Transcript Business Data Communications and Networking

Business Data
Communications
8/e, John Wiley & Sons 2004, FitzGerald and Dennis
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Topic 1
Introduction to Data
Communications
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Some Hot Topics in Data
Communications
Email Spamming
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13 billion spam emails/day, $10 billion losses this year
Worm/virus attacks
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W32/SirCam@MM (Mass Mailer Worm) Alert
Blaster worm
Hacking
Great Global Grid (GGG)
Web services
Wi-Fi
WiMAX
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Outlines
A brief history of data communications
Moore’s law
The Internet
Network concepts
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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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A Brief History of
Telecommunications
1837 - Samuel Morse exhibited a working telegraph system.
1843 - Alexander Bain patented a printing telegraph.
1876 - Alexander Graham Bell, invented the first telephone.
1880 - first pay telephone
1915 - first transcontinental telephone service and first transatlantic voice
connections.
1947 - transistor invented in Bell Labs
1951 - first direct long distance dialing
1962 - first international satellite telephone call
1968 - Carterfone court decision allowed non-Bell equipment to connect to Bell
System Network
1970 - permitted MCI to provide limited long distance service in competition to
AT&T.
1984 - deregulation of AT&T
1980s - public service of digital networks
1990s - cellular telephones commonplace
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Phases of Telecommunications
Development
Telegraph & Telephone (19th century)
Satellite communications (1960s)
Digital communications (1980s)
Internet age (1990s)
Wireless communications (1990s)
21st century?
Trends: From wired to wireless, from analog to
digital, from voice communicating to data
communicating
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The Invention of Telephone
Who invented the telephone?
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Alexander Graham Bell?
Elisha Gray's caveat, as it was filed in the
United States Patent Office, February 14,
1876
Elisha was a new immigrant, who did not
have good English communication skills.
The economic condition was too bad to
have enough money to pay the patent fee.
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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
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1962
1965
1970
1975
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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:
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1908
1911
1946
1951
1959
(Hollerith Tabulator)
(Monroe Calculator)
(ENIAC)
(Univac I)
(IBM 7090)
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CPU’s Capacity Growth
2000
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Internet, Intranet and
Extranet
The Internet: a network of networks
servicing the users worldwide
Intranet: an organization's private
network that uses Internet technology
Extranet: The intranet that some of its
functions are accessible to the
organization's business partners
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The Internet
Three aspects of the Internet
evolution
Capacity growth
 Application and traffic growth
 Internet policy change
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Internet Capacity
ARPANET (1969): The Internet was started by the U.S.
Department of Defense as a network of four computers.
- 1974, 62 hosts
- 1983, 1000 hosts
- 1989, decommissioned
NSFNET (1986): Built up by National Science Foundation with a
3-tier structure
- 1987, 10,000 hosts in the Internet, 1000 in BITNET
- 1988, upgraded to T1 (1.544 Mbps).
- 1991, upgraded to T3 (45Mbps)
- 1995, decommissioned
vBNS* (1995): 622Mbps in 1995
vBNS+ (now): 2.5 Gbps (or more)
*Short for very high-speed Backbone Network Service, an experimental wide-area network backbone
sponsored by the National Science Foundation (NSF) and implemented by MCI. vNBS has replaced NSFnet
and is designed to serve as a platform for testing new, high-speed Internet technologies and protocols.
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NSFNET
By 1991, the NSFNET's
backbone network service
has been upgraded to
T3 (45 Mbps) links
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Internet Policy and
deregulations
Originally, commercial traffic was forbidden on
the Internet, because the major portions of
these networks were funded by the various
national governments and research
organizations.
In the early 1990s, commercial networks began
connecting into these networks, opening it to
commercial traffic.
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Today’s Internet
Abilene
vBNS
CA*Net 3
Figure 9-11 Gigapops and high speed backbones of Internet 2/Abilene, vBNS, and CA*Net 3
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vBNS Components
The vBNS is accessible
to select application
sites through four NAPs
in New York, San
Francisco, Chicago,
and Washington, D.C.
The vBNS is mainly
composed of OC3 /T3
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NAP
Network access point (NAP)
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The NAP is defined as a high-speed network or switch to
which a number of routers can be connected for the purpose
of traffic exchange. NAPs must operate at speeds of at least
100 Mbps and must be able to be upgraded as required by
demand and usage.
The concept of the NAP is built on the FIX (Federal Internet
eXchange) and the CIX (Commercial Internet eXchange),
which are built around FDDI rings with attached Internet
networks operating at speeds of up to 45 Mbps.
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Some vBNS Facts (2001)
Speed: 2.5 Gbps (OC-48)
Multi-protocol Label Switching (MPLS)
0.001% Packet loss and 100%
availability
both unicast and multicast
IPv6 enabled
Extends to Europe and Asia
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Abilene
Abilene is an advanced backbone network
that supports the development and
deployment of the new applications being
developed within the Internet2 community.
Abilene connects regional network
aggregation points, called gigaPoPs, to
support the work of Internet2 universities as
they develop advanced Internet applications.
Abilene complements other high-performance
research networks.
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Internet Hosts Growth
(Recent statistics)
July 1999:
January 2000:
July 2000:
January 2001:
Now: ?
56,218,000 Internet hosts
68,862,283 Internet hosts
86,509,613 Internet hosts
113,873,000 Internet hosts (MIDS)
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Internet Addresses
Anyone with access to the Internet can
communicate with any computer on the
Internet.
Addresses consist of two parts, the computer
name and its domain.
computer.domain
Each domain has an addressing board that
assigns addresses for its domain.
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Internet Domain Names
Domain Names
EDU
COM
GOV
MIL
ORG
NET
Country Codes
CA (Canada)
AU (Australia)
UK (United Kingdom)
DE (Germany)
FR (France)
CN (China)
IN (India)
MX (Mexico)
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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
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Types of Networks
Networks can be classified in many
different ways. One of the most
common is by geographic scope:
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Local Area Networks (LAN)
Backbone Networks (BNs)
Metropolitan Area Networks (MANs)
Wide Area Networks (WANs)
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Types of Networks
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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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What is a Protocol?
A standard that allows entities (i.e.
application programs) from different
systems to communicate
Shared conventions for communicating
information
Includes syntax, semantics, and timing
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Standardized Protocol
Architectures
Vendors like standards because they make their
products more marketable
Customers like standards because they enable
products from different vendors to interoperate
Two protocol standards are well-known:
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TCP/IP: widely implemented
OSI: less used, still useful for
modeling/conceptualizing
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Internet Standards
Email related standards
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IMAP, POP, X.400, SMTP, CMC, MIME, binhex, uuencode
Web related standards
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http, CGI, html/xml/vrml/sgml
Internet directory standards
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X.500, LDAP
Application standards
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http, FTP, telnet, gopher, wais
Videoconferencing standards
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H.320, H.323, Mpeg-1, Mpeg-2
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*Telecommunication
Standards Organizations
International Telecommunications Union - Telecommunication
Standardization Sector (ITU-TSS). Formerly called the Consultative
Committee on International Telegraph and Telephone (CCITT)
International Organization for Standards (ISO). Member of the ITU,
makes technical recommendations about data communications
interfaces.
American National Standards Institute (ANSI)
Institute of Electrical and Electronics Engineers (IEEE)
Internet Engineering Task Force (IETF)
Electronic Industries Association (EIA)
National Institute of Standards and Technology (NIST)
National Exchange Carriers Association (NECA)
Corporation for Open Systems (COS)
Electronic Data Interchange -(EDI) of Electronic Data Interchange
for Administration Commerce and Transport (EDIFACT).
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*Internet Engineering Task
Force
A protocol proposed by a vendor
IETF working group study the proposal
IETF issues a request for comment (RFC)
IETF reviews the comments
IETF proposes an improved RFC
The RFC becomes a proposed standard
The proposed standard becomes a draft
standard if two or more vendors adopt it
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