Enterasys b5 - Chapter 16: DHCP Server Configuration; DHCP Overview; DHCP Relay Agent; DHCP Server

Enterasys B5 CLI Reference 16-1
16
DHCP Server Configuration
ThischapterdescribesthecommandstoconfiguretheIPv4DHCPserverfunctionalityona
EnterasysB5switch.
DHCP Overview
DynamicHostConfigurationProtocol(DHCP)forIPv4isanetworklayerprotocolthat
implementsautomaticormanualassignmentofIPaddressesandotherconfigurationinformation
toclientdevicesbyservers.ADHCPservermanagesauser‐configuredpoolofIPaddressesfrom
whichitcanmakeassignmentsuponclientrequests.A
relayagentpassesDHCPmessages
betweenclientsandserverswhichareondifferentphysicalsubnets.
DHCP Relay Agent
TheDHCP/BOOTPrelayagentfunctioncanbeconfiguredonalloftheEnterasysB5’srouting
interfaces.TherelayagentcanforwardaDHCPclient’srequesttoaDHCPserverlocatedona
differentnetworkiftheaddressoftheserverisconfiguredasahelperaddressonthereceiving
interface.The
relayagentinterfacemustbeaVLANwhichisconfiguredwithanIPaddress.Refer
totheiphelper‐addresscommand(“iphelper‐address”onpage 19 ‐14)formoreinformation.
DHCP Server
DHCPserverfunctionalityallowstheEnterasysB5switchtoprovidebasicIPconfiguration
informationtoaclientonthenetworkwhorequestssuchinformationusingtheDHCPprotocol.
DHCPprovidesthefollowingmechanismsforIPaddressallocationbyaDHCPserver:
• Automatic—DHCPserverassignsanIPaddresstoaclientfor
alimitedperiodoftime(or
untiltheclientexplicitlyrelinquishestheaddress)fromadefinedpoolofIPaddresses
configuredontheserver.
•Manual—Aclient’sIPaddressisassignedbythenetworkadministrator,andDHCPisused
simplytoconveytheassignedaddresstotheclient.Thisismanagedby
meansof“static”
addresspoolsconfiguredontheserver.
TheamountoftimethataparticularIPaddressisvalidforasystemiscalledaleas e.The
EnterasysB5maintainsaleasedatabasewhichcontainsinformationabouteachassignedIP
For information about... Refer to page...
DHCP Overview 16-1
Configuring General DHCP Server Parameters 16-3
Configuring IP Address Pools 16-12