Top Tips for Passing the Nokia 4A0-265 Exam on Your First Try

Performance Measurement (PM) is a feature that collects and reports various statistics related to the performance of an optical network element. PM data can be retrieved at different levels, such as Optical Channel (OCh), Optical Channel Data Unit (ODU), Optical Channel Transport Unit (OTU), and Ethernet. An Optical Transponder (OT) is a device that converts an electrical signal into an optical signal and vice versa. An OT has two interfaces: a client interface and a line interface. The client interface connects to the service provider network, while the line interface connects to the optical transport network. At the OT line interface, PM data can be retrieved for the OCh, ODU, OTU, and Digital Wrapper (DW) levels. The DW is a layer that encapsulates the client signal and provides overhead information for monitoring and management purposes. Ethernet collision counters are not typically retrieved at the OT line interface, as they are related to the Ethernet level, which is usually monitored at the client interface. References: Nokia Optical Diagnostics and Troubleshooting Course, Nokia 1830 PSS-32 and PSS-16 Photonic Service Switch Release 8.0 Performance Monitoring Reference Guide

 The statement that an “Incoming SUPVY LOS” alarm is raised on the local node is NOT a characteristic of an Optical Supervisory Channel Loss of Signal (OSC LOS) issue, in case that no “LD Input LOS” alarms are raised against the involved amplifiers. An “Incoming SUPVY LOS” alarm indicates that the input signal of the Optical Supervisory Channel (OSC) is lost or below the threshold6. The OSC is a bidirectional channel that connects two adjacent nodes in a DWDM network and carries OAM information and other services7. An OSC LOS issue can occur due to a fiber cut, a defective or dirty OSC fiber, or a faulty OSC transmitter or receiver8. However, if there is no “LD Input LOS” alarm raised against the involved amplifiers, it means that there is no loss of signal on the line interface of the amplifier, which carries both service channels and OSC channels9. Therefore, an “Incoming SUPVY LOS” alarm on the local node is not related to an OSC LOS issue, but rather to an OSC configuration issue or a faulty OSC card10. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, Optical User Guide - Nokia, Alcatel-Lucent 1830 PSS-8 and PSS-16 Photonic Service Switch