P_LOS Alarm Is Generated Because Cable Is Too Long

When the routed cable exceeds the maximum cable length supported by the equipment, the P_LOS alarm is generated. Hence, it is recommended that the cable length is maintained within 50 meters. Otherwise, the services may be affected.

Fault Type

  • Service interruption
  • P_LOS

Symptom

The OptiX OSN equipment provides a client with a VC-3 service. This service is mapped from the PL3 board to the SL64 board. The client complained that the PL3 board continues to report the P_LOS alarm for more than 30 seconds and the services were affected.

Cause Analysis

The possible causes are as follows:

  • The interface board PL3 is faulty or the PL3 board is not inserted properly into the slot.
  • The equipment grounding is improper.
  • The connection of the DDF is loosened.
  • The cable routed from the DDF to the equipment exceeds the maximum cable length supported by the equipment.

Procedure

  1. Check the interface board that corresponds to the PL3 board. It is found that the interface board is corrected inserted. It indicates that the problem is not with the interface board.
  2. Check the connection between the equipment port and the DDF and find the connection is correct.
  3. Check the length of the cable routed from the DDF to the equipment. It is found that the cable length exceeds 70 meters. In this case, adjust the position of the equipment to ensure that the cable length from the DDF to the equipment is less than 50 meters. Then, the alarm is cleared.

ECC Communication Is Available Between Two Isolated Rings

During the deployment of the OptiX OSN equipment, two rings are isolated from each other, but the ECC communication is available between the two rings. Check the relevant information. It is found that the extended ECC function is automatically enabled. Hence, to isolated two rings, you need to disable the extended ECC function.

Product

OptiX OSN 3500

Fault Type

DCN fault

Symptom

The OptiX OSN 3500 forms two rings: north ring and south ring. The two rings are isolated from each other. The north and south rings are connected to the NMS in the central equipment room through a hub for centralized monitoring. Check the ECC routing of the NE. It is found that the ECC routes between the north ring and the south ring are abnormally available.

Cause Analysis

The possible causes are as follows:

  • The fiber connection between the north ring and the south ring in the central equipment room is incorrect. For example, the fibers of the south ring are connected to the north ring.
  • The extended ECC function is automatically enabled.

Procedure

  1. Disable the laser by using the T2000. It is found that the fiber connection on the north and south rings is correct.
  2. Check the ECC routing. The OptiX OSN equipment is newly deployed. Thus, the extended ECC function is not preset and is in the default mode. That is, the AUX board automatically enables the extended ECC function. Disable the extended ECC function. It is found that the ECC communication between the north and south rings is unavailable.

Reference Information

When the OSI protocol is started at the network interfaces, the ECC communication is available between isolated subnetworks. For details, see MC-B9 Fibers Are Not Connected Between Equipment but ECC Communication Between Equipment Is Available.

Fibers Are Not Connected Between Equipment but ECC Communication Between Equipment Is Available

The fibers between the three independent subnetworks are not connected but the ECC communication is available. Check the relevant information. It is found that the OSI communication protocol is enabled by default and thus the routes are automatically created. In this case, to isolate the three subnetworks, you need to disable the OSI communication protocol.

Fault Type

DCN fault

Symptom

The OptiX OSN 3500 forms three independent rings: north ring, southeast ring, and southwest ring. The fiber connection is unavailable between the three rings. Three sets of equipment on the three rings are respectively connected to the hub through a network cable. The hub is connected to the NM computer. Check the ECC routing. Log in to an NE on the north ring and query the ECC routing. It is found that the ECC can be connected to the equipment on the other two rings. The fiber connection, however, is unavailable between the three rings. Log in to an NE on the southeast and southwest rings respectively, and find the same fault exists. The extended ECC is disabled at the gateway NEs on the three rings. Normally, the NEs on the three rings cannot log in to each other in this case.

Cause Analysis

The problem may exist with the fiber connection or the communication protocol of the gateway NE.

Procedure

  1. Check whether the fibers are correctly connected. Remove the network from the gateway NE on the southwest ring to the hub. Log in to an NE on the north ring and check the ECC routing. It is found that the NE fails to connect to the NEs on the southwest ring. Then, remove the network from the gateway NE on the southeast ring to the hub. At this time, only the gateway NE on the north ring is connected to the NMS at the hub. Log in to an NE on the north ring, check the ECC routing. It is found that this NE fails to connect to the NEs on the southwest and southeast rings. It indicates that the fiber connection is correct.
  2. Check whether the extended ECC is configured.
  3. Check the status of the OSI protocol of the gateway NEs. The OptiX OSN equipment supports the OSI communication protocol. Hence, the OSI protocol is enabled at the network port by default. That is, when the equipment is interconnected through a hub, the corresponding routes are automatically created. Disable the OSI protocol of the gateway NE and then the ECC communication between the subnetworks becomes unavailable. All the NEs can log in to NEs on the same ring only.

Reference Information

None.

Wrong Calculation for Dispersion in One DWDM Project

DSC_6275

Wrong calculation for dispersion in OptiX Metro 6100, which leads to B1, B2 and B3 errors. In addition, the R_LOF alarm is detected on SDH analyzer sometimes.

Product

OptiX Metro 6100

OptiX Metro 6040

Fault Type

Bit Errors

Dispersion Abnormity

R_LOF

Symptom

One OptiX Metro 6100 project consists of two OTM stations, five OLA stations, and two OADM stations. The network transmits two STM-16 services and two GE services. In the case of the STM-16 services, two pairs of LWX boards are used for transmission; in the case of the GE services, one pair of LDG boards are used for transmission.

After the hardware installation and software commissioning, it is found that the performance of the STM-16 services is very poor, in which a great deal of B1, B2, and B3 errors are detected. In addition, the R_LOF alarm is detected on SDH analyzer sometimes.

Cause Analysis

Try to reduce the transmission distance by moving the LWX boards into other proper stations. Then, we found the STM-16 services were normal.

Check the real dispersion and find that that the dispersion of the customer’s optical cable does not comply with the international standard for the dispersion. In this case, the dispersion is 8400 ps/nm instead of 7000 ps/nm, whereas the connection is made by 330 km G.652 fiber and 225 km G.655 fiber. In quotation, it describes as follows: two “SS-LWX(S/M,Rx1PIN, I-16,7200ps/nm)” boards used for one station, and two “SS-LWX (S/L,Rx1APD,L-16.2,12800ps/nm)” boards used for the remote station. The dispersion tolerance of LWX board at the first station is insufficient and cannot meet the transmission requirement (8400 ps/nm).

Procedure

  1. Connect the SDH analyzer to the LWX board at one station and created the hardware loop on the client side of the LWX at the remote station. In the case of the locale loop, the STM16 is normal. In the case of the software loop or hardware loop in remote station, the STM16 services is abnormal. On the T2000, no alarm on the LWX boards is reported, but on the SDH analyzer a lot of B1, B2 and B3 errors are detected. Furthermore, sometimes the LOF is detected on the SDH analyzer. After the SDH analyzer is set to send STM-4 services, it is found that the STM-4 services are normal.
  2. Replace the LWX boards at the first station with the LWX boards with 12800 ps/nm dispersion tolerance.

Reference Information

Not every time the features of the optical fiber comply with the international standards. In the system, sometimes aging fibers with poor performance are used. Thus, before the design, collect the information of all the fibers that are used in the existing system. When necessary, consult with customers for the right information about the optical cables.

Communication Between Equipment and NMS Fails After Standby CXL Board Is Switched to Main Mode

08-Rear_looking down

After the standby CXL board is switched to the main mode, the communication between the equipment and the NMS fails. Check the relevant information. It is found that the MAC address of the port is changed after the switching, and as a result the network is blocked. In this case, ensure that the router supports different MAC addresses of the same port.

Product

OptiX OSN 2500

Fault Type

  • Protection Switching Failure
  • DCN fault

Symptom

The OptiX OSN 2500 forms an STM-4 ring, where there is one gateway NE. During the acceptance test, the standby CXL4 board is switched to the main mode, and then the communication between the NEs and the NMS fails but the corresponding alarms are not reported.

Cause Analysis

The software of the standby CXL board may be different from the software of the main CXL board or the DCN may be faulty.

Procedure

  1. Access the NE at the local end and the switching of the CXL4 boards is successful. It indicates that the software of the main CXL4 board and the software of the standby CXL4 board are the same.
  2. Contact the DCN service personnel. It is learnt that the router port in the DCN is already blocked. Although the OptiX OSN 2500 has only one ETH port, the MAC address of this port is still changed when the CXL boards are switched. As a result, the router port is blocked.
  3. The DCN service personnel enable the two MAC addresses of the same router port. Then, the communication is restored to normal.

NM Reports Abnormal ETH_LOS Alarm

DSC_6387

The EFS4 boards at certain stations report the ETH_LOS alarm after the cross-connections of the FE services are added or deleted. This fault can be rectified by disabling the unused MAC ports.

Product

OptiX OSN 1500

Fault Type

  • Alarms and performance events
  • ETH OAM
  • Ethernet fault
  • ETH_LOS

Symptom

The network management (NM) center adds and deletes certain cross-connections of FE services when adjusting certain FE services between the nodes. After the services are adjusted, the EFS4 boards at certain stations report the ETH_LOS alarm.

Cause Analysis

During the service adjustment, the ETH_LOS alarm is generated after services are added or deleted. Hence, the fault may exist in the added or deleted FE services.

Procedure

  1. Check the FE services between two stations. It is found that the corresponding EFS4 board does not report the ETH_LOS alarm after an FE service is normally added.
  2. Check the FE service trails that report the ETH_LOS alarm. It is found that the trails are deleted during the maintenance phase of the service adjustment process, that is, the trails do not exist.
  3. Log in to the T2000 and select NE Explorer. Select the FE service where the ETH_LOS alarm is generated, and check the port attributes of the corresponding EFS4 board. It is found that Enable port of the deleted service is set to Enable. At this time, however, the client-side signals are not accessed. Hence, the board misreports the ETH_LOS alarm.
  4. Set Enable port to Disable for the deleted service. Then, check the alarm. It is found that the ETH_LOS alarm is cleared.
  5. Check all the Ethernet boards on which the ETH_LOS alarm is generated. It is found that this alarm occurs due to the same causes. Set Enable port to for the boards on which the Ethernet services are already deleted. Then, the ETH_LOS alarm is cleared.

Reference Information

None.

End-to-end GE Services Cannot Be Created

04-Front_right 30°down 15°

 

On the OptiX OSN 6800, end-to-end GE services cannot be created.

Product

OptiX OSN 6800

Fault Type

End-to-End Trail

Symptom

The OptiX OSN 6800 V100R003 system is used in a new site. In the ROADM network comprising the WSD9 and RMU9, the L4G is used. After fiber connections are created, OTS and OMS routes are found. Create GE services by using the end-to-end trail function on the T2000V200R006C01. Firstly, create OCh service trails end to end by using the WDM trails. The system should automatically complete the optical cross-connection configuration. It, however, cannot continue to create end-to-end GE services.

Cause Analysis

In the ROADM network comprising the WSD9 and RMU9, after we created OCh trails, only the OCh trails on optical layer are created. The electrical-layer service trails of the ODU 5G and OTU 5G, however, are not created. Currently, the ODU 5G and OTU 5G can be discovered only through searching. Client GE services must be created on OCh optical-layer trails and the electrical-layer service trails of the ODU 5G and OTU 5G. For the relation between trails on each layer, refer to the attachment.

Procedure

  1. After OCh trails are created, use the WDM trail searching function. The electrical-layer service trails of the ODU 5G and OTU 5G are discovered after the searching. Then, use the WDM trail function to create client GE services. In this case, the system automatically completes the electrical cross-connection configuration.

Reference Information

The end-to-end grooming is a very important section in WDM service management. The T2000 supports the creation of end-to-end services on the network layer. After the user specifies the source and sink of a service, the T2000 is able to generate a client trail after it searches out the service trail. The creation of WDM trails effectively simplifies the service configuration process and guarantees the correctness of the operation. In addition, the service grooming and allocation in deployment or capacity expansion are more flexible. When you create end-to-end services on the T2000, search the trails after you create OCh trails. Then, configure client services.