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Module 3: Networking Media / Overview

Overview
Copper cable is used in almost every LAN. Many different types of copper cable are available. Each type has advantages and disadvantages. Proper selection of cabling is key to efficient network operation. Since copper uses electrical currents to transmit information, it is important to understand some basics of electricity.


Optical fiber is the most frequently used medium for the longer, high bandwidth, point-to-point transmissions required on LAN backbones and on WANs. Optical media uses light to transmit data through thin glass or plastic fiber. Electrical signals cause a fiber-optic transmitter to generate the light signals sent down the fiber. The receiving host receives the light signals and converts them to electrical signals at the far end of the fiber. However, there is no electricity in the fiber-optic cable. In fact, the glass used in fiber-optic cable is a very good electrical insulator.

Physical connectivity allows users to share printers, servers, and software, which can increase productivity. Traditional networked systems require the workstations to remain stationary and permit moves only within the limits of the media and office area.

The introduction of wireless technology removes these restraints and brings true portability to computer networks. Currently, wireless technology does not provide the high-speed transfers, security, or uptime reliability of cabled networks. However, flexibility of wireless has justified the trade off.

Administrators often consider wireless when they install or upgrade a network. A simple wireless network could be working just a few minutes after the workstations are turned on. Connectivity to the Internet is provided through a wired connection, router, cable, or DSL modem and a wireless access point that acts as a hub for the wireless nodes. In a residential or small office environment these devices may be combined into a single unit.

This module covers some of the objectives for the CCNA 640-801, INTRO 640-821, and ICND 640-811 exams.

Students who complete this module should be able to perform the following tasks:

• Discuss the electrical properties of matter
• Define voltage, resistance, impedance, current, and circuits
• Describe the specifications and performances of different types of cable
• Describe coaxial cable and its advantages and disadvantages compared to other types of cable
• Describe STP cable and its uses
• Describe UTP cable and its uses
• Discuss the characteristics of straight-through, crossover, and rollover cables and where each is used
• Explain the basics of fiber-optic cable
• Describe how fiber-optic cables can carry light signals over long distances
• Describe multimode and single-mode fiber
• Describe how fiber is installed
• Describe the type of connectors and equipment used with fiber-optic cable
• Explain how fiber is tested to ensure that it will function properly
• Discuss safety issues related to fiber optics

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