Configure Your Router As DHCP Server

Well.. if you have situation like: you have 20 to 100 clients, and you don’t have a DHCP server (becouse of your company doesn’t want waste money for buying a Server? he he..), you may configure your router as the DHCP server for the networks. Okay, here we go:

1. Define a DHCP address pool
MyRouter(config)#ip dhcp pool network-address subnet-mask
you may replace subnet mask number with /prefix or the CIDR number

2. Configure Basic Parameters
a. Router(dhcp-config)#default-router ip-address (usually the the network gateway’s ip address on router’s interface)
b. Router(dhcp-config)#Network first-ip-address last-ip-address

3. Configure Additonal Parameters
a. Router(dhcp-config)#dns-server dns-server-ip-address
b. Router(dhcp-config)#netbios-name-server net-bios-server-ip-address
c. Router(dhcp-config)#domain-name NAME
d. Router(dhcp-config)#lease DAYS HOURS MINUTES or
e. Router(dhcp-config)#lease infinite

4. Configure the IP addresses to be excluded from the pool
This is usually done to avoid the conflicts caused by the DHCP with servers and printers. Remember to give ALL servers and network printers static IP addresses in the same range of the DHCP pool. And then exclude these addresses from the pool to avoid conflicts.

Router(config)#ip dhcp excluded-address ip-address (repeat this as many static ip addresses you have to exclude it from the pool, or
Router(config)#ip dhcp excluded-address start-ip-address end-ip-address

5. Enable the DHCP service in the router
Router(config)#service dhcp
To disable it use
Router(config)#no service dhcp

Usually the DHCP service is enabled by default on your router.

6. Verify your DHCP configuration
Router#show ip dhcp binding
Router#show ip dhcp server statistics
Router#debug ip dhcp server

DHCP server software is supported for these series; 800, 1000, 1400, 1600, 1700 series (Cisco IOS Release 12.0[2]T), 2500, 2600, 3600, 3800, MC3810, 4000, AS5100, AS5200, AS5300, 7000, 7100, 7200, MGX 8800 with an installed Route Processor Module, 12000, uBR900, uBR7200, Catalyst 5000 family switches with an installed Route Switch Module, Catalyst 6000 family switches with an installed MultiLayer Switch Feature Card, and Catalyst 8500.