Reference Guide

When you use DHCP to manage a pool or IP addresses among hosts, you reduce the number of IP addresses you need. DHCP
manages the IP address pool by leasing an IP address to a host for a limited period, allowing the DHCP server to share a
limited number of IP addresses. DHCP also provides a central database of devices that connects to the network and eliminates
duplicate resource assignments.
Automatic address allocation
Automatic address allocation is an address assignment method that the DHCP server uses to lease an IP address to a client from
a pool of available addresses. You cannot configure an empty DHCP pool, under a DHCP pool configuration. For a successful
commit, you must have either a network statement or host/hardware-address (manual binding) configuration. An IP address
pool is a range of addresses that the DHCP server assigns. The subnet number indexes the address pools.
1. Enable DHCP server-assigned dynamic addresses on an interface in DHCP <POOL> mode.
ip dhcp server
2. Create an IP address pool and provide a name in DHCP mode.
pool name
3. Enter the subnet from which the DHCP server may assign addresses in DHCP <POOL> mode. The network option specifies
the subnet address. The prefix-length option specifies the number of bits used for the network portion of the address
(18 to 31).
network network/prefix-length
4. Enter a range of IP addresses from the subnet specified above, which the DHCP server uses to assign addresses in DHCP
<POOL> mode.
range {ip-address1 [ip-address2]}
NOTE:
NOTE: Configure at least one interface to match one of the configured network pools. An interface matches a
network pool when its IP address is included in the subnet defined for that network pool. For example, an interface with
IP address 10.1.1.1/24 matches a pool configured with network 10.1.1.0/24.
DHCP server automatic address allocation
OS10(config)# ip dhcp server
OS10(config-dhcp)# pool Dell
OS10(config-dhcp-Dell)# default-router 20.1.1.1
OS10(config-dhcp-Dell)# network 20.1.1.0/24
OS10(config-dhcp-Dell)# range 20.1.1.2 20.1.1.8
Show running configuration
OS10(conf-dhcp-Dell)# do show running-configuration
...
!
ip dhcp server
!
pool Dell
network 20.1.1.0/24
default-router 20.1.1.1
range 20.1.1.2 20.1.1.8
Address lease time
Use the lease {days [hours] [minutes] | infinite} command to configure an address lease time (default 24
hours).
OS10(config)# ip dhcp server
OS10(conf-dhcp)# pool Dell
OS10(conf-dhcp-Dell)# lease 36
464
System management