Hello,
Today, I'd like to share with you a case concerning the analysis of ONU frequent instantaneous breakdown fault under PON port.
Fault description:
There are 10 ONUs connected to the PON port of the GPBC board on the OLT, and all ONU network management services are frequently interrupted.
The troubleshooting process is as follows:
1- The optical power of the measurement branch optical path is -17dBm, which is within the normal range to eliminate the optical path problem.
2- Replace the beam splitter, the fault remains the same, eliminate the beam splitter fault.
3- Replace the GPBC board, the fault remains the same, and eliminate the GPBC board problem.
4- Use the minimum configuration method to exclude. Deactivate all ONUs under port 0/1/3, and then activate in turn. It was finally found that as soon as the ONU with ID 9 went online, all ONUs under this port started to lose packets instantly, so it was concluded that the ONU with ID 9 was a rogue ONU.
5-Replace the ONU with ID 9. The fault remains the same, eliminating rogue ONUs.
6- From the management IP address of the ONU with the long ping ID of 9 in the OLT, use the display icmp statistics command on the ONU to perform packet statistics and find that the number of echo messages and echo reply messages in the ICMP message are the same, indicating that the instantaneous loss The packet does not occur on the ONU side.
7- According to packet statistics on the OLT, it is found that the number of echo messages and echo reply messages in ICMP messages is inconsistent, and is smaller than the number of echo relay messages counted on the ONU side, thus inferring that packet loss occurs on the OLT side.
8- Further analysis of the data and found that the bandwidth allocation type of the DBA template bound to the ONU with ID 9 is type 4 and the maximum bandwidth is 1024000 Kbit/s. It is inferred that the upstream bandwidth configuration is too large, causing congestion.
9- Change the maximum bandwidth of this DBA template to 102400Kbit / s, the fault is resolved.
Note:
The upstream bandwidth of GPON is 1.25Gbit / s. If the bandwidth is configured as 1Gbit / s, there may be congestion caused by excessive upstream traffic.
DBA--Dynamic Bandwidth Assignment dynamic bandwidth allocation protocol. That is, the OLT dynamically adjusts and allocates upstream bandwidth to the ONU according to the upstream burst traffic demand of the ONU, which not only meets the upstream bandwidth requirement of the ONU, but also improves the utilization rate of the PON system bandwidth.
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