Zte ZXR10 8900 Series - DHCP Snooping Overview; Configuring DHCP

ZXR108900SeriesUserManual(BasicCongurationVolume)
DHCPRelayRoutersdonotsendthereceivedbroadcastpacketfromasub-net-
worktoanotherbydefault.Buttherouterasthedefaultgateway
oftheclienthostmustsendthebroadcastpackettothesub-net-
workwheretheDHCPserverlocateswhentheDHCPserverand
clienthostarenotinthesamesub-network.Thisfunctioniscalled
DHCPrelay.
ZXR108900seriesswitchcanactasaDHCPserverorDHCPrelay
toforwardDHCPinformation.
DHCPSnoopingOverview
DHCPbringsconvenienceforIPaddressallocation,butitalso
bringsproblems.
DHCPserviceallowsmultipleDHCPserverstoexitinasubnet.
Therefore,theadministratorcannotensurethatIPaddressesof
usersareallocatedbythedesignatedDHCPserver .Theaddresses
maybeallocatedbyDHCPserversthataresetbyotherusers
illegally.
InaDHCPservicesubnet,hostswithlegalIPaddressesandmasks
canaccessthissubnet.DHCPservermayallocatetheselegalad-
dressestootherhosts.Thiscausesaddressconiction.
Tosolvetheaboveproblems,ZXR108900seriesswitchusesDHCP
snoopingfunctiontopreventbogusDHCPserverinasubnet.The
portconnectingwithDHCPservermustbesetastrustport.Com-
biningwithdynamicARPinspectiontechnology,DHCPsnooping
functionpreventsbindingofillegalIPandMAC.Thisensuresthe
servertoallocateIPaddressescorrectly.
ConfiguringDHCP
ConfiguringDHCPServer
TocongureDHCPserver ,performthefollowingsteps.
Step
CommandFunction
1
ZXR10(config)#ipdhcpenableThisenablesDHCPserver
processglobally.
2
ZXR10(config)#iplocalpool<pool-name><low-ip-add
ress><high-ip-address><net-mask>
ThisconguresanIPaddress
poolforaDHCPserver .
3
ZXR10(config)#ipdhcpserverleasetime<time>
Thissetstheleasetimeofthe
IPaddressleasedbyaDHCP
servertoclient.
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