Understanding Computers, Chapter 7

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Computer Networks
Chapter 7
Overview

This chapter covers:
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Common networking and communications applications
Networking concepts and terminology
Technical issues related to networks

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general characteristics of data transmission
types of transmission media in use today
Communications protocols and networking standards
Types of hardware used with a computer network
2
What Is a Network?

Define a network

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A connected system of objects or people
What is a computer network?

A collection of computers and other hardware devices connected
together so users can share hardware, software, and data, and
electronically communicate
3
Understanding Computers: Today and Tomorrow, 13th Edition
LAB NETWORK
SERVERS
SCANNER
PRINTER
Rita
NETWORK
SERVER
CJ
Alejandra
Immanuel
Understanding Computers: Today and Tomorrow, 13th Edition
CAMPUS NETWORK
LIBRARY
ADMISSIONS
NETWORK
SERVER
Taylor
IT DEPT
Yudhis
NETWORK
SERVER
CIS LAB
Rita
LAURIE
Immanuel
BUSINESS
DIVISION
KEVIN
CJ
Alejandra
MONICA
CAMPUS POLICE
Understanding Computers: Today and Tomorrow, 13th Edition
SOUTH BAY NETWORK
ECC
WHOLE
FOODS
AARON
DANICA
JOES CAR
REPAIR
SUSIE
NICHOLAS
24 HOUR FITNESS
BANANA REPUBLIC
MANNY
CHRYSLER
MONICA
RITA
SARAH
BARNES AND NOBLE
ELYSE
STARBUCKS
ANGELICA
ABERCROMBIE
Understanding Computers: Today and Tomorrow, 13th Edition
WORLDWIDE NETWORK
Why learn
aboutComputers:
networks?
Understanding
Today and Tomorrow, 13th Edition


All around us
Use them all the time





Homes
Jobs
Schools
Airports
Hospitals
PHONES, GPS, MONITORING, CONFERENCES,
REMOTE CONSULTATIONS
9
NETWORKED HOME
10
Understanding Computers: Today and Tomorrow, 13th Edition
Network Enabled Appliances
http://www.youtube.com/watch?v
=WWgy1Y27QnI&feature=share&
list=PLF5B83361104F301B
SETTING UP A NETWORK

Networking hardware

Network adapter: Used to connect a computer to a network
or the Internet



Also called network interface card (NIC) when in the form of an
expansion card
Modem: Device that connects a computer to the Internet or
to another computer (cable, DSL, etc.)
Wired/Wireless router: Connects wired/wireless devices in a
network
12
Network Adapters
13
Networking Hardware for Connecting
Devices and Networks

Repeater: Amplifies signals along a network

Range extender: Repeater for a wireless network

Wireless router: Typically connects both wired and wireless
devices in a network
14
Networking Hardware for Connecting
Devices and Networks
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Hub:
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Switch:
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Connects devices in a network like a hub but only sends data to the
device for which the data is intended
Wireless access point:
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Central device that connects all of the devices on the network and
sends data to all devices
Used to grant network access to wireless client devices
Bridges:

Used to connect two networks together usually on a local network
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Understanding Computers: Today and Tomorrow, 13th Edition
Network Characteristics

Communication Architecture
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Topology
Size/Coverage Area
Transmission Characteristics
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Client/server and P2P
Bandwidth
Signal
Transmission Method
Data Organization
Transmission Direction
Delivery Method
Hardware
Connection method
Protocols and Standards
Network Communication Architectures

The way networks are designed to communicate

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Client-server networks
Peer-to-peer (P2P) networks: All computers at the same
level
17
Network Topologies

How the devices in the network (called nodes) are
arranged
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Star networks
Bus networks
Mesh networks
Ring networks
Tree networks
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Network Topologies
19
Network Size and Coverage Area
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Personal area network (PAN)
Home area network (HAN)
Local area network (LAN)
Campus area network (CAN)
Metropolitan area network (???)
Wide area network (???)
Storage area network (???)
Virtual private network (???)
20
Data Transmission Characteristics

Bandwidth: The amount of data that can be transferred in
a given period of time
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
Measured in bits per second (bps)
Analog (waves) vs.
digital Signal (discrete
chunks/packets)
Serial vs. parallel
transmission method


Serial = 1 bit
Parallel = at
least 1 byte at
a time = usually 8
21
Understanding Computers: Today and Tomorrow, 13th Edition
Transmission Timing
Organization
Data Transmission Characteristics

Transmission direction:



Simplex transmission
Half-duplex transmission
Full-duplex transmission
23
Data Transmission Characteristics

Type of delivery method:

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Circuit-switched
Packet-switched
Broadcast
24
Network Connection Method
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Wired


connected to the network via physical cables
Wireless networks

data is typically sent via radio waves
25
Communications Protocols and Networking
Standards
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Protocol: A set of rules for a particular situation

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Standard: A set of criteria or requirements approved by a
recognized standards organization



Communications protocol: A set of rules that determine how
devices on a network communicate
TCP/IP: The most widely used communications protocol – used
with the Internet
Networking standards: Address how networked computers
connect and communicate
Needed to ensure products can work with other products
Communications protocol: A set of rules that determine
how devices on a network communicate
26
HERTZ
How communications work
Understanding Computers: Today and Tomorrow, 13th Edition
Electro-magnetic Spectrum

The range of all possible frequencies of electromagnetic
radiation

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Measured in Hertz (Hz)
Consists of the Electromagnetic radiation and frequency bands

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Range of Hz (energy – radiation)
Spectrum controls distance, volume, ability to pass through barrier
Wireless Spectrum 
Radio Signals - Frequencies assigned by FCC
The Electromagnetic Spectrum
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CONNECTIONS
 CELLULAR
 SATELLITE
 WiFi
 Ethernet
ETHERNET
A wired connection
Ethernet (802.3)

Ethernet: Most widely used standard for wired networks

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Continually evolving
Original (10Base-T) Ethernet networks run at 10 Mbps
Newer 100 Mbps, 1Gbps, and 10 Gbps versions are common
100 Gbps and Terabit Ethernet are in development
Power over Ethernet: Allows electrical power to be sent
along with data on an Ethernet network

Most often used by businesses
33
Power over Ethernet (PoE)
34
Phoneline, Powerline, G.hn, and BPL (802.5)
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Phoneline: Allows networking via ordinary telephone
wiring
Powerline: Allows networking via ordinary electrical
outlets
G.hn: An emerging standard for home networks creating
via phone lines, power lines, and coaxial cable
Broadband over powerline (BPL): Uses existing power
lines to deliver broadband internet to some homes

Limited areas
35
Wi-Fi
Wireless Fidelity
Wi-Fi (802.11)

Wi-Fi (802.11): A family of wireless networking
standards using the IEEE standard 802.11
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Current standard for wireless networks in homes and
offices
Designed for medium-range
transmission
Wi-Fi hardware built into most
notebook computers and many
consumer devices today
Wi-Fi hotspots are rapidly
multiplying
37
Wi-Fi (802.11)
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Speed and distance of Wi-Fi networks depends on:
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Standard and hardware being used (continually
evolving)
Number of solid
objects between
the access point
and the
computer or
device
Possible
interference
38
WiMAX and Mobile WiMAX
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WiMAX (802.16): Fairly new wireless standard for longer
range wireless networking connections
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Designed to deliver broadband to homes, businesses, other
fixed locations
Hotzones close to 2 miles (similar in concept to cell phone
towers)
Mobile WiMAX: Mobile version of the standard

Broadband by via mobile phone, portable computer, etc.
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WiMAX and Mobile WiMAX
40
CELLULAR
Wireless
Cellular Standards
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Cellular standards: Continually evolving
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1st generation: Analog and voice only
2nd generation: Digital, both voice and data
3rd generation: HSDPA/UMTS (high speed downlink, universal
mobile,) EV-DO (evolution data optimized)
4th generation: mobile WiMAX, LTE
42
Short-Range Wireless Standards
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Bluetooth:Very short range (less than 10 feet)
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For communication between computers or mobile devices
and peripheral devices
Bluetooth devices are
automatically
networked with each
other when they are
in range (piconets)
43
Cellular Radio Transmissions
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Cellular radio: Uses cellular towers within cells
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Calls are transferred from cell tower to cell tower as the
individual moves
Cell tower forwards call to the MTSO
Data works in similar manner
Cell phone transmission speed depends on the cellular
standard being used
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Cellular Radio Transmissions
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MICROWAVE & SATELLITE
A wireless connection
Microwave and Satellite Transmissions
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Microwaves: High-frequency radio signals
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Sent and received using microwave stations or satellites
Signals are line of sight, so microwave stations are usually built
on tall buildings, towers, mountaintops
Communication satellites are launched into orbit to send and
receive microwave signals from earth
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Traditional satellites use geosynchronous orbit
Low earth orbit (LEO) satellites were developed to combat delay
Medium earth orbit (MEO) satellites are most often used for GPS
systems
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Microwave and Satellite Transmissions
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Infrared (IR) Transmissions
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IR: Sends data as infrared light
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Like an infrared television remote, IR requires line of sight
Because of this limitation, many formerly IR devices (wireless
mice, keyboards) now use RF technology
IR is still sometimes used to beam data between portable
computers or gaming systems, or send documents from
portable computers to printers
49
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