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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
Communications and Networks

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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
LANs, MANs, and WANs
Network Architectures
Network Topologies
Intranets

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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