DHCP

Dynamic host Control Protocol

So in the typical world we use DHCP to get a IP address from a server. This allows us to have a server give out IP address to devices instead of them having staticlly assisgned. This also allows for easier troubelshooting.


For CUCM there is a DHCP server on the server. It just needs to be turned on. The helper address on routers needed to be configured so the Phones can get to the server. The other option is to configure DHCP on a IOS device. Key things to remember is to not give out sever address or router interfaces. The easy way to do this is to do a exclusion rule. Then the DHCP pool and key for VOIP is Option 150. Option 150 has the TFTP server that will be used give the phones there configs and other items from the call manager.

So for the config There is a order of operations according to cisco

1. Exclude the IP's you don't want to have given out.

IP dhcp excluded-address x.x.x.x(we can do a range if need be)

2. Create Pool

IP DHCP POOL VOICE site 1

3. Define network

Network 192.168.1.0/24(we can define the network with slash notation)

4. Default gateway

Default-Router 192.168.1.1

5. Option 150

Option 150 ip X.X.X.X (address of TFTP server)


I can't do screen caps of a call manager here, but once you configured the device on call manager we would need to add helper address

on the voice vlan add

ip helper-address X.X.X.X address of the call manager.