Enterasys b5

DHCP Overview
16-2 DHCP Server Configuration
address,theMACaddresstowhichitisassigned,theleaseexpiration,andwhethertheaddress
assignmentisdynamic(automatic)orstatic(manual).TheDHCPleasedatabaseisstoredinflash
memory.
InadditiontoassigningIPaddresses,theDHCPservercanalsobeconfiguredtoassignthe
followingtorequesting
clients:
•Defaultrouter(s)
•DNSserver(s)anddomainname
•NetBIOSWINSserver(s)andnodename
• Bootfile
•DHCPoptionsasdefinedbyRFC2132
Configuring a DHCP Server
ForDHCPtofunctiononEnterasysB5systems,thesystemhasto“knowabout”theIPnetwork
forwhichtheDHCPpoolistobecreated.
OntheB5,therearetwowaystoconfigureaDHCPserver:oneistoassociatetheDHCPaddress
poolwiththeswitch’shostport
IPaddress,andtheotheristoassociatetheDHCPaddresspool
witharoutedinterface.
SinceonaB5system,thehostportIPaddresscannotfallwithinaconfiguredroutedinterfaceon
thesystem,atypicalB5systemconfiguredwithroutinginterfaceswillnothaveahostport
IP
address.Therefore,allDHCPpoolswouldbeassociatedwithroutedinterfaces.
ThefollowingtasksprovidebasicDHCPserverfunctionalitywhentheDHCPpoolisassociated
withthesystem’shostIPaddress.ThisprocedurewouldtypicallybeusedwhentheB5systemis
NOTconfiguredforrouting.
1. Configurethesystem(stack)
hostportIPaddresswiththesetipaddresscommand.Oncethe
system’sIPaddressisconfigured,thesystemthen“knows”abouttheconfiguredsubnet.For
example:
set ip address 192.0.0.50 mask 255.255.255.0
2. EnableDHCPserverfunctionalityonthesystemwiththesetdhcpenablecommand.
3. ConfigureanIPaddresspoolfordynamicIPaddressassignment.Theonlyrequiredstepsare
tonamethepoolanddefinethenetworknumberandmaskforthepool.Notethatthepool
hastobeinthe
samesubnetandusethesamemaskasthesystemhostportIPaddress.For
example:
set dhcp pool auto-pool network 192.0.0.0 255.255.255.0
AllDHCPclientsservedbythisswitchmustbeinthesameVLANasthesystem’shostport.
ThefollowingtasksprovidebasicDHCPserverfunctionalitywhentheDHCPpoolisassociated
witharoutedinterface.
1. CreateaVLANandaddportstotheVLAN.OnlyDHCPclientsassociatedwiththisVLAN

willbeservedIPaddressesfromtheDHCPaddresspoolassociatedwiththisroutedinterface
(VLAN).Inthisexample,VLAN6iscreatedandportsge.1.1throughge.1.10areaddedto
VLAN6:
set vlan create 6
Note: A total of 16 address pools, dynamic and/or static, and a maximum of 256 addresses for the
entire switch, can be configured on the Enterasys B5
.