What Is Behind the Outage?

About this interactive

The lesson's four groups of causes: - **Service provider:** the ISP or the carrier of a leased line has a fault; your own gear tests fine. - **Cabling:** an incorrect pinout, a run too long (attenuation; copper Ethernet runs are limited to 100 m), noise and interference from power lines and motors, a short or open circuit, a dirty fiber connector. - **Hardware or resources:** CPU or memory overwhelmed, a failed power supply, a failed port, a device that has simply died. - **Configuration:** mismatched duplex or speed, the wrong VLAN, a missing or wrong IP address or mask. The lesson calls configuration one of the most common causes. The lesson files all of these under Layer 1 issues, though a VLAN or address error lives higher up the stack; the symptom, lost or poor connectivity, is what they share.

What you'll learn

Trace a connectivity or performance symptom to its probable cause from the evidence: the service provider, the cabling, the device's hardware or resources, or its configuration
Recognize the lesson's causes in practice: an ISP outage, attenuation, interference, a bad pinout, a short, a dirty fiber, an overloaded CPU, a failed power supply or port, a duplex mismatch, a wrong VLAN or address

Aligned to

CompTIA Network+

5.2 Given a scenario, troubleshoot common cabling and physical interface issues.

5.4 Given a scenario, troubleshoot common performance issues.

Cisco CCST Networking

3.1 Identify cables and connectors commonly used in local area networks

Key terms

Attenuation: The gradual degradation of a signal's strength and clarity as it travels over a physical medium across distance.
Interface Misconfiguration: An incorrect setting on a network device interface, such as a duplex mismatch or wrong VLAN assignment, that causes connectivity or performance issues.
Half Duplex: A communication mode that allows data to be transmitted in both directions but only one direction at a time.
Full Duplex: A communication mode that allows data to be transmitted in both directions simultaneously.
Electromagnetic Interference: Unwanted electrical or electromagnetic energy that disrupts the operation of electronic equipment or degrades the performance of network cabling and wireless signals. EMI can be caused by motors, fluorescent lights, and other electronic devices operating nearby.
Internet Service Provider: A company that provides end users with access to the internet by connecting them to the internet backbone.

Topics

Troubleshooting Layer 1 Cabling Duplex Mismatch Attenuation Interactive Categorize

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