7a) Lan Standards

8/12/2019 7a) Lan Standards

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UGANDA CHRISTIAN UNIVERSITYUGANDA CHRISTIAN UNIVERSITY

FACULTY OF SCIENCE AND TECHNOLOGYFACULTY OF SCIENCE AND TECHNOLOGY

Department of Information Technology Department of Information Technology

Computer Networks

Program !SIT "

#a$uar% Semester & "'()

*+ LAN STANDARDS, -IRELESS LANs a$.VLANS

Le/turer Re0e//a As11mwe

P2o$e Num0er3"45 *("677*6 488 9'*'8 4"" ':(

Ema1; ras11mwe


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Introduction

Range of technologies - also calledLAN Standards

Ethernet

Fiber Channel

Token Ring

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Ethernet and its Evolution

Standard Ethernet- !"b#s

Fast Ethernet- !!"b#s

$igabit Ethernet-$b#s

Ten-$igabit Ethernet- !$b#s

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Ethernet The IEEE &!2'% co((ittee has been the

(ost active in definingalternative #h)sicalconfigurations' To distinguish the various

i(#le(entations

that are available* theco((ittee has develo#ed a concisenotation+

,.ata rate 1$ =0ps,s1g$a;1$gmet2o., ma>1mumsegme$t;e$gt2in hundreds of (eters

The defined alternatives are sho.n inthe table sho.n in the

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!"b#s S#ecifications 1Ethernet

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EEE &!2'% !"b#s 4h)sical La)er "ediu(alternatives


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!"b#s S#ecifications 1Ethernet

IEEE :'"+) ('=0ps P2%s1/a; La%er =e.1uma;ter$at1?es+

The defined alternatives for 10-Mbps are:

10BASE5:Specifies the use of 50-ohm coaxial cable

and Manchester digital signaling. Themaximum length of a cable segment is set at

500 meters. Can extend using up to 4 repeaters.5


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10BASE2: lower-cost alternative to 10BASE5

using a thinner cable, with fewer taps over a

shorter distance than the 10BASE5 cable.

10BASE-T:Uses unshielded twisted pair in a

star-shaped topology, with length of a link is

limited to 100 meters. As an alternative, an

optical fiber link may be used out to 500 m.

10BASE-F:Contains three specifications using

optical fibre6


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In teleco((unications and signal#rocessing* 0ase0a$.is an ad7ectivethat describes signalsand s)ste(s .hose range of

fre8uencies is (easuredfro( 9ero to a(a/i(u( band.idth or highest signalfre8uenc)'

Trans(ission of signals .ithout(odulation' In a baseband localnet.ork* digital signals are inserteddirectl) onto the cable as

voltage #ulses' The entires#ectru( of the cable is

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!:ASE-T+ ;T< stands for t.isted #air

and !:ASE-F+ ;F< stands

for o#tical fiber'

!:ase3-Thick Ethernet

!:ase2-Thin Ethernet

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IEEE &!2'% !!"b#s S#ecifications1Fast Ethernet

Fast Ethernet refers to a set ofs#ecificationsdevelo#ed b) the EEE &!2'% co((itteeto #rovide lo. cost*Ethernet co(#atible LANs o#erating at(''=0ps'

The blanket designation for thesestandards is!!:ASE-T

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!!"b#s Fast Ethernet

1 0 0 B A S E - T X 1 0 0B A S E -F X 1 0 0 B A S E - T 4

Transmiss ion

m e d i u m

2 pair , ST P 2 pair , Catego ry

5 U T P

2 opt ical f ibers 4 pair , Catego ry

3 , 4 , o r 5 UT P

Signal ing

technique

M L T - 3 M L T - 3 4 B 5 B , N R Z I 8 B 6 T , N R Z I

Da ta rate 1 0 0 M b p s 1 0 0 M b p s 1 0 0 M b p s 1 0 0 M b p sM a x i m u m

segm ent l ength

1 0 0 m 1 0 0 m 1 0 0 m 1 0 0 m

N e t w o r k s p a n 2 0 0 m 2 0 0 m 4 0 0 m 2 0 0 m

EEE &!2'% !!:ASE-T 4h)sical La)er "ediu(alternatives


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!!:ASE->

?ses a unidirectional data rate !! "b#s

over single t.isted #air or o#ticalfiber link

t.o #h)sical (ediu( s#ecifications one fort.isted #air kno.n as !!:ASE T> andone for o#tical fiber kno.n as !!:ASE-F> !!:ASE-T>

uses t.o #airs of t.isted-#air cable for t/@ r/ 1trans(ission and receiving

ST4 and Categor) 3 ?T4 allo.ed "TL-% signaling sche(e is used

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(''!ASE6F@

uses t.o o#tical fiber cables fort/ 1trans(ission @ r/

1rece#tion

(''!ASE6T8

esigned to #roduce a !!-"b#s datarate over lo.er-8ualit) Cat %Bcategor) %?T4 thus takes advantage of large

installed base of cat % in office buildings

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Full u#le/ #eration

Traditional Ethernet is half du#le/+ a stationcan either trans(it or receive a fra(e but itcannot do both si(ultaneousl) Bat the sa(e ti(e

?sing full-du#le/* station can trans(it and

receive si(ultaneousl) A !!-"b#s Ethernet ran in full-du#le/ (ode*

gives a theoretical transfer rate of 2!! "b#s

Stations (ust have full-du#le/ ada#ter cards

and (ust use s.itching hub

each station constitutes se#arate collisiondo(ain

CS"ABC algorith( no longer needed

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"i/ed Configurations

Fast Ethernet su##orts (i/ture of e/isting!-"b#s LANs and ne.er !!-

"b#s LANs

su##orting older and ne.er technologies

e'g' !!-"b#s backbone LAN su##orts !-"b#s hubs stations attach to !-"b#s hubs using!:ASE-T

hubs connected to s.itching hubs using!!:ASE-T

high-ca#acit) .orkstations and servers attachdirectl) to !B!! s.itches

s.itches connected to !!-"b#s hubs use

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$igabit Ethernet Configuration

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Fast Ethernet - etails

Sa(e (essage for(at as ! "b#s Ethernet Fast Ethernet (a) run in full du#le/ (ode

So effective data rate beco(es 2!! "b#s

Full du#le/ (ode re8uires star to#olog) .ith

s.itches

In fact* shared (ediu( no longer e/ists .hens.itches are used

no collisions* thus CS"ABC algorith( no longerneeded

but stations still use CS"ABC and sa(e(essage for(at is used for

back.ard co(#atibilit) reasons


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$igabit Ethernet

Strateg) sa(e as Fast Ethernet Ne. (ediu( and trans(issions#ecification

Retains CS"ABC #rotocol and fra(efor(at

Co(#atible .ith ! and !! "b#sEthernet

Dh) gigabit Ethernet !B!! "b#s load fro( end userscreates increasedtraffic on backbones


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$igabit Ethernet 4h)sical

!!!:ase-S> Short .avelength* (ulti(ode fiber

!!!:ase-L>

Long .avelength* "ulti or single (ode fiber

!!!:ase-C> A s#ecial ST4 1,23(

one for each direction !!!:ase-T

0 #airs* cat3 ?T4 1bidirectional

!! (


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!$b#s Ethernet

Dh) sa(e reasons+ increase in traffic* (ulti(ediaco((unications' etc'

4ri(aril) for high-s#eed* local backbone

interconnection bet.een large-ca#acit) s.itches Allo.s construction of "ANs

Connect geogra#hicall) dis#ersed LANs

ariet) of standard o#tical interfaces

1.avelengths and link distances s#ecified for !$b Ethernet

%!! ( to 0! k(s

full du#le/


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E/a(#le ! $igabit EthernetConfiguration


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!-$b#s Ethernet ata Rate and istance#tions 1Log Scale

We also have copper alternatives. 10GBASE-T uses Cat 6 up

to 55 m; Cat 6a improve! Cat 6" up to 100 m.


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Fibre Channel Re8uire(ents

full du#le/ links .ith t.o fibers #er link

!! "b#s to &!! "b#s on single line

su##ort distances u# to ! k(

s(all connectors high-ca#acit) utili9ation* distance insensitivit)

greater connectivit) than e/isting (ultidro#channels

broad availabilit) Support for multiple cost/performance levels, from

small systems to supercomputers

carr) (ulti#le e/isting interface co((and sets

for e/isting channel and net.ork

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Fiber Channel Ele(ents

The ke) ele(ents of a fiber channelnet.ork are the end s)ste(s alsocalled nodes* and the net.ork itself.hich consists of one or

(ore s.itching ele(ents' The collectionof s.itching ele(ents isreferred to as fabric'

These ele(ents are interconnected b)#oint-to-#oint links bet.een #orts onthe individual nodes and s.itches'

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Co((unication consists of thetrans(ission of fra(es across the#oint-to-#oint bidirectionallinks'

An) node can co((unicate .ith an)other node connectedto the sa(e fabric using the

services of the fabric' Routing done b)fabric

Fra(es (a) be buffered .ithin fabric(aking it #ossible for different nodes to

connect to the fabric at different data

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Fabric can be i(#le(ented as a singlefabric ele(ent .ith attached nodes-asi(#le star arrange(ent or

as a (ore general net.ork of fabricele(ents as sho.n in the figure in slide2&

Fiber net.ork is like a s.itching

net.ork in contrast tothe LANs shared (ediu(* this fiberneeds not get concerned .ith (ediu(

access control issues25


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Fiber scales easil) in ter(s of #orts*data rate and distancecovered' This a##roach#rovides great fle/ibilit)'

Fiber channel can readil) acco((odate

ne. trans(ission (edia and data ratesb) adding ne. s.itches .ith a nu(berof #orts to an e/istingfabric'

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Fiber Channel Net.ork

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TGEN RIN$ 1IEEE &!2'3 TGEN RIN$Standard

A Ring consists of a nu(ber of re#eaters

each connected to t.o others b)unidirectionaltrans(ission links to for( a single closed#ath' ata are transferred se8uentiall)*bit b) bit fro( one re#eater to the ne/t'

Each re#eater regenerates andretrans(its each bit' Fora ring to o#erate as a

co((unication net.ork*three functions arere8uired+

ata insertion

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These functions are #rovided b) there#eaters

ata are trans(itted in #ackets each of

.hich contains a destination addressfield'

As a #acket circulates #ast a re#eater

the address field isco#ied' If the attached stationrecogni9es the address the rest of the#acket is co#ied' %!


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Re#eaters #erfor( the data insertion andrece#tion function in

a (anner not unlike that of ta#s .hichserve as device attach(ent #oints

on a bus or tree'

ata re(oval ho.ever is (ore difficult ona ring' For a bus or tree* signals inserted

onto the line #ro#agate to the end#ointsand are absorbed b)ter(inators' Hence shortl) aftertrans(ission ceases* the bus or tree isclean of data'

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Ho.ever* because the ring is a closedloo#* a #acket .ill circulateindefinitel) unless it isre(oved'

A #acket (a) be re(oved b) theaddressed re#eater*alternativel) each #acket could be

re(oved b) the trans(itting

re#eater after it has (adeone tri# around the loo#' This latter

a##roach is (ore desirable because

' It #er(its auto(atic ackno.ledge(ent

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A variet) of strategies can be used todeter(ine ho. and .hen #acketsare inserted into the ring'

These strategies are in effect (ediu(access control #rotocols'The (ethod used is token ring'

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"ediu( Access Control

The token ring techni8ue is based on theuse of a s(all fra(e called a token thatcirculates .hen all stations are idle'

A station .ishing to trans(it (ust .aituntil it detects a token#assing b)' It then sei9es the

token b) changing one bit in the token.hich transfor(s itfro( a token to a start of fra(e

se8uence for a data fra(e'%0


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Dhen a station sei9es a token and begins

to trans(it a fra(e* there isno token on the ring so other stations.ishing to trans(it (ust .ait' The fra(eon the ring .ill (ake a round tri# and be

absorbed b) the trans(ittingstation' In the defaulto#eration the trans(itting station .ill

insert a ne. token on the ring .henboth of the follo.ing conditions

have been (et'

'The station has co(#leted trans(ission ofits fra(e

2' The leading edge of the trans(itted

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nce the ne. token has been insertedon the ring* another station 1ne/tdo.n-strea( .ith data to send .ill beable to sei9e the token and trans(it'

Note that under lightl) loaded conditions*there is so(e inefficienc) .ith token

ring because a station (ust .ait for thetoken to co(e around beforetrans(itting' %5


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Ho.ever under heav) loads* .hich is.hen it (atters* the ring functions in around robin fashion .hich isboth efficient and fair'

The #rinci#al advantage of token ring isthe fle/ible control over access

that it #rovides

The #rinci#al disadvantage .ith it is there8uire(ent for

token (aintenance' Loss of

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=ore o$ -1re;ess Networks

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Wireless Comes of Age

Guglielmo Marconi invented the wireless telegraphin 1896 Communication b encoding alphanumeric characters in

analog signal

!ent telegraphic signals across the Atlantic "cean Communications satellites launched in 196#s

Advances in wireless technolog $adio% television% mobile telephone% communication

satellites More recentl

&roadband wireless networ'ing% cellular technolog%=


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&roadband Wireless (echnolog

)igher data rates obtainable with broadband wirelesstechnolog

Graphics% video% audio

!hares same advantages of all wireless services*

convenience and reduced cost

!ervice can be deploed faster than fi+ed service

,o cost of cable plant

!ervice is mobile% deploed almost anwhere

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-imitations and .ifficulties of Wireless

(echnologies

Wireless is convenient and less e+pensive

-imitations and political and technical difficulties

inhibit wireless technologies

-ac' of an industr/wide standard

.evice limitations

0g% small -C. on a mobile telephone can onl

displaing a few lines of te+t

0g% browsers of most mobile wireless devices usewireless mar'up language 2WM-3 instead of )(M-

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DEFINITION OF A -IRELESS NET-OR

A $rou# of interconnected nodes that e/changeinfor(ation and share

resources through a .irelesstrans(ission (ediu(

TYPES OF -IRELESS NET-ORS

Direless 4AN

Direless LAN

Direless :roadband Direless DAN 1satellite * "icro.ave *''etc

Cellular Net.orks02

Ch t i ti # Wi l


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Characteristics o# Wireless

WA$s

Covers large geographical areas

Circuits provided b a common carrier

Consists of interconnected switching nodes

(raditional WA,s provide modest capacit 64### bps common

&usiness subscribers using (/1 service 5 144 Mbps

common

)igher/speed -1re;essWA,suse sate;;1te* and 1#sof Mbps common

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Characteristics o# Wireless %A$s

?sed to be a net.ork .ith high #rices* lo.data rates* occu#ational safet)concerns* and licensing re8uire(ents

4roble(s have been addressed and#o#ularit) of .ireless LANs has gro.nra#idl)'

03

&i## ' t Wi l %A$


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&i##erences 'et(een Wireless %A$s

an! WA$s

!cope of a -A, is smaller

-A, interconnects devices within a single building

or cluster of buildings

-A, usuall owned b organi;ation that owns theattached devices

:or WA,s% most of networ' assets are not owned b

same organi;ation

nternal data rate of -A, is much greater

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(he ,eed for DirelessMA,s

(raditional point/to/point and switched networ'techni


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Direless Standards

4AN * LAN and "AN standards .eredefined b) IEEE and Industrial foru(s

A LAN standard define (edia* coding

sche(e* fra(e for( at * "AC#rotocol and other data link la)er#rotocols

E/a(#les of standards + Direless 4AN+ :luetooth * IEEE &!2'3

Direless LAN + IEEE &!2' 1a *b * g

:roadband Direless Net.orks + IEEE &!%'5

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Single Cell Direless LANConfiguration

3!


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"ulti-Cell Direless LANConfiguration

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Infrastructure Direless LAN

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Add Hoc LAN

3%


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Factors To Consider+ ForDireless LAN

Sa(e as an) LAN High ca#acit)* short distances* fullconnectivit)* broadcast ca#abilit)

Through#ut+ efficient use .ireless(ediu( Nu(ber of nodes+Hundreds of nodesacross (ulti#le cells

Connection to backbone LAN+ ?secontrol (odules to connect toboth t)#es of LANs

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Factors To Consider+ For Direless


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Factors To Consider For Direless

LAN

Service area+ !! to %!! ( Lo. #o.er consu(#tion+Need longbatter) life on (obile stations"ustnt re8uire nodes to (onitor access#oints or fre8uenthandshakes

Trans(ission robustness and

securit)+Interference #rone andeasil) eavesdro##ed

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C i


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Factors To Consider+ ForDireless LAN

Collocated net.ork o#eration+T.o or(ore .ireless LANs in sa(earea

License-free o#eration

HandoffBroa(ing+ "ove fro( one cell toanother

)na(ic configuration+ Addition* deletion*

and relocation of end s)ste(s

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Direless LAN A##lications

LAN E/tension Cross-:uilding Interconnect

No(adic Access

Ad Hoc Net.orking

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A li ti LAN t i


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A##lications - LAN E/tension

Saves installation of LAN cabling

Eases relocation and other (odifications tonet.ork structure

Direless LAN to re#lace .ired LANs has notha##ened

In so(e environ(ents* role for the .irelessLAN :uildings .ith large o#en areas

"anufacturing #lants* stock e/change trading

floors* .arehouses Historical buildings S(all offices .here .ired LANs notecono(ical

"a) also have .ired LAN

3&

A##lications


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A##lications Cross-:uilding Interconnect

Connect LANs in nearb) buildings 4oint-to-#oint .ireless link

Connect bridges or routers

Not a LAN #er se ?sual to include this a##lication under

heading of .ireless LAN

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A##lications - No(adic Access

Link bet.een LAN hub and (obile datater(inal

La#to# or note#ad co(#uter

Enable e(#lo)ee returning fro( tri# totransfer data fro( #ortable co(#uter toserver

Also useful in e/tended environ(ent such as

ca(#us or cluster of buildings ?sers (ove around .ith #ortableco(#uters

"a) .ish access to servers on .ired

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A li ti Ad H N t ki


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A##lications Ad Hoc Net.orking

4eer-to-#eer net.ork Set u# te(#oraril) to (eet so(e

i((ediate need

E'g' grou# of e(#lo)ees* each .ithla#to# or #al(to#* in business orclassroo( (eeting

Net.ork for duration of (eeting

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VLANs

LANs 1irtual LANs .ere introduced tohel# divide our #h)sical andlogical net.orks* .ithout additional coststo hard.are* b) using the sa(e s.itch'

Not all s.itches su##ort LANs* so inorder to (ake use of the(* )our

s.itch (ust su##ort the(' Joucan then define .hich #orts on )ours.itch .ill belong to the different LANs)ou .ill create'

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VLANs

For e/a(#le* )ou can configure )ours.itch .ith #orts *2*% and 0 as #art ofLAN No'* .hile #orts 3*5*6and & belong to LAN No'2' Jou

then configure all (achines in eachLAN to be #art of one logical net.ork*isolating the( fro( the rest'

All broadcasts* (ulticasts and other data

are #ro#agated onl) to the#orts that belong to the sa(eLAN fro( .hich the data ca(e fro(' 5%


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T2e Ne>t a$. Last Top1/

-ANs

S.itching

Routing

I4

So(e (ore #rotocols

Read about these in advance 50


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Documents

7a) Lan Standards