Business Data Communications

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Transcript Business Data Communications

Business Data Communications
Chapter One
Introduction to Data Communications
Changing our World
Primary Learning Objectives
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Identify five data communications phases
Understand the importance of protocols and
standards
Be familiar with the OSI and TCP/IP networking
models
Describe the benefits of a layered architecture
Recognize the general categories of networks
What is data communication?
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Not to be confused with telecommunication—
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Any process that permits the passage from a sender to one or
more receivers of information of any nature, delivered in any easy
to use form by any electromagnetic system.
Data communication
Defined as a subset of telecommunication involving the
transmission of data to and from computers and components of
computer systems.
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More specifically data communication is transmitted via mediums such
as wires, coaxial cables, fiber optics, or radiated electromagnetic waves
such as broadcast radio, infrared light, microwaves, and satellites.
Five Data Communications Phases
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1960s - Digitization of Data
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1970s - Growth of Data Communications
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1980s - An Era of Deregulation
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1990s - The Internet as a Common Tool
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2000s - Pervasive Computing
History of Telecommunications
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Invention of telegraph Samuel Morse – 1837
Invention of telephone- Alexander Graham Bell –
1876
Development of wireless By ??? – 1896
Concept of universal access and growth of AT&T
Divestiture of AT&T—what year??
History of Telecommunications
Continued….
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Telecommunications Act of 1996
Three main developments that led to the growth of data
communications systems:
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Large-scale integration of circuits reduced the cost and size of
terminals and comm equipment
Developments of software systems made establishment of
communication networks easy
Competition among providers of transmission facilities reduced the
cost of data circuits
History of Data Communication
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Transistor developed by Bell Labs (which is now ???) 1947
Hush-a-Phone Case
Carterphone case
MCI and Long Distance
Creation of networks (LAN’s and WAN’s)
Data Link Protocols
Microcomputers
History of the Internet
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See web page link–
http://carl.sandiego.edu/itmg360/internet_history.htm
1960s –
Digitization of Data
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Digitization transcribes data into binary form
First large-scale, mainframe computer systems are
proprietary and they use a closed architecture
technology
The trend today is for open architecture technologies
1960s –
Digitization of Data
1970s –
Growth of Data Communications
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With greater frequency, businesses automate their
previously manual processes, using computer
technology
As a result, computers become more prevalent
Increasingly, computers need to communicate with
each other so that their data and resources can be
shared
Data communication infrastructures evolve in
response to this need, particularly packet-switching
networks
1970s –
Growth of Data Communications
1980s –
An Era of Deregulation
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Initially, the telecommunications industry in the
United States runs as a monopoly under Bell
Telephone/AT&T
In 1984, the United States deregulates long
distance telecommunication resulting in the breakup
of Bell Telephone/AT&T
Deregulation’s intent is to provide greater
competition in a given market
1990 –
Internet as Common Tool
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In 1969, ARPA evolves into ARPANET, which
eventually evolves into today’s Internet
IPv4, the original protocol version for the Internet
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Not designed with multimedia data in mind
Today, hundreds of millions of people worldwide
connect to the IPv4 Internet
IPv6, the latest version of the Internet, will gradually
replace IPv4
1990 –
Internet as Common Tool
2000s –
Pervasive Computing
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Pervasive Computing
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A technology so commonly used it can be taken for granted
Essential to future pervasive computing will be
wireless technologies
For example, telemetry allows the wireless
transmission and reception of data for monitoring
equipment and environmental conditions
2000s – Pervasive Computing
Acme’s use of Telemetry
Data Communications
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Currently a subset of telecommunications, although
the differences are beginning to blur
Telecommunications includes television, telegraphy,
and telephony
Data communications focuses primarily on the
transmission of data between computing devices
0110010101110001010101
Encoding Schemes
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Data is transmitted using binary encoding schemes
Binary encoding schemes, of which there are several,
use the binary digits 0 and 1
A new binary encoding scheme called Unicode will
allow for the encoding of more than 64,000 unique
characters
Traditional encoding schemes, such as EBCDIC and
Extended ASCII, allow for only 256 unique characters
Features of Communication
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Four things required
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Types of messages
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Sender, receiver, medium, and message
File
Request
Response
Status
Control
Correspondence
Understandability
Error Detection
Online System Requirements
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Response Time
Throughput
Consistency
Flexibility
Online Systems Requirements
Continued
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Availability
Reliability
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Mean time between failure (MTBF)
Mean time to repair (MTTR)
Fault Tolerance
Recovery
Security
Protocols
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Data communications also depend on protocols
Protocols determine the rules for how something is
performed or accomplished
Protocols become established or defined through a
standards process
Standards
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Standards may be formal or informal
Informal standards are also called “de facto”
standards
Standards can be proprietary or open
The trend is toward open standards
There are numerous standard-setting bodies
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ISO, ANSI, IEEE, IETF, to name a few
Network Topology, Architecture, and
Complexity
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Network topology refers to the physical layout of a network, the
way that nodes attach to the communication medium
Network architecture refers to the way in which media,
hardware, and software are integrated to form a network
Network complexity is concerned with extent to which network
architectures are simple or diverse in their make
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Figures 1-5, 1-6, and 1-7 illustrate various levels of complexity
Figure 1-5
Figure 1-6
Figure 1-7
Networking Models
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Models are logical and based on theory
In data communications, two important models are:
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OSI – Open Systems Interconnection
TCP/IP – Transmission Control Protocol/Internet Protocol
The OSI and TCP/IP models are both open system
models that use a layered architecture
The OSI has seven Layers
The TCP/IP has four or five layers, depending on the
source
The Layering Approach
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In a layered model, each layer is responsible for
specific functions
A layer must be able to communicate with the layer
immediately above or below it
However, a layer does not have to “understand” how
a layer above or below works
Designers of networking technologies can create
products that function within a specific layer
Data Communication Frameworks
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Two major data communication frameworks have
been developed to help ensure that networks meet
business and communication requirements:
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Open Systems Interconnection (OSI) reference model
developed by the International Standards Organization (ISO)
Transmission Control Protocol/Internet Protocol (TCP/IP)
suite
History of the OSI Model
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Open Systems Interconnected Model
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was created in the 70’s by the ISO (although the CCITT came up
with their own model)
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10 different people got together and considered all functions of
communications
was created because people realized that our computers needed to
talk to each other(and there was no one dominant computer
system)
ISDN was a big factor
7 layers = 4 upper and 3 lower
OSI Reference Model in Practice
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The OSI reference model is used in many ways:
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To provide assistance when troubleshooting network problems
To provide a common terminology and framework for networking
technology developers
To facilitate the development of connectivity standards needed for
flexible open architectures
To enable the development of protocol stacks that allow network
nodes to communicate with one another
The OSI Model
THE OSI MODEL
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LAYER
LAYER
LAYER
LAYER
7
6
5
4
Application
Presentation
Session
Transport
LAYER
LAYER
LAYER
3
2
1
Network
Data Link
Physical
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LAYER 7– APPLICATION
The visual interface level between the user and the
network, or computer. (Ex Word, Excel, Access,
Email)
LAYER 6-- PRESENTATION
This layer is responsible for converting the visual
interface into a code that is then sent through the
computer or network. For example, this layer may
convert ASCII code (what many applications like
Word use) to an 8-bit code.
LAYER 5 – SESSION
This layer keeps track of whose turn it is to receive
traffic, basically it is a dialog control. This is the
level that acknowledges receipt of a transmission as
well as sends the message to the network.
LAYER 4 – TRANSPORT
All streams of data are received and combined into
one single stream so that data may be sent through
the network. Multiplexing and demultiplexing
occurs on this layer.
The OSI Model
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THE OSI MODEL
LAYER
LAYER
LAYER
LAYER
7
6
5
4
Application
Presentation
Session
Transport
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LAYER
LAYER
LAYER
3
2
1
Network
Data Link
Physical
BOTTOM/LOWER LAYERS
LAYER 3– NETWORK
On this level the router exists to determine if the
message is meant for the system or if it needs to be
redirected to its final destination. This is done by a
header system, which is programmed to accept or
reject depending if the header is the one used by the
network.
LAYER 2– DATA LINK
There is where a check of the message occurs. That
is the message is checked for the proper frame,
formation, synchronization, power level, voltage,
and wavelength. If the test is a successful, the
message is sent to the network layer to determine if
the message is truly meant for the system.
LAYER 1– PHYSICAL
Where the actual physical makeup of the message is
identified. That is the duration of bits, the right
number of bits, and the right wavelength is checked.
As with the other two layers, if this test is
successful, the message is sent up the chain.
OSI LAYER INTERACTIONS
Application
Process
DATA
Application
Process
Incoming Frame
Reduction
Outgoing Frame
Application
Construction
Presentation
PCI DATA
PCI APDU
Session
Transport
Network
Link
PCI PPDU
PCI SPDU
PCI TPDU
PCI NPDU
Physical
Application
Presentation
Session
Transport
Network
Link
Physical
encoded bit stream
TCP/IP Protocol Suite
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The TCP/IP suite provides insights into the inner workings of the
Internet
Like the OSI model, the TCP/IP suite is layered
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Because the protocols found at each layer are independent of those
at the other layers, a given protocol can be modified without
affecting those found at other layers
TCP/IP layers and layer-specific protocols are illustrated in Figure 19
Figure 1-9
Moving Bits through the Network
Analog Signal
1
0
Digital Signal
1
1
1
0
digital
Computer
0
analog
Modem
0
digital
Modem
telephone lines
Computer
Putting It all Together
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Data Communications Supports Applications
The Operating System manages the resources of the computer.
There must however, be a system that provides a bridge
between applications and the devices so they can
communicate—this is called a Transaction Control Process (TCP)
The TCP/IP Layers
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Application
Transport
Network
Data Link
Physical
The application layer of the
TCP/IP model includes the
application, presentation,
and session layers of the
OSI model.
OSI and TCP/IP
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These models have several similarities
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Both offer layered architectures
Both are open models
They have similar data link layer functions
They have similar physical layer functions
Of the two, TCP/IP is the older and the more popular
Business Data Communications
Issues
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Major data communications issues include:
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Cost-effectiveness
The Internet
Bandwidth
Evolving technologies
Convergence
Standards
Privacy and security
Important Standard-Setting
Organizations
Table 1-5
Business Data Communication
Careers
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There are numerous job opportunities and career
paths for individuals interested in data
communications and networking
Table 1-6 includes examples of data communication
job titles
Table 1-7 summarizes some of the major professional
certifications for networking and data
communications specialists
Table 1-6
Table 1-7
Networks
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Standards and protocols are critical in data
communications when creating a network
Networks have four general classifications
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Local Area Network – LAN
Backbone Network – BN
Metropolitan Area Network – MAN
Wide Area Network – WAN
Networks are based on models
Key Data Communication Concepts
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Session: communication dialog between network users or applications
Network: interconnected group of computers and communication devices
Node: a network-attached computer
Link: connects adjacent nodes (see Figure 1-4)
Path: end-to-end route within a network
Circuit: the conduit over which data travels
Packetizing: dividing messages into fixed-length packets prior to transmission
over a network’s communication media
Routing: determining a message’s path from sending to receiving nodes.
A Local Area Network
A Possible Backbone Network
A Metropolitan Area Network
A Wide Area Network
In Summary
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Data communications is a multifaceted field
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Many technologists end up specializing in specific areas
Many standard-setting bodies affect its direction
Pervasive computing will transform how the average
person uses and experiences data communications
technology