網(wǎng)絡(luò)課后習(xí)題(Onlinehomeworkproblems)

Whatisacomputernetwork?Whatarethemainfunctionsof

computernetwork?ComputernetworkreferstoaSharedresource,

forthepurposeofusingthemethodsofcommunicationtospread

outgeographicallyrelativenumberofindependentcomputer

systems,terminalequipmentanddataequipmentconnected,and

underthecontroloftheagreementfordataexchangesystem.

Function:1torealizeresourcesharing2breakthegeographic

boundary3andincreasereliability4toimproveprocessing

power5fordatacommunication.

2.Trytoexplaintheprincipleofpacketswitching.Atypeof

storageandforwardswitching.Thepaperisdividedintogroups

(packets)toforward,andthedatalinkandcacheofcascaded

cascadescanbeusedtoimprovecommunicationefficiencyand

reliability.Themainreasonsforthedevelopmentofcomputer

networkarebrieflydescribed.

Whatisthepurposeoferrorcontrol?Whatarethebasicmethods

oferrorcontrol?Improvereliability.1.Methodof4FECmethod

of4FECmethod

4.Whatarethemainmethodsofrouteselectionincomputer

networks?Pathselection1.Determinethetype1totype2

stationaryprobabilitydistributionforms2.Adaptiverouting

1centralized2isolatedtype3hybriddistributed4(1)the

shortestpathalgorithm(2)afterfillingpathalgorithm(3)

pathtocalculatelink-stateroutingalgorithm(4)

probability.,

5.TheOSImodelisalayeredstructurethatinterconnects

heterogeneoussystems.Layerlayerlayerlayerlayerlayer

layerlayerlayerlayerlayerlayerlayerlayer.

Characteristics:1providesastandardframeworkfor

controllingtheinteractionrulesofinterconnectedsystems.

2definesanabstractstructure,notadescriptionoftheactual

implementation.Anentityonthesamelevelondifferent

systemsiscalledanequallayerentity.Communicationbetween

theequivalentlayerentitiesisgovernedbytheprotocolof

thelayer.Theinterfacebetweenadjacentlayersdefinesthe

primitiveoperationandtheserviceprovidedbythelowerlayer

totheupperlayer.Thepublicserviceprovidedisa

connection-orientedorconnectionlessdataservice.7direct

datatransmissionisonlyimplementedatthelowestlevel.Each

layercompletesthedefinedfunction,modifyingthefunction

ofthislayerdoesnotaffecttheotherlayers.

1.WhatisacomputerLAN?Communicationisoften1imitedto

amediumgeographicalarea,andcanrelyonphysicalchannels

withhighdatarates,andthischannelhasaconsistentlowber

rate.

WhatarethecharacteristicsofcomputerLAN?Duetothelimited

geographicalscopeofthenetwork,thecostofcommunication

mediaaccountsforasmallproportion.Commonlyused

communicationphysicalmediasuchastwistedpair,coaxial

cableandopticalfiber(2)thechannelhasawidecommunication

frequencyband,highdatatransferrate(3)hasthe

characteristicsofhighlyinterconnectedandexpansionofthe

flexibilityof(4)doesnotnecessarilyneedthecentralhost

nodesinthenetwork,butonlyneedtoprovidetheuserwith

distributedcomputingfunctionoftheeffectivedata

processingandcanmessagetransmissionina5)channelcontrol

methodandthemechanismissimpleandreliable6whenthe

networkafailurewillnotaffecttherunningofthewhole

system7)thecostofthenetworksystemisnotmuch,often

belongtoacareer/businessunits,anddoesnotbelongtopublic

serviceswasatecycleshort,quickeffect,lowcostandsocial

benefit.

WhatisLAN'scommonlyusedmediaaccesscontroltechnology?

Whatarethecharacteristicsofeach?Comparedwiththecontrol

methodofdeterminingmedium,theCSMA/CDmethodhasthe

followingcharacteristics:themethodofCSMA/CDmediaaccess

controlmethodissimpleandeasytoimplement.

TheCSMA/CDisamethodofrandomcompetitionbuswhichusers

canaccessbustime,whichisapplicabletotheapplication

environmentofdatatransmissionrealtime.TheCSMA/CDshows

betterthroughputrateanddelaycharacteristicswhennetwork

communicationloadislow.However,whenthenetwork

communicationloadincreases,thenetworkthroughputrate

decreasesandthetransmissiondelayincreasesduetothe

increasedconflict.Therefore,theCSMA/CDmethodisgenerally

usedinapplicationswithlightercommunicationloads.

Comparedwithrandommediaaccesscontrolmethod,todetermine

thetypeofmediaaccesscontrolmethodtokenbusandtokenring

hasthefollowingcharacteristics:(1)tokenbusandtokenring

networknodeinthemaximumtimeintervalbetweentwotokenis

certain,andsuitableforreal-timedatatransmissiontodemand

higherenvironment.Suchasproductionprocesscontrolarea.

Thetokenbusandtokenringshowgoodthroughputrateandlow

transmissiondelaywhenthenetworkcommunicationloadis

heavier,soitissuitablefortheenvironmentwithheavy

communicationload.Theshortcomingofthetokenbusandtoken

ringisthattheyrequirecomplexringmaintenancefunctions,

whicharedifficulttoachieve.

Whatarethefunctionsofnic?(1)dataconversion:and-string,

stringandconvert(2)datacache:setupdatacachespace,data

exchange(3)communicationservice:communicationprotocolto

achievedatacommunication.(4)networkcardrealizesapart

ofthefunctionofLANdatalinklayer,includingnetworkaccess

control,informationframesendingandreceiving,error

checking,stringandcodeconversion,etc.

WhatarethemainperformanceindicatorsofLAN?Channel

throughputrate(S)channelutilization(U)delaytime(D)

6.Whatarethemainfactorsofnetworklatency?Queuing,access,

sending,propagationdelay.

1.Whatisthenetworkoperatingsystem?Whatarethemain

functionsofnetworkoperatingsystem?TheNetworkOperating

System(NOS,NetworkOperatingSystem)isacollectionof

softwareandrelatedrulesthatenablecomputersintheNetwork

toeffectivelyandeffectivelyshareNetworkresourcesand

provideallkindsofservicesforNetworkusers.

2.Currently,whatarethemodesofnetworkoperatingsystem?

NT,NETWARE,UNIX,LINUX.

Whatarethecharacteristicsofcomputerwideareanetwork?It

haswidescopeofscope,communicationmedium,communication

mode,complexcommunicationmanagement,lowcommunication

efficiency,wideservicescopeandnetworkperformance,which

focusesoninformationtransmissionandinvestment.

2.Trytoexplainthecompositionofx.25network.X.25standard

sub-physicallayer,data1inklayerandgrouplayer3protocol,

respectivelycorrespondingtothelower3layersofISO/OSI

referencemodel.

3.Brieflydescribethegeneralcommunicationprocessofthe

x.25groupinglayer.TheHDLCcommunicationprocesscanbe

dividedintofourstages:linkbuilding,information

transmission,linkresetandlinkdismantling.Linkresetonly

occursinfaultprocessing,andthereareonlythreestagesof

generalcommunication.

4.BriefintroductionofCHINAPAC，snetworkapproachandthe

maincommunicationprotocolsused.X.25/SDLCsynchronous

special1inefeed,x.28asynchronousspeciallineintothe

network,theinputlinecanbedividedintoanalogspecialline

anddigitalspecialline.Dialinthenetwork.

What'stheroleofx.25Internetaddresses?Thenetworkaddress

(DNA)isusedtodistinguishthenetworkofDTEandDTE

WhatarethemainfeaturesofDDN?TheDDNissynchronousdata

transmissionnetworkwithnoexchangefunctionandhigh

transmissionrate,andthenetworkdelayissmall.DDNisthe

all-transparentnetwork.DDNisanunconstrained

all-transparentnetworkwhichcanbesupportedbyany

discipline.Itcantransmitdata,image,soundandother

information.

Whatarethemajorissuesthatthewanshouldpayattentionto?

Doyouneedtoexchangebetweenthepointsofthenetwork

transmissionrate

Whatarethetypesofnetworkinterconnection?LAN-LAN

interconnection,LAN-wan-LANinterconnection,wan-wan

interconnection

Whatarethelevelsofnetworkinterconnection?Whatarethe

correspondinginterconnectiondevices?Thephysicallayer

interconnection,therepeater,theconcentrator,thedatalink

layerinterconnection,thenetworklayerinterconnection,the

routerthehighlevelinterconnection,thegateway.

3.Trytoexplaintheworkingprincipleoftransparentbridge.

AutomaticidentificationofbridgesegmentMACaddress,

forminganaddressmappingtable,everytimethebridgeframe

forwarding,consultthepurposesites,suchas,tothe

correspondingportforwarding,ifnot,alltheportforwarding

tobesidesreceivingportordiffusion.

4.Trytoexplaintheprincipleandadvantagesofthethird

layerswitch.Itcanaccomplishtheportswitchingfunctionof

thetraditionalswitchandtheroutingfunctionofsomerouters.

Advantages:thetransmissionbandwidthofsubnetcanbe

randomlyassigned,canreasonablyallocateinformation

resources,canreducethecost,theconnectionbetweenthe

switchisflexible.

5.TesttheroutingselectionprocessofIPdatagram.1)

extractedfromthedatasubmittedtothefirstdestinationIP

addressD,itisconcludedthatthedestinationnetworknumber

forN.(2)ifNisawiththerouterdirectlyconnectedtoa

network,donotneedtothroughotherrouters,anddirectly

throughthenetworkwilldatagramdeliverytodestinationD,

otherwise,theexecution(3).(3)hasthedestinationaddress

intheroutingtableforDindicatethehostrouting,

transmittingthedatagramissetoutintheroutingtablenext

router;IfthereisaroutetothenetworkNintheroutingtable,

thedatagramwillbetransmittedtothenextstoprouter

specifiedintheroutingtable;Ifotherwise,execution(5).

(5)a,asubnetmaskintheroutingtableissaidtousethe

subnetmask,andthendealwiththeroutingtableofeachline,

withasubnetmaskandthedestinationIPaddress"and"Dphase

ofoperation,settheresultsforM.IfMisequaltothe

destinationstationnetworknumberinthisline,thedatagram

istransmittedtothenextrouterspecifiedintheroutingtable;

Ifthereisadefaultrouteintheroutingtable,thedatagram

istransmittedtothedefaultrouterspecifiedintherouting

table;Otherwise,executethesystem.Theroutingselectionof

thereportiswrong.

6.TrytoexplainthemainroleofICMPprotocol.Improvethe

opportunitiesforsuccessfulIPdatagramdelivery.

7.TrytoexplainthedifferenceinservicebetweenTCPandUDP.

TCPprovidesconnection-orientedandreliableservices,UDP

providesefficientbutunreliableservices,andits

reliabilityishandledbyapplications.

WhatisthedifferencebetweenIPv4addressandIPv6address?

IPV4addresses32-bit,IPV6address128-bit.

1.WhatarethecharacteristicsofInternetstructure?The

flexibleanddiversifiedapproachtothenetworkhasadopted

themostpopularclient/servermodeindistributednetwork,

whichgreatlyimprovestheflexibilityofnetworkinformation

service.