Understanding How Networks Communicate

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24 Οκτ 2013 (πριν από 4 χρόνια και 17 μέρες)

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Understanding
How Networks
Communicate

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-
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Copyright © Texas Education Agency, 2011. All rights reserved.

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We Will Learn:



Basic networked
communications and services


Components essential to a
network


Determine limitations of area
networks

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4

Define Networking


Connecting computers to
share information and
resources


Involving physical
connections and software


Vital to modern
-
day
workplace

Copyright Texas Education Agency (TEA)

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Fundamentals


In it’s basic form, two
computers connected with a
cable


Data is shared efficiently


Offers access to peripheral
devices: printers, scanners,
fax machines

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Why Use a Network?


Groups of users share and
exchange data


Communication is easier


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Standalone and
Sneakernet


Standalone computer


Single computer not attached
to a network


Cannot match power and
convenience of network



Sneakernet



Passing floppy disk from
machine to machine


Old alternative to networking

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LANS and Internetworks


Early networks



custom
-
built, expensive,
severe restrictions


Early Ethernet



no more than 30 users
with total span of 607 feet


Local area network (LAN)



works within
limited geographic area


Building block for constructing larger
networks, called internetworks


Internetwork



network 100 or more
computers at distances in excess of 1000
feet


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WANS and the Internet


Wide area network (WAN)



spans
distances measured in miles; links two or
more separate LANS


Metropolitan area network

(MAN)



uses
WAN technology to interconnect LANs
within a specific geographic region


Internet



global WAN internetwork;
includes millions of machines and users
worldwide


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Networking Lexicon


Must understand specialized networking
vocabulary, including


Server


shares resources across network,
typically with more central processing unit
(CPU) power and storage capacity than other
computers


Client


accesses shared resources


Request
-
response


client requests
information; server responds by providing
information


Client
-
server relationship


see Figure 1
-
3


Peer
-
to
-
peer


computers share and request
resources from one another


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Network Medium


Computers share access to common network
medium that carries signals from one computer to
another


Medium may be physical
cable
, such as twisted
pair, coaxial, or fiber
-
optic


Medium may be
wireless


Physical interface to medium is usually
network
interface card

(NIC) or network adapter


Kind of medium dictates type of connector and limits
number and type of devices as well as distance a
single LAN can span


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Protocols


Network protocols



a common set of
rules


Define how to interpret signals, identify
individual computers, initiate and end
networked communication, and manage
information exchange across network
medium


Include
TCP/IP
,
NetBEUI
,
IPX/SPX
, and
NWLink


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Software


Network software

issues requests and
responses


Network operating system (NOS)

controls which computers and users
access network resources


Include both client and server components


Popular NOSs include Windows .NET Server,
Windows XP, Windows 2000, Windows NT, and
Novell NetWare


Network applications

access the network


Include e
-
mail programs, web browsers, and
network
-
oriented utilities


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Network Services



Services include file and print services,

file
-
sharing, e
-
mail, and other capabilities


Network communications are layered


Network applications use NOS or client
networking software to get network
protocol

to access medium


Medium exchanges information with other
computers


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Network Process

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Summary


Basic elements of networks include
networking medium (cabling) and
computers with physical interface (network
adapter) to medium


Computers must also have network
protocol and network software to send and
receive messages across network


Network services include file sharing,
printing, e
-
mail, and other messaging
services


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