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Communications & Networks
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Communications and
Networks
Internet Resources
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Unit Objectives
After completing this chapter you will be able to:
Discuss the purpose of the components required for successful
communications and identify various sending and receiving devices
Describe various uses of computer communications
List the advantages of using a network, and differentiate among
LANs, MANs and WANs
Differentiate between client/server and peer-to-peer networks, and
describe how P2P networks work
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Unit Objectives
Differentiate among a star, bus, and ring network
Describe the various network communications standards
Explain the purpose of communications software
Describe commonly used communications devices
Discuss different ways to set-up a home network
Describe various physical and wireless transmission media
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Communications
Computer communications describes a process in which two or
more computers or devices transfer data, instructions, and
information
Today, even the smallest devices can communicate with each
other – often via the Internet
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Communications
For successful communications you need:
A sending device that initiates an instruction to transmit data,
instructions or information
A communication channel or transmission media on which the data,
instructions, or information travel
A communication device that connects the communications channel
to a receiving device that accepts the transmission
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Uses of Communications
Communications and Networks
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Uses of Communications
Computer communications are everywhere
Many require that you subscribe to an Internet access provider
With others, organizations such as a business or school provide the
communications services
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Summary of Communications
Previously Discussed
Communications Previously Discussed
Blogs Newsgroups
Chat Rooms RSS
E-Mail Video Conferencing
Fax VoIP
FTP Web 2.0
Instant Messaging Wikis
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Wireless Messaging Services
Users can send and receive wireless messages to and from
smartphones, cell phones, and handheld game consoles using
three techniques
Text messaging
Picture/Video messaging, and
Wireless Instant Messaging
The type of messaging depends on the on the services offered
by your wireless Internet service provider, or WISP
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Text Messaging
A mobile device with text messaging allows users to send and
receive short text messages on a phone or other mobile device
Services allow the user options to send and receive:
Mobile to Mobile
Mobile to E-Mail
Web to Mobile, and
Mobile to Provider
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Picture/video messaging
With picture messages users can pictures and sound files, as
well as short text messages, to another device
With video messages users can send short, about :30, videos
is addition to other type of messages
Smart phones and other devices using MMS, typically have a
built-in camera
As a consumer, you should be aware of memory availability and
camera quality
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Wireless Instant Messaging
Wireless instant messaging (IM) is a real-time communications
service that allows mobile devices to exchange messages with
other online users
Some WISPs partner with IM services
AT&T allows communications through AIM, Windows Live
Messenger, and Yahoo! Messenger
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Wireless Access Points
People connect everyday to wireless access points using their
mobile devices to access Internet-based services
Two Types:
Hot Spots, &
Mobile Wireless Networks
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Hot Spots
Is a network that provides wireless Internet connections to
mobile devices
Three technologies
Wi-Fi (local, within a building or room)
WiMax (regional, withing a community)
Bluetooth (location-based hot spots)
Some hot spots are free, schools & coffee shops, and some are
subscription-based
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Mobile Wireless Network
Provided by cell phone companies, for their devices to access
their networks
Coverage and speed depends on the carrier
Most common speed is 3G
“4G” networks are becoming available
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GPS
Short for Global Positioning System
Uses satellite triangulation to pinpoint a location usually within
10-100 meters
Examples
Smart phones
Car Navigation systems
Handheld systems for hiking
Access to additional features
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Geocaching
Geocaching is a real-world outdoor treasure hunting game.
Players try to locate hidden containers, called geocaches,
using GPS-enabled devices and then share their experiences
online.
www.geocaching.com
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Collaboration
People use the Internet to collaborate, or work together online
Methods of collaboration
E-mail
Collaborative Software
Document Management Systems
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E-mail
Oldest form of collaboration
Users send information and documents back and forth through
their e-mail accounts
Pros
Quick and inexpensive
Cons
Creates multiple versions of a document
Information can get lost in the mix
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Collaborative Software
Tools that enable users to share documents via online
meetings and communicate with other connected users
Sometimes called a Web Conference or Web Meeting
Examples
Microsoft Groove or Office Live Meeting
WebEx
Google Apps
GoToMeeting
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Document Management Systems
Provides storage and management of a users documents
Users can be granted access to each others documents
Only one document exists, not multiple versions
Examples
Windows Live SkyDrive
Google Docs
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Cybercafés
Also know as an Internet Café, is a location, usually a
coffeehouse or restaurant, that provides Internet access to its
customers
Examples
Starbucks
Burger King
McDonalds
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Web Services
A Web service is a method of communication between two
electronic devices over the web.
The service can be integrated into any web page so users can
easily access it
They do not require a specific programming language, operating
system or web browser
Examples
Google Apps, Google Cloud Print, Office 365
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Networks
A network is a collection of computers and devices connected
together via communications devices and transmission media
A network can be internal to an organization or span the entire
world
Why network?
Facilitating communications
Sharing hardware
Sharing data and information
Sharing software
Transferring funds
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LANs, MANs, & WANs
Networks can be classified is three categories
1. Local Area Network
2. Metropolitan Area Network
3. Wide Area Network
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Local Area Network (LAN)
A network that connects computers and devices in a limited geographical
area, such as a home, computer lab, or office building
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WLAN
A wireless LAN is a LAN that uses no physical wires
Computers and devices that access a WLAN must have built-in
wireless capability, or an appropriate adapter
Very often WLANs are setup side-by-side with a traditional LAN
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Metropolitan Area Network (MAN)
A high-speed network that connects local area networks in a
metropolitan area such as a city or town
A MAN typically includes one or more LANs but covers a
smaller geographic area then a WAN
Managed by a Network Provider such as a state government,
telephone company, or cable provider
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Wide Area Network (WAN)
Network that covers a large
geographic area, such as a city,
country or the world
A WAN can be one large
network or consist of two or
more LANs
The Internet is the worlds
largest WAN
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Network Architectures
The design of computers, devices, and media in a network,
sometimes called network architecture, is categorized as either
client/server or peer-to-peer
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Client/Server
On a client/server network, one or more computers act as a
server, and the other computers request services from the
server
A server, sometimes called a host computer, control access to
the hardware, software, and other resources on the network
The clients are other computers or mobile devices on the
network that rely on the server for its resources
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Peer-to-Peer
Simple, inexpensive network
that typically connects fewer
than 10 computers or other
devices
Each computer, or peer, has
equal responsibilities and
capabilities
Each computer stores files on
its own hard drives for sharing
Ideal for very small businesses
and home networks
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Internet Peer-to-Peer
P2P describes an Internet network on which users access each
other’s hard disks and exchange files
Sometimes called a file-sharing network
Examples:
BitTorrent
Gnutella
Kazaa
LimeWire
Responsible for the majority of illegal file-sharing on the
Interent
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Network Topologies
A network topology refers to the layout of computers and
devices in a communications network
Three most common topologies:
1. Star
2. Ring, and
3. Bus
Most networks, including the Internet, use a combination of the
three
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Star Network
All of the computers and Node Hub/Switch
devices, called nodes, connect
to a central device, usually
called a hub or a switch
All data is transferred through
the hub or switch
Fairly easy to install
Nodes can be added and
removed without affecting the
rest of the network
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Bus Network
Bus
Consists of a central cable to
which all computers and other
devices connect
The bus is the physical cable
that connects everything
Popular because they are
inexpensive and easy to install
Devices can be added,
removed, and moved with ease
If the bus fails, the entire
Node network goes down
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Ring Network
Node
A cable forms a closed loop, or
ring, with every device
Data travels from device to
device on the ring until it
reaches its destination
If one device fails, the entire
network could possibly go down
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Intranets
An intranet is an internal network that uses Internet
technologies
Intranets usually make company information accessible to
employees
Examples:
Telephone directories
Event calendars
Job postings
Video conferencing
Accessed through a web browser where changes can be made
by everyone
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Network Communication
Standards
Ethernet UWB
Token Ring IrDA
TCP/IP RFID
Wi-Fi WiMAX
Bluetooth WAP
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Network Communication Standards
Today’s networks connect a variety of devices across many
different networks, such as wide area, local area and wireless.
All networks must use similar techniques for connecting
devices to ensure compatibility
Two regulating organizations
1. ANSI
2. IEEE
These organizations propose, develop, and approve network
standards
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Network Communications
Standards
A network standard defines guidelines that specify:
The way computers access the medium to which they are attached,
The type(s) of medium used,
The speeds used on different types of networks, and
The type(s) of physical cable and/or the wireless technology used
A that standard outlines characteristics of how two networks
communicate is called a protocol
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Widely Used Standards & Protocols
You are to choose a standard or protocol below to research on
a and report to the class
1. Ethernet
2. Token Ring
3. TCP/IP
4. Wi-Fi
5. Bluetooth
6. UWB
7. IrDA
8. RFID
9. WiMAX
10. WAP