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Whenchoosingaswitch,selectthatoffersthefollowingcriteria:

Sufficientports:knowhowmanyportsyouneedforthenetwork(todayandinthefuture).

AmixtureofUTPspeeds:considerhowmanyportswillneed1Gbpscapabilityandhow

manyportsonlyrequire10/100Mbpsbandwidths.

UTPandfiberports:considercarefullyhowmanyUTP/fiberportswillbeneeded

Figure104depictsthedifferentportspeeds,typesandexpandabilityconsiderations.

ChoosingaRouter

Whenselectingarouter,youneedtomatchthecharacteristicsoftheroutertoitspurpose.Costand

interfacetypesandspeedsmustbeconsidered.Additionalfactorsforchoosingarouterinclude:

expandability,mediaandoperatingsystemfeatures.

Networkdevices,suchasroutersandswitches,comeinbothfixedandmodularphysical

configurations.Fixedconfigurationshaveaspecificnumberandtypeofportsorinterfaces.Modular

deviceshaveexpansionslotsthatprovidetheflexibilitytoaddnewmodulesasrequirementsevolve.

Mostmodular

devices

come

with

abasic

number

of

fixed

ports

as

well

as

expansion

slots.

Additionalmodules,suchasfiberoptics,canincreasethecosts,sothemediausedtoconnecttothe

routershouldbesupportedwithoutneedingtopurchaseadditionalmodules.(Figure105)

Theroutercansupportcertainservicesandfeatures:

Security

Qualityofservice(QoS)

VoiceoverIP(VoIP)

RoutingmultipleLayer3protocols

SpecialservicessuchasNetworkAddressTranslation(NAT)andDHCP

DeviceInterconnectionsThischapterisaboutthedifferentcablestandardsandrequirements.

LANandWAN:GettingConnected

Therearefourphysicalareas:

Workarea

Telecommunicationsroom(distributionroom)

Horizontalcabling(distributioncabling)

Backbonecabling

(vertical

cabling)

WhenlookingattheinterconnectivitybetweentheLANcablingareas,thereareafewrequirements,

suchastypeofmedia,cablelengths,costs,theactualworkareasandbandwidth.

WorkAreas

Theworkareasarethelocationsdevotedtotheenddevicesusedbyindividualusers.Eachworkarea

hasaminimumoftwojacksthatcanbeusedtoconnectanindividualdevicetothenetwork.Apatch

cableorpatchcordisanelectricalcable,usedtoconnectoneelectronicdevicetoanotherforsignal

routing.Patchcordsareusuallyproducedinmanydifferentcolorssoastobeeasilydistinguishable,

andarerelativelyshort.Youusepatchcablestoconnectindividualdevicestothesewalljacks.

Straightthroughcableisthemostcommonpatchcableusedintheworkarea.Thistypeofcableis

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usedtoconnectenddevices,suchascomputers,toanetwork.Whenahuborswitchisplacedinthe

workarea,acrossovercableistypicallyusedtoconnectthedevicetothewalljack.

TelecommunicationsRoom

Thetelecommunicationsroomiswhereconnectionstointermediarydevicestakeplace.Theserooms

containthe

intermediary

devices

that

tie

the

network

together.

These

devices

provide

the

transitions

betweenthebackbonecablingandthehorizontalcabling.

Insidethetelecommunicationsroom,patchcordsmakeconnectionsbetweenthepatchpanels,

wherethehorizontalcablesterminate,andtheintermediarydevices.

ThestandardsspecifytwodifferenttypesofUTPpatchcables.

HorizontalCabling

Horizontalcablingreferstothecablesconnectingthetelecommunicationsroomswiththework

areas.Thelengthofthecablemustnotexceed90metersandisreferredtoasthepermanentlink.

Thehorizontalmediarunsfromapatchpanelinthetelecommunicationsroomtoawalljackineach

workarea.

Connections

are

made

with

patch

cables.

BackboneCabling

Backbonecablingreferstothecablingusedtoconnectthetelecommunicationsroomstothe

equipmentrooms,wheretheserversareoftenlocated.Backbonecablingalsointerconnectsmultiple

telecommunicationsroomsthroughoutthefacilityandisalsousedtointerconnectLANsbetween

buildings.Backbonesorverticalcablingareusedforaggregatedtraffic.Backbonesrequirehigh

bandwidthmediasuchasfiberopticcabling.

TypesofMedia

UTP

Fiberoptics

Wireless

Eachtypehasitsadvantagesanddisadvantages:

Cable

Length

Thetotallengthofcablerequiredtoconnectadeviceincludesallcablesformtheenddevicesin

theworkareatotheintermediarydeviceinthetelecommunicationsroom.

Attenuationisreductionofthestrengthofasignalasitmovesdownamedium.Thelongerthe

mediumthemoreattenuationwillaffectthesignal.

Cost

Thebudgetmightallowusingamoreexpensivemediatype

Bandwidth

Thedevicesinanetworkhavedifferentbandwidthrequirements.

Currentlythetechnologyusedinfiberopticmediaoffersthegreatestbandwidthavailableamong

thechoicesforLANmedia.Wirelessisalsosupportinghugeincreasesinbandwidthbutithas

limitationsindistanceandpowerconsumption.(Table101)

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EaseofInstallation

Theeaseofcableinstallationvariesaccordingtocabletypesandbuildingarchitecture.Cablesin

buildingsaretypicallyinstalledinraceways.Aracewayisanenclosureortubethatprotectsthe

cable.(Figure108)

UTPcableisrelativelylightweightandflexibleandhasasmalldiameter,whichallowsittofitinto

smallspaces.

Many

fiber

optic

cables

contain

athin

glass

fiber.

This

creates

issues

for

the

bend

radiusofthecable.

Wirelessnetworksrequirecabling,atsomepoint,toconnectdevicessuchasaccesspointstothe

wiredLAN.WirelessisofteneasiertoinstallthanUTPoffibercable.

Electromagnetic

Interference

(EMI)

and

Radio

Frequency

Interference

(RFI)

EMI/RFIinanindustrialenvironmentcansignificantlyimpactdatacommunicationsifthewrong

cableisused.

Electricalmachines,lighting,andothercommunicationsdevices,includingcomputersandradio

equipmentcanproducesinterference.WirelessitthemediummostsusceptibletoRFI.

MakingLANConnections

UTPcablingconnectionsarespecifiedbytheEIA/TIA.

TheRJ45connectoristhemalecomponentcrimpedontheendofthecable.Whenviewedfromthe

front,thepinsarenumberedform8to1.(Figure109)

TypesofInterfaces

InanEthernetLAN,devicesuseoneoftwotypesofUTPinterfaces:mediadependentinterface

(MDI)ormediadependentinterface(MDIX).

TheMDIusesthenormalEthernetpinout.Pins1and2areusedfortransmitting,andpins3and6

areused

for

receiving.

Devices

such

as

computers,

servers

or

routers

have

MDI

connections.

ThedevicesthatprovideLANconnectivityhubsorswitchesuseMDIXconnections.TheMDIX

cablesswapthetransmitpairsinternally.

Whenconnectingdifferenttypesofdevicesyouuseastraightthroughcable.Whenconnectingthe

sametypeofdevicesuseacrossovercable.

ManydevicesallowtheUTPEthernetporttobesettoMDIorMDIX.Thiscanbedoneinoneofthree

ways:

Onsomedevices,portscanhaveamechanismthatelectricallyswapsthetransmitand

receivepairs

SomedevicesallowselectingwhetheraportfunctionsasMDIorasMDIX

Manynewerdeviceshaveanautomaticcrossoverfeature

Straight-ThroughUTPCables

Astraightthroughcablehasconnectorsoneachendthatareterminatedthesameinaccordance

witheithertheT568AorT568Bstandard.(Figure1010)

Usestraightthroughcablesforthefollowingconnections:

SwitchtorouterEthernetport

Computertoswitch

Computertohub

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CrossoverUTPCables

Fortwodevicescommunicatethroughacablethatdirectlyconnectsthem,thetransmitterminalof

onedeviceneedstobeconnectedtothereceiveterminaloftheotherdevices.

ToachievethistypeofconnectionwithaUTPcable,oneendmustbeterminatedasEIA/TIAT568A

pinoutandtheotherendterminatedwithT568Bpinout.(Figure1011)

Crossovercables

directly

connect

the

following

devices

on

aLAN:

Switchtoswitch

Switchtohub

Hubtohub

RoutertorouterEthernetportconnection

Computertocomputer

ComputertorouterEthernetport

Figure1012showsanetworkwithstraightthroughandcrossovercables.

MakingWAN

Connections

WANlinkscanspanextremelylongdistances.Thesedistancescanrangeacrosstheglobeasthey

providethecommunicationlinksthatweusetomanageemailaccounts,viewwebpages

Wideareaconnectionsbetweennetworkstakeanumberofforms,including:

PhonelineRJ11connectorsfordialupordigitalsubscriberline(DSL)connections

60pinserialconnections

Therearetwotypesofphysicalserialcables.BothcablesusealargeWinchester15pinconnectoron

thenetworkend.ThisendofthecableisusedasaV.35connectiontoaphysicallayerdevicesuchas

achannelserviceunit/dataunit(CSU/DSU).

ThefirstcabletypehasamaleDB60connecterontheCiscoendandamaleWinchesterconnector

onthenetworkend.ThesecondtypeisamorecompactversionofthiscableandhasaSmartSerial

connectorontheCiscodeviceend.(Figure101315)

DataCommunicationsEquipmentandDataTerminalEquipment

Thetypesofdevicesthatmaintainthelinkbetweenasendingandareceivingdeviceare:

Datacommunicationsequipment(DCE):adevicethatsuppliestheclockingservicesto

anotherdevice.ThisdeviceisattheWANaccessproviderendofthelink.

Dataterminalequipment(DTE):adevicethatreceivesclockingservicesfromanotherdevice

andadjustsaccordingly.ThisdeviceisattheWANcustomeroruserendofthelink.

DCEsandDTEsareusedinWANconnections.ThecommunicationthroughaWANconnectionis

maintainedbyprovidingaclockratethatisacceptabletoboththesendingandthereceivingdevice.

TheDCEdeviceassignsaclockratetotheDTErouter,ineffect,settingthetimingfortheDTErouter.

Thisallowsthatroutertoadjustthespeedofitscommunicationoperations,therebysynchronizing

withthedevicesconnectedtoit.(Figure1016)

SettingUpWANConnectionsintheLab

RoutersareDTEdevicesbydefault,buttheycanbeconfiguredtoactasDCEdevices,andassuch,

theyhavetoprovidetheclocking.

TheV.35

compliant

cables

are

available

in

DTE

and

DCE

versions.

To

create

apoint

to

point

serial

connectionbetweentworouters,joinaDTEandDCEcable.(Figure1017)

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DevelopinganAddressingScheme

HowManyHostsintheNetwork?

Todevelopanaddressingschemeforanetwork,startbydeterminingthetotalnumberofhosts.

ConsidereverydevicethatwillrequireanIPaddress,nowandinthefuture.

TheenddevicesrequiringanIPaddressincludethese:

Usercomputers

Administratorcomputers

Servers

Otherenddevicessuchasprinters,IPphonesandIPcameras

NetworkdevicesrequiringanIPaddressincludethese:

RouterLANinterfaces

RouterWANinterfaces

NetworkdevicesrequiringanIPaddressformanagementincludethese

Switches

Wirelessaccesspoints

Whenthetotalnumberofhostshasbeendetermined,considertherangeofaddressesavailableand

wheretheyfitwithinthegivennetworkaddress.Nextdeterminewhetherallhostswillbepartofthe

samenetwork.Thenumberofhostsorsubnetiscalculatedusingthefollowingformula:2n2

HowManyNetworks?

Therearemanyreasonstodivideanetworkintosubnets,includingthefollowing:

Managebroadcasttraffic:broadcastscanbecontrolledbecauseonelargebroadcastdomain

isdivided

into

anumber

of

smaller

domains

Differentnetworkrequirements:itiseasiertomanagerequirementsifuserswhoshare

requirementsarealltogetherononesubnet

Security:differentlevelsofnetworksecuritycanbeimplementedbasedonnetwork

addresses.

CountingtheSubnets

Eachsubnet,asaphysicalnetworksegment,requiresarouterinterfaceasthegatewayforthat

subnet.Inaddition,eachconnectionbetweenroutersisaseparatesubnet.

Thenumberofsubnetsononenetworkisalsocalculatedusingtheformula:2n.(Figure1018)

SubnetMasks

Applyonesubnetmaskfortheentirenetworkandthencalculatethefollowingvalues:

Auniquesubnetandsubnetmaskforeachphysicalsegment

Arangeofusablehostaddressesforeachsubnet

DesigningtheAddressStandardforYourInternetwork

Groupdevicesaccordingtotypes,andallocatethemtoalogicalblockofaddresseswithinthe

addressrangeofthenetwork.

Someofthedifferentcategoriesforhostsareasfollows:

Generalusers

Specialusers

Networkresources

RouterLANinterfaces

RouterWAN

links

Managementaccess

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CalculatingtheSubnets:examplesp391-398

DeviceInterconnectionsMostnetworkdevices,suchasroutersandswitches,havebetweentwoandfourdifferentinterfaces

onthemtoconnectto.

DeviceInterfaces

Interfaces,alsocalledports,arewherecablesareconnectedtothedevice.(Figure1023)

Sampleinterfaces:

EthernetInterface

TheEthernetinterfaceisusedforconnectingcablesthatterminatewithLANdevicessuchas

computersandswitches.Thisinterfacecanalsobeusedtoconnectrouterstoeachother.

SerialInterface

SerialWANinterfacesareusedforconnectingWANdevicestotheCSU/DSU.Serialinterfaces

betweenrouterswillalsobeusedinthelabs.

ConsoleInterface

TheconsoleinterfaceistheprimaryinterfaceforinitialconfigurationofaCiscorouterorswitch.It

isalsoanimportantmeansoftroubleshooting.Physicalsecurityofnetworkdevicesisextremely

important.

AuxiliaryInterface

Theauxiliary(AUX)interfaceisusedforremotemanagementoftherouters.Amodemis

connectedto

the

AUX

interface

for

dialup

access.

From

asecurity

standpoint,

it

is

responsible

for

maintainingvigilantdevicemanagement.

MakingtheDeviceManagementConnection

Networkingdevicesdonothavetheirowndisplays,keyboardsorinputdevicessuchastrackballsand

mice.Accessinganetworkdeviceforconfiguration,verificationortroubleshootingismadethrougha

connectionbetweenthedeviceandacomputer.Toenablethisconnection,thecomputerrunsa

programcalledaterminalemulator.(Figure1024)

Thefollowingpointsapplytotheuseofaterminalemulator:

ThePCsrequireanRJ45toDB9orRJ45toDB25adapter

COMportsettingsare9600bps,8databits,noparity,1stopbitandnoflowcontrol

Thisconnectionprovidessomethingcalledoutofbandconsoleaccess.

AnAUXswitchportcanbeusedforamodemconnectedconsole

Aterminalemulatorisasoftwareprogramthatallowsonecomputertoaccessthefunctionson

anotherdevice.Itallowsapersontousethedisplayandkeyboardononecomputertooperate

anotherdevice.Thecableconnectionbetweenthecomputerrunningtheterminalemulation

programandthedeviceisoftenmadethroughtheserialinterfaceonthePCs.