Application of optical fiber automatic switch Protection System

1. Introduction

To achieve non-blocking communication on the existing 100,000-kilometer high-speed trunk cable network, the operator must first consider how to implement automatic protection of optical transmission physical routes. The optical fiber automatic switch protection system is an automatic monitoring and protection system that integrates monitoring, protection, and management. It is independent of the transmission system and completely built on the optical fiber physical layer. The system can implement real-time, online, remote, automatic monitoring of the optical fiber running status and performance indicators and switch protection of the active/standby optical fiber cables to ensure the safe and reliable operation of the optical fiber network.

2. Working Principle

The automatic switch module can be divided into the single-chip microcomputer control circuit, optical power monitoring circuit, optical switching circuit, and test light source circuit. Its Working Principle 1 is shown in. The control circuit controls the circuits of other modules for coordination. The optical power monitoring circuit monitors the changes in the optical power value of the active and standby optical fibers in real time. It has a built-in photoelectric sensor and a 1 × 2 optical splitter. The optical splitting ratio is usually 97: 3, this is equivalent to increasing the attenuation of about 0.25 dB on the transmission line, and is suitable for online applications. The optical switching circuit has a built-in 1X2 or 2x2 optical switch, which is controlled to automatically switch between the active and standby optical channels. The switching control process is as follows: the optical power monitoring circuit collects the optical power value on the active and standby optical fiber in real time and reports it to the control circuit for analysis. It is found that the optical power change value exceeds the preset switching threshold, the control circuit immediately sends a switch command to the optical switching circuit. After receiving the command, the optical switching circuit completes the switch.

3. Handling of the low return loss value of the Nortel DWDM Device

After the DWDM device is connected to the optical fiber automatic switch protection system, manual core scheduling is not required during cutover. You only need to perform simple switching on the network management system. During core-core scheduling, the most common problem is that the return loss value is too low, which is sometimes troublesome to handle.

The most basic requirement to ensure smooth scheduling is to clean the slave core before switching. Because most Bureau stations are not equipped with a return loss tester, if the fiber core is not connected to the device, it cannot be judged whether the return loss value after cleaning is qualified. Therefore, after switching the active/standby fiber core on the network management system, go to the DWDM network management system of beidian immediately. If the return loss value is too low and there is no other alarm information, you need to handle the return loss. The system is enabled normally on the core of the main device. There is generally no problem between the DWDM amplifier and the optical fiber automatic switch protection system, the loss point can basically be determined between the standby output port of the optical fiber automatic switch protection system and the ODF of the standby fiber.

In this case, the optical fiber of the output port of the optical fiber automatic switch protection system can be switched to a circle of 4 circles with a diameter of 15mm). If the return loss value is still too low, check and clean the output ports of the optical fiber automatic switch protection system. If the return loss value changes to normal, the return loss point is not between the optical fiber automatic switch protection system and the winding area, subsequent inspections should be conducted. Clean the pigtails and flanges at the ODF end of the backup fiber core. If necessary, replace the flange or automatically switch the optical fiber to protect the pigtails from the system output port to the ODF. Before fiber pulling, the optical amplifier must exit the service on the network management system.

Note that after the slave core is disconnected, the automatic switch protection system automatically switches the slave core back to the master core. After the slave core is processed, you must first switch the backup fiber core, and then go to the Nortel DWDM network management system to view the return loss value. Otherwise, the returned loss value will be the primary fiber core; you can also set the status to manual/standby in the optical fiber automatic switch protection system, so that the system is locked on the backup core, and the change of the return loss value of the backup core can be monitored in real time.

4. Handling of network failures

When the network is disconnected, follow these steps.

◆ If the network management system does not monitor all network element devices, you can eliminate device faults. The problem may occur on the network.

◆ Use the Ping command to test the IP address of each device to see if the IP address of the device can be viewed through the "static resources" item under the "Statistics" menu of the network management system, or from the completion data ).

◆ If the Ping rule is not general, find the network fault.

◆ If Ping is enabled, open "system settings" under "system" in the network management system and select "communication parameters ", check whether the IP address of the Communication Server is the IP address of the computer where the communication proxy server is installed. The Network Administrator usually uses the IP address of the Local Computer and the IP address of the network administrator ).

◆ If you cannot monitor a single network element device, run the Ping command to test the device.

◆ If the device can be pinged but the device status information cannot be uploaded, You can reset the NIC and still cannot notify the vendor.

◆ If the Ping fails, you can test the local crossover network cable. If the connection fails, it may be a network fault. If the connection fails, inform the manufacturer.

5. General principles of troubleshooting

Once a device fails, maintenance personnel are required to quickly determine the nature and location of the fault for timely repair. In the process of troubleshooting, the first and most critical step is to accurately locate the fault point and then take appropriate measures. Fault Handling personnel should first determine whether the fault is a line fault or a device fault. If the fault is a line fault, the fault point should be determined and then the maintenance personnel should be notified to fix the fault. If the fault is a device fault, determine the station where the fault is located, whether the transmission equipment or the optical protection equipment is faulty, to timely repair.

Due to the characteristics of the transmission device, clarifying the connection relationship between each device module helps to locate the fault accurately and take corresponding measures to eliminate the fault. Before a fault is accurately located, it is dangerous to take it for granted. This will not only delay troubleshooting, but also lead to more serious human faults.

6. application implementation across multiple trunk Stations

In the SDH or DWDM System, when a medium segment is blocked, the adjacent trunk station will report to the network management system a non-light alarm signal. For example, the Network Management System of the transmission system will send this signal to the network management system of the switching system, the Network Manager of the switched system immediately controls the site to be switched for protection. The entire process is automatic and switches are completely controlled at the network management layer. This solution enables large loose switching to protect devices that can be switched across multiple trunk stations), reduces the number of switching sites, and reduces the investment of equipment in the switchover protection system.

The key to this solution is that each SDH device manufacturer must provide a no-light alarm signal. Because only one digital signal is needed, it is technically difficult and feasible. A single interface protocol can be developed for network pressure so that the switched network management system can recognize the no-light alarm signal. network management controls the automatic switching process 2.

7. Conclusion

The optical fiber automatic switch protection system is designed for anti-blocking of transmission networks. It is completely independent of the Network Element equipment of SDH and DWDM systems. When combined with the standby Optical Fiber routing or idle wavelength channel, you can set up a switchover protection network. Practice has proved that the optical fiber automatic switch protection is fast, reliable, secure, and flexible, and the service recovery capability is strong. At the same time, the switching protection network management and SDH device network management are combined, it provides a practical and economical solution for trunk line communication without blocking.

1. Optical Wireless Technology FSO extended optical fiber network
2. Expert Q & A: puzzles about the inability to automatically switch redundant routes