Troubleshooting Physical Networks

CompTIA+ Network Learning

Network troubleshooting methodology

A systematic approach used to solve problems in a network.

Identify the problem

The first step in the troubleshooting process, where the issue is clearly understood and more information is gathered.

Establish a theory of probable cause

The second step in the troubleshooting process, where a possible solution to the identified problem is determined.

Test the theory to determine the cause

The third step in the troubleshooting process, where the theory is tested through actions such as pinging or checking network configurations.

Establish a plan of action to resolve the problem and identify potential effects

The fourth step in the troubleshooting process, where a plan is created to resolve the issue and potential impacts are identified.

Implement the solution or escalate as necessary

The fifth step in the troubleshooting process, where the solution is implemented or the problem is escalated to higher-level technicians if beyond the scope of abilities.

Document findings, actions, outcomes, and lessons learned

The seventh and final step in the troubleshooting process, where the results and actions taken are documented for future reference and learning.

Level two or level three engineer

An engineer with the expertise to replace a router, cable it up, load baseline configurations, and get it working again.

Escalation

The process of involving higher level technicians to solve a problem.

Verify full system functionality

Testing the system to ensure that it is working properly after implementing a solution.

Implement preventative measures

Taking steps to prevent the recurrence of a problem or issue.

Routing loop

A situation where network traffic is continuously routed in a loop, causing high CPU utilization and other issues.

Document findings, actions, outcomes, and lessons learned

Recording information about the problem, actions taken, results, and any lessons learned for future reference.

Network troubleshooting methodology

A set of steps to follow when troubleshooting network issues, including identifying the problem, establishing a theory of probable cause, testing the theory, establishing a plan of action, implementing the solution, verifying system functionality, and documenting the process.

CAT 5

Twisted pair copper cable that operates at 100 megabits per second at a distance of up to 100 meters.

CAT 5e

Twisted pair copper cable that operates at 1,000 megabits per second at a distance of up to 100 meters.

CAT 6

Twisted pair copper cable that can operate at 1,000 megabits per second at a distance of up to 100 meters or at 10 gigabits per second at a distance of up to 55 meters.

CAT 6a and CAT 7

Twisted pair copper cables that operate at 10 gigabits per second at a distance of up to 100 meters.

CAT 8

Twisted pair copper cable that operates at 40 gigabits per second at a distance of up to 30 meters.

Coaxial cable

Cable that can support speeds of up to 100 megabits per second at a distance of up to 500 meters.

Twinaxial cable

Cable that can support speeds of up to 10 gigabits per second at a distance of up to 5 meters or less.

Fiber cable

Cable that can support various speeds and distances depending on the type, such as 100 megabits per second at a distance of up to 2 kilometers using multimode fiber.

Shielded twisted pair cable

Twisted pair cable with additional shielding to protect against electromagnetic interference (EMI).

Unshielded twisted pair cable

Twisted pair cable without additional shielding, commonly used in local area networks.

Plenum rated cable

Cable with a higher fire rating and fire retardant plastic jackets, used in spaces between the ceiling and the floor above.

Riser rated cable

Cable used to run network cables vertically between floors in a building, with special coatings to prevent flames from spreading.

Rollover or console cable

A null modem cable used to connect a computer terminal to a router's console port for out-of-band communication.

Crossover cable

A special type of network cable used to connect two ethernet devices directly.

Power over Ethernet

A technology that allows electrical power to be transmitted over ethernet cables, eliminating the need for separate power cables.

Crossover Cable

A cable used to connect two computers, routers, or network devices for complex data transfers, created by using TIA 568 B pinout on one side and TIA 568 A pinout on the other side.

Power over Ethernet (PoE)

A technology that delivers electrical power over twisted pair Ethernet cables to devices such as wireless access points, IP cameras, and VoIP phones, enabling data and power transmission through a single cable.

Category 5E

A minimum requirement for supporting Power over Ethernet, a type of copper twisted pair cable that ensures proper functioning and safety when transmitting data and power.

Cable Strippers

Tools used to remove the outer plastic jacket and insulation from a cable, preparing it for attachment to a connector.

Cable Crimpers

Tools used to attach connectors, such as RJ45 or RG6, to the end of a cable.

Cable Testers

Devices used to verify the continuity and proper connection of individual wires within a twisted pair cable, ensuring correct pinouts for straight-through or crossover cables.

Wire Mapping Tools

Tools specifically designed for testing and diagnosing issues in twisted pair Ethernet cables, including open pairs, shorts, reverse pairs, cross pairs, and split pairs.

Cable Certifiers

Devices used to determine the category and data throughput of an existing cable, providing information on length, delay, and resistance.

Multimeters

Tools used to check voltage, amperage, and resistance in copper cables, verifying cable integrity and power sources.

Punch Down Tools

Tools used to terminate wires on punch down blocks, stripping off excess insulation and trimming unnecessary wires.

Tone Generators

Devices used to generate a tone on one end of a connection and detect it audibly using a probe on the other end, helping to locate and identify cables in walls or unlabeled networks.

Loopback Adapter

A device used to create a loopback in a network, either by connecting twisted pair wires or using a fiber patch cable.

TDR (Time-Domain Reflectometer)

A tool used to locate breaks in copper cables and estimate the severity and distance to the break.

OTDR (Optical Time-Domain Reflectometer)

An optical version of the TDR used for fiber optic cables, which measures breaks and distances using light reflection.

Fiber Light Meter

Also known as an optical power meter, it measures the amount of light transmitted through a fiber optic cable and detects any loss or attenuation.

Fusion Splicer

A machine used to permanently join or splice two fiber optic cables together, typically used for long cables or underground connections.

Tap

A device that connects to the cable infrastructure and copies packets for analysis, security, or network management purposes.

Spectrum Analyzer

A device that measures and displays the signal strength and frequency variations in a medium, such as copper cables or radio waves.

Attenuation

The decrease in signal strength that occurs when the outside plastic of a wire melts away, exposing the inside wire to flammable materials.

Well-insulated wires

Wires that are properly insulated to prevent exposure to flammable materials and minimize attenuation.

Temperature control

Maintaining the appropriate temperature for network connections to ensure a strong signal and minimal attenuation.

Shielded twisted pair

A type of cable that provides better protection against attenuation in hotter or colder environments compared to unshielded twisted pair.

Shortening the distance

Using cables that are shorter than the maximum length of 100 meters to ensure a clear and strong signal on all connections.

Amplifier or repeater

Layer one devices that boost and retransmit signals, allowing for longer cable runs without signal loss.

Fiber cables

Cables that use light instead of electricity, experiencing attenuation at much longer distances compared to copper cables.

Dirty connectors

Fiber connectors that have dirt or contaminants, causing signal loss and attenuation.

dB loss

The measure of signal deterioration on a given connection, used to assess attenuation on copper and fiber cables.

Incorrect pinouts

Incorrect wiring connections on patch panels, wall jacks, or RJ45 connectors, leading to network connection issues.

Bad ports

Faulty or malfunctioning ethernet ports on network interface cards, switches, or routers.

Opens and shorts

Breaks or disconnections in the wires of a cable connection, causing signal loss and network issues.

Wall Jack Connection

The physical connection point on a wall for network cables.

Short

A connection between two wires that should not be connected, usually caused by poor cable construction or accidental contact between wires.

Rewire

The process of replacing or adjusting the connections in an RJ45 connector to fix a short or connectivity issue.

Cable Tester

A tool used to test for incorrect pinouts, opens, and shorts in network cables.

Loopback Adaptor

A tool used to test for a bad port by creating a loopback connection.

Fiber Cable

A type of cable used for transmitting data using light signals.

Transceiver

A device that combines a transmitter and receiver in one, used to convert network connections from one type to another.

Dirty Optical Cables

Fiber optic cables that have dirt, dust, or other substances interfering with the clear optical connection.

Dry Cleaning

A method of cleaning fiber cables or connectors using light pressure and a dry cleaning cloth.

Wet Cleaning

A more invasive method of cleaning fiber cables or connectors using a lint-free cloth moistened with a fiber optic cleaning solution.

Ethernet

A network protocol commonly used for local area networks (LANs).

LED Status Indicators

Lights on network interface cards and switches that indicate the status and activity level of the network connection.

Duplexing Issues

Problems related to the negotiation of full duplex or half duplex connections in Ethernet connections.

Duplex Mismatch

A situation where one device in an Ethernet connection thinks the connection is full duplex while the other device thinks it is half duplex.