Zte ZXR10 8900 Series - Chapter 7 DHCP Configuration; DHCP Overview

Chapter7
DHCPConfiguration
TableofContents
DHCPOverview.................................................................65
DHCPSnoopingOverview...................................................66
ConguringDHCP..............................................................66
DHCPCongurationExamples.............................................68
DHCPMaintenanceandDiagnosis........................................71
DHCPOverview
DHCPallowsahostonanetworktoobtainanIPaddressfornor-
malcommunicationsandrelatedcongurationinformationfroma
DHCPserver .DetailsofDHCParedescribedinRFC2131.
Working
Procedure
DHCPusesUDPasthetransmissionprotocol.Thehostsendsmes-
sagestoport67oftheDHCPserver ,whowillreturnmessagesto
port68ofthehost.ADHCPworksinthefollowingsteps:
1.AhostsendsaDHCPDiscoverbroadcastmessagerequesting
anIPaddressandothercongurationparameters.
2.ADHCPserverreturnsaDHCPOffermessagecontainingavalid
IPaddress.
3.HostselectstheserveratwhichtheDHCPOfferarrivesrst,
andsendsaDHCPRequestmessagetotheserver ,whichindi-
catesitacceptstherelatedcongurations.
4.SelectedDHCPserverreturnsaDHCPAckmessageforac-
knowledgement.
BynowthehostcanusetheIPaddressandrelevantconguration
obtainedfromtheDHCPserverforcommunication.
DHCPsupportsthreemechanismsforIPaddressallocation:
�DHCPassignsapermanentIPaddresstoaclient.
�DHCPassignsanIPaddresstoaclientforalimitedperiodof
time(oruntiltheclientexplicitlyrelinquishestheaddress).
�NetworkadministratorassignsanIPaddresstoaclientand
DHCPisusedsimplytoconveytheassignedaddresstothe
client.
UsuallyDynamicallocationmethodisadopted.Thevalidtimeseg-
mentofusingtheaddressiscalledleaseperiod.Oncethelease
periodexpires,thehostmustrequesttheserverforcontinuous
lease.Thehostcannotcontinuetoleaseuntiltheserveraccepts
therequest,otherwiseitmustgiveupunconditionally.
CondentialandProprietaryInformationofZTECORPORATION65