计网实验Problem-11

Problem111.ARPmeansAddressResolutionProtocol.ItprovidesanimportantconceptualboundarybetweenMACaddressesandIPaddresses.2.Translationfromacomputer'sIPaddresstoaMACaddressisknownasaddressresolution.3.Onecomputercanresolvetheaddressofanothercomputeronlyifbothcomputersattachtothesamephysicalnetwork.Acomputerneverresolvestheaddressofacomputeronaremotenetwork..4.WhenanARPmessagetravelsacrossaphysicalnetwork,itisencapsulatedinahardwareframewithtypeof0x806.5.ICMPmeansInternetControlMessageProtocol.6.IPandICMPareco-dependent.IPdependsonICMPtoreporterrors,andICMPusesIPtocarryerrormessages.7.ICMPMessageEncapsulationusestwolevelsofencapsulation:IPprotocoltype:1forICMP,Frametype:0x800forIPpacket.8.Aprotocolwasinventedtoallowahosttoobtainmultipleparameterswithasinglerequest,knownasastheBootstrapProtocol(BOOTP).Currently,DHCPisusedtotakecareofmostconfigurationneeded.9.Whenacomputerboots,thecomputerbroadcastsaDHCPRequest,theserversendsaDHCPReply.10.ADHCPservercansupplytwotypesofaddresses:permanentlyassignedaddressesasprovidedbyBOOTPorapoolofdynamicaddressestobeallocatedondemand.11.Amechanismwasinventedthatallowsmultiplecomputersatasitetoshareasingle,globallyvalidIPaddress,knownasNetworkAddressTranslation(NAT)..12.NATsolvestheIPaddressexhaustionproblembyusingtwo2typesofaddresses:TheNATdeviceitselfisassignedasingleglobally-validIPaddress.asiftheNATdevicewereahostontheInternet;Eachcomputeratthesiteisassignedauniqueprivateaddressalsoknownasanonroutableaddress..