POLLER 240 to monitor local alarm / power protocol / operator command monitoring, transfer priority determination / power request and response, transfer operation. , And perform alteration event reporting. An event task (EVENT TASK) 270 processes a transfer operation / transfer priority / operation unit report and the like. K1 and K2 bytes are used in the switching operation of the auto-protection switching task 260.

The automatic protection switching task 260 which periodically monitors the switching condition and performs the switching operation when establishing the switching condition is generated as many as the number of groups of units performing automatic protection switching.

The auto-protection switching function will be described focusing on the interrupt and polling tasks stored in global variables generated from hardware and optical signals, and the auto-protection switching task 260 which periodically monitors and switches over global variables.

One auto-protection switching task 260 periodically operates in the following order.

First of all, the status of global variables (unit hernia, hardware failure, RS-LOS, RS-LOF, MS-AIS, MS-EBER, MS-SD) is checked for signal failure and signal degradation. Classify the transfer conditions.

The transfer operation or status change shall be determined in accordance with the transfer priorities required in ITU-T G.783 (Lockout, Forced, Signal Fail, Signal Degrade, Manual).

The operator's Manual, Forced, and Lockout commands operate by changing the transfer state buffer during the polling task.

When a switchover condition is established, the software buffer is updated, the hardware operation and spare status are changed, and the event manager is notified of the operation and spare status of the changed unit.

Figure 3 shows the service disconnection time in the conventional one-way automatic protection switching. When the unit hernia, which is one of the automatic protection switching conditions, occurs during unidirectional switching (S210), the service is disconnected (S220 ~ S230) until the software prioritization and transfer processing is completed and the operating state of the hardware is changed.

Figure 4 shows the service disconnection time in the conventional two-way automatic protection switching. If the unit is dismounted, there is a loss of signal (LOS) in the power station. A request for automatic protection transfer is sent from the home country to the power station, which causes the power transfer. In case of a power transfer, an auto protection transfer response is sent from the power station to the own station, and transfer of own station is performed. Therefore, the service disconnection time of the home country is the time from the dismounting of the unit to the response of the counterparty to the changeover of the home country.

However, according to the related art described above, there are the following problems in terms of switching operation and system performance within 50 ms required by ITU-T G.783.

First, all transfer operations are software controlled. There are two ways to control the operation and preliminary state of the hardware: using the functions provided by the hardware directly and using the buffer of the software. However, switching by current operator's command and switching by auto-protection switching conditions (unit hernia, hardware failure, signal failure, signal degradation) are all controlled by software. In this case, switching by auto-protection switching condition rather than the operator's command becomes difficult to guarantee the switching speed within 50ms when operating with other tasks in the real-time operating system.

In addition, the system takes up a lot of system resources. In order to switch within 50ms, the polling task should poll quickly with high priority. The problem, however, is that, under normal conditions without affecting service, the load is placed on the system by constantly monitoring the switching conditions. In addition, since polling tasks are generated as many as the number of redundant unit groups for automatic protection switching, the more redundant units, the lower the performance of the system.

The present invention was created to solve the above-mentioned conventional problems, and an object of the present invention is to improve the speed and system performance of the automatic switching of the optical path and the unit by using a switching method by hardware in the multiplexing section in the transmission equipment. It is to provide an automatic protection switching processing method of a transmission system.

The automatic protection switching processing method of the transmission system of the present invention for achieving the above object comprises the steps of: monitoring whether or not the automatic protection switching conditions set by the hardware for performing automatic protection switching; When the auto protection switching condition is determined to be established, transferring the hardware to a spare unit by performing an auto protection switching operation; And when the transfer to the spare unit is performed, updating the transfer processing software with information on the current operation and the reserve state of the unit of the hardware.

In addition, the automatic protection switching processing method of the transmission system of the present invention for achieving the above object comprises the steps of: checking whether the automatic protection switching conditions set in the set task; Sending an ID, an event type, and an event of a corresponding unit to a task for determining the priority of the switching condition when the set automatic protection switching condition occurs; Changing, by the task of determining the transfer condition, an operation and a preliminary state of hardware to perform the transfer operation according to the priority of the generated transfer condition; And changing the operation and the preliminary state of the hardware according to the generated switching condition, and updating the software according to the operation and the preliminary state information of the hardware.

1 is a block diagram of a transfer processing of a general transmission system.

Figure 2 is a software structure diagram of the automatic protection switching processing of the transmission system according to the prior art.

Figure 3 is a flow chart showing the service disconnection time in the one-way automatic protection switching of the transmission system according to the prior art.

Figure 4 is a flow chart showing the service disconnection time in the two-way automatic protection switching of the transmission system according to the prior art.

5 is a software structure diagram related to automatic protection switching processing of a transmission system according to an embodiment of the present invention.

6 is a flowchart showing a service disconnection time in one-way automatic protection switching of a transmission system according to an embodiment of the present invention.

7 is a flowchart showing a service disconnection time in two-way automatic protection switching of a transmission system according to an embodiment of the present invention.

8 is a flowchart of an automatic protection switching processing method of a transmission system according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

410: Check national transfer condition task 420: Check the power protocol protocol task

430: queue pending task 440: transfer priority determination task

450: transfer operation task 460: event task

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

FIG. 5 is a block diagram illustrating a software structure related to automatic protection switching processing of a transmission system according to an embodiment of the present invention. FIG. 6 is a flowchart showing a service disconnection time in one-way automatic protection switching of a transmission system according to an embodiment of the present invention. 7 is a flowchart illustrating a service disconnection time in the bidirectional automatic protection switching of the transmission system according to an embodiment of the present invention, and FIG. 8 is a flowchart of the automatic protection switching processing method of the transmission system according to the embodiment of the present invention.

This embodiment consists of two parts: a software process for increasing the automatic protection switching speed and an algorithm for improving the performance of the system.

First, the process for improving the speed of automatic protection switching is the process for improving the speed of automatic protection switching using a function provided by hardware. Unlike the prior art which used only the switching method by software, automatic protection switching It is a situation where conditions are established, that is, a switching method by hardware is used when the unit is dismounted.

Redundant units with automatic protection switching are only signaled by the working unit. If the input signal is received from both the working unit and the standby unit, the signal sent to the next stage (unit) sends only the signal from the working unit. This is done with the hardware buffers in the unit.

The method of determining the working unit may be made by an electrical signal of the hardware itself or may be controlled by software. Both of these methods allow you to change the setting by auto-protection switching priority during operation. After determining the automatic protection switching priority, set or clear the working control bits of the unit's application specific IC (ASIC). For example, if the current state is Normal, Manual, or Auto, the working control bit of the ASIC is cleared. Then, the service disconnection time can be shortened by performing the hardware switchover in the next switching condition. In addition, when the current state is a forced transfer or a transfer prohibited state, the working control bit of the ASIC is set. This ensures that ITU-T G.783 Recommendations are not met because no switchover occurs due to unit hernia, signal failure or operator transfer orders.

If the condition of automatic protection switching (unit hernia, signal failure) occurs in the redundant operation unit, the hardware first determines it and transfers it to the spare unit before the software processes it. After the transfer operation, the software updates the buffer by determining the hardware operation and preliminary status.

If the hardware should not be switched, that is, locked out, the software activates the lockout bit in the hardware to prevent the hardware from switching.

If the software does not enable the lockout bit in the hardware in the event of a unit disconnection, the operating state is changed by the hardware and service is maintained. After that, the software sees the status of the hardware and updates the operational and reserve status.

On the contrary, if the lockout bit for prohibition of switching in the hardware is enabled, switching operation by hardware does not occur even if a unit detachment occurs, thereby satisfying the requirements of the ITU-T G.783 Recommendation.

As shown in FIG. 5, the algorithm for improving the performance of the system uses an event driven method, and is largely composed of four task modules. Such tasks include the tasks 410, 420, and 430 for monitoring a switching condition, a task 440 for determining a switching priority, a task 450 for performing a switching operation, and an event task 460. The number of tasks used in the event-driven method is constant regardless of the number of groups of auto-protection switching units.

Tasks 410, 420, and 430 for monitoring the switching condition include a polling task 410 for checking the auto-protection switching condition of the own station, and a polling task 420 for checking the K1K2 protocol (Remote Request) of a large country when bidirectional switching is performed. ), A queue pending task (Queue Pend Task) (430) waiting for the operator command.

The task 450 that performs the switching operation includes a part for making and sending a K1K2 protocol to a power station and a part for updating a software buffer when performing a bidirectional switching.

Conventionally, auto protection switching manager tasks are generated by the number of groups of redundant units performing automatic protection switching, and each automatic protection switching manager monitors switching conditions, transfer priority determination, hardware switching operation, operation and preliminary status for the corresponding redundant unit. It was responsible for both buffer update and alternating event occurrence.

On the other hand, in the present embodiment, a local request and a large station are transmitted to a redundant unit that performs automatic protection switching by using two polling tasks 410 and 420 and one cup hold task 430 that monitor switching conditions. The request (Remote Request) and the user command (User Request) is polled or queued (Queue).

In the case of unidirectional switching, as shown in FIG. 6, the automatic protection switching condition is directly determined by the hardware and transferred, and the software buffers are updated (S310 to S330).

Therefore, the service disconnection time in the unidirectional switching corresponds to the time from the unit hernia to the hardware switching, and is significantly shortened compared with the time from the conventional unit hernia to the hardware switching after the software processing. Software processing in this embodiment is performed after hardware switching is performed.

In the case of bidirectional switching, as shown in Fig. 7, the automatic protection switching request is transmitted to the counter side when the unit detaches its own station. This is the moment when a loss of signal (LOS) occurs in a large country and service disconnection begins. After the self-transmission request is sent to the power station, the own country performs its own transfer without waiting for a response from the power. Upon receiving the request of its own country, the large country performs the automatic protection switching process so that the large country can be transferred and sends a response to the request to the own side. Therefore, the service disconnection time due to the automatic protection switching becomes the time until the switching of the power is made after the signal loss occurs on the power side.

Referring to the automatic protection switching processing procedure according to this method, as shown in FIG. 8, each task 410, 420, and 430, which checks the occurrence of the switching condition, continuously checks whether the automatic protection switching condition is generated. (S51).

When the auto-protection switching condition occurs, the ID (ID) of the unit, the generated event type and the event are queued to the task 440 for determining the priority of the switching condition (S52).

The task 440 that determines the priority of the transfer condition compares the event to determine whether to perform the transfer operation. If bidirectional transfer is required, the transfer operation should not be performed (S53).

Therefore, when it is determined that the transfer operation should be performed, the task 450 performing the transfer operation is changed to change the operation and preliminary states of the hardware, the buffer is updated, and the transfer is performed to the event manager through the event task 460. Informs the occurrence of the operation and the status of the current operation and the spare unit (S54 to S56).

On the other hand, in the case of bidirectional transfer, the automatic protection transfer protocol is sent to the power station without performing the transfer operation. This auto-protection switching protocol is the K1K2 protocol (S57).

Therefore, it is a structure that can reduce the load of the system because it is in the queued state when no transfer operation has occurred, and in particular, the transfer speed can be improved by separating hardware transfer operation and K1K2 protocol processing from the bidirectional transfer structure.

The event-driven auto-protection switching structure can be used together with the process to improve auto-protection switching speed, thereby improving the auto-protection switching speed and system performance simultaneously.

Algorithms that improve the performance of these systems monitor local alarms, K1K2 protocols, and operator commands, respectively, in the task of monitoring three switching conditions. Local alarm and K1K2 protocol operate by polling, and operator command operates whenever event queue occurs.

The task for determining the transfer condition, the task for determining the transfer priority, and the task for performing the transfer operation each have a queue interface structure. The task that performs the transfer operation receives the queue from the task of determining the transfer priority, performs the transfer operation, or sends the K1K2 protocol to the power station, and updates the operation and preliminary status buffers.

When a transfer operation occurs, the event manager notifies the occurrence of the transfer operation and information on the current operation and the spare unit.

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 automatic protection switching processing method of the transmission system of the present invention, it is possible to improve the speed of the automatic protection switching (APS) to minimize the failure time of the service, and to improve the performance of the system by using an event driven method.

By determining and operating automatic protection switching as a hardware, it can reduce the service down time due to software processing during the switching and can block the operation of the hardware by software when the transfer is prohibited. Therefore, within 50ms required by ITU-T G.783. It is possible to effectively satisfy the operation by the transfer time and transfer priority.

In addition, by changing the software structure from the existing polling method to the event-driven method, the load on the system can be greatly reduced in the absence of a switching operation, and the time to send and receive the K1K2 protocol can be reduced when using the bidirectional switching. Speed is improved.

Claims (9)

Monitoring whether or not a set automatic protection switching condition is established by a hardware that performs automatic protection switching; When the auto protection switching condition is determined to be established, transferring the hardware to a spare unit by performing an auto protection switching operation; Updating the transfer processing software with information on the current working and reserve status of the unit of the hardware when the transfer is made to the spare unit. The method of claim 1, And in the case where the set automatic protection transfer prohibition condition occurs and the hardware should not be transferred, the software further comprises the step of activating the set lockout bit for the hardware so that the switching by the hardware does not occur. How to handle automatic protection switching of the system. The method of claim 1, If the software does not activate a specific bit for prohibiting the transfer of the hardware in the event of the automatic protection switching condition, the spare unit is switched by the hardware to change the operation state and maintain the service, and then the state of the hardware in the software. The automatic protection switching processing method of the transmission system, characterized in that for updating the information on the operation and preliminary status. Checking whether an auto-protection switching condition set in the set task is generated; Sending an ID, an event type, and an event of a corresponding unit to a task for determining the priority of the switching condition when the set automatic protection switching condition occurs; Changing, by the task of determining the transfer condition, an operation and a preliminary state of hardware to perform the transfer operation according to the priority of the generated transfer condition; And changing the operation and the preliminary state of the hardware according to the generated switching condition, and updating the software according to the operation and the preliminary state information of the hardware. The method of claim 4, wherein In the case where the set auto-protection switching condition is generated, if the bi-directional transfer is set, the auto-protection switching of the transmission system further comprising the step of sending an auto-protection switching protocol set to a power station without performing the switching operation. Treatment method. The method of claim 4, wherein A task of monitoring whether the set automatic protection switching condition is established, a task of determining a switching priority of the switching condition when the set automatic protection switching condition occurs, a task of performing hardware switching according to the determined priority, and And an event task for generating an auto-protection switching event in the event manager according to the execution of the auto-protection switching. The method of claim 6, wherein the task of monitoring whether the automatic protection switching condition is established And a task for checking a home alarm according to the occurrence of the set auto-protection switching condition, a task for checking a set auto-protection switching protocol of a large station in the case of bidirectional switching, and a queue pending task waiting for an operator command. Method of automatic protection switching of transmission system. The method of claim 7, wherein The task for checking the own alarm and the task for checking the set auto-protection switching protocol operate in a polling manner, and the queue-pend task waiting for the operator command operates every time an event queue occurs. How to handle transfer. The method of claim 6, wherein the task of performing hardware switching comprises: While performing a hardware ablation operation according to the generated auto-protection switching condition, during the bidirectional switching, the automatic protection switching processing of the transmission system, characterized in that to create and send the set auto-protection protocol to the power station, and to update the software buffer. Way.