4A0-265 Nokia Optical Diagnostics and Troubleshooting Exam Questions and Answers

The recommended order for the troubleshooting steps is A, as follows:

• Retrieve the channel power trace. This step is useful to identify the affected channel and its power level, as well as to check if there are any fluctuations or anomalies in the power trace that could indicate a clock source issue1.
• Determine the active clock reference source. This step is necessary to verify which clock source is currently used by the node, and if it matches the expected configuration. The clock source can be either a local oscillator (LO) or a phase-locked loop (PLL) that synchronizes with an external reference2. The active clock source can be determined by using the command show interface ot 1/1/lineout detail3.
• Switch to alternate clock source (PF). This step is helpful to isolate the problem and confirm if the suspect PF is indeed causing the channel-related alarm. By switching to an alternate clock source, such as another PF or an external reference, the node can recover from the alarm if the original clock source was faulty4.
• Replace the suspect PF. This step is the final solution to resolve the issue and restore the normal operation of the node. The suspect PF should be replacedwith a new one that has the same specifications and configuration as the original one5. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, Optical User Guide - Nokia, Alcatel-Lucent 1830 PSS-8 and PSS-16 Photonic Service Switch

The command show interface am2125a 1/6/lineout detail is used to retrieve the total output power level of the AM2125A amplifier module. This command displays detailed information about the lineout interface, including the current optical power, wavelength, and status. The total output power level is shown as Output Power (dBm) in the output of this command1. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia

The exhibit shows a diagram of an OT module with a client port and a DWDM port. The client port is looped back to itself with an OEO (Optical-Electrical-Optical) device. This means that the signal received by the client port is converted to an electrical signal, then back to an optical signal, and then transmitted back to the same port. This type of loopback is called a client portterminal loopback. It is used to test the functionality of the client port without involving the DWDM port or any other network element4. A client port facility loopback would involve looping back the signal from the DWDM port to the client port. A line port facility loopback would involve looping back the signal from another OT module or network element to the DWDM port. A line port terminal loopback would involve looping back the signal from the DWDM port to itself5. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, Loopback - Wikipedia

 A Threshold Crossing Alert (TCA) alarm is a type of alarm that indicates that a monitored parameter has crossed a predefined threshold. For example, a TCA alarm can be triggered when the optical power received at a port is too high or too low. The default severity level for a TCA alarm is warning, which means that it does not affect the service but may require attention. The other severity levels are critical, major, and minor, which indicate different degrees of impact and urgency of the alarms. The severity level of a TCA alarm can be changed by the user using the Nokia 1830 Engineering and Planning Tool (EPT) or the Nokia 1350 Optical Management System (OMS). References: Nokia Optical Diagnostics and Troubleshooting Course, Nokia 1830 PSS-32 and PSS-16 Photonic Service Switch Release 8.0 Alarms and Conditions 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)

 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

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

The payload type setting is an attribute that is recorded within the client payload and can be set automatically or manually. The payload type setting indicates the type of client signal that is carried by the OTN frame, such as Ethernet, Fibre Channel, or SDH/SONET. The payload type setting can be used for service identification and performance monitoring purposes. The payload type setting can be set automatically by the ML-Series card, which can detect the client signal type and encode it in the payload header. Alternatively, the payload type setting can be set manually by the user using the command config interface encmode payloadtype , where  is the client interface name,  is the encapsulation mode, such as GFP-F or BMP, and  is the client signal type, such as 10GE LAN or FC-1200. The other options are incorrect because they either state that the payload type setting is recorded within the OTN overhead, which is not true, or that it must be entered manually, which is not necessary. References: Nokia Optical Diagnostics and Troubleshooting Course, OAM and Diagnostics Guide

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