ONU fault types

1. ONU with time slot drift

ONU

This kind of fault is usually caused by the aging of the laser and other reasons, resulting in the drift of the time slot of the ONU upstream data transmission. It is also possible that an error occurs in the data of the downlink OLT sending bandwidth map, resulting in an error in the sending time slot of the ONU. This kind of faulty ONU is difficult to detect. Generally, the OLT needs to monitor the upstream data of the ONU in real time. Determine whether it sends data in the time slot allocated by the OLT. For this type of abnormally luminous ONU, since it mainly affects two adjacent ONUs, in addition to isolation, the protection bandwidth between time slots can also be increased to alleviate its impact on other ONUs.

2. Long light ONU

This failure is due to the ONU's laser emitting light for a long time. As a result, the ONUs under the entire PON port cannot communicate normally. If the ONU emits strong light, the abnormal light emission of the ONU can be judged by testing the optical power at the optical splitter during troubleshooting. However, if the ONU is weakly emitting light, it is difficult to judge, and the abnormal light emission of the ONU cannot be measured at the optical splitter. Only through the intervention of the OLT, a specific detection algorithm can be used to determine the abnormal ONU. Usually, the services under the entire PON port will be affected, but because the fault phenomenon always exists, it brings convenience to the troubleshooting to a certain extent.

3. Intermittent glow

This kind of fault is the most difficult and irregular to judge. It is also the largest fault that accounts for abnormally luminous 0NUs on the live network. It is not only impossible to measure the abnormal luminescence of the ONU at the spectroscope. In addition, it is necessary to observe and monitor the faulty PON port for a long time, which brings great challenges to network maintenance.

There are many fault phenomena of abnormal light ONU in the network. There is no complete mechanism and process in the industry to solve this failure. Other operators have no controllable experience. in the operation of the actual network. The author summarizes a set of procedures and experience for troubleshooting abnormal light-emitting ONUs. It can effectively solve the vast majority of existing network failures.