THe Internet
Objectives
• Internet Technology
• Fixed Internet Access
• Portable and Mobile Internet Access
• Internet Services
Background
• The Internet, or net, is a network of computer networks
that enable the flow of data between networks.
• The World Wide Web, or web is a system of hypertext
links that enables access to information from different
computers connected to the Internet.
• The Internet and World Wide Web seem to be the same
thing to many people, when in fact they are both
different entities that people use to communicate.
• In other words, you need to have the Internet in order to
use the World Wide Web.
• Other communication tools that use the Internet include
email, instant messaging, P2P (peer to peer) file sharing,
and VoIP (Voice over Internet Protocol).
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Background• The ARPANET, (Advanced
Research Projects Agency
Network) created in 1969,
connected computers at UCLA,
Stanford Research Institute,
University of Utah, and
University of California at Santa
Barbara
• Early Internet pioneers used
primitive command-line user
interfaces to send e-mail,
transfer files, and run scientific
calculations on Internet
supercomputers
Internet Infrastructure
• The Internet is not owned or operated by any
single corporation or government
• The Internet backbone is a network of highcapacity
communications links that provides the
main routes for data traffic across the Internet
• Backbone links and routers are maintained by
network service providers (NSPs).
• NSP equipment and links are tied together by
network access points (NAPs).
• An Internet service provider (ISP) is a company
that offers Internet access to individuals,
businesses, and smaller ISPs
Internet Infrastructure
• To communicate with an ISP, your computer uses
some type of communications device, such as a
modem
How to access the Web?
• Once you have your Internet connection, then
you need special software called a browser to
access the Web.
• Web browsers are used to connect you to
remote computers, open and transfer files,
display text and images.
• Web browsers are specialized programs.
• Examples of Web browser: Netscape Navigator
(Navigator) and Internet Explorer.
Client/Server Structure of the Web
• Web is a collection of files that reside on computers,
called Web servers, that are located all over the
world and are connected to each other through the
Internet.
• When you use your Internet connection to become
part of the Web, your computer becomes a Web
client in a worldwide client/server network.
• A Web browser is the software that you run on your
computer to make it work as a web client.
Hypertext Markup Language
(HTML)
• The public files on the web servers are ordinary
text files, much like the files used by wordprocessing
software.
• To allow Web browser software to read them, the
text must be formatted according to a generally
accepted standard.
• The standard used on the web is Hypertext
markup language (HTML).
Hypertext Markup Language (HTML)
• HTML uses codes, or tags, to tell the Web browser
software how to display the text contained in the
document.
• For example, a Web browser reading the following
line of text:
<B> A Review of the Book<I>Wind Instruments
of the 18th Century</I></B>
• recognizes the <B> and </B> tags as instructions to
display the entire line of text in bold and the <I> and
</I> tags as instructions to display the text enclosed
by those tags in italics.
Addresses on the Web:IP Addressing
• Each computer on the internet does have a
unique identification number, called an IP
(Internet Protocol) address.
• The IP addressing system currently in use on the
Internet uses a four-part number.
• Each part of the address is a number ranging
from 0 to 255, and each part is separated from
the previous part by period,
• For example, 106.29.242.17
IP Addressing
• The combination of the four IP address parts
provides 4.2 billion possible addresses (256 x 256
x 256 x 256).
• This number seemed adequate until 1998.
• Members of various Internet task forces are
working to develop an alternate addressing
system that will accommodate the projected
growth.
• However, all of their working solutions require
extensive hardware and software changes
throughout the Internet.
Domain Name Addressing
• Most web browsers do not use the IP address t
locate Web sites and individual pages.
• They use domain name addressing.
• A domain name is a unique name associated with
a specific IP address by a program that runs on an
Internet host computer.
• This program, which coordinates the IP addresses
and domain names for all computers attached to
it, is called DNS (Domain Name System )
software.
• The host computer that runs this software is called
a domain name server.
Domain Name Addressing
• Domain names can include any number of parts separated
by periods, however most domain names currently in use
have only three or four parts.
• Domain names follow hierarchical model that you can
follow from top to bottom if you read the name from the
right to the left.
• For example, the domain name gsb.uchicago.edu is the
computer connected to the Internet at the Graduate
School of Business (gsb), which is an academic unit of the
University of Chicago (uchicago), which is an educational
institution (edu).
• No other computer on the Internet has the same domain
name.
Uniform Resource Locators
• The IP address and the domain name each identify a
particular computer on the Internet.
• However, they do not indicate where a Web page’s HTML
document resides on that computer.
• To identify a Web pages exact location, Web browsers rely
on Uniform Resource Locator (URL).
• URL is a four-part addressing scheme that tells the Web
browser:
? What transfer protocol to use for transporting the file
? The domain name of the computer on which the file
resides
? The pathname of the folder or directory on the computer
on which the file resides
? The name of the file
Structure of a Uniform Resource Locators
http://www.chicagosymphony.org/civicconcerts/index.htm
protocol
Domain name
pathname
filename
http => Hypertext Transfer Protocol
HTTP
• The transfer protocol is the set of rules that the
computers use to move files from one computer
to another on the Internet.
• The most common transfer protocol used on the
Internet is the Hypertext Transfer Protocol
(HTTP).
• Two other protocols that you can use on the
Internet are the File Transfer Protocol (FTP) and
the Telnet Protocol
Internet Protocols,
Addresses, and Domains
• A computer can have a permanently assigned
static IP address or a temporarily assigned
dynamic IP address
Internet Protocols,
Addresses, and Domains
Types of Internet Connection
Connection Speed
• Data travels over the Internet at an incredible
speed
• The elapsed time for data to make a round trip
from point A to point B and back to point A is
referred to as latency
– Ping
– Traceroute
• Upstream vs. downstream speed
Connection Speed
• When upstream speeds differ from downstream
speeds, you have an asymmetric Internet
connection
• When upstream and downstream speeds are the
same, you have a symmetric Internet connection
• Internet connection options
– Fixed Internet access
– Portable Internet access
– Mobile Internet access
Dial-up Connections
• A dial-up connection is a fixed Internet
connection that uses a voiceband modem and
telephone lines to transport data between your
computer and your ISP
• A voiceband modem converts the signals from
your computer into audible analog signals that
can travel over telephone lines
• Modem speed is measured in bits per second
Digital Subscriber Line
• DSL is a high-speed, digital, access technology that
runs over standard phone lines with constant
internet connection.
• The speed of a DSL connection varies
Cable Internet Service
• Cable Internet service distributes, broadband Internet
access over the same infrastructure that offers cable
television service
• Cable modems convert your computer’s signal into
one that can travel over the CATV network
• Always-on connection
• DOCSIS-compliant cable
modems
Satellite Internet Service
• Satellite Internet service distributes always-on, highspeed
asymmetric Internet access by broadcasting
signals to and from a personal satellite dish
• A satellite modem is a device that modulates data signals
from a computer into a frequency band that can be
carried to the satellite dish where it is converted to
another frequency, amplified, and transmitted
Fixed Wireless Service
• Fixed wireless Internet service broadcasts signals
in order to offer Internet access to large areas
– WiMAX
– A WiMAX system transmits data
to and from WiMAX antennas
mounted on towers
– Under ideal conditions, WiMAX
can transmit data at 70 Mbps
Internet To Go
• Portable Internet access can be defined as the
ability to easily move your Internet service from
one location to another
• Mobile Internet access offers a continuous
Internet connection as you are walking or riding
in a bus, car, train, or plane
Wi-Fi Hotspots
• A Wi-Fi hotspot is an area in which the public can access a
Wi-Fi network that offers Internet service
• Wi-Fi does not typically provide acceptable mobile Internet
access because you can only remain connected within
range of the network’s hotspot
Portable and Mobile WiMAX
• WiMAX can be used as a portable
technology because Internet access is
available to subscribers anywhere within
a tower’s coverage area
• You use the same Internet service
provider whether you are at home or on
the road
• Mobile WiMAX
Cellular Data Services
• Using cell phone technology to access the Internet
offers mobility that is not yet possible with most of
today’s wired or wireless computer network
technologies
Cellular Data Services
• The 3G cellular technologies for
Internet access are EDGE, EV-DO,
and HSUPA
• WAP (Wireless Application Protocol)
is a communications protocol that
provides Internet access from
handheld devices
• For the real Internet, cellular service
providers offer data services,
sometimes referred to as mobile
broadband
• Most cellular service providers offer
wireless modems for broadband
data access
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Cellular Data Services• MiFi is a brand name
for a compact, mobile,
wireless router offered
by Novatel Wireless
• Some cell phones,
such as the iPhone,
can act as a Wi-Fi
hotspot by becoming
the router for a
wireless network
Processes Supported by the
Internet
• Real time Messaging
• Cloud computing
• Wiki, blogs etc
• File transfer
• VoIP
Real-Time Messaging
• A networked-based, real-time messaging system
allows people to exchange short messages while
they are online
– Instant messaging (IM)
– Chat
Voice over IP
• VoIP (Voice over Internet Protocol) or Voice over IP, is a
technology in which a broadband Internet connection is
used to place telephone calls instead of the regular
phone system
• If you want to set up free computer-to-computer VoIP,
you and the people you communicate with can
download and install freeware or open source VoIP
clients
Forums, Wikis, Blogs,
and Tweets
• An Internet forum is a Web-based online
discussion site where participants post
comments to discussion threads
• A wiki allows participants to modify material
• A blog (short for Web log) is similar to an online
diary; it is maintained by one person and
contains a series of entries on one or more
topics
• A tweet is a short message of 140 characters or
less, posted to the Twitter Web site
FTP
File Sharing Networks
• File sharing, sometimes
called P2P file sharing,
allows users to obtain
files from other users
located anywhere on the
Internet
• BitTorrent is a file sharing
protocol that distributes
the role of file server
across a collection of
dispersed computers
NAT
• Routers are intended to work on LANs to
monitor and direct packets being transported
from one device to another
• A routable IP address is one that can be accessed
by packets on the Internet
• A private IP address is a non-routable IP address
that can be used within a LAN, but not for
Internet data transport
• Network address translation (NAT) is the process
your router uses to keep track of packets and
their corresponding private or public IP
addresses
Virtual Private Networks
• It is possible to secure remote connections by
setting up virtual private network (VPN) access
to a remote access server in the corporate office
• Access to a VPN is usually by invitation only;
employees who need to access a VPN are given
the necessary instructions, addresses, and
passwords to make connections
Summary
• Internet
• Internet Protocols
• Internet Security
Quick Review
• NAPs such as Earthlink and Comcast offer dialup
and cable Internet access.
• TCP, IP, HTTP, and FTP are examples of protocols
used on the Internet.
• 204.127.129.100 is an example of an IP address.
• .edu and .ca are examples of top-level domains.
• The Domain Name System stores IP addresses
and their equivalent domain names.
Quick Review
• Utilities such as Ping and Traceroute help you
gauge the speed of your Internet connection.
• Dial-up and DSL provide Internet access using
telephone cabling.
• Cable Internet service is fast because it has lots
of latency.
• WiMAX uses low-earth orbiting satellites to
transport data to the Internet.
• Public Wi-Fi hotspots provide mobile Internet
access.
• With mobile broadband, you can use a cell
phone to set up a mobile Internet connection.
• Cloud computing uses distributed grid
computing to predict weather.
• VoIP uses circuit switching technology to send
analog data.
• FTP makes it easy to anonymously use a search
engine.
• BitTorrent is an Internet security protocol.
• Consumers should use port probes to encrypt
data sent over the Internet.
• NATs are used by hackers to intercept packets
traveling over the Internet.