name=CCNA2BestNotes

exam=640-507

CiscoCCNA2STUDYGUIDE

Thisstudyguideconsistsofmaterialwhichwillprovideyouwiththeknowledgeto

passtheCCNAexam.Allyouneedtodoisstudyandmemorizethethematerial

providedwithin…andyouwillbereadytotaketheexam.

Averagestudytimeis36to48hours.Thenyouareready.

GOODLUCK!

NOTE:Itisveryimportantthatyoutotallyunderstandalltheconceptsyouwillfind

inthisstudyguide.Readandrereadthesepagesuntilyouknowthembyheart.

OSIModelOverview

Foranyonewhowantstobeanetworkengineer,itisimperativeyouunderstandthe7

LayerOSImodel.Itisimportanttocommitthisentiremodeltomemoryandtruly

learntheprocessofnetworkcommunications.Ofcourse,youwillbetestedonthese

conceptsontheCCNAexam,andanynetworkingexamforthatmatter.But,theseare

valuableconceptsyouwilluseforyourentirecareer.

In1977,theInternationalStandardsOrganization(ISO),composedofindustry

representatives,createdasubcommitteetodevelopdatacommunicationstandardsthat

promotemultivendorinteroperabilityanduniversalaccessibility.In1978,thefirst

documentwasreleasedwhichoutlinedthereferencemodeltoachievethe

interoperabilityandstandardizationthatwasneeded.Theoriginaldocumentapplied

tosystemsthatwereopentoeachotherbecausetheycouldallusethesameprotocols

andstandardstoexchangeinformation.

In1984,theISOreleasedarevisionofthismodelandcalledittheOpenSystems

Interconnections(OSI)ReferenceModel.

Areferencemodelisaconceptualblueprintofhowcommunicationsshouldtakeplace.

Itaddressesalltheprocessesrequiredforeffectivecommunicationsanddividesthese

processesintologicalgroupingscalledlayers.

VendorsdesignnetworkproductsbasedonthespecificationsoftheOSImodel.It

providesadescriptionofhownetworkhardwareandsoftwareworktogetherina

layeredfashiontomakecommunicationspossible.Italsohelpswithtroubleshooting

byprovidingaframeofreferencethatdescribeshowcomponentsaresupposedto

function.

WhywehaveaLayeredModel?

1)Itreducescomplexity

2)Allowsforastandardizedinterface

3)Facilitatesmodularengineering

4)Ensuresinteroperabletechnology

5)Acceleratesevolution

6)Simplifiesteachingandlearning

Itshouldbenotedthatalayeredmodeldoesnotdefineorconstrainan

implementation;itissimplyaframework.Notallimplementationwillstrictlyadhere

orconformtotheOSIreferencemodel,buttheydoconformtothestandardsfromthe

OSImodelprinciples.

Eachlayerusesitsownlayerprotocoltocommunicatewithitspeerlayerintheother

system.Eachlayer*sprotocolexchangesinformation,calledProtocolDataUnit

(PDUs),betweenpeerlayers.Thisisknownbetterasatypeoflogicalcommunication

calledpeer-to-peercommunications.Whenoneormoreprotocolisneededto

successfullycompleteacommunicationprocess,they'regroupedintowhatiscalleda

protocolstack.

Layeringspecifiesdifferentfunctionsandservicesatdifferentlevels.EachOSIlayer

haswell-definednetworkingfunctions,andthefunctionsofeachlayercommunicate

andworkwiththefunctionsofthelayersimmediatelyaboveandbelowit.Eachlayer

providessomeserviceoractionthatpreparesthedatafordeliveryoverthenetworkto

anothercomputer.Allrequestsarepassedfromonelayer,throughtheinterface,tothe

nextlayer.Eachlayerbuildsuponthestandardsandactivitiesofthelayerbelowit.

OSIMODEL

7

ApplicationLayer

Program-toprogramcommunication.Identifyandestablishtheavailabilityofthe

intendedcommunicationpartner,anddetermineifsufficientresourcesexistforthe

communication.PopularapplicationprotocolsincludeWWW,SMTP,EDI,FTP,

Telnet,andSNMP

6

PresentationLayer

Managesdatarepresentationconversions.Forexample,thePresentationlayerwould

beresponsibleforconvertingfromEDCDICtoASCII.Datacompression,

decompression,encryption,anddecryptionarepresentationlayer.Presentationlayer

standardsincludeMPEG,MIDI,PICT,TIFF,JPEG,ASCII,andEBCDIC.

5

SessionLayer

Responsibleforestablishingandmaintainingcommunicationschannels.Inpractice,

thislayerisoftencombinedwiththeTransportLayer.Dialogcontrolbetweendevices

ornodes.Organizesthecommunicationthroughsimplex,halfandfullduplexmodes.

Dealswithconnectionestablishment,datatransfer,andconnectionrelease.Protocols

includeNFS,SQL,RPC,AppletalkSessionProtocol(ASP),XWindows,and

NetBEUI.

4

TransportLayer

Responsibleforend-to-endintegrityofdatatransmission.Handlesmultiplexing

upper-layerapplication,sessionestablishmentandteardownofvirtualcircuits.Hides

detailsofnetworkdependentinfofromthehigherlayersbyprovidingtransparentdata

transfer.The"windows"worksatthisleveltocontrolhowmuchinformationis

transferredbeforeanacknowledgementisrequired.

3

NetworkLayer

Routesdatafromonenodetoanother.Senddatafromthesourcenetworktothe

destinationnetwork.Therouterwillusepacketswitchingtomoveapacketfromone

interfaceorport,toanotherthroughthenetworkcloud.

2

DataLinkLayer

Responsibleforphysicallypassingdatafromonenodetoanother.Translates

messagesfromtheupperlayersintodataframesandaddscustomizedheaders

containingtheHardwaredestinationandsourceaddress.

LogicalLinkControlSublayer-Actsasamanagingbufferbetweentheupperlayers

andthelowerlayers.UsesSourceServiceAccessPoints(SSAPs)andDestination

ServiceAccessPoints(DSAPs)tohelpthelowerlayerstalktotheNetworkLayer.

1

PhysicalLayer

Managesputtingthedataontothenetworkmediaandtakingthedataoff.Sendand

receivesbits.Communicatesdirectlywithcommunicationmedia.

DataEncapsulation

EachlayeroftheOSImodeldependsontheservicefunctionbelowit.Toprovide

service,thelowerlayerusesencapsulationtoputthePDUfromtheupperlayerinto

itsdatafield;itthencanaddanyheadersandtrailersthelayerwillusetoperformits

function.

DataEncapsulationcanbebrokendowninto5steps:

Action

OSIModel

Keyword

Userinformationisconvertedtodata

Application/Presentation/Session

DATA

Dataisconvertedtosegments

Transport

SEGMENTS

SegmentsareconvertedtoPacketsorDatagrams

Network

PACKETS

PacketsorDatagramsareconvertedtoFrames

DataLink

FRAMES

Framesareconvertedtobits

Physical

BITS

Connection-orientedvs.Connectionless

Connection-oriented

Tousereliabletransportservices,oneuserofthetransportlayermustestablisha

connection-orientedsessionwithitspeersystem.

Connection-orientedcommunicationissupportedbyTCPonport6(RFC1700details

allthewell-knownportnumbers).

Connection-orientedserviceinvolvesthreephases:

Connectionestablishment-Duringtheconnectionestablishmentphase,asinglepath

betweenthesourceanddestinationsystemsisdetermined.Networkresourcesare

typicallyreservedatthistimetoensureaconsistentlevelofservice,suchas

guaranteedthroughputrate.

Datatransfer-Onceaconnectionisestablisheddataistransferredsequentiallyover

thededicatedpaththathasbeenestablished.Duringtransfer,thetwomachineson

eachendcontinuetocommunicatewiththeirprotocolsoftwaretoverifythatdatais

receivedcorrectly.Dataisalwaysreassembledatthedestinationsystemintheorder

inwhichitwassent.

Connectiontermination-Duringtheconnectionterminationphase,anestablished

connectionthatisnolongerneededisterminated.Ifcommunicationbetweenthe

sourceanddestinationsystemsisrequiredagain,anewconnectionmustbe

established.

Staticpathselection-Alltrafficmusttravelalongthesamestaticpath,ifafailure

occursanywherealongthatpath,itwillcausetheconnectiontofail.

Staticreservationofnetworkresources-Aguaranteedrateofthroughputrequiresthe

commitmentofresourcesthatcannotbesharedbyothernetworkusers.Unlessfull,

uninterruptedthroughputisrequiredforthecommunication,bandwidthisnotused

efficiently.

Connection-orientedservicesareusefulfortransmittingdatafromapplicationsthat

areintolerantofdelaysandpacketre-sequencing.FTPandTelnetapplicationsare

basedonconnection-orientedservicesaswellassomevoiceandvideoprograms.

Connectionless-oriented

ConnectionlesscommunicationissupportedbyUDPonport17(RFC1700).Itisnot

guaranteedandnoacknowledgementsaresentorreceived.Itisfasterthan

connection-oriented.Itisuptotheapplicationorhigherlayerstocheckthatthedata

wasreceived.

Connectionlessnetworkservicedoesnotpredeterminethepathfromthesourcetothe

destinationsystem,norarepacketsequencing,datathroughput,andothernetwork

resourcesguaranteed.Eachpacketmustbecompletelyaddressedbecausedifferent

paththroughthenetworkmightbeselectedfordifferentpacket,basedonavarietyof

influences.Eachpacketistransmittedindependentlybythesourcesystemandis

handledindependentlybytheintermediatenetworkdevices.Connectionlessservice

offerstwoimportantadvantagesoverconnection-orientedservice:

Dynamicpathselection-Pathareselectedonapacket-by-packetbasis,trafficcanbe

routedaroundnetworkfailures.

Dynamicbandwidthallocation-Bandwidthisusedmoreefficientlybecausenetwork

resourcesarenotallocatedbandwidththattheyarenotgoingtouse,unlike

connection-orientedservices.

Connectionlessservicesareusefulfortransmittingdatafromapplicationsthatcan

toleratesomedelayandre-sequencing.Data-basedapplicationsaretypicallybasedon

connectionlessservice.

AninterestingexampleofaUDPbasedapplicationisTrivialFileTransferProtocol

(TFTP).CiscorouterIOSandconfigurationfilesaresentandreceivedusingTFTP.

ThisisavaluabletoolfortheInternetworkEngineerforconfiguringandbackingup

Ciscorouters.AfreeversionislocatedfromCiscoontherewebsite:

http://www.cisco,com/?TFTPcanonlyreadandwritefilesto/fromaremote

server.Itcannotlistdirectories.

Iknowwhatyouarethinking;wearesendingIOSimagesandconfigurationfiles

usingUDP?But,thatisanunreliableconnectionless-orientedprotocol.Isn*tthatabit

sillybecausethereisnoguaranteeofdelivery?Thesefileandconfigurationsare

importantright?Whyyes,youarecorrectonallcounts.Butremember,theupper

layersofthemodelcanalsoensuredataissentreliablyandrequestpacketstobe

resent.Thecreatorcandesignandimplementapplicationsinvariousways.Thisis

exactlywhattheTFTPapplicationprotocoldoes.TFTPridesontopofUDP.The

applicationtakestheresponsibilityforreliabledeliveryofthedata.Eachnon-terminal

packetisacknowledgedseparately.Eachpacketmustbeacknowledgedbeforethe

nextpacketissent.Thus,ourIOSimagesandconfigurationfilesaresafe.

Unfortunately,TFTPisnotveryrobustandmosterrorscauseterminationofthe

connection.ThenewestIOSversion12fromCiscosupportsFTP.Formore

informationonTFTP,seeRFC1350.

FlowControl

Flowcontrolisthemeansthatpreventsnetworkcongestionbyensuringthat

transmittingdevicesdonotoverwhelmreceivingdeviceswithdata.

Therearemanypossiblecauseofnetworkcongestion.Highspeedserversmaybe

capableofsendingdatafasterthanthenetworkcandeliverit,orthedestination

deviceiscapableofreceivingandprocessingit.

Therearethreecommonmethodsforhandlingnetworkcongestionandflowcontrol:

1)Buffering

2)SourceQuenchMessages

3)Windowing

Buffering-Bufferingisusedbynetworkdevicestotemporarilystoreburstsofexcess

datainmemoryuntiltheycanbeprocessed.Occasionaldataburstsareeasilyhandled

bybuffering.However,bufferscanoverflowifdatacontinuesathighrates.

SourceQuenchMessages-Sourcequenchmessagesareusedbyreceivingdevicesto

helppreventtheirbuffersfromoverflowing.Thereceivingdevicesendsasource

quenchmessagetorequestthatthesourcereduceitscurrentrateofdatatransmission.

Windowing-Windowingisaflow-controlmethodinwhichthesourcedevice

requiresanacknowledgementfromthedestinationafteracertainnumberofpackets

havebeentransmitted.

Windowingisanend-to-endfacilitybetweensenderandreceiver.

1)Thesourcedevicesendsapredeterminednumberofpacketstothedestination

device.

2)Afterreceivingthepackets,thedestinationdevicesendsanacknowledgementto

thesource.

3)Thesourcereceivestheacknowledgementandsendsthesameamountofpackets.

4)Ifthedestinationdoesnotreceiveoneormoreofthepackets,itdoesnotsendan

acknowledgment.Thesourcewillthenretransmitsthepacketsatareduced

transmissionrate.

Windowingworkswiththeconnection-orientedprocesstoensurereliabledeliveryof

thedataandtheproperandconsistentflowofthatdata.Byusingacknowledgements,

packetscanberesentiflostduetooverflowingbuffersorothernetworkerrors.

Windowingcanalsobeusedtoincreasenetworkperformance.Whendevicescreatea

connection,theydetermineanappropriatewindowsizefortransferringdata.For

example,10packetsmaybesentbeforeanacknowledgmentisrequiredthatthose

packetshavebeenreceived.Labtestinghasproventhatbymanipulatingthewindow

size,increasesinnetworkthroughputcanbeachieved.RFC1106,2414,and2415

discussthesefindings.

DataLinkandNetworkAddressing

MACaddresses-Addressesare48bitsinlengthandareexpressedas12hexadecimal

digits.Thefirst6digitsspecifythemanufacturerandtheremaining6areuniqueto

thehost.NottwoMACaddressesarethesameintheworld.Ultimatelyall

communicationismadetotheMACaddressoftheNIC.ProtocolssuchasARPand

RARPareusedtodeterminetheIPtoMACaddressrelationship.Thefollowingisan

exampleofaCiscorouterEthernetinterface.

Example:00e0.le5d.2782

OOeOle(Cisco'svendornumber)

5d2782(uniquehostnumber)

ThesenumbersareoftenreferredtoastheBurnedInAddress(BIA).Itshouldbe

notedthatmostvendor'ssoftwarethatisprovidedwiththeNICwouldallowyouto

modifythisnumber,althoughitisnotrecommended.Therearecircumstanceswhen

thisisnecessary.Amachineatthemanufacturergeneratesthesenumberssequentially

andautomatically.Thesemachineshavebeenknowntooccasionallygetcaughtina

loopandthesameMACaddressbegiventohundreds,orthousandsofNICswithout

qualitycontrolfindingtheerrorandtheproductbeingsoldtothepublic.Ibelieve

3COMhadasituationlikethismanyyearsagoandcausedsomeaggravating

momentsfortheengineersworkingwiththelotofNICsonsitewhocouldnot

determinewhycommunicationwasnotoccurringwithseveralPCsonthenetwork.

Datalinkaddresses-Addressesthatoperateatthedatalinklayer.AMACaddressis

adatalinklayeraddressandthesearebuiltinbythemanufacturer.Theycanbe

virtualizedforAdapterFaultToleranceorHSRP.SwitchesandBridgesoperateatthe

DataLinklayeranduseDataLinkaddressestoswitch/bridge.

Networkaddresses-AddressesthatoperateattheNetworklayer.TheseareIP

addressesorIPXaddressesthatareusedbyRouterstoroutepackets.Network

addressesaremadeupoftwoparts,theNetworkIDandtheHostID.Network

addressesarehostspecificandonemustbeboundtoeachinterfaceforeveryprotocol

loadedonthemachine.Thereisnofixedrelationshipbetweenthehostandthe

networkaddress.AnexamplewouldbearouterwiththreeinterfaceseachwithIPX/

IPandAppleTalkrunningoneach.Therouterthereforehasninenetworklayer

addresses.

CISCOIOS

TheCiscoInternetworkOperatingSystem(IOS)istheoperatingsystemsoftwarethat

comeswithallCiscorouters.

IOSRouterModes

TheIOSinterfaceprovides6basicmodesofoperation.TheCommandPromptand

thesymbolsareimportanttorecognizingthemodeyouarecurrentlyworkingwith.

MODE

Description

Access

CommandPrompt

UserEXECMode

Providesforlimitedexaminationofrouterinformation.

Defaultmodeatlogin

Router>

PrivilegedEXECMode

Providesdetailedexamination,testing,debugging,andfilemanipulation.

Typeenableatcommandprompt,

Router>enable

Router#

GlobalconfigurationMode

Allowsyoutochangehighlevelrouterconfiguration

TypeconfigtatPrivilegedmodeprompt,

Router#configt

Router(config)#

ROMMonitorMode

AutomaticiftheIOSdoesnotexistorthebootsequenceisinterrupted

N/A

>orrommon>

SetupMode

Prompteddialogthathelpsyousetuptherouterconfiguration

TypesetupatPrivilegedmodeprompt

Willdisplayaseriesofquestionstoanswer

RXBootMode

HelpersoftwarethathelpstherouterbootwhenitcannotfindtheIOSimagein

FLASH

N/A

Router<boot>

GlobalConfigurationMode

TheGlobalconfigurationmodealsoallowsyouaccesstomorespecificrouter

configurationmodes.The2primaryonesyouneedtoknowaretheInterfaceandthe

Subinterfacemodes.

Router(config-if)#-TheInterfaceconfigurationmodeisenteredbytypingthework

InterfaceattheGlobalconfigurationprompts.

Router(config)#interface<interfacetypeandnumber>

Router(config-subif)#-ThisisavariationontheInterfacecommandandcanbe

accessedasshownbelow.Thisletsyoudivideanyinterfaceintosmallervirtual

interfaces.

Router(config)#interface〈interfacetypeandnumber>.<subinterface-number>

Example:

Router(config)#interfacesO.lpoint-to-point

LoggingIn

Whenyoufirstlogintoarouteryouarepromptedwith:

Router>

ThisiscalledUserEXECmodeandonlycontainalimitedfeaturesetofcommands.

EnteringthecommandenableandthepasswordwillputyouinPrivilegedEXEC

modethatisindicatedbytheprompt:

Router#

FromthismodeyoucannowusealloftheavailablecommandsandenterGlobal

ConfigurationMode.

ContextSensitiveHelp

TheIOShasabuiltinContext-sensitivehelp.Themaintoolisthe?symbol.Ifyou

areunsureofwhatacommandortheentiresyntaxforacommandshouldbe,typeina

partialcommandfollowedbya?andthehelpfacilitywillprovideyouwiththe

availableoptions.

Tolistallcommandsavailableforaparticularcommandmode:

Router>?

Tolistcommand'sassociatedkeywords:

Router>command?

Tolistakeyword'sassociatedarguments:

Router>commandkeyword?

CommandHistory

TheIOSuserinterfaceprovidesahistoryorrecordofcommandsthatyouhave

entered.Thisfeatureisparticularlyusefulforrecallinglongorcomplexcommand

entries.Bydefault,thesystemrecordsthe10mostrecentcommandlinesinitshistory

buffer.

Todisplaytheentriesinthehistorybuffer:

Router>showhistory

TochangethenumberofcommandlinesrecordedduringthecuiTentterminalsession,

usethefollowingcommand:

Router>terminalhistory<sizenumberofcommandlines>

Toconfigurethenumberofcommandlinesthesystemrecordsbydefault,enterthe

followingcommandlineinconfigurationmode:

history<sizenumberofcommandlines>

EditingCommands

Ctrl-W-Erasesaword

Ctrl-U-ErasesaLine

Ctrl-A-Movesthecursortothebeginningofthecurrentline

Ctrl-E-Movesthecursortotheendofthecurrentline

Ctrl-F(orrightarrow)-Moveforwardonecharacter

Ctrl-B(orleftarrow)-Movebackonecharacter

Ctrl-P(oruparrow)-Recallcommandsinthehistorybufferstartingwiththemost

recentcommand

Ctrl-N(ordownarrow)-Returntomorerecentcommandsinthehistorybufferafter

recallingcommandswithCtrl-Portheuparrowkey

ESC+B-Movebackwardoneword

ESC+F-Moveforwardoneword

Ctrl-Z-EndconfigurationmodeandreturnstotheprivilegedEXECmode

TABkey-Finishesapartialcommand

RouterElements

RAM

ThisistheworkingareafortheRouter.Itcontainsroutingtables,ARPcache,IOS,

etc.ItalsoholdstheRoutersRunning-Configfile.ThecontentsofRAMarelostwhen

youpowerdown.

Router>showversion-ToviewinformationaboutIOSinRAM

Router>showprocesses-ToviewinformationabouttheprogramsinRAM

Router>showmemory/showbuffers/showstacks-Toviewtablesandbuffers

Router#showrunning-config-Toviewtheactiveconfigurationfile(Note:EXEC

Mode#)

NVRAM

Non-VolatileRAMstorestherouter'sStartup-Configfile.NVRAMcontentsare

retainedwhenyoupowerdownorreload.

Router#showstartup-configuration-Toviewthecontents

FLASH

FlashisanEPROM.Flashmemoryholdstheoperatingsystemimage(IOS).Having

Flashallowsyoutoupdatesoftwarewithoutremovingoraddingchips.Flashcontent

isretainedwhenyoupowerdownorreload.MultiplecopiesofIOScanbestoredin

Flashmemory.

ROM

ROMcontainsthepowerondiagnostics,abootstrapprogramandoperatingsystem

software.Toperformupgradesthephysicalchipsmustberemovedandreplaced.

CDP

CiscoDiscoveryProtocolisaproprietaryprotocoltoallowyoutoaccess

configurationinformationonotherroutersandswitcheswithasinglecommand.It

usesSNAPattheData-LinkLayer.BydefaultCDPsendsoutabroadcastevery60

secondsanditholdsthisinformationfor180seconds.CDPisenabledbydefault.

Router(config)#cdprun

CDPisdisabledonaspecificinterfacebyenteringtheinterfaceconfigurationmode

andtyping:

Router(config-if)#nocdpenable

AttheinterfaceconfigmodeyoucanonlyenableordisableCDP.Attheglobal

configmodeyoucanalsosettheholdtimeandtimer.Forexample:

Router(config)#cdptime30

Router(config)#cdpholdtime120

WhenCDPisenabledyoucanviewdetailsofotherCiscodevicesbytyping:

Router>showcdpneighbor

TodisplaydetailedinformationabouttheneighboringCiscorouterstype:

Router>showcdpneighbordetail

Thisdisplaystheplatformandprotocolinformationonyourneighboringdevices.

TodeletetheCDPtableofinformationaboutneighborstype:

Router#clearcdptable

CommandShortcuts

Allcommandscanbeshortenedtotheminimumtosavetimeandeffortwhenatthe

routerprompt.TheentirecommanddoesnothavetobetypedfortheIOSto

understandwhatitisyouaretryingtoaccomplish.Becomingfamiliarwithseveral

differentwaystotypethesamecommandisrequiredfortheCCNA.Herearesome

examples:

TokeepwiththeaboveexamplesaboutCDP,lets'tryafew:

Router>showcdpneighbor

also

Router>shcdpneigh

Aslongasthecommandsareuniqueandnoothercommandhasthesamefirstletters,

theIOSunderstandswhatyouaretryingtoaccomplish.

Anotherexample,thisoneregardinginterfacesanddisplayingtheinterface.

Router>showinterfaceethernet0

or,

Router>shintethernet0

or,

Router>shintethO

oreven,

Router>sineO

AllofthesecommandswillworktodisplayEthernet0ontherouterandthestatistics

andinformation.Thismakeslifemucheasierforyouwhenconfiguringarouterand

shortensthecommandsgreatlysavingagreatdealoftime.

ManagingConfigurationFiles

Routerconfigurationinformationcanbegeneratedbyseveralmeans.Fromprivileged

EXECmodeyoucanentertheconfigurecommandtoconfiguretherunning

configurationfromeitheraTerminal(console),Memory(NVRAM),orNetwork

server(TFTP).

Router#configterm-Allowsyoutoconfiguremanuallyfromtheconsoleterminal.

Router#configmem-LoadstheconfigurationfilefromNVRAM,sameascopystart

run.

Router#confignet-LoadstheconfigurationfromaTFTPserver,sameascopyTFTP

start.

Youcanalsousethecopycommand:

Router#copyrunningstartup-Copiestherunningconfig(RAM)totheStartup

config

(NVRAM).Thisisusedafterrealtimechangesviaconfigtermhavebeen

madethatrequiretheconfigtobesaved.

Router#copystartuprunning-CopiesthestartupconfigurationfromNVRAMto

RAMwhereit

becomestherunningconfiguration.

Router#copyruntftp-MakesabackupoftherunningconfigfiletoaTFTPserver.

Router#copytftprun-LoadsconfigurationinformationfromaTFTPserver.

Router#copytftpstart-CopiestheconfigfilefromtheTFTPserverintoNVRAM.

RouterPasswords,Identification,andBanners

PasswordConfiguration

TherearefivedifferentpasswordsthatcanbeusedwhensecuringyourCiscorouter;

EnableSecret,EnablePassword,VirtualTerminalPassword,AuxiliaryPassword,and

ConsolePassword.

ConsolePassword-usedforconnectionsviatheconsoleportontherouter.

Router(config)#lineconsole0

Router(config)#login

Router(config-line)#passwordcisco

AuxiliaryPassword-UsedforconnectionsviatheAuxportontherouter.

Router(config)#lineaux0

Router(config-line)#login

Router(config-line)#password<password>

VirtualTerminalPassword-UsedforTelnetsessionstotherouter.Mustbespecified

oryouwillnotbeabletologintherouter.

Router(config)#linevty04

Router(config-line)#login

Router(config-line)#passwordcisco

EnablePassword-UsedwhenthereisnoEnableSecret,orusingoldersoftware.

Router(config)#enable-password<password>

PerformPasswordEncryption

Router(config)#servicepassword-encryption

(setpasswordshere)

Router(config)#noservicepassword-encryption

EnableSecret-Thisisacryptographicpasswordwhichhasprecedenceoverthe

enable

passwordwhenitexists.

Router(config)#enablesecret<password>

RouterIdentification

RouterName-TheroutercanbegivenanameenteredinGlobalconfigmode.Ifno

nameis

entered,thenthenameRouterisused.

Router(config)#hostnameFlorida

Florida#

LoginBanner-Abannercanbedisplayedwhenauserlogsintotherouter.Youmust

use

adiliminatingcharactersuchasa#sign.Thisbannerisalsoknownasthe

MessageoftheDay(motd).

Florida(config)#bannermotd#

WelcometorouterFlorida

4thFloorInfosystems

#

InterfaceDescription-Youcangiveeachinterfaceadescriptiontohelpidentifyits

purpose.

Florida(config)#interfacee0

Florida(config-if)#descriptionInfosysLAN,Bldg.1

IOSStartupCommandsandStartupSequence

OverviewofSystemStartup

ThestartuproutinesforCiscoIOSsoftwarehavethegoalofstartingrouteroperations.

Theroutermustdeliverreliableperformanceconnectingtheusernetworksitwas

configuredtoserve.Todothis,thestartuproutinesmust:

?Makesurethattheroutercomesupwithtestedhardware.

?FindandloadtheCiscoIOSsoftwarethattherouterusesforitsoperatingsystem.

?Findandapplytheconfigurationstatementsaboutrouter-specificattributes,

protocolfunctions,andinterfaceaddresses.

Therouterwillmakesurethatitcomesupwithtes