Transcript ch1[1].

Business Data
Communications
7/e, John Wiley & Sons 2002, FitzGerald and Dennis
4/e, Prentice Hall 2001,
William Stallings
1
Organization of the Textbook (FD)
Part
Part
Part
Part
1:
2:
3:
4:
Introduction (Ch1)
Fundamentals (Ch2-5)
Networking (Ch6-9)
Network management (Ch10-12)
Chapter 11 will not be covered
2
Organization of the Textbook (WS)
Part
Part
Part
Part
Part
Part
1:
2:
3:
4:
5:
6:
Requirements (Ch2-3)
TCP/IP and The Internet (ch4-5)
Data Communications (Ch6-10)
Networking (Ch11-15)
Applications (Ch16-17)
Management Issues (Ch18-20)
3
Topic 1/Chapter 1
Introduction to Data
Communications
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Discussion
Why is it important to study data
communication?
What is the definition of data communication?
Do you know the following figures:
the fastest CPU available on the market
the highest bandwidth of the Internet backbone
the number of ISPs in the US
What is the trend of data communications?
5
Semiconductor Industry – the
foundation of IT
Vacuum tube – Early the 20th century (?)
Transistor (Transfer resistor), 1947 at Bell Lab
invented by John Bardeen, Walter Brattain,
and Willian Shockley (Physics Nobel prize
winner in 1956)
Integrated circuit, invented by Jack Kilby, TI,
in 1959 (Physics Nobel prize winner in 2000)
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Moore’s Law
When: 1965
Who: Gordon Moore, co-founder of Intel.
Dr. Moore was preparing a speech and made a memorable
observation. When he started to graph data about the growth in
memory chip performance, he realized there was a striking trend.
What: Each new chip contained roughly twice as
much capacity as its predecessor, and each chip was
released within 18-24 months of the previous chip.
An Analogy: If this trend were applicable to airline
industry, the plane would cost $500, weigh a few
pounds, travel around the world in 20 minutes.
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Analyses
Moore’s minimum cost
1962
1965
1970
1975
–
–
–
–
12 components/chip
50 components/chip
10% of the cost in 1965 per transistor
65,000 components/chip
The speed growth is faster than size reduction, because there
has been a rapid increase in clock frequency.
Kuzweil (1999) pointed out that the doubling of processing
power started earlier:
1908
1911
1946
1951
1959
(Hollerith Tabulator)
(Monroe Calculator)
(ENIAC)
(Univac I)
(IBM 7090)
8
CPU’s Capacity Growth
2000
9
Moore’s Law (Cont’d)
Moore's observation, now known as Moore's Law, described a
trend that has continued and is still remarkably accurate. It is the
basis for many planners' performance forecasts. In 26 years the
number of transistors on a chip has increased more than 3,200
times, from 2,300 on the 4004 in 1971 to 7.5 million on the
Pentium II processor.
Machrone’s Law:the machine you want always costs $5,000
Rock’s Law: the cost of capital equipment to build
semiconductors will double every four years
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Questions from Moore’s Law
What are implications of Moore’s law to the
information age?
Will Moore’s law hit the wall eventually?
What are its implications to recent economy
downturn?
Any impact on data communication
technologies?
How does it affect your career?
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Data Communications
Definitions:
Data Communications
The movement of computer information from one
point to another by means of electrical or optical
transmission systems. (How about satellite system?)
Such systems are often called data communications
networks.
Telecommunications
Includes the transmission of voice and video as well
as data.
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Data Communications
Another vision of information forms
(VIViD):
Voice communications
Image communications
Video communications
Data communications (limited to text)
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Components of a Network
Server (or Host computer)
Central computer in the network, storing data or software that can
be accessed by the clients.
Client
The input/output hardware device at the other end
of a communications circuit.
Circuit
The pathway through which the messages travel.
Peer-to-peer networks
Do not need a server or host, but are designed to connect similar
computers which share their data and software with each other.
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Components of a Network
15
Types of Networks
Networks can be classified in many
different ways. One of the most
common is by geographic scope:
Local Area Networks (LAN)
Backbone Networks (BNs)
Metropolitan Area Networks (MANs)
Wide Area Networks (WANs)
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Types of Networks
17
Types of Networks
Local Area Networks (LAN)
A group of microcomputers or other workstation
devices located in the same general area and
connected by a common circuit.
Covers a clearly defined small area, such as
within or between a few buildings,
Support data rates of 10 to 100 million bits per
second (Mbps).
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Types of Networks
Backbone Network (BN)
A larger, central network connecting several
LANs, other BNs, metropolitan area networks,
and wide area networks.
Typically span up to several miles.
Support data rates from 64 Kbps to 45 Mbps.
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Types of Networks
Metropolitan Area Network (MAN)
Connects LANs and BNs located in different
areas to each other and to wide area
networks.
Typically span from 3 - 30 miles.
Supports data rates of 100 to 1000 Mbps.
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Types of Networks
Wide Area Network (WAN)
Connects BNs and MANs and are usually
leased from inter-exchange carriers.
Typically span hundreds or thousands of
miles.
Supports data rates of 28.8 Kbps to 2 Gbps.
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Network Model
A method of describing and analyzing data
communications networks, by breaking the
entire set of communications functions into a
series of layers, each of which can be defined
separately.
This allows vendors to develop software and
hardware to provide the functions separately.
22
Open Systems Interconnection (OSI)
Developed by the International Organization for
Standardization (ISO) in 1984
The primary architectural model for intercomputer
communications.
A conceptual model composed of seven layers, each
specifying particular network functions.
Describes how information from a software
application in one computer moves through a
network medium to a software application in another
computer.
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ISO’s OSI Model
OSI has 7 layers:
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
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OSI Model
Internet Model
F-D’s Model
OSI Model
Application layer:
http, telnet, snmp,
smtp, nfs, ftp
Application
layer
TCP, UDP
Network
layer
IPv4, IPv6
Data Link Layer
Physical layer
(HDLC)
Data Link layer
Physical layer
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OSI Model
Network layer
provides routing and related functions
Transport layer
implements reliable internetwork data transport services
Session layer
establishes, manages and terminates communication
sessions between presentation layer entities
Presentation layer
provides a variety of coding and conversion functions
Application layer
closest to the end user
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Sender
Application
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Receiver
HTTP
Request
TCP HTTP
Request
IP
TCP HTTP
Ethernet IP
Application
Layer
Transport
Layer
Request
TCP HTTP
Request
Network
Layer
Data Link
Layer
HTTP
Request
TCP HTTP
Request
IP
TCP HTTP
Ethernet IP
Request
TCP HTTP
Request
Physical
Layer
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Telephone and Access Technologies
1980
Modem
300 bps
1990
Modem
9600 bps
2000
Modem
56 Kbps
2000
DSL
1.5 Mbps
2003
Wireless
40 Mbps
2007
Wireless
10 Gbps
LAN and Backbone Technologies
1980
128 Kbps
1990
1-4 Mbps
2000
Desktop
10 Mbps
2000
Backbone
100 Mbps
2005
Backbone
10 Gbps
2000
High Speed
622 Mbps
2005
High Speed
25 Tbps
WAN and Internet Technologies
1980
56 Kbps
1990
1.5 Mbps
2000
Typical
45 Mbps
Figure 1-6 Relative capacities of telephone, LAN/BN and WAN/Internet Circuits
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Before Next Class Meeting
Think of the following questions:
How do you define the Internet?
What are intranet and extranet?
What are the most popular Internet applications?
What is e-commerce?
How data communications play roles in ecommerce?
How do you explain current economic conditions?
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