Commissioning Procedure (OTN)

This section describes the general commissioning procedures for the OTN system.
The commissioning procedures for the equipment can be divided into two parts: optical power commissioning and network commissioning.

• Optical power commissioning procedures individually commission the optical power values of NEs and boards based on the optical signal flow. They also remove the abnormal attenuation of lines or boards based on the requirements of optical power, and the gain and insertion losses of the boards.
• Network commissioning procedures include the commissioning protection function, commissioning feature function, testing bit errors, and other functional commissioning operations at the network level.

 NOTE:

For the ASON network, the commissioning procedures and requirements refer to Automatic Commissioning Process and Commissioning Items for ASON Network.

Figure 1 and Figure 2 provides the general commissioning procedures.

Figure 1 General commissioning procedures for OptiX OSN 8800/OSN 6800

Figure 2 General commissioning procedures for OptiX OSN 3800

You can perform the commissioning and configuration during deployment of the equipment by using either the iManager U2000 (U2000 for short) or the OptiX iManager U2000 Web LCT (Web LCT for short). All the operations that can be performed on the Web LCT can be performed on the U2000. Compared with U2000, the Web LCT has lower requirements on the computer hardware and can be started quickly.
Table 1 lists the tasks for the commissioning and configuration during deployment.

Table 1 List of tasks for the commissioning and configuration during deployment

No.	Task	Mandatory/Optional	Tool
1	Creating NEs in Batches.	Mandatory	U2000 or Web LCT
2	Creating Optical NEs.	Mandatory	U2000
3	Setting NE Power Consumption Threshold.	Mandatory	U2000
4	Uploading the NE Data.	Mandatory	U2000
5	Setting NE ID and IP.	Mandatory	U2000 or Web LCT
6	Synchronizing the NE Time with the U2000/Web LCT Server Manually.	Mandatory	U2000 or Web LCT
7	Setting Performance Monitoring Parameters of an NE.	Mandatory	U2000 or Web LCT
8	Setting Manually Extended ECC Communication. Perform this task when the network uses HWECC for communication and more than four Huawei equipment NEs use the extended ECC for communication.	Optional	U2000
	Configuring IP over DCC. Perform this task when the network uses IP over DCC for communication.	Optional	U2000
	Configuring OSI over DCC. Perform this task when the network uses OSI over DCC for communication.	Optional	U2000
10	Checking Network-Wide Software Version.	Optional	U2000
11	Configuring Boards.	Mandatory	U2000 or Web LCT
12	Creating Fiber Connections in Graphic Mode. Perform this task on the U2000.	Mandatory on the U2000	U2000
13	Creating Single-Station Optical Cross-Connection. Perform this task when ROADM stations are configured on the actual network.	Optional according to the network	U2000 or Web LCT
14	Creating OCh Trails by Trail Search. Perform this task on the U2000.	Mandatory on the U2000	U2000
15	Configuring the OSNR Detection Based on Optical Doctor. Perform this task on the U2000.	Optional	U2000
16	Commission optical power by using one of the following methods as required: Commissioning Optical Power on Site Remotely Commissioning Optical Power NOTE: This document uses a 40-channel system as an example to describe optical power commissioning. The optical power commissioning methods for an 80-channel system are similar. The main difference is that the 40-channel system and 80-channel system have different requirements on nominal single-wavelength optical power and single-wavelength incident optical power for OA boards.	Mandatory	U2000 or Web LCT
17	Configuring Services.	Mandatory	U2000
18	Configuring System Features.	Mandatory	U2000
19	Viewing Current Alarms on an NE and Removing Abnormal Alarms.	Mandatory	U2000 or Web LCT
20	Testing Protection Switching.	Mandatory	U2000
21	Testing Data Features.	Mandatory	U2000
22	Testing System Features.	Mandatory	U2000
23	Testing Ethernet Service Channels.	Mandatory	U2000
24	Configuring Orderwire of OTN System and Configuring the Orderwire Phone in an OCS System.	Optional	U2000 or Web LCT
25	Testing Orderwire Functions.	Optional	U2000 or Web LCT
26	Testing Bit Errors.	Mandatory	OTN analyzer or SDH analyzer
27	Checking the entire network against the Checklist for Commissioning During Deployment. Ensure that the network configurations are correct.	Mandatory	U2000 or Web LCT
28	Backing Up the NE Database to the SCC Board.

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Switching Fails Due to Incorrect SNCP Protection Mode on the WDM Equipment

Switching fails due to incorrect SNCP protection mode on the WDM equipment.

Product

OptiX OSN 6800

OptiX OSN 3800

Fault Type

Protection

ODU2_PM_SSF

Symptom

 At site A, the TN12NS2 board is configured with SNCP protection. At site D, SNCP protection is configured. At sites B and C, the TN12NS2 boards are configured in electrical regeneration mode. After the fiber between site B and site C is broken, however, site A does not perform any switching. As a result, services are interrupted.

Cause Analysis

The possible causes of the fault are as follows:

• The TN12NS2 board at site A is faulty.
• The SCC board at site A is faulty.
• The cross-connect board at site A is faulty.
• The protection type at site A is incorrectly configured.

Procedure

1. Query the alarms and performance events of site B on the T2000. It is found that the output optical power of the NS2 board at site B is –60 dBm after the fiber between site B and site C is broken. The NS2 board reports the R_LOS alarm.
2. Query the alarms at site A. The TN12NS2 board at site A reports the ODU2_PM_SSF alarm, but does not report any OTU-layer alarm. In addition, the ODU-layer signals at site A are detected invalid.
3. Query the protection type at site A. The SNCP protection scheme works in SNC/I mode. When the electrical regeneration function is provided, the SNCP protection scheme in SNC/I mode triggers a switching only after it detects an SM-layer alarm, instead of a PM-layer alarm. Huawei's engineers change the SNC/I mode to the SNC/N mode. Then, services can be switched successfully.

Result

The problem is resolved.

Reference Information

Conclusions and suggestions for this case are as follows:

When the SNCP protection scheme is configured for the WDM equipment with the electrical regeneration function, the protection type needs to be set to the SNC/N mode.

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Incorrect Client-Side Service Type Causes Failure of Interconnection With a Router

Incorrect client-side service type causes a failure of interconnection with a router.

Product

OptiX BWS 1600G, OSN 6800, OSN 8800

Fault Type

Equipment Interconnection

Client Equipment

Symptom

On a network, an ETMX board on the OptiX BWS 1600G is used to receive a 2.5 Gbit/s service from a router on the client side. Client-side channels run properly after an expansion is performed on the network.

When the ETMX board on the OptiX BWS 1600G receives the 2.5 Gbit/s service, interconnections with ports on the router are successful but exchanges of protocols fail. After an outloop is configured on the ETMX board at the local end by using the NMS to loopback the service to the router, port interconnections and protocol exchanges are successful. After an inloop is configured on the WDM-side optical port on the ETMX board at the remote end by using a fiber patch cord to loopback the service to the router, port interconnections are successful but protocol exchanges fail. This indicates that the fault lies on the WDM-side link or interconnected ports.

Cause Analysis

The analysis of the problem is as follows:

1. An SDH analyzer is used to test the WDM-side channel after the expansion is performed. No exception is found.
2. After the outloop on the ETMX board at the local end is performed, port interconnections and protocol exchanges are successful. This indicates that the router is running properly.
3. After the inloop on the ETMX board at the remote end through a fiber patch cord is performed, protocol exchanges fail. This indicates that protocol configuration is incorrect after signals are transmitted from the router to the ETMX board.

The preceding information shows that the problem is due to incorrect configurations of the ETMX board.

Procedure

1. Check the WDM-side configurations of the board. Service Type for services received from the client side of the ETMX board can beSDH, SONET, or ODU1.. By default, Service Type is set to SDH and J0 byte in the SDH interface overhead is set to Null.
2. Check the interconnected ports and no alarm is generated. This indicates that the no error is generated in the J0 byte.
3. Confirm that on the client side of the OptiX BWS 1600G, the service type interconnected with the router is OC48, which is different from the service type of the ETMX board. This is why the problem occurs.
4. Change Service Type of the ETMX board to SONET. Then, protocol exchanges are successful and services are normal.

Result

The problem is resolved.

Reference Information

None.

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Inconsistency of Fiber Jumper Model and Fiber Connector Type of a Board

The receive optical power of a board is lower than the specified threshold because the fiber connector mismatches the port connector on the board, the connected OAU board at the downstream station reports MUT_LOS and R_LOS alarms.

Product

OptiX BWS 1600G, OSN 6800, OSN 8800

Fault Type

Optical Power Abnormality

Fiber

MUT_LOS

R_LOS

Symptom

At an OptiX BWS 1600G station, a fiber connector on the RPC board is damaged and the fiber jumper must be replaced. After the fiber jumper is replaced, the receive optical power on the WDM side is low (-53 dBm).

The connected OAU board at the downstream station reports MUT_LOS and R_LOS alarms.

Cause Analysis

After a detailed check, it is found that:

1. The transmit optical power of the FIU board at the downstream station is within the permitted range.
2. The receive optical power of the ODF connected to the local station is within the permitted range. That is, the line attenuation is within the permitted range.
3. The receive optical power of the OAU at the local station is low.
4. The receive optical power at the IN port on the FIU board at the local station is low.
5. The fiber jumper between the IN port on the FIU board and the SYS port on the RPC board is normal.

The preceding information shows that the fault is located between the ODF and the FIU board. Possible causes of the problem are as follows:

• The fiber jumper between the ODF and the RPC board is damaged.
• The RPC board is malfunctioning.

Procedure

1. Check the fiber jumper between the ODF and the RPC board. The fiber jumper uses an FC/PC connector at one end and an LHS/UPC connector at the other end, while the LINE port connector on the RPC is LSH/APC. The end faces of the FC/PC and LSH/UPC connectors of the fiber jumper is flat while the end face of the LSH/APC connector is tilted. Therefore, air exists between the LINE port on the RPC board and the fiber jumper connector. As a result, the transmit optical power of the pump laser on the RPC board is abnormal and the receive optical power on the WDM side is low. Change connectors of the fiber jumper on the RPC board so that the fiber jumper uses an FC/PC connector at one end and an LSH/APC connector at the other end. Then, the system operates properly.

Result

The problem is resolved.

Reference Information

None.

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After an OptiX OSN 6800 NE Is Upgraded from V100R004C04 to a Later Version

After an OptiX OSN 6800 NE is upgraded from V100R004C04 to a later version, a slave subrack of the NE is unreachable by the U2000 due to incorrect TN11AUX02 jumper settings.

Product

OSN 8800, OTN

Fault Symptom

When an OptiX OSN 6800 NE was upgraded from V100R004C04 to V100R005C00 or a later version, slave subrack 4 on the NE was unreachable by the U2000 at the software activation stage.

Network Topology

None.

Cause Analysis

There are the following possible causes for a slave subrack to be unreachable by the U2000:

1. The SCC board in the subrack is faulty.
2. The network cable of the subrack is abnormal.
3. The AUX board in the subrack is faulty.

Procedure

1. Considering that the slave subrack was unreachable by the U2000 when the AUX board in the subrack was being activated, Huawei suspected that the AUX board was faulty.
2. Interchanged the AUX boards in slave subracks 3 and 4 and exchanged the jumper settings of the two AUX boards. Slave subrack 3 was still reachable by the U2000, but slave subrack 4 was still unreachable by the U2000. This information shows that the AUX board originally installed in slave subrack was normal.
3. Confirmed that slave subrack 4 was still unreachable after the SCC board in the subrack was reseated or replaced. In addition, the replaced SCC board was functioning properly after it was installed in a slave subrack on another NE. Therefore, the SCC board in slave subrack 4 was normal.
4. Checked the network cable connection. No fault was found.
5. Considering that slave subrack 4 was unreachable during the upgrade of its AUX board, Huawei compared V100R004C04 and V100R005C00 files and discovered that the logic of the AUX board had been upgraded from V100 to V130. During the logic upgrade from V100 to V130, to ensure that the extended subrack ID could meet the requirement of the new PCB version, the default jumper setting was changed from 1 to 0. After confirmation, Huawei learnt that the AUX board in slave subrack 4 was TN11AUX02.
   The TN11AUX02 board with a logic of V100 uses only J4, J3, and J2 jumpers to set the subrack ID, while the TN11AUX02 board with a logic of V130 uses J16, J15, J4, J3, and J2 to set the subrack ID.
   
   
6. Checked the jumper settings of the TN11AUX02 board. J15 and J16 were not capped. In V100R004C04, this setting matched the logic of V100. By default, when J15 and J16 are not capped, they indicate the value 1. After the NE was upgraded to V100R005C00, the logic version of the TN11AUX02 board was V130 and the default value of J15 and J16 jumpers changed to 0, causing a change in the ID of slave subrack 4. As result, the subrack ID became invalid and the subrack was unreachable by the U2000.
7. Reconfigured the jumpers on the TN11AUX02 board according to the information provided in the product documentation. The problem was then resolved.
   NOTE:

   For the TN11AUX01 board equipped with PCB VER.D, the issue will also occur on the board after an upgrade if the J15 and J16 jumpers on the board are not capped.

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40G Wavelengths Are Unavailable Due to a DCM Module Connection Problem

40G wavelengths are unavailable due to a DCM module connection problem.

Product

OptiX OSN 6800, OSN 8800

Fault Type

DCM Module

Symptom

10G and 40G wavelengths are transmitted in an OptiX OSN 6800 network. The network topology is shown in the following figure. 40G wavelengths in two directions between station A and station G are unavailable. In addition, the performance of 10G wavelengths is lower than the expected performance although it is stable.

Cause Analysis

The optical power and OSNR after commissioning are normal and the optical fibers are newly routed. In this case, it is impossible that the PMD is excessively high. In addition, the link in the network is long, which results in use of many DCM modules. Therefore, it is possible that the DCM modules at a station are incorrectly connected.

Procedure

1. Each station between station A and station G uses different DCM modules in two directions and the compensation distance of the two DCM modules differs by more than 40 km. In this case, incorrect connection of DCM modules at any station can make the 40G wavelengths unavailable.
2. At each station, query the optical power of the optical amplifier boards and calculate the attenuation of the DCM modules. The attenuation of a DCM module increases with the compensation distance of the DCM module.
3. Check station D. The result shows that station D is abnormal. That is, the attenuation of the DCM module connected to optical amplifier board A03 is lower than that of the DCM module connected to optical amplifier board A05.
4. Check whether the DCM modules at station D are incorrectly connected. After rectifying the connections, confirm that the 40G wavelengths are available.

Result

The problem is resolved.

Reference Information

None.

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An SCC Board Fails to Start After Multiple Board Replacement Operations

An SCC board fails to start after multiple board replacement operations.

Product

OTN, OSN 6800, OSN 8800

Fault Symptom

A site at office A in country D is configured with one master subrack and three slave subracks. The master subrack is configured with active and standby SCC boards. When the standby SCC board reports the HARD_BAD alarm, users consecutively replace the standby SCC board twice. After that, the standby SCC board malfunctions according to NMS statistics.

Network Topology

None.

Cause Analysis

There are the following possible causes:

• The new standby SCC boards that are being used have defects.
• The slot for housing a standby SCC board malfunctions, resulting a startup failure on the new standby SCC boards.
• The database of the standby SCC board is abnormal, resulting a startup failure on the new standby SCC boards.

Procedure

1. Replace the standby SCC board for two consecutive times.
   The fault persists. This indicates that the fault is not caused by the original standby SCC board.
2. Inspect the slot for housing a standby SCC board.
   No bent pin is found in the slot. This indicates that the fault is not caused by the slot.
3. Inspect the PROG indicator on a new standby SCC board.
   The PROG indicator blinks quickly, indicating that the standby SCC board is being repeatedly reset.
   Result: According to this analysis, the possible cause of that fault is that the database of the standby SCC board is abnormal, which results in start failures and repeated resets of the standby SCC board.
   When the SCC boards that are in the slave subracks start, the data modules in the slave subracks will not start. Therefore, the fault may be caused by the data module on the SCC boards that are in the master subrack.
4. Insert the original standby SCC board from the master subrack into a slave subrack.
   The board starts properly after 5 minutes. You can now determine that the repeated resets of the standby SCC board in the master subrack result from the abnormal data module.
5. Obtain the package loading logs of the SCC boards in the slave subracks using the UpgradeKit tool.
   According to the logs, downgrade operations have been performed on the SCC boards.
6. Clear the database for the SCC board by referring to the Upgrade Guide and insert the original SCC board into the master subrack.
   The board starts properly.

Conclusion and Suggestion

1. NG WDM systems support smooth upgrades but not smooth downgrades. Databases must be cleared before a downgrade. Therefore, determine the version of a spare part before replacing it on an SCC board. If you downgrade a spare part that has a version later than the version of a target SCC board before starting the board, the database of the board will fail to start.
2. Perform the following workaround if an SCC board is incorrectly downgraded and fails to start: Insert the SCC board into a slave subrack of the NE and clear the database by referring to the Upgrade Guide.

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The services on a network fail to be deployed

The services on a network fail to be deployed because the connectors on the live network mismatch the connectors of new devices.

Product

OSN 6800, OSN 8800

Fault Symptom

According to engineering design files, the insertion loss and distance between sites A and B on an OTN network are 40 dB and 130 km respectively. On the live network, however, the line insertion loss in the east direction and that in the west direction are 45 dB and 46 dB respectively, and the actual line distance is 160 km. Services on the network cannot be deployed.

Network Topology

The following figure shows the network topology.

Cause Analysis

The connectors on the ODF are the FC/APC type, and the connector of the E2000 jumper for connecting the new RPC board is the FC/UPC type. After these two types of connectors are interconnected, the line insertion loss significantly increases, which introduces intensive reflection after lasers on the RPC boards are enabled. As a result, services on the OTN network cannot be deployed.

Procedure

1. Check the configurations of the link insertion loss and dispersion.
   The configurations comply with the design requirements.
2. Check the optical power of the line between the OBU205 board (the board at site A is used for the purpose of this example) to the receive end on the ODF.
   The insertion loss of link A–B is 45 dB and that of the link B–A is 46 dB. The lines are in a normal state.
3. Measure the insertion loss of the link between the RPC board and the OBU101 board.
   The link insertion loss is about 2 dB.
   Measure the insertion loss of the link from the ODF to the RPC board and then to the OBU101 board.
   The link insertion loss is 2 dB (the insertion loss of the RPC board is 1.5 dB). This indicates that the RPC board and the jumper are normal.
4. Measure the ODF and the RPC board using an optical power meter after they are connected.
   No light is measured. This result conflicts with the measured results of the links between the ODF and the RPC board. This indicates that the insertion loss was introduced by the connector of the ODF.
5. Replace the connector on the ODF and jumper.
   The fault persists. The insertion loss of the connector is larger than 5 dB.
   Further analyze the connector on the ODF and the connector of the jumper.
   The connector on the ODF is the FC/APC type, and the E2000 jumper on the RPC board is the FC/UPC type. After these two types of connectors are interconnected, the line insertion loss significantly increases, which introduces intensive reflection after lasers on the RPC board are enabled. As a result, services on the OTN network cannot be deployed.
6. Replace the jumper with a new one whose connectors at the two ends are the FC/UPC and FC/APC types.
   Services on the network are available.
   
   Figure 1 Parameters for different connectors

Conclusion and Suggestion

Familiarize yourself with different types of connectors and be aware that some types of connectors cannot be directly interconnected.

There is a slight difference between the FC/APC and FC/UPC connectors: An FC/UPC connector has a plane surface, and an FC/APC connector has an inclined surface with a slope of 8 degrees.

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R_LOS Is Reported by a Line Board on a Regular Basis Because of Incorrect Wavelength Monitoring Configuration on the Electrical Regeneration NE (NG WDM Equipment)

R_LOS is reported by a line board on a regular basis because of incorrect wavelength monitoring configuration on the electrical regeneration NE.

Product

OSN 6800, OSN 8800

Fault Symptom

On network L of operator Y in country Z, the TN52ND2 board in slot 4 on NE A reported an R_LOS alarm for its optical port 1 at a specific time in every early morning (00:00–06:00). In addition, on the peer NE (NE B), the TN52ND2 board in slot 6 reported a WAVELEN_OVER alarm for its optical port 1. After a field inspection of the NE configurations, Huawei frontline engineer determined that the wavelength monitoring configuration on NE B was incorrect. After the configuration was corrected, the TN52ND2 board on NE B stopped reporting the WAVELEN_OVER alarm, but the R_LOS alarm on NE A was still reported on a regular basis.

Network Topology

Cause Analysis

As the TN52NQ2 board reported an R_LOS alarm at a specific time in every early morning (00:00–06:00), one can determine that a wavelength drift had occurred on the TN52NQ2 board of the peer NE.

If the wavelength monitoring configuration of the TN52NQ2 board on the peer NE is correct, then there are the following possible causes:

• A multi-NE wavelength locking function has been configured for the TN52NQ2 board on the peer NE and the configuration is incorrect.
• The logical and physical fiber connections between the two NEs are inconsistent.
• An electrical regeneration NE is located between NEs A and B, as shown in the following figure, and the wavelength monitoring configuration on this NE is incorrect.

Procedure

1. Checked the NE monitoring configuration of other NEs on the network. The multi-wavelength locking function was not configured for these NEs.
2. Sent test TTI bytes from optical port 1 on the TN52ND2 board in slot 6 of NE B to optical port 1 on the TN52ND2 board in slot 4 of NE A.
   1. When test TTI bytes were sent in the SM section, optical port 1 on the TN52ND2 board in slot 4 of NE A had not received any TTI bytes.
   2. When test TTI bytes were sent in the PM section, optical port 1 on the TN52ND2 board in slot 4 of NE A received the TTI bytes.
   Based on the preceding information, Huawei determined that an electrical regeneration NE was located between NEs A and B.
   The following describes how to set and check test TTI bytes:
   1. 1. Start the NE Explorer of the transmitting NE, select the board that you use to transmit TTI bytes, and choose OTN Overhead Management > SM Overhead or OTN Overhead Management > PM Overhead.
      
   2. Enter a required value in TTI to be Sent on the right of the window.
      
   3. Start the NE Explorer of the receiving NE, select the board for receiving the TTI bytes, and choose OTN Overhead Management > SM Overhead or OTN Overhead Management > PM Overhead.
   4. Check the value of TTI Received to see whether it is the same as the value of TTI to be Sent.
      
3. Confirmed that the TTI bytes from optical port 1 on the TN52ND2 board in slot 6 of NE B to optical port 1 on the TN52ND2 board in slot 4 on NE A traversed an electrical regeneration NE. Checked that the wavelength monitoring configuration on this NE was incorrect.
4. Correctly the wavelength monitoring configuration for the regeneration NE. Then the TN52ND2 board on NE A stopped reporting the R_LOS alarm.

Conclusion and Suggestion

When a line board on an NE reports an R_LOS alarm at a regular basis, if the wavelength monitoring configuration on the peer NE is correct, check whether:

• The logical and physical fiber connections between the two NEs are consistent.
• An electrical regeneration NE is located between the two NEs.

The following provides the check methods:

1. To check whether the logical and physical fiber connections are consistent, send TTI bytes in the PM section between the two NEs.
2. To check whether an electrical regeneration NE is located between the two NEs, send TTI bytes in the SM section between the two NEs

When the data communication is unavailable or interrupted intermittently, or when packet loss occurs, check the working mode of the interconnected ports. In most cases, the problem is due to the mismatch of the port working modes at the two ends.

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Dispersion Topology Affects System Performance

Dispersion topology affects system performance.

Product

OptiX BWS 1600G, OptiX OSN 6800, OSN 8800, WDM

Fault Type

Dispersion Abnormity

BEFFEC_EXC

Symptom

The AB network uses the OptiX BWS 1600G 80-channel system, the system OSNR satisfies the requirement for transmitting 10G services. However, BEFFEC_EXC alarms are reported for some wavelengths, indicating that the pre-FEC BER exceeds the permitted range. In addition, the multi-channel spectrum analyzer (MCA) scanning result shows that the OSNRs for some wavelengths are low.

The OSNRs for all wavelengths transmitted from site B to site A are low, and BEFFEC_EXC alarms are reported for some wavelengths.

The following figure shows the network topology.

Figure 1 The Network Topology of AB Network

Cause Analysis

The inherent dispersion of G.655 fibers is near 0 ps/nm.km. Therefore, the signal transmission performance is likely affected by non-linear effects during long-haul transmission of wavelengths over G.655 fibers. The non-linear effects lead to a wider spectrum. A wider spectrum results in a higher noise base than the actual noise base and lower scanned OSNRs than the actual OSNRs.

Dispersion and non-linearity affect one other. The dispersion topology in the direction from site A to site B has a relatively good quality and minimizes the impact of non-linear effects on the optical spectrum. Therefore, the scanned OSNRs in this direction are close to the actual OSNRs. The dispersion topology in the direction from site B to site A has a relatively poor quality and fails to effectively suppress the impact of non-linear effects on the optical spectrum. Therefore, the scanned OSNRs in this direction are lower than the actual OSNRs.

The impact of non-linear effects on the system performance can be minimized by optimizing the dispersion topology in the direction from site B to site A. By doing this, the scanned OSNRs will be closer to the actual OSNRs.

Procedure

1. Collect data from the live network. The network conditions satisfy the requirements for commissioning line optical power.
2. Verify that the flatness of each wavelength. The flatness of each wavelength is within the permitted range using the MCA.
3. Calculate the residual network dispersion according to the design documents. The residual dispersion is within the range defined in 10G OTU board specifications.
4. Optimize the dispersion topology in the direction from site B to site A to minimize the impact of non-linear effects on the system performance. The scanned OSNRs are closer to the actual OSNRs. The problem is resolved.

Result

The problem is resolved.

Reference Information

Optical fibers (such as LEAF and G.653 fibers) with smaller dispersion coefficients cause more intensive non-linear effects than optical fibers (such as SMF fibers) with larger dispersion coefficients. To improve the receive-end system performance, you can optimize the dispersion topology.

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