The OSN8800 device integrates product features such as 6.4 Tbit/s cross-capacity, 40 Gbit/s and 100 Gbit/s high-speed lines, high reliability, and green and easy maintenance. Ultra-large capacity switching capability. Single-subrack 6.4 Tbit/s crossover realizes free scheduling of large-capacity nodes. No need to interconnect subracks, low power consumption, and small footprint of server room. Unified line single-board VC/ODU/PKT encapsulation capability, cross board with VC/ODU/PKT unified switching capability, so that the equipment has a truly convergent scheduling plane, to achieve flexible bandwidth allocation. Support perfect soft judgment (SDFEC, SDFEC2) and hard judgment (HFEC, HFEC2 and HFEC PLUS) programs to meet different long-distance transmission needs.

The OSN8800 WDM network in a certain region consists of five rings, and each network element adopts OSN8800 M40V and D40 for combining and splitting waves, and each network element is configured with N blocks of LDX for 10GE LAN service forwarding, and the DCP board is configured with double-ended inverted in-board 1+1 protection. After the project PAT is completed, the inversion often occurs between sites 12, 13 and site 2, and the related DCP boards report INTRA_OTU_STA_INDI and INTRA_OTU_PS alarms. the INTRA_OTU_STA_INDI alarm disappears immediately, and the service is inverted to the protection channel, and the INTRA_OTU_PS alarm does not disappear. The INTRA_OTU_PS alarm does not disappear. A total of two inversions occur as follows:

First time: due to the maintenance of the line on the user side, the line attenuation between site 13 and site 2 increased momentarily by 6.5 dB and then returned to normal (queried from the 15-minute history performance), and the inversion of Wavelength1 from site 13 to site 2, and Wavelength2 and Wavelength3 from site 12 to site 2 occurred, and the service inversion to site 1 Reaching site 2.

The second time: also due to the maintenance of the line on the user side, the line attenuation between site 13 and site 2 momentarily increased by 1.8 dB and then returned to normal (queried from the 15-minute historical performance of the OBU veneer), and the Wavelength1 from site 13 to site 2 and the Wavelength2 from site 12 to site 2 were inverted, and the service was inverted to site 1 to reach site 2.However, the Wavelength3 of site 12 was inverted, and the service was inverted to site 1 to reach site 2. Wavelength3 of site 12 did not invert.

The topology of this network is shown in Figure 1:

OSN8800 T32/P16 host version: v100r008c00t

Huawei U2000 network management system version: V100R009C00

The related DCP board reports INTRA_OTU_STA_INDI and INTRA_OTU_PS alarms. the INTRA_OTU_STA_INDI alarm disappears immediately, the service is reversed to the protection channel, and the INTRA_OTU_PS alarm does not disappear.

Processing

There are two conditions for the protection inversion of OLP optical line boards: R_LOS and POWER_DIFF_OVER, and the cause of these two inversions is the deterioration of the subscriber line fiber optic cables and the POWER_DIFF_OVER alarm. the default optical power variation threshold between the working channel and the protection channel of the DCP board in the U2000 is 5 dB, and this value can be modified by selecting the DCP single board of the network element in the NE Explorer. This value can be modified in the NE of the network element by selecting the DCP board of this network element in Explorer and modifying it in Configuration-WDM Interface- Variance Threshold Between Primary and Secondary Input Power. This network uses the default value of 5 dB.

For the first inversion:

The DCP board at site 13 uses Port1, which is TI1/RO1, and the optical power profile for operating and protection ports RI11 RI12 is as follows:

RI11 -4.9 dBm

RI12 -5.3 dBm

When the overall optical power of the working channel decreases by 6.5 dBm (queried from the 15-minute historical performance of the OBU veneer), the original optical power decreases from -4.9 dBm to -11.4 dBm, and the difference in the optical power with the protection channel RI12 is -5.3 - (-11.4) = 6.1 dB, which is greater than the threshold value of 5 dB, triggering the generation of the POWER_DIFF_OVER alarm. This alarm is not reported to the NMS by default. In the main interface of the U2000, select the network element 13 where the inversion occurs, right-click and select More Alarm Operations-History Alarm on NE, and you will find that the DCP board of the network element reports the POWER_DIFF_OVER alarm at the moment of the inversion. You can change it to report NMS in U2000.

Therefore, the reversal is normal and recognized by the user. Similarly, the inversion of Wavelength2 and Wavelength3 from site 12 to site 2 is also based on the above reason.

Second inversion:

The DCP board at site 13 uses Port1, i.e., TI1/RO1, with the following optical power profile for operating and protection ports RI11 RI12:

RI11 -4.9 dBm

RI12 -5.3 dBm

When the overall optical power of the working channel decreases by 1.8 dBm (queried from the 15-minute historical performance of the OBU veneer), the original optical power decreases from -4.9 dBm to -6.7 dBm, and the difference in optical power with the protection channel RI12 is -5.3 - (-6.7) = 1.4 dB, which is less than the threshold value of 5 dB, and there is no reason for the inversion. However, in the main interface of the U2000, select the network element 13 where the inversion occurs, right-click and select More Alarm Operations-History Alarm on NE, and find that at the moment of the inversion the DCP board of the network element reports the alarm POWER_DIFF_OVER, and the user questions the accuracy of the history performance. Similarly, the exact same situation occurred for the Site 12 to Site 2 Wavelength2 inversion.

The reasons for this are analyzed below:

The OBU veneer collects and reports the optical power to the host software in 1-second intervals; if the optical power degradation period happens to be monitored by the veneer, the prepared optical power value can be reported; if the optical power degradation period is shorter and not at the instantaneous time point of the veneer's monitoring, the accurate optical power value cannot be reported, and the actual OBU input optical power is lower than the historical performance value, greater than 5 dB, and the inversion threshold is reached, which The trigger generates the POWER_DIFF_OVER alarm. As shown in Figure 2:

Root Cause

Instantaneous increase in loss due to fiber optic cable deterioration

Solution

Since the reversal is caused by the deterioration of the optical power of the line, no special treatment is needed, and the line will be manually reversed to the working channel after the line of the working channel is stabilized.

Suggestion and summary

Due to the poor quality of the user's fiber optic cable, shallow laying, and very frequent maintenance, there is often an instantaneous increase in attenuation, which is difficult to be resolved in a short period of time, so the following recommendations are provided to the user:

1, the inversion mechanism is to cope with line cable degradation or abnormal interruption, improve the security of the business, and inversion are within 50mm. If the inversion occurs, the service is also non-destructive, so there is no need to pay special attention to it;

2. On U2000, the parameter of the alarm threshold is "Main and backup input optical difference threshold (dB)". The default value is 5dB. The value range is 0dB, 3dB ~ 8dB, you can set a larger threshold to increase the threshold of inversion, but it will also cause the working channel optical power is poor and not up to the threshold is not inverted, need to be used with caution.

OSN8800 TN13DCP Functions and Features

The DCP single board supports functions and features such as on-board 1+1 protection, customer-side 1+1 protection, and optical wavelength sharing protection, etc. The specific functions and features of the DCP single board are shown in Table 1.

This chapter of related technical information and SDH equipment troubleshooting process by the Shenzhen Optical Transmission Network Technology Co. Our company specializes in Huawei SDH optical transmission equipment, SDH transmission equipment sales.