Transcript T1-lecture-04

CSC 330 E-Commerce
Teacher
Ahmed Mumtaz Mustehsan
GM-IT CIIT Islamabad
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Virtual Campus, CIIT
COMSATS Institute of Information Technology
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T1-Lecture-4
The Internet and The Web
Chapter-2
Part-II
T1-Lecture-4
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Objectives
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Explain the current structure of Internet.
Understand the limitations of todays internet
Describe the potential capabilities of Internet II
Understand how the world wide web works
Describe how internet and web features and
services support e-commerce.
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The Hourglass Model of the Internet
SOURCE: Adapted from Computer
Science and Telecommunications
Board (CSTB), 2000.
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The Hourglass Model of the Internet
The Internet can be characterized as an hour-glass
modular structure with a lower layer containing the
bit-carrying infrastructure (including cables and
switches) and an upper layer containing user
applications such as e-mail and the Web.
 In the narrow waist are transportation protocols such
as TCP/IP.
Network Technology Substrate layer
 Layer-1 of Internet technology that is composed of
telecommunications networks and protocols
Transport Services and Representation Standards layer
 Layer-2 of Internet architecture that houses the
TCP/IP protocol
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The Hourglass Model of the Internet
Middleware Services layer
 Layer-3: The “glue” that ties the applications to the
communications networks, and includes such
services as security, authentication, addresses, and
storage repositories.
Applications layer
 Layer-4 of Internet architecture that contains client
applications; such as World Wide Web, e-mail, and
audio or video playback.
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Internet Network Architecture
Metropolitan Area Exchanges (MAEs),
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Network Access Points (NAPs)
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Internet Network Architecture Concepts
Backbone:
◦ High-bandwidth fiber-optic cable networks
◦ Private networks owned by a variety of Network Service
Providers (NSPs).
◦ Bandwidth: 155 Mbps 2.5 Gbps
◦ Built-in redundancy
Network Service Provider (NSP)
 Owns and controls one of the major networks comprising the
Internet’s backbone
Bandwidth
 measures how much data can be transferred over a
communications medium within a fixed period of time; is usually
expressed in bits per second (bps), kilobits per second (Kbps),
megabits per second (Mbps),or gigabits per second (Gbps)
Redundancy
 Multiple duplicate devices and paths in a network
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Internet Network Architecture Concepts
Internet Exchange Points (IXPs).
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Hubs where backbones intersect with regional and local
networks, and backbone owners connect with one
another (older term NAPS)
Campus area networks (CANs)
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LANs operating within a single organization that leases
Internet access directly from regional or national carrier.
such as New York University or Microsoft Corporation
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Internet Network Architecture Concepts
Internet Service Providers (ISPs)
 Provide lowest level of service to individuals, small
businesses, some institutions
Narrowband
 the traditional telephone modem connection, now
operating at 56.6 Kbps
broadband
 refers to any communication technology that permits
clients to play streaming audio and video files at
acceptable speed generally anything above 100 Kbps.
Digital Subscriber Line (DSL)
 a telephone technology for delivering high-speed
access through ordinary telephone lines found in
homes or businesses
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Internet Network Architecture Concepts
Cable modem
 A cable television technology that piggybacks digital
access to the Internet on top of the analog video cable
providing television signals to a home
T1 Line
 an international telephone standard for digital
communication that offers guaranteed delivery at 1.54
Mbps
T3
 an international telephone standard for digital
communication that offers guaranteed delivery at 45
Mbps
Satellite
 bulk transfers at variable rates (250 Kbps–1 Mbps)
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Intranets and Extranets
Intranet (Internal network)
 A TCP/IP network located within a single
organization for purposes of communications and
information processing. e.g. Intranet of CIIT
Extranet (external network)
 Formed when firms permit outsiders to access their
internal TCP/IP networks. e.g. General Motors permits
parts suppliers to gain access to GM’s intranet
Note:
Intranets and extranets generally do not involve commercial
transactions in a marketplace, however, extranets supports certain
types of B2B exchanges
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Who Governs the Internet?
Promoters of internet claim that no one governs internet as it is
public domain and inherently above and beyond the law. However,
there are certain organization that influence Internet and monitor
its operations such as :
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Internet Architecture Board (IAB)
Internet Corporation for Assigned Names and
Numbers (ICANN)
Internet Engineering Steering Group (IESG)
Internet Engineering Task Force (IETF)
Internet Society (ISOC)
World Wide Web Consortium (W3C)
International Telecommunications Union (ITU)
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Limitations of current Internet Infrastructure
Bandwidth limitations: Backbone, MAN,CAN & last-mile
Quality of service limitations
 Latency : delays in messages caused by the uneven flow of
information packets through the network.
 “best-effort” quality of service (QoS), which makes no
guarantees about when or whether data will be delivered,
Network architecture limitations
 Downloading same music by thousands of clients slows down
network performance as the same music track is sent out a thousand
times to clients that might be located in the same metropolitan area
Language development limitations
 HTML, the language of Web pages, is fine for text and simple graphics,
but poor at defining and communicating “rich documents,” such as
databases, business documents, or graphics.
Wired Internet limitations
 Copper cables use a old technology, and fiber-optic cable is expensive
to place underground. The wired nature of the Internet restricts
mobility of users as compared to wifi.
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The Internet2® Project
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Consortium of 200+ universities, government agencies, and
private businesses collaborating to find ways to make the Internet
more efficient, faster, reliable and affordable.
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GigaPoP : a regional Gigabit Point of Presence, or point of access to the
Internet2 network, that supports at least one gigabit (1 billion bits) per
second information transfer
Primary goals:
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Create leading edge very-high speed network for national
research community
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Enable revolutionary Internet applications
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Ensure rapid transfer of new network services and applications to
broader Internet community
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The Larger Internet II Technology Environment:
GENI Initiative
 Global Environment for Networking Innovations (GENI) Initiative
to develop new core functionality for the Internet, including new
naming, addressing and identity architectures;
 enhanced capabilities, including additional security architecture
and a design that supports high availability;
 new Internet services and applications
Proposed by NSF
 to develop new core functionality for Internet
Most significant private initiatives (Fiber-Optic and Wireless)
 Fiber optics is concerned with the first mile or backbone Internet
services that carry bulk traffic long distances.
 Wireless Internet is concerned with the last mile from the larger
Internet to the user’s cell phone or laptop. Mobile wireless Internet
services
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Fiber Optics and the Bandwidth Explosion in the
First Mile
“First mile”:
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Backbone Internet services that carry bulk traffic over
long distances
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Older transmission lines being replaced with fiber-optic
cable
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Much of fiber-optic cable laid in United States is “dark”,
but represents a vast digital highway that can be utilized
in the future
◦ Photonic technologies expand capacity of existing
fiber lines
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Optical Fiber
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Optical Fiber
Source: Adapted from Panko, Raymond, Business Data Communications and Networking (3rd ed.), Upper Saddle
River, NJ: Prentice-Hall, 2001, p. 278.
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Mobile Wireless Internet Access: The Last Mile:
“Last mile”:
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From Internet backbone to user’s computer, cell
phone, PDA, etc.
Two different basic types of wireless Internet
access:
1. Telephone-based (mobile phones,
smartphones)
2. Computer network-based
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Telephone-based Wireless Internet Access
Evolution:
(1-G) The first generation of cellular networks were analog-based.
(2G) Second generation cellular networks
 Relatively slow circuit-switched digital network that can
transmit data at about 10 Kbps
(2.5G) network interim cellular network
 that provides speeds of 60–144 Kbps using General Packet
Radio Services (GPRS)
 GPRS (General Packet Radio Services) : next generation
technology carries data in packets, just like the Internet, but
over radio frequencies that make wireless communication
possible.
(3G) Third generation cellular network new generation of cellular
phone standards that can connect users to the Web at 2.4 Mbps
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Telephone-based Wireless Internet Access
Competing 3G standards
 GSM (Global System for Mobile Communications) mobile
communications system widely used in Europe and Asia that
uses narrowband Time Division Multiple Access (TDMA)
 CDMA (Code Division Multiple Access) mobile communications
system widely used in the United States that uses the full
spectrum of radio frequencies and digitally encrypts each call
(4 G) Fourth Generation: (LTE and WiMax )
Long Term Evolution:
 True broadband cell phone provides up to 100 - 300 Mbps
WiMax
 Alternative to LTE wide area network for cities provides 72
Mbps.
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Wireless Local Area Networks (WLANs)
Wi-Fi
 High-speed, fixed broadband wireless LAN, different versions
for home and business market, limited range.
WiMax
 High-speed, medium range broadband wireless metropolitan
area network.
Bluetooth
 Low-speed, short range connection.
Ultra-Wideband (UWB)
 Low power, short-range high bandwidth network.
Zigbee
 Short-range, low-power wireless network technology for
remotely controlling digital devices.
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Wi-Fi Networks
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