Pass the Nokia Optical Network Services Expert 4A0-265 Questions and answers with ExamsMirror

A “Loss of Signal” (LOS) alarm is a critical alarm that indicates that there is no or very bad signal at the physical interface. LOS alarm is also raised when the signal level drops below the threshold, at which a high bit error rate (BER) is predicted. LOS alarm can be caused by physical damage, power outage, or misconfiguration of the equipment. LOS alarm can affect the service availability and performance of the optical network. Therefore, it is typically assigned a critical severity level, which means that it requires immediate attention and resolution2. Other severity levels are major, minor, and warning, which indicate different degrees of impact and urgency of the alarms. References: Troubleshooting Guide for Cisco NCS 1002, T1: A Survival Guide, M-series SONET/SDH alarms and troubleshooting tips

The exhibit shows a diagram of a network of nodes and edges, where a single directional fiber cut is occurring between two amplifiers in bidirectional configuration. The node that will report a “LD Input LOS” alarm is node B only. A “LD Input LOS” alarm indicates that the input signal to the laser diode (LD) of an amplifier is lost or below the threshold3. In this case, node B will not receive any signal from node A due to the fiber cut, and will generate this alarm. Node A will not report this alarm, because it can still receive a signal from node C through the other fiber. Node C will not report this alarm either, because it is not directly affected by the fiber cut between node A and node B. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, Troubleshooting Guide for Synchronous Digital Hierarchy - Cisco

The Wavelength Router (WR8-88) block is a device that can route optical signals based on their wavelengths. It can also perform wavelength conversion, multiplexing, and demultiplexing functions. The Wavelength Router (WR8-88) block is part of the Nokia 1830 PSS-8x platform, which is optimized for metro aggregation switching applications in optical transport networks1. In the exhibit, the number 1 refers to the Wavelength Router (WR8-88) block, as indicated by the label WR8-88AF. The other numbers refer to different components of the system, such as transponders, amplifiers, and switches. References: Nokia Optical Diagnostics and Troubleshooting Course, DWDM 1830 PSS-8 WR8-88AF Board

The available output optical power range is the difference between the maximum gain and the minimum gain range of the ingress amplifier. According to the EPT Power Management Report, the maximum gain is 25.7 dB and the minimum gain range is 14 dB. Therefore, the available output optical power range is 25.7 - 14 = 11.7 dB. To convert this to a logarithmic scale, we use the formula 10^(x/10), where x is the value in dB. Therefore, the available output optical power range in logarithmic scale is 10^(11.7/10) - 10^(14/10) = 14.68 - 25.12 = -0.6 to 1.72dB. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, EPT Power Management Report | Nokia

1-Day PMs are one of the types of PM data that can be retrieved from an optical network element. 1-Day PMs show measurements collected over the preceding 24 hours, with each hour being a bin. Up to 8 bins are available for data storing, which means that only the most recent 8 hours of data can be accessed. The other types of PM data are 15-Minute PMs, which show measurements collected over the preceding 15 minutes, with each minute being a bin, and Total PMs, which show measurements collected since the last reset of the PM counters. References: Nokia Optical Diagnostics and Troubleshooting Course, Nokia 1830 PSS-32 and PSS-16 Photonic Service Switch Release 8.0 Performance Monitoring Reference Guide

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 exhibit shows a conditions list from the 1830 PSS GUI, which displays the alarms and events that occur on the network elements. The total number of alarms reported is equal to the number of rows that have a red or yellow icon in the Severity column, indicating a critical or major alarm. In this case, there are 7 rows with such icons, so the total number of alarms is 7. The number of service affecting alarms is equal to the number of rows that have a “Yes” valuein the Service Affecting column, indicating that the alarm affects the service quality or availability. In this case, there are 5 rows with such values, so the number of service affecting alarms is 5. The number of conditions is equal to the total number of rows in the table, regardless of their severity or service affecting status. In this case, there are 7 rows in the table, so the number of conditions is 7. References : Optical User Guide - Nokia, Security Target Nokia 1830 Photonic Service Switch (PSS)

A “Loss too low” message can be displayed after a power adjustment has been provided if there is an issue with unstable optical power levels. Unstable optical power levels can be caused by various factors, such as environmental conditions, fiber aging, equipment malfunction, or configuration errors. Unstable optical power levels can affect the accuracy and reliability of the power adjustment process, which relies on measuring the optical loss between two points in the network. A “Loss too low” message means that the measured optical loss is lower than the expected value, which can indicate a problem with the optical signal quality or integrity. The other issues are incorrect because they either cause a different type of message or do not affect the power adjustment process. References: Nokia Optical Diagnostics and Troubleshooting Course, OAM and Diagnostics Guide

The command that the user should enter to retrieve the OSC pluggable module type is show interface 1/13/OSCSFP detail. This command will display detailed information about the OSC interface on slot 1/13, including the type of pluggable module that is installed in it. The pluggable module type can be either SFP or SFP+, depending on the speed and distance requirements of the OSC link. The command will also show other parameters, such as wavelength, frequency, transmit power, receive power, and status. The other commands are incorrect because they either do not show the pluggable module type or have invalid syntax. References: Nokia Optical Diagnostics and Troubleshooting Course, OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE

 The available output optical power range is the same as in question 5, since the EPT Power Management Report refers to the same ingress amplifier with the same settings and parameters. Therefore, the answer is also A, -0.6 to 1.72 dB. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, EPT Power Management Report | Nokia