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Basic Networking Guide
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1Lesson 2—Networking BASICS
Networking BASICSNetwork Media
Unit 1
Lesson 2
Lesson 2—Networking BASICS 2
Types of Networks• There are two types of
networks by which information is transmitted:– circuit switched networks– packet switched networks
Lesson 2—Networking BASICS 3
Circuit Switched Network
• There is a dedicated and direct physical connection between sender and receiver.
• No other transmissions can take place while the connection is active.
• Once the transmission is ended, other connections can be made with other devices.
• It is ideal for voice communications because there are no interruptions from other devices or delays.
Lesson 2—Networking BASICS 4
Packet Switched Network
• This network requires data transmission be broken into smaller units called packets.
• Each packet is sent independently through the network.
• It is used for data transmission because data is not as time-sensitive as voice communication.
• It allows multiple devices to share one line or frequency.
• It facilitates error correction.
Lesson 2—Networking BASICS 5
Signaling Techniques
• There are two ways that a signal is sent across a network medium:– baseband signaling
– broadband signaling
Lesson 2—Networking BASICS 6
Baseband Signaling• Sends one data signal across the network
media• Entire capacity of the media is used for the
one data signal• Signals are transmitted in a digital format • Many devices can send and receive across
the medium, but only one at a time
Lesson 2—Networking BASICS 7
Baseband Signaling
Lesson 2—Networking BASICS 8
Broadband Signaling• Divides the cable into several different
channels• Signals are transmitted at different
frequencies in an analog mode• Allows many different signals to be sent
simultaneously on a single cable• Signal sent in only one direction• Used for computer network data
transmissions
Lesson 2—Networking BASICS 9
Broadband Signaling
Lesson 2—Networking BASICS 10
Factors Affecting Transmissions
• The flow of a signal down the network media can become distorted.
• Common types of distortions are attenuation and interference.
Lesson 2—Networking BASICS 11
Attenuation• Loss of signal power
• Measured by the decrease in decibels (db) over a specific distance
Lesson 2—Networking BASICS 12
Interference• Interference is caused when a strong external signal
interferes with a signal. • Radio frequency interference (RFI) - interference
caused by broadcast signals from a radio or television transmitter.
• Electromagnetic interference (EMI) - motor or source of intense electrical activity creates an electromagnetic signal that interferes with a data signal.
• Near end crosstalk (NEXT) and Far end crosstalk (FEXT) - interference from another data signal being transmitted on adjacent wire.
Lesson 2—Networking BASICS 13
Transmission Media• Copper cables
• Fiber optic cables
• Wireless
Lesson 2—Networking BASICS 14
Copper Cables• Thin coaxial
• Shielded twisted pair (STP)
• Unshielded twisted pair (UTP)
• UTP rated by Category 1 - 6
Lesson 2—Networking BASICS 15
Copper Cables
Lesson 2—Networking BASICS 16
Copper Cables
Lesson 2—Networking BASICS 17
Fiber Optic• This cable uses a thin cylinder of glass to
send light impulses. • The cable consists of a strand of glass (core)
surrounded by a glass tube (cladding). • Single mode - one light source flashes a light
down the cable.• Multimode - supports many simultaneous
light transmissions.
Lesson 2—Networking BASICS 18
Fiber Optic
Lesson 2—Networking BASICS 19
Wireless• Transmission is sent and received through
invisible waves• Less expensive than copper or fiber optic
lines. • Allows the user to move freely around the
office or campus and still remain connected to the network
• Fastest-growing segment of network media today
Lesson 2—Networking BASICS 20
Wireless Transmissions• Infrared transmits data using infrared (IR)
light.• IR shares many of the same properties as
visible light .• Radio frequency signals can be transmitted
over radio waves similar to local radio station transmissions.
• The signal comes in at a lower power level and does not reach as far.
Lesson 2—Networking BASICS 21
Network Interface Card• The NIC serves as the connection between
the personal computer and the network media.
• It connects to the computer on its base by plugging into an expansion slot of the computer.
• Another connection is accessible from the outside of the computer and has connections for the cables to plug into the network.
Lesson 2—Networking BASICS 22
Network Interface Card
• Changes from parallel to serial transmission
• Creates packets
• Determines when to send
• Transmits packet
Lesson 2—Networking BASICS 23
Network Interface Card