Introduction to Computer Networks

cottonseedfearnotElectronics - Devices

Nov 7, 2013 (3 years and 9 months ago)

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Chapter 1:

Introduction to Computer Networks

and Data Communications


2


Objectives

After reading this chapter, you should be able to:


Define the basic terminology of computer networks


Recognize the individual components of the big
picture of computer networks


Outline the basic network configurations


Cite the reasons for using a network model and
explain how they apply to current network systems

3


Objectives (continued)


List the layers of the OSI model and describe the
duties of each layer


List the layers of the TCP/IP protocol suite and
describe the duties of each layer


Compare the OSI model and TCP/IP protocol suite
and list their differences and similarities

4







Who today has
not

used a computer network?



Mass transit, interstate highways, 24
-
hour bankers,
grocery stores, cable television, cellular telephones,
most businesses and schools, and other retail outlets
can support some form of computer networks



Introduction








5



The Language of Computer Networks
















Computer network

-

an interconnection of computers and
computing equipment using either wires or radio waves over
small or large geographic distances



Local area network

-

networks that are small in geographic
size spanning a room, building, or campus



Metropolitan area network

-

networks that serve an area
of 3 to 30 miles
-

approximately the area of a typical city


6


The Language of Computer Networks















Wide area network

-

a large network that encompasses
parts of states, multiple states, countries, and the world


Data communications

-

the transfer of digital or analog
data using digital or analog signals


Voice network

-

a network that transmits telephone signals


Data network

-

a network that transmits computer data

7



The Language of Computer Networks


(continued)
















Telecommunications

-

the study of telephones and the
systems that transmit telephone signals


Network management

-

the design, installation, and
support of a network and its hardware and software


Personal area network



a network of a few meters,
between wireless devices such as PDAs, laptops, and similar
devices

8



The Big Picture of Networks
















Networks are composed of many devices, including:



Workstations (computers and telephones)



Servers



Network hubs and switches (bridges)



Routers (LAN
-
WAN and WAN
-
WAN)



Telephone switching gear

9



The Big Picture of Networks (continued)















10



Computer Networks

-

Basic Configurations
















Computer terminal/microcomputer to mainframe
computer



Microcomputer to local area network



Microcomputer to Internet



Local area network to local area network



Personal area network to workstation

11



Computer Networks


Basic Configurations





(continued)
















Local area network to metropolitan area network


Local area network to wide area network



Sensor to local area network



Satellite and microwave



Wireless telephone and wired telephone to network

12



Terminal/microcomputer
-
to
-
mainframe



Computer Configurations

















Predominant form in 60s and 70s



Still used in many types of businesses for data
entry and data retrieval



Usually involves a low
-
speed connection

13


Terminal/microcomputer
-
to
-




mainframe Computer


Configurations (continued)














14



Microcomputer
-
to
-
Local Area Network

















Highly common throughout business and academic
environments, and now even homes



Typically a medium
-

to high
-
speed connection



Microcomputer requires a NIC (network interface
card)



NIC connects to a hub
-
like device

15



Microcomputer
-
to
-
local Network



Configurations (continued)















16



Microcomputer
-
to
-
Internet Configurations

















Very popular with home users and some small
businesses



Typically, a dial
-
up modem is used to connect
user’s microcomputer to an Internet service provider



Newer technologies such as DSL and cable
modems are replacing modems

17


Microcomputer
-
to
-
Internet Configurations




(continued)












18



Local Area Network
-
to
-
Local Area Network



Configurations (continued)













Found in businesses and schools that have two or
more LANs and a need for them to
intercommunicate



A bridge
-
like device (such as a switch) is typically
used to interconnect LANs



Bridge
-
like device can
filter

frames

19


Local Area Network
-
to
-
Local Area Network




Configurations (continued)











20



Personal Area Network
-
to
-
Workstation





Configurations

















Interconnects wireless devices such as PDAs,
laptops, and music playback devices



Used over a short distance such as a few meters

21



Personal Area Network
-
to
-
Workstation





Configurations (continued)










22



Local Area Network
-
to
-
Metropolitan



Area Network Configurations

















Used to interconnect companies (usually their local
area networks) to networks that encompass a
metropolitan city



High speed networks with redundant circuits

23



Local Area Network
-
to
-
Metropolitan Area




Network Configurations (continued)















24



Local Area Network
-
to
-
Wide Area




Network Configurations

















One of the most common ways to interconnect a
user on a LAN workstation to the Internet (a wide
area network)



Router



Typical device that performs LAN to WAN connections



More complex devices than bridges/switches

25


Local Area Network
-
to
-
Wide Area Network



Configurations (continued)















26


Wide Area Network
-
to
-
Wide Area Network




Network Configurations

















High
-
speed routers and switches are used to
connect one wide area network to another



Thousands of wide area networks across North
America



Many interconnected via these routers and
switches

27



Sensor
-
to
-
Local Area Network




Configurations

















Not all local area networks deal with
microcomputer workstations



Often found in industrial and laboratory
environments



Assembly lines and robotic controls depend
heavily on sensor
-
based local area networks

28




Sensor
-
to
-
Local Area Network




Configurations (continued)















29



Satellite and Microwave Configurations

















Long distance wireless connections



Many types of applications including long distance
telephone, television, radio, long
-
haul data transfers,
and wireless data services



Typically expensive services but many companies
offer competitive services and rates

30



Satellite and Microwave Configurations





(continued)














31



Wireless Telephone Configurations

















Constantly expanding market across the U.S. and
world



Second generation PCS services available in most
areas and under many types of plans



Next generation services beginning to replace PCS
phones

32



Wireless Telephone Configurations




(continued)















33



Wireless Telephone Configurations






(continued)

















An additional basic configuration is telephone to
network



Telephone systems are ubiquitous and can now carry
more data than voice



Common configuration


telephone connected to
POTS



Newer configuration


telephone to LAN via
gateway (VoIP)

34





Network Architectures

















Reference model that describes the layers of hardware
and software necessary to transmit data between two
points or for multiple devices / applications to
interoperate



Reference models are necessary to increase the
likelihood that different components from different
manufacturers will converse



Two architectures are required learning: The OSI
Model, and the TCP/IP protocol suite


35



The Open Systems Interconnection





(OSI) model















36



The Open Systems Interconnection




(OSI) model (continued)















Application layer

-

where the application using the
network resides


Common network applications include remote login, file
transfer, e
-
mail, and web page browsing


Presentation layer

-

performs series of miscellaneous
functions necessary for presenting the data package properly
to the sender or receiver

37


The Open Systems Interconnection




(OSI) model (continued)






Session layer

-

responsible for establishing sessions
between users


Transport layer

-

provides end
-
to
-
end error
-
free network
connection


Makes sure data arrives at destination exactly as it left
the source


Network layer

-

responsible for creating, maintaining and
ending network connections


Transfers a data packet from node to node within the
network

38




The Open Systems Interconnection




(OSI) model (continued)







Data link layer

-

responsible for taking data and
transforming it into a
frame

with header, control and address
information, as well as error detection code


Physical layer

-

handles the transmission of bits over a
communications channel



Includes voltage levels, connectors, media choice,
modulation techniques

39



The Open Systems Interconnection




(OSI) model (continued)







40



The TCP/IP Protocol Suite







41



The TCP/IP Protocol Suite (continued)








Application layer

-

equivalent to the OSI’s presentation
and application layers


Transport layer

-

performs same function as OSI transport
layer


Network (Internet or internetwork) layer

-

roughly
equivalent to the OSI’s network layer


Network access (data link/physical) layer

-

equivalent to the OSI’s physical and data link layers

42



Logical and Physical Connections







Logical connection



exists only in the software


Physical connection


exists in the hardware



In a network architecture



Only lowest layer contains physical connection


All higher layers contain logical connections

43



Logical and Physical Connections





(continued)







44



Logical and Physical Connections





(continued)






45



Network Configurations in Action






46



The TCP/IP Protocol Suite in Action







Note the flow of data from user to web browser and
back



At each layer, information is either added or
removed



Depends on whether data is leaving or arriving at a
workstation



Encapsulation
-

adding information over pre
-
existing
information

47



The TCP/IP Protocol Suite in Action





(continued)






48






Summary







Basic terminology of computer networks


Individual components of computer networks


Basic network configurations


Network models and how they apply to current
network systems


Layers of the OSI model and the TCP/IP protocol
suite