Cable connectivity issues
In this section, we will address some of the most common connectivity and performance issues that transpire on wired networks. As most of these issues exist at layer 1 and layer 2 of the OSI model, higher-layer protocols will frequently exhibit issues when these problems exist since these higher-layer protocols depend on the services offered by the lower layers. It is therefore recommended that network professionals become familiar with the symptoms of these issues and perform a bottom-to-top troubleshooting methodology when they suspect that these problems are present.
Link lights/status indicators
Most equipment, such as switches, routers, and firewalls, includes lights on each physical interface where cables can be plugged into the equipment, which helps network professionals to diagnose physical layer issues on those links. Lighting schemes differ between different equipment vendors, but a lack of lights on an interface generally corresponds to no...
