How To Assign IP Addresses with DHCP on Cisco Router.
DHCP assigns IP addresses and other important network configuration information to clients dynamically. Cisco router uses the Cisco IOS feature known as Easy IP as an optional DHCP server. Easy IP leases IP configurations to network clients for 24 hours by default.
We use the topology diagram below as sample network topology.
Configure excluded address(es):
These addresses are reserved for network hosts or clients that need Static Addresses, such as servers, routers and printers. These IP addresses are not included in the address pools that are available for assigning to other clients.
DHCP excluded address on R1#config terminalR1:
R1(config)#ip dhcp excluded-address 192.168.30.1 192.168.30.9
Configure the address pool:
Define the pool of addresses from which DHCP assigns addresses to clients on the network. in this case (R1) the available addresses are all addresses on the 192.168.30.0 network, except for the range excluded on step 1.
Configure address pool on R1: define the address pool, default gateway, and DNS server that are assigned to each client requesting for DHCP IP configuration.
R1(config)#ip dhcp pool R1LAN
R1(dhcp-config)#network 192.168.30.0 255.255.255.0
Do the same on R3 in this case:
Excluded address for R3:
R3(config)#ip dhcp excluded-address 192.168.20.1 192.168.20.9
Address pool for R3:
R3(config)#ip dhcp pool R3LAN
R3(dhcp-config)#network 192.168.20.0 255.255.255.0