Computer network maintenance is a critical responsibility for ICT technicians in Kenya, ensuring that organizational networks operate efficiently and securely. Networks in institutions such as hospitals, banks, and county government offices must be consistently monitored to prevent downtime and data loss, which can disrupt vital services and lead to financial losses. This chapter focuses on the practical aspects of monitoring and maintaining computer networks, equipping ICT technicians with the knowledge and tools necessary to sustain network health and performance.

3.1 Monitoring computer network

Monitoring a computer network involves the continuous observation and analysis of network components to detect faults, performance issues, and security breaches. In the Kenyan professional context, where many organizations rely on stable connectivity for service delivery, proactive monitoring helps prevent costly network failures. Effective network monitoring also supports compliance with regulatory requirements by identifying unauthorized access or configuration changes early.

3.1.1 Introduction to computer network monitoring and maintenance

Network monitoring and maintenance are complementary processes essential for sustaining network availability and performance. Monitoring focuses on real-time observation of network traffic, device status, and connectivity, while maintenance involves the corrective and preventive actions taken based on monitoring insights. For instance, a SACCO using an online banking platform must monitor its network to ensure transactions are processed without delay or interruption.

Network monitoring: purpose and scope

• Detecting Network Failures: Early identification of outages or hardware malfunctions to minimize downtime.
• Performance Analysis: Tracking bandwidth usage, latency, and packet loss to maintain optimal speed and reliability.
• Security Surveillance: Monitoring suspicious activities such as unauthorized access attempts or malware propagation.
• Resource Utilization: Assessing how network resources like routers and switches are being used to optimize capacity.
• Compliance Monitoring: Ensuring network configurations meet organizational policies and regulatory standards.

Network maintenance: objectives and activities

• Fault Correction: Repairing or replacing malfunctioning devices identified during monitoring.
• Preventive Maintenance: Scheduled updates and checks to avoid unexpected failures.
• Configuration Management: Regular updating of device settings to enhance security and performance.
• Backup and Recovery: Maintaining current backups of configurations and data to enable quick restoration.
• Documentation: Keeping detailed records of network changes and maintenance activities for accountability and troubleshooting.

Benefits of combined monitoring and maintenance

• Reduced Downtime: Proactive detection and resolution of issues prevent extended outages.
• Improved Security: Continuous oversight helps identify and mitigate threats promptly.
• Cost Efficiency: Early fault detection lowers repair costs and prevents expensive network replacements.
• Enhanced User Experience: Reliable network availability supports uninterrupted business operations.
• Compliance Assurance: Regular maintenance ensures adherence to standards such as Kenya’s Data Protection Act.

3.1.2 Computer network monitoring physical tools

Physical monitoring tools let an ICT technician check cables, ports, connectors and power without relying only on software. A technician who carries the right tools can confirm in minutes whether a fault lies in the cable, the connector, the port or the power feed. The table below lists the tools used in this unit, followed by examples of where each one is applied.

• Multimeters help technicians in hospitals verify that power adapters and distribution boards feeding network devices deliver stable voltage.
• Tone generators and probes are essential when tracing network cables in complex office environments such as banks where cables are routed through ceilings and walls.
• Loopback adapters facilitate quick testing of network interfaces on switches and routers in universities to confirm port operability.
• Visual fault locators are critical in telecommunications companies and large enterprises for maintaining fiber optic infrastructure.

3.1.2.1 Cable testers

A cable tester is a handheld device made of a main unit and a remote unit that checks whether each wire in a network cable is connected correctly from end to end. It saves time because a faulty patch cord or wall-socket termination is found before users complain of a dead connection. Example: ICT technicians at a county government office use a cable tester to verify every newly installed Ethernet cable before computers are connected.

Common features and types:

• Basic continuity tester: Lights eight LEDs in sequence to show that each conductor is continuous and wired in the right order.
• Wire-map function: Shows open circuits, short circuits, crossed pairs and reversed pairs.
• Length measurement: Better testers estimate cable length, which helps confirm that a run stays within the 100 m limit for twisted-pair Ethernet.
• Split-pair detection: Only advanced testers detect split pairs, where continuity looks correct but the wires of a pair are not twisted together, causing crosstalk.
• Certification testers: Measure performance parameters such as attenuation and crosstalk against a cable category and give a pass or fail report.

Interpreting a wire-map result:

Procedure for testing a patch cord or installed cable:

1. Inspect the cable and plugs for cuts, crushed jackets and bent or missing contacts.
2. Switch on the tester and select the wire-map or continuity mode.
3. Plug one end of the cable into the main unit and the other end into the remote unit. For a cable already installed, connect the remote unit at the wall socket and the main unit at the patch panel.
4. Press the test button and watch the LEDs on both units step from 1 to 8.
5. Compare the sequence with the table above. A straight-through cable shows 1 to 8 in the same order on both units.
6. Record the result and label the cable with its identification number.
7. Re-terminate any failed cable, retest it, and replace it if it still fails.

3.1.2.2 Crimping tool

A crimping tool presses the metal contacts of an RJ45 plug into the conductors of a twisted-pair cable and locks the plug body onto the jacket. A good crimp gives a gas-tight connection that stays reliable for years, while a poor crimp causes intermittent drops and slow links. Example: a technician fitting out a new computer laboratory crimps RJ45 plugs on patch cords cut to the exact length needed between each computer and the wall socket.

Features to look for when selecting a crimper:

• Ratchet mechanism: Forces the handle to complete the full stroke so that every crimp has the same pressure.
• Correct die: The 8P8C die fits RJ45 plugs, while the smaller 6P die fits RJ11 telephone plugs.
• Built-in cutter: Trims the conductors square before insertion.
• Built-in stripper: Some models include a blade for removing the jacket, but a separate stripper gives cleaner results.
• Plug compatibility: Use plugs rated for the cable category, for example Cat6 plugs for Cat6 cable, because the conductor thickness and plug design differ.

Wiring colour order used when terminating both ends the same way (straight-through):

Procedure for crimping an RJ45 plug:

1. Cut the cable to the required length with a clean, square cut.
2. Strip about 25 to 30 mm of the outer jacket, taking care not to nick the conductors.
3. Untwist the four pairs only as far as needed and straighten the wires between your fingers.
4. Arrange the conductors in the chosen colour order (T568B in the table above) and keep them flat and side by side.
5. Trim the ends square so that about 12 mm of conductor shows beyond the jacket.
6. With the plug clip facing down, slide the conductors fully into the plug until each one touches the front end and the jacket enters the plug body.
7. Place the plug in the correct die and squeeze the handle until the ratchet releases.
8. Repeat on the other end using the same colour order, then test the cord with a cable tester.

3.1.2.3 Stripping tool

A stripping tool removes the outer jacket of a cable so that the conductors can be arranged and terminated. Its blade depth is set to cut only the jacket, which protects the thin copper conductors from nicks that later become breaks. Example: when preparing cable runs in a ceiling for a new office floor, a technician uses a rotary UTP stripper to prepare dozens of cable ends quickly and consistently.

Types and care:

• Rotary UTP stripper: Clamps around the cable and is turned once or twice to score the jacket, which is then slid off.
• Combination crimp and strip tool: Convenient for field work, but the blade depth is less adjustable.
• Coaxial cable stripper: Cuts the jacket, braid and insulation in stages for coaxial cable.
• Fibre stripper: Removes the coating and buffer from optical fibre without damaging the glass, and is only used with the correct size for the fibre.
• Blade condition: A dull or misadjusted blade crushes the jacket or cuts into conductors, so blades should be checked and replaced when worn.

Procedure for stripping a UTP cable:

1. Check that the cable is not connected to any active equipment.
2. Open the stripper and set the blade depth for the cable thickness, testing on a spare piece of cable first.
3. Place the cable in the stripper so that the cut point is about 25 to 30 mm from the end.
4. Close the tool gently and rotate it around the cable one to two turns to score the jacket.
5. Pull the cable end away to slide off the jacket piece.
6. Inspect the exposed conductors for nicks. If any are found, cut the end off and strip again.
7. Remove any rip cord or separator and proceed to untwist and arrange the pairs for termination.

3.1.3 Physical networking device status monitoring

Monitoring the physical status of networking devices is crucial to identify hardware issues before they escalate into network-wide failures. In Kenya’s dynamic ICT environments, such as insurance firms or hotels, maintaining device health ensures service continuity and customer satisfaction. The points below cover the main physical elements checked on routers, switches, access points and modems.

3.1.3.1 Port and interface

Ports and interfaces are the points where cables connect to a device and where data enters and leaves it. Their status shows quickly whether a link is working, idle or failing. Example: in a hotel back office, a technician notices that the link light of one switch port is off and finds that the connected workstation was moved without its patch cord being reconnected.

What to check:

• LED Status Lights: A steady link LED normally shows that a connection is established, and a blinking activity LED shows traffic. Colours and meanings differ between manufacturers, so check the device manual.
• Port Connectivity: Regular checks ensure all ports in use are active and transmitting data correctly, and that unused ports are recorded as free or disabled.
• Link Speed and Duplex: A port that negotiates 100 Mbps instead of 1 Gbps, or a duplex mismatch, points to a poor cable or a configuration problem.
• Error Counters: Rising counts of input errors, CRC errors or dropped packets on an interface show a faulty cable, connector or port.
• Interface State: The management interface of a managed switch reports whether a port is up, down or administratively disabled.
• Port Damage: Bent contacts or a loose socket inside a port prevent a plug from seating and cause intermittent links.

Procedure for checking a suspect port:

1. Note the port number and the device connected to it.
2. Look at the link and activity LEDs and record their state.
3. Check the interface state and error counters in the device management interface.
4. Move the same patch cord to a known good port. If the fault moves with the cord, the cable is the problem.
5. Insert a loopback adapter into the port. If the port will not come up, the port or interface is faulty.
6. Record the findings and report any faulty port for repair.

3.1.3.2 Cable and connection

Cables and connectors carry every signal on the network and are exposed to bending, pulling, dust and rodents. Inspecting them regularly finds weak points before they cause intermittent faults. Example: in an insurance office, a patch cord squeezed under a moved cabinet leg is found with a flattened jacket, and replacing it removes complaints of random disconnections.

What to inspect:

• Physical Damage: Look for cracks, cuts, kinks, corrosion and loose connectors that may impair device function.
• Plug and Socket Fit: Plugs should click firmly into ports, and the retaining clip must not be broken.
• Bend and Strain: Cables should not be sharply bent, pulled tight or stretched between racks, as this changes the pair geometry and breaks conductors.
• Labelling and Patch Panel Order: Clear labels at both ends make it possible to trace a connection without disturbing other cables.
• Cable Length: A twisted-pair channel should not exceed 100 m in total, including patch cords.
• Separation from Power Cables: Network cables laid next to mains cables can pick up interference.

Procedure for a routine cable and connection inspection:

1. Obtain the network diagram and cable register for the area.
2. Walk along each rack and work area, checking patch cords and sockets for damage.
3. Gently tug each connector to confirm it is seated firmly.
4. Check that cable ties are not too tight and that cables have a gentle bend.
5. Test any suspect cable with a cable tester.
6. Replace or re-terminate damaged cables and update the cable register.

3.1.3.3 Power supply

Network devices depend on a clean, stable power supply. A weak adapter, failing internal power unit or unstable mains can cause reboots and damage hardware. Example: a switch in a small branch office keeps restarting at the same time every afternoon, and a multimeter check shows that its external adapter output is below the rated voltage.

What to monitor:

• Power LED: A power LED that is off or blinking abnormally may signal a supply fault.
• Supply Voltage: Measure the adapter or supply output with a multimeter and compare it with the rating on the device label.
• UPS Condition: An uninterruptible power supply should show normal status, and its battery should be tested so that it can carry the load long enough for a safe shutdown during an outage.
• Surge Protection: Surge protectors and power strips should not show damage, and sensitive equipment should not share circuits with heavy loads such as air conditioners.
• Temperature Levels: Overheating devices can cause intermittent failures or permanent damage, so air intake and exhaust must stay clear and the room temperature should stay within the manufacturer’s operating range.
• Fan Operation: Proper cooling is essential, and malfunctioning or noisy fans increase the risk of hardware failure.
• Environmental Sensors: Temperature and humidity sensors in server rooms give early warning of cooling failures.

Procedure for checking power to a network device using a multimeter:

1. Switch off and unplug the device before disconnecting the adapter.
2. Read the adapter label to find the rated output voltage and polarity.
3. Set the multimeter to DC voltage and choose a range above the rated value.
4. Plug the adapter into the mains supply and keep the output unloaded or connected to a suitable test load, following the manufacturer’s instructions.
5. Touch the probes to the output contacts with the correct polarity and read the voltage.
6. Compare the reading with the label. A reading far below it means the adapter is faulty.
7. Switch off, reconnect or replace the adapter, and record the result.

Safety note: never open a power supply that is connected to the mains, and only trained persons should work on mains wiring.

3.1.3.4 Network optimization

Network optimization means using the status and performance data gathered from monitoring to make the existing network work more efficiently, without replacing it. It begins with knowing how the network normally behaves so that changes can be measured. Example: an office technician finds that the link to the file server is regularly busy during the morning, and rearranges backup schedules so that large transfers run after working hours.

Link utilisation shows how much of a link’s capacity is in use:

Utilisation (%) = (measured traffic ÷ link capacity) × 100

Example: a 1 Gbps link (1000 Mbps) carries 400 Mbps of traffic.

Utilisation = (400 ÷ 1000) × 100

Utilisation = 0.4 × 100

Utilisation = 40%

Optimisation actions based on monitoring:

• Baseline Measurement: Record normal utilisation, latency and error rates so that unusual behaviour is easy to recognise.
• Traffic Prioritisation: Give voice, video and business applications priority over file downloads using the quality of service settings of the device.
• Load Balancing: Spread users or traffic across several links or access points where busy ones show high utilisation.
• Disabling Unused Ports and Services: Switch off ports and services that are not in use to reduce security risks and unnecessary traffic.
• Cable and Airflow Management: Tidy cables, remove excess slack and keep vents clear so that devices stay cool and connectors are not strained.
• Firmware and Configuration Review: Apply stable firmware updates and correct settings such as duplex mismatches that reduce throughput.
• Scheduling of Heavy Tasks: Run backups and large updates outside peak hours.

Hardware and cable upgrades that go beyond tuning are covered in 3.3.

Methods for monitoring device status

• Visual Inspection: Routine checks of LEDs, fans, and physical condition to detect obvious faults.
• Remote Management Tools: Use of SNMP-based software to monitor device health metrics such as CPU load and temperature.
• Event Logs: Analysis of device logs to identify patterns of faults or warnings.
• Scheduled Testing: Periodic testing of ports and cables to confirm operational status.
• Alerts and Notifications: Setting thresholds so that the monitoring system sends an email or message when a device goes offline or a value is exceeded.

Impact of device status on network performance

• Preventing Downtime: Early detection of failing hardware avoids sudden network outages.
• Maintaining Data Integrity: Properly functioning devices reduce packet loss and data corruption.
• Enhancing Security: Hardware failures can expose vulnerabilities that attackers may exploit.
• Maintaining Throughput: Healthy devices ensure maximum throughput and low latency.
• Extending Equipment Lifespan: Timely maintenance based on status monitoring delays costly replacements.

Chapter Summary

This chapter focused on the essential practices for maintaining a computer network, starting with the importance of monitoring network performance and health. It detailed the physical tools used in network monitoring, including cable testers, crimping tools, and stripping tools, which help ensure the integrity of network connections. The chapter then examined how to monitor the status of physical networking devices by checking ports, interfaces, cables, connections, and power supply to identify potential faults and maintain network optimization. Troubleshooting techniques were discussed as a critical part of resolving network issues efficiently. Finally, the chapter explored ways to optimize the network through upgrading hardware devices and computer network cables, which enhances overall performance and reliability. These maintenance activities collectively ensure a stable and efficient network environment.