Description of the problem

Multiple ces services of a bureau point electricity are often interrupted at night, and one of the most frequently interrupted services is grouped as follows:

The service starts to be interrupted at 6 or 7 o'clock in the afternoon every day, without any human operation during the interruption, and automatically recovers after it lasts for a few hours.

Alarm messages

No

Processing

1. the network manager queries the transmission link configuration and status and finds:

(1) The clocks of OSN3500 and OSN550 at site 115 and OSN550 at site 158 are tracked to OSN7500II at site 100 through synchronous Ethernet, and OSN7500II at site 100 tracks the external clock source; however, the user devices at both ends are unable to set up the clock tracking for tracking transmission.

(2) OSN550 has a small number of buffer underflow records, which are suspected to be related to the user equipment not tracking the transmitted clock, but the number is too small to be the cause of the service interruption for a few hours every night.

3) Site 115 OSN3500 E1 port 24-hour history performance, found that 19-md75-23 and several other ports had a large number of misroutes reported.

Further querying the historical performance, it was found that the BERs were generated only at night, and there were no BERs during the daytime. Moreover, the BER time is about 6 hours, which is more consistent with the business interruption time.

2, the service will be disconnected, one end of the loopback, one end of the hanging meter (CMA3000) test, test time for 3:30 p.m. to the next day 8:30 a.m., the test time to cover the night time business interruption time, found that there is no long business interruption. This indicates that at least the network side is working normally.

3, the customer to check other business conditions, found that the agricultural banking business, financial network business, etc. also exist in the evening at 6:00 pm, 7:00 pm to start interrupting the situation, just because the customer-side terminal equipment of these services are not 24 hours on, so there is no report of daily interruptions of the fault.

And all of these interrupted services are transmitted through the 158th network element 3500 19-md75:

19-md75-18 Service 1

19-md75-20 Service 2

19-md75-21 operation 3

19-md75-22 operation 4

19-md75-23 Pending Meter Test Operations

19-md75-1 through 19-md75-10 Other Operations

Once these ports are out, they are connected to different opto-electronic converters or protocol converters (all in the 158th network element room), and then pulled out to different customer rooms via fiber optics.

At this point, the problem is basically locked in the 158th network element room.

4. At the time of the radar station's business interruption, the following tests were done:

(1) No. 158 network element 3500 19-md75-23 port software external loop, at this time, the 158 network element user room terminal "signal loss" fault light is still on; but will be docked with the port of the optical-electrical converter cable looped back to the fault light off. It means that the fault lies between port 3500 19-md75-23 of network element No. 158 and the photoelectric converter connected to it.

(2) There is an error code indication on both the 19-md75-23 and the photoconverter at the time of the fault, but the error code disappears at both ends when each end is looped back through the E1 cable. Adjust the transmission on the ces service port from 19-md75-23 to 19-md75-1, the fault did not disappear; replace the E1 port of the photoelectric converter, the fault did not disappear; both ends of the equipment were powered down and restarted, the fault did not disappear. This indicates that the error code is not caused by the failure of the equipment at one end.

(3) 19-md75 access services were unplugged from the E1 port, found that the other ports of the BER situation has not improved significantly. This indicates that the error code is not introduced by the interference of a remote device.

From the above test results and fault phenomenon analysis, it is suspected that the power supply, grounding problems or external interference in the server room of the 158th network element caused this fault.

5. Field observation of the surrounding environment of network element 158 server room was found:

(1) Although there are a number of communication base stations, large outdoor lighting billboards and utility transformers and other equipment in the vicinity, but did not find and the fault time coincides with the exact source of interference. The instrument also did not detect any significant change in radio interference before or after the failure. The source of external interference could not be specified.

(2) The utility power supply has been stabilized at about 233V during the day, but when the peak of power consumption starts at 6 or 7 p.m., the voltage will rise significantly, up to 240 V. It is much higher than that of the UPS output of the server room, which is stabilized at about 220 V. The voltage is much higher than that of the computer room, which is stabilized at about 220V.

(3) The 3500 ground wire is connected to the UPS power supply, and the three-phase mains plug of each optical converter and protocol converter interfaced with the 3500 E1 port is plugged directly into the terminal block, and the ground wire of each terminal block is also ultimately connected to the UPS power supply. However, the UPS ground is suspended from the server room and is not really grounded.

From the above environment of the server room, the server room is not grounded is the biggest doubt.

6. After grounding the equipment room and observing for 7 days, it was found that there was no more interruption of the radar station service which was interrupted every day before, and there was no more error code record on each E1 port of network element 3500 of No. 158, confirming that the problem was solved.

Root Cause

Construction irregularities caused the problem to occur due to the lack of grounding of both the OSN3500 equipment and the docking equipment for network element 158.

Solution

Connect the equipment ground to the ground drain according to the specification.

Recommendations and Summary

If the CES service or packet service encounters some regular BERs and the cause of the problem cannot be found, it is recommended to find the commonality of the interrupted service and first check the clock tracking and the grounding of the equipment room.

This chapter of related technical information and SDH equipment troubleshooting process by Shenzhen Optical Transmission Network Technology Co. Huawei SDH Optical Transmission Equipment,SDH Transmission Equipment Sales