Reference Guide

DHCP automates network-parameter assignment to network devices. Even in small networks, DHCP is useful because it makes it easier to
add new devices to the network. The DHCP access service minimizes the overhead required to add clients to the network by providing a
centralized, server-based setup. This setup means you do not have to manually create and maintain IP address assignments for clients.
When you use DHCP to manage a pool or IP addresses among hosts, you reduce the number of IP addresses you need on the network.
DHCP does this by leasing an IP address to a host for a limited period of time, 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.
You can congure a device either as a DHCP server or as a DHCP relay server — but not both. A DHCP server replies to a client with an IP
address. A DHCP relay server relays DHCP messages to and from a remote DHCP server, even if the client and server are on dierent IP
networks. You can congure the identity (IP address) of the remote DHCP server.
1 Congure the DHCP remote server address on the interface to which DHCP UDP broadcasts are sent in INTERFACE mode.
ip helper-address address
2 Save the conguration.
do commit
Congure DHCP relay server
OS10(config)# interface eth 1/1/22
OS10(conf-if-eth1/1/22)# ip helper-address 20.1.1.1
OS10(conf-if-eth1/1/22)# do commit
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 congure an empty DHCP pool, under a DHCP pool conguration. For a successful commit, you must have
either a network statement or host/hardware-address (manual binding) conguration. 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 range of IP addresses from which the DHCP server may assign addresses in DHCP<POOL> mode. The network option
species the subnet address. The prefix-length option species the number of bits used for the network portion of the address
(18 to 31).
network network/prefix-length
4 Save the conguration.
do commit
DHCP server automatic address allocation
OS10(config)# ip dhcp server
OS10(conf-dhcp)# pool Dell
OS10(conf-dhcp-Dell)# network 20.1.1.0/24
OS10(conf-dhcp-Dell)# do commit
Show running conguration
OS10(conf-dhcp-Dell)# do show running-configuration
...
!
ip dhcp server
!
pool Dell
lease 24
network 20.1.1.0/24
default-router 20.1.1.1
336
System management