Zte ZXR10 5900 Series - Chapter 9 DHCP Configuration; DHCP Overview

Chapter9
DHCPConfiguration
TableofContents
DHCPOverview.................................................................83
ConguringDHCP..............................................................84
DHCPCongurationExample...............................................99
DHCPMaintenanceandDiagnosis......................................103
DHCPOverview
DynamicHostCongurationProtocol(DHCP)enablesahostonthe
networktoobtainanIPaddressensuringitsnormalcommunica-
tionandrelevantcongurationinformationfromaDHCPserver .
DHCPadoptsUDPasthetransmissionprotocol.Hostsendsames-
sagetoPort67oftheDHCPserverandtheDHCPserverreturns
themessagetoPort68ofthehost.TheDHCPworksinthefol-
lowingsteps:
1.HostsendsabroadcastpacketDHCPDiscoverincludingthere-
questofIPaddressandothercongurationparameters.
2.DHCPserverreturnsaunicastpacketDHCPOfferincludingthe
validIPaddressandconguration.
3.HostselectstheserverwhichreturnsDHCPOfferarrivingat
rstandsendsaunicastDHCPRequesttotheserver ,indicating
toacceptrelevantconguration.
4.SelectedDHCPserverreturnsaunicastpacketDHCPAckfor
conrmation.
BynowthehostcanusetheIPaddressandrelevantconguration
obtainedfromtheDHCPserverforcommunication.
DHCPsupportsthreemechanismsforIPaddressallocation:
1.Automaticallocation—DHCPassignsapermanentIPaddress
toaclient.
2.Dynamicallocation—DHCPassignsanIPaddresstoaclientfor
alimitedperiodoftime(oruntiltheclientexplicitlyrelinquishes
theaddress).
3.Manualallocation—thenetworkadministratorassignsanIPad-
dresstoaclientandDHCPisusedsimplytoconveytheas-
signedaddresstotheclient.
UsuallyDynamicallocationmethodisadopted.Thevalidtimeseg-
mentofusingtheaddressiscalledleaseperiod.Oncethelease
periodexpires,thehostmustrequesttheserverforcontinuous
lease.Thehostcannotcontinuetoleaseuntilitacceptsthere-
quest,otherwiseitmustgiveupunconditionally.
CondentialandProprietaryInformationofZTECORPORATION83