Final Introduction to Networking Chapt -1

7/25/2019 Final Introduction to Networking Chapt -1

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Introductionto

Networking


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Network A networkis a collection of computers and devices connected

together via communications devices and media.

Networks allow users to share resources, such as hardware,software, data and information.

Some companies allow their employees to access their company

networks through a virtual private network.

A network can be relatively small or extensively large.

A local area network (LAN):is a network that connects computers

in a limited geographic area.

A wide area network (WAN):is a network that covers a large

geographic area.

The Internetis a worldwide collection of networks linked together.


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Network

Advantagesof using a network

acilitates communications because people can communicate efficientlyand easily via e!mail, instant messaging, chat rooms, telephony, and

videoconferencing.

"educe cost by sharing hardware #i.e., a printer$ and software

#e.g., using a network version or site license of a program$.

Sharing data and information stored on other computers on thenetwork.

Allow tight control over who has access to what data.

Disadvantagesof using a network The hardware, software, and expertise re%uired to set up a network

can be expensive.

Networks are vulnerable to security problems.

&f the server fails to work, the complete network may also fail to work.


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Types of Network 'ased on the computing model used, networks are classified into three

types namely(Client-Server Network, Peer to Peer Network and!"ridNetwork#

'ased on the si)e, distance covered and transmission media used, networksare classified into four types namely( LAN, $AN, WAN and %AN#

LAN (Local Area Network)

*sed to interconnect computers and +s within a relatively small area such

as a building, office or campus. overs distance of up to - to / km.

Speed / 0bps to // 0bps.

$AN ($etro&olitan Area Network)

overs a 0etropolitan city. &t connects many 1ANs located at different office buildings.

&t has larger geographical scope compared to 1AN.

overs distance up to few hundred km.

Speed .- to -/ 0bps.


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Types of NetworkWAN (Wide Area Network)

*sed to interconnect computers over a very large geographic area such as

different cities within the country. overs distance of up to // km to /// km.

Speed .- 0bps to 2.3 4bps.

%AN (%lo"al Area Network)

Are the network connections between countries around the globe.

A good example is 5&nternet6.

&ts reach is several thousand km.

Speed .- 0bps to // 4bps.

Network Topology'e &!sical structure "! wic co&uters are connected, re&resents te

&!sical to&olog! o* te network# Term 5topology6 refers to the way in which the end points or stations or

computer systems, attached to the network.

Topology Selection parameters( ease of installation, ease of reconfiguration,ease of trouble shooting and number of nodes affected in case of mediafailure.


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Network Topologyive basic topologies are as follows.

$es, Star, +us, ingand 'ree#

$es 'o&olog! &t has dedicated point 7 to 7 point link between

devices.

&t re%uires n(n-)./physical channels to connect8n9 devices #every device must have n -&:;ports$.

Advantages


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Network TopologyStar 'o&olog!

>very computer is connected through a cableto a centrally located device called as u"or

switc.

Advantages

>asy to modify and add new computer.

1ess expensive than mesh topology.

>ach device needs only one link and one

port. >asy to install and configure.

Single node failure does not affect thenetwork.

>asy to diagnose the network faults.

Disadvantages

ailure of central hub:switch brings the entirenetwork down.

0ore cabling re%uired as compared to ringand bus topology.

Star


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Network Topology+us 'o&olog!

;ne long cable acts as a "ack "one.

Nodes are connected to the bus cable by using drop lines and taps.

A drop line running between the device and main cable.

A tap is a connector #T connector$ that splices into the main cable.

Terminating points are placed at each end.

Advantages

Simple, reliable, easy to use and less cabling.

>asy for installation and cheaper than other topologies.Disadvantages

*sed only in relatively small networks and a fault on the "ack "onecablestops all transmission.

Adding new node and also ault identification is difficult.

&ncrease in number of computers degrades the performance of the network.

'us


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Network Topologying 'o&olog!

>ach device has a dedicated point topoint line configuration only with two

devices on either side of it. Signals travel in one direction from one

node to all other nodes around the loop.

Advantages

>asy to install and reconfigure, adding ordeleting new node is easy.

No signal loss since data is regeneratedat each node.

No terminators re%uired.

Disadvantages

A break in ring can stop the transmission

in the network. xpensive than other topologies.

"ing


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Network Topology'ree 'o&olog!

&t is similar to star topology, but thenodes are connected to the

secondary hub which in turnconnected to the central hub.

A central hub is an active hub#regenerates the signals$.

Secondary hubs are either activeor passive hubs.

A passive hub provides simplephysical connection betweenattached devices.


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Transmission 0edia The physical path through which computers can send and receive electronic

signals is called as transission edia#

>lectronic signals can be send by using electric currents, radio waves,

microwaves, light spectrum etc. Transmission media can be classified into two main types

. 4uided Transmission 0edia

2. *nguided Transmission 0edia

%uided 'ransission $edia

&t has a central conductor enclosed in a plastic ?acket. They are typically used for small 1ANs.

*ses lower end of electromagnetic spectrum such as simple electricity and

some times radio waves #in electronic circuits$.

>xamples( Twisted pair, oaxial cable, iber optic cable etc.

0nguided 'ransission $edia @nown as wireless media.

*ses higher electromagnetic fre%uencies such as radio waves, microwaves

and infrared.

Necessary for mobile computers.

>xamples( "adio waves, 0icrowaves and &nfrared etc.


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Transmission 0ediaTo choose best type of transmission media for the network following factors are

considered.

# Cost

/# Installation

1# +andwidt ca&acit!:capacity of medium is usually measured in

"andwidt, #bandwidth is measured in terms of 0ega bits per second$.

2# Node ca&acit!:it is how many computers you can easily attach to the

network cable.

3# Attenuation:electromagnetic signals tends to weaken during transmission,refers to attenuation. This phenomenon imposes limits on the distance a

signal can travel through medium without an unacceptable degradation.

4# 5lectroagnetic inter*erence: it affects the signal that is send through the

transmission media. >0& is caused by outside electromagnetic waves such

as noise.


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4uided Transmission 0edia'wisted &air

&t is commonly used as telecommunications cable.

To decrease the amount of cross talkand outside inter*erence the wire

are twisted to each other.

These are two 7 color coded, insulated copper wire that are twisted around

each other.

onsist of one or more twisted pairs in a common ?acket.


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Twisted +air( *T+0nsielded 'wisted &air

onsist of number of twisted!pairs with simple plastic casing.

ommonly used in telephone systems and computer systems.

>&A #>lectrical &ndustries Association$ divides *T+ into different categories.

*T+( "!3- onnector


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Twisted +air( *T+CA'5%6

7+ANDWID'

($8)

$A9I$0$ DA'A A'5 APPLICA'I6N

CA' ;;


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Twisted +air( ST+Sielded 'wisted &air

onsist of shield #aluminum:polyester$ between outer ?acket and wires.

Shield makes ST+ less susceptible to >0& because it is grounded.

0ore reliable for 1ANs, it was the first T+ cable used in 1ANs .

*sed in &'09s token ring Networks.

&t offers B 0bps data rate.


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oaxial cable onsist of 2 conductors shares the same axis.

A solid copper wire runs down the center of the cable, surrounded by

&nsulator #+C$, surrounded by second conductor #shield$, surrounded by

insulator and thick plastic ?acket forms the cover of the cable. lassified by si)e % (adio grade)and cable9s resistance to


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oaxial cable'!&e A&&lication

3; o, %-@ and %- 'ick 5ternet

3; o, %-3@ 'in 5ternet

?3 o, %-3 'B ca"le

1 o, %-4/ ACnet

'N #'ayonet Neill!onnector$ connectors


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iber ;ptic cable &t has inner core of glass:plastic that conducts the light, surrounded by

cladding.

iber is surrounded by plastic sheath which can be tigtor loose.

&n tigt con*igurationplastic sheath is surrounded by fibers:wires tostrengthen the cable.

&n loose con*igurationspace between plastic sheath and outer ?acket is

filled with li%uid gel.

&t offers data rates from // 0bps 7 2 4bps.

or back bone networks offers data rate of B// 4bps. Also used in TC cables.


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iber ;ptic cable( Pro&agation odes) $ultiode

7 0ultiple beams from a light source move through the core.

i$ Ste&-inde *i"er The density of core remains constant from the center to the edge.

A beam of light moves in a straight line 7 suddenness of the change.

ii$ %raded-inde *i"er


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iber ;ptic cable( >i"er t!&es

>i"er-o&tic ca"le connectors SC(su"scri"er cannel)connector( used in cable TC.

S'(straigt-ti&) connector( used for connecting cable to networking devices. $'-( a new connector with the same si)e as "3- #*T+ connector$.


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*nguided Transmission 0edia *nguided transmission media transport*nguided transmission media transport electroagnetic waveselectroagnetic waveswithoutwithout

using a physical conductor.using a physical conductor. This type of communication is often referred to as wirelessThis type of communication is often referred to as wireless

communication.communication.

or example( adio waves, $icro waves, In*raredetc.

>lectromagnetic spectrum used for wireless communication is D

@=) 7 E// T=).

+ands+andsThe section of the electromagnetic spectrum defined as radio waves andThe section of the electromagnetic spectrum defined as radio waves and

microwaves is divided into eight ranges, called asmicrowaves is divided into eight ranges, called as "ands"ands.. >ach range is regulated by government authorities.>ach range is regulated by government authorities.

These bands are rated from very low frequency #C1$ to extremely high

frequency #>=$.


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+ands (adio waves and $icrowaves)*nguided Transmission 0edia


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*nguided Transmission 0ediaadio Wavesadio Waves >lectromagnetic waves ranging in fre%uencies between D k=) and 4=)>lectromagnetic waves ranging in fre%uencies between D k=) and 4=)

are normally called asare normally called as radio wavesradio waves.. "adio waves( ;mni directional 7 propagated in all directions.

an travel for long distances and also penetrate the walls for example(

A$ radio.

A&&lications:A0 and 0 radio, television, cordless phones and paging are

the examples of ulticasting#one sender many receivers$.

6ni directional antenna: send out signals in all directions, used for

multicast communications such as radio, televisionand &aging s!stes.

6ni directional antenna


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*nguided Transmission 0edia$icro Waves$icro Waves >lectromagnetic waves ranging in fre%uencies between and D// 4=) are>lectromagnetic waves ranging in fre%uencies between and D// 4=) are

normally called asnormally called as $icro waves$icro waves.. 0icro waves( *nidirectional and narrowly *ocused #sending and receiving

antennas need to aligned$.

0icro wave propagation is line!of!sight and repeaters are often needed for

long distance communication.

Cery high fre%uency microwaves cannot penetrate walls #disadvantage$.

0icrowave band is relatively wide almost, 2EE 4=) #due to wider sub!bands

high data rate is possible$.

*se of certain bands re%uires permission from authorities.

A&&lications: 0icrowaves are very useful when *nicast #one to one$

communication is needed between sender and receiver.

*sed in cellular &ones, satellite networksand wireless LANs.


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*nguided Transmission 0edia0nidirectional antennae

Two types of antennas are used for 0icrowaves( parabolic dish and the horn.

A &ara"olic dis antenna: it works as a funnel, catching a wide range of waves and

directing them to a common point.

;utgoing transmissions are broadcast through a horn aimed at the dish. The

microwaves hit the dish and are deflected outward in a reversal of the receipt path.

A orn antenna:looks like gigantic scoop.

;utgoing transmissions are broadcast up a stem and deflected outward in a series of

narrow parallel beams by the curved head.

"eceived transmissions are collected by the scooped shape of the horn and deflected

down into the stem.


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*nguided Transmission 0edia$icro Waves$icro Waves:: 'errestrial $icrowave *ses +arabolic dish.

*ses ocused beam.

1ine of sight is maintained.

*sed in 1ong haul telecommunications.

=igher fre%uencies give higher data rates.


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*nguided Transmission 0edia$icro Waves$icro Waves:: Satellite $icrowave Satellite acts as relay station #repeater$.

Satellite receives on one fre%uency, amplifies or repeats signal and transmitson another fre%uency.

"e%uires geo!stationary orbit ! =eight of D-,FG3km.

*sed in Television, 1ong distance telephone and +rivate business networks.


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*nguided Transmission 0ediaIn*raredIn*rared &t uses re%uency range from D// 4=) 7 3// T=).

&t can be used for short!range communication in a closed area using line!of!sight propagation.


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Switching Switching allows temporary connections to be established,

maintained and terminated between sources and destinations.

1ong distance transmission is typically done over a network of switched

nodes.

Nodes not concerned with content of data.

>nd devices are stations

7 omputer, terminal, phone, etc.

A collection of nodes and connections is a communications network.


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ircuit Switching stablish

7 Transfer

7


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ircuit SwitchingS&ace division switces (S&ace division switced network) The paths in the circuit are separated from each other spatially.

;riginally designed for analog networks #but currently used in both analog and digital

networks$ Cross-"ar switces:connects 8n9 inputs to 8m9 outputs in a grid by using

micro!switches #transistors$ at each cross point.

$ulti-stage switces( it combines cross!bar switches in several stages.


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ircuit SwitchingS&ace division switces (S&ace division switced network)

Cross-"ar switces $ulti-stage switces

i it S it hi


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ircuit Switching'ie division switces ('ie division ulti&leed network) *ses time division multiplexing to achieve switching.

'SI ('ie = Slot Intercange)

- it changes the ordering of slots based on the desired connections.- 'SI consist of a "A0 with several memory locations #input, outputlocations and control unit $.

Switcing ('SI)

No switcing

+ k t S it hi


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+acket SwitchingNote: Circuit switcing is designed *or voice counication#

It is less suited to data and oter non-voice data#

&n packet switching packets are transmitted in discrete units of potentially

variable length blocks called as &ackets. 0aximum length of packet is decided by network.

>ach packet contains dataand eader#priority, source and destination

address$.

Transmission node to node, routed according to information in the header.

Two popular approaches( datagra and virtual circuitpacket switching.

+ k t S it hi


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+acket SwitchingDatagra Packet Switcing

>ach packet is treated independently from all other packets and are referred

as datagrapacket.


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+acket SwitchingBirtual Circuit Packet Switcing

"elation between all packets belonging to same message is preserved.

"oute is selected at the beginning of the session.

+ackets of same message travels along the same route one after another.

&mplemented in two ways( Switced Birtual Circuit (SBC)and Peranent

virtual circuit (PBC).

Switced Birtual Circuit (SBC):

1ike dial up lines in circuit switching.

ircuit is created whenever needed and exist only for the duration of specificexchange.

+ k t S it hi


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+acket SwitchingPeranent virtual circuit (PBC)

1ike leased lines in circuit switching.

&n this same virtual circuit is provided between two users on a continuous

basis. ircuit is dedicated to specific users and no one else can use it.

&t can be used without connection establishment and connection termination.

0 S it hi


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0essage Switching 'est known by term store and *orward.

&t was common in the EB/s and EF/s.

A node receives a message, stores it until the appropriate route is free, then

it sends along. The messages are stored and relayed from secondary storage #disk$.

"e%uirement of large capacity storage media at each node.

N t k & t f d #N&$


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Network &nterface ard #N&$ or any computer, a network inter*ace card (NIC) performs two crucial tasks

7 >stablishes and manages the computer9s network connection.7 Translates digital computer data into signals #appropriate for the networking medium$

for outgoing messages, and translates signals into digital computer data for incoming

messages. N& establishes a link between a computer and a network, and then manages that link. N&s also manage transformations in network data9s form

7 The co&uter "ushas series of parallel data lines Parallel transission

or nearly all forms of networking media, signals traversing the media consist of a linearse%uence of information that corresponds to a linear se%uence of bits of data #serial

transission$. To redistribute serial data to parallel lines #and vice versa$, one of the most important

components on a N& is memory, which acts as a "u**er#


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Network Inter*ace Card (NIC) and $AC address

NIC 'ransission: rom +arallel to Serial and Cice Cersa

Networking devices( "epeater


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Networking devices( "epeater "eceives the signal before it becomes to weak or corrupted, regenerates the original bit

pattern and puts the refreshed copy back onto the link. Allows the extension of the physical length of a network.


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Networking devices( =ub They have a number of incoming lines that are ?oined electrically. rames coming on one line

#port$ are sent on all the other lines #ports$. &t forms a single collision domain

7 &f two frames are arriving at the same time, they will collide in same way as on coaxial

cable. They don9t examine nor use in any way the G/2 addresses. They operates at the physical layer. Passive u"s:rames coming on one line are sent on all the others #passively without

amplifying$. Active u"s:rames coming on one line are sent on all the others # by amplifying$ and it

functions in a similar manner to a "epeater.

Networking devices( Switch


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Networking devices( Switch Similar to bridges in that both route on frame addresses. The main difference is that switches interconnect individual computers. &t functions at


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Networking devices( 'ridge onnect two or more 1ANs. unctions in thernet this is 3G bit address #0A$.

LAN-

LAN-

/

LAN-

LAN-

/

Networking devices( "outer


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Networking devices( "outer "elay packets among multiple interconnected networks. unctions in Network layer of ;S& 0odel. =ave access to network layer addresses and have two

or more networks at the same time.

A packet sent from a station on one network to a stationon a neighboring network, goes first to the ?ointly heldrouter, which forwards it to the destination network.

&f the router is not connected to both source anddestination network, then the sending router transfersthe packet across one of its connected networks to thenext router, in the direction of the destination, and so

on, until the destination is reached.

Networking devices( 'router


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Networking devices( 'router unctions both as 'ridge and a "outer 7 hence called as 'router. an work on networks using different protocols. an be programmed only to pass data frames using a specific protocol forward to a segment 7 in this

case it is functioning in a similar manner to a 'ridge. &f a 'router is set to route data packets to the appropriate network with a routed protocol such as &+,

it is functioning as a "outer.

Networking devices( 4ateway onnects 2 or more networks that can be of different types and provides protocol conversion so that

end devices with dissimilar protocol architectures can communicate. Transport 4ateways

7 ;perate at Transport 1ayer7 onnect two or more computers that use different connection!oriented transport layer protocols.

i.e. transport gateway translate T+:&+ packet into S+J:&+J packet #Netware$. Application 4ateways

7 ;perate at Application 1ayer.7 *nderstand the format and contents of the data and translate one format into another

i.e. an e!mail gateway may translate &nternet >!mails into S0S messages of mobile phones.

Gateway

137.22.144.6

145.65.23.102

Netware

TCP/IP

Networking devices! "emote Access


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Networking devices! "emote Access nable communication between networks or connecting to the world beyond

the 1AN.

D. annot send digital signal directly to telephone line.3. Sending end( 0;


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THAN

K

YOU

Final Introduction to Networking Chapt -1

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Transcript of Final Introduction to Networking Chapt -1