Cisco Router as DHCP Server
Using a Cisco router as a DHCP server is a somewhat common practice in smaller networks.In this example we have two VLANs one for Voice and one for DATA.
DATA VLAN IP Nework Range 172.16.1.0 Gateway IP 172.16.1.1 DNS Server 10.31.144.1
Voice VLAN IP Nework Range 172.16.2.0 Gateway IP 172.16.2.1 DNS Server 10.31.144.1
TFTP Server for Cisco Phones 172.16.2.1
GK_RTR#configure terminal
GK_RTR(config)#ip dhcp excluded-address 172.16.1.1 172.16.1.9
GK_RTR(config)#ip dhcp excluded-address 172.16.2.1 172.16.2.9
GK_RTR(config)#ip dhcp pool DATA_SCOPE
GK_RTR(dhcp-config)#network 172.16.1.0 255.255.255.0
GK_RTR(dhcp-config)#default-router 172.16.1.1
GK_RTR(dhcp-config)#dns-server 10.31.144.1
GK_RTR(dhcp-config)#exit
GK_RTR(config)#ip dhcp pool VOICE_SCOPE
GK_RTR(dhcp-config)#network 172.16.2.0 255.255.255.0
GK_RTR(dhcp-config)#default-router 172.16.2.1
GK_RTR(dhcp-config)#option 150 ip 172.16.2.1
GK_RTR(dhcp-config)#dns-server 10.31.144.1
If you are using Windows server or some other centralized device for DHCP services. Even Cisco Unified Communications Manager includes DHCP server capabilities. you need to configure ip helper-address <central DHCP server IP address> to your VLAN interface to forward DHCP requests to the central DHCP server for the voice and Data VLANs.
