Basic functions of OSN2500 equipment COA optical amplifier: configured in the receiving end of the SDH system, the sending end with the output power of 17dBm EDFA optical amplifier, together to complete the 170km or more ultra-long-distance optical signal transmission.COA01: BA module output optical power: 14dBmCOA02: BA module output optical power: 17dBm. veneer has 61, 62 and N1 three functional versions, are box-type external fiber amplifier, does not take up subrack slots, the main completion of the optical signal amplification function, suitable for long-distance fiber optic transmission. 62COA and 61COA, N1COA principle is basically the same, the difference is that the 62COA uses Raman optical amplification module, while 61COA and N1COA uses EDFA optical amplification module. The 61COA has the same application as BA and PA in OptiX OSN system to realize optical power amplification and preamplification, while the 62COA and N1COA have the same application as PA in OptiX OSN system to realize preamplification. 61COA and N1COA are erbium-doped fiber amplifiers configured with only one EDFA optical module, which can be used as a power amplifier, a preamplifier, or a line amplifier. 62COA is a Raman fiber amplifier unit, used in the receiving end of the optical transmission system, using the optical fiber's excited Raman scattering effect to amplify the optical signal in the transmission process. 62COA needs to be used in conjunction with the EDFA optical amplifier, 62COA injects pumped light into the transmission fiber through reverse pumping to achieve distributed Raman optical amplification. Unlike 61COA, the distributed Raman amplification gain medium is line fiber, which reduces noise. Therefore, the use of 62COA can increase the transmission distance and improve the optical signal-to-noise ratio, thus realizing single-segment ultra-long span transmission.

Problem Description

An SNCP ring consisting of OSN 2500 devices is organized as shown in the following diagram.

There is an E1 from station E to station F. Due to the special requirements of the power industry, the E1 does not take the short path E-F, but takes the longest path E-D-C-B-A-F, and is not equipped with SNCP protection, and runs on the unprotected chain. Customers report that the E1 will be disconnected at irregular intervals, and the ports of station F report TU_AIS alarm, and the ports of station E report LP_RDI alarm.

Alarm information

TU_AIS

LP_RDI

Processing

1. Because the service is only instantaneous, and take a long path, through the site more, the frequency of failure is low, sometimes once a day, sometimes do not occur, increasing the difficulty of troubleshooting

2. query the E1 through the site equipment for 15 minutes SDH performance monitoring, found that the A station's S11 slot and the B station's S8 slot irregular performance overruns, query the A station's S11 slot and the B station's S8 slot receiving and transmitting power, are in the normal range.

3. A of the clock tracking S11 slot line clock, business transient break in the abnormal event to see the A station clock switching, from the S11 slot line clock switched to the internal clock, after a period of time and cut back to the S11 slot line clock, business transient break in the A station has an SCNP abnormal event, the preliminary judgment is that there is a failure between the A station and the B station, but still can not determine that the board faults

4. Considering the relatively low frequency of the failure, 15-minute performance monitoring data is likely to be incomplete, because the 15-minute performance monitoring of only 16 registers, open the 24-hour performance monitoring to continue observation

5. the next day to the network management to check the occurrence of a business transient break, 24 hours of performance data show: station B to the A station of the optical amplifier COA output power fluctuations, luminous maximum value of: 19.3 dBm, minimum value of: 9.3 dBm, with the COA standard output optical power 17 dBm difference is large, the corresponding A station 11 slot optical board of the receiving optical power fluctuations, maximum receiving power of -14 dBm, the maximum power of -14 dBm, the maximum receiving power of -14 dBm, the maximum receiving power of -14 dBm, the maximum receiving power of -14 dBm, the maximum receiving power of -14 dBm, the maximum receiving power of -14 dBm, the maximum receiving power of -14 dBm. The maximum received power is -14dBm, and the minimum received optical power is -25.9dBm. The fault is localized to the abnormal output power of external COA, which leads to service interruption.

Root cause

The external COA emits light abnormally, and the light-emitting power fluctuates greatly in an instant, resulting in instantaneous interruption of service.

Solution

Replace the external optical amplifier COA to solve the problem.

Suggestion and Summary

In troubleshooting, for part of the business interruption, first of all, we should find out the commonality of the interruption of business, which is conducive to fault location, and secondly, we should collect as comprehensive information as possible, and then carry out a comprehensive analysis of the troubleshooting process, the beginning of the process, ignoring the role of 24-hour performance monitoring to monitor the stability of the operation of the equipment, which led to difficulties in localization.