Solved: DHCP Relay

Luis Salazar · ‎09-09-2010

Hi everybody, i need some help!

I just want to know how DHCP Relay Works.

This is my case:

I configure a router cisco 1841 with a DHCP Pool

************************************************************************************
!
no ip dhcp use vrf connected
ip dhcp excluded-address 192.168.240.254
ip dhcp excluded-address 192.168.240.26
ip dhcp excluded-address 192.168.240.10
ip dhcp excluded-address 192.168.240.12
ip dhcp excluded-address 192.168.240.1
ip dhcp excluded-address 192.168.240.2
ip dhcp excluded-address 192.168.240.3
!
ip dhcp pool telno
   network 192.168.240.0 255.255.255.0
   default-router 192.168.240.1
   dns-server 192.168.200.4 200.35.65.3
!
!

****************************************************************************************

This perfectly works, i test every computer, and each one adquired a valid IP address.

The problem is that the client said to me:

"The configuration i asked was DHCP Relay, Only was configured DHCP on the router, and the idea is configured DHCP Relay for I can control the ip addressing from our principal DHCP Server located in a remote location"

What this really mean, i don´t understand what he want to configure. Can anybody help me with this please?

What commands i have to agregate?

I really apreciate your time and answers, thank you very much!

Regards,

LS

gatlin007 · ‎09-09-2010

In order to configure DHCP relay on a Cisco router configure an 'ip helper' address on the LAN interface facing the clients.

int fa0/0

ip helper-address X.X.X.X ### This address is the enterprise DHCP server.

This configuration will enable the router to forward DHCP requests to your DHCP server and allow the DHCP server to send the DHCP response back to the originating subnet.

It would be a good idea to remove the previously configured DHCP scope on the router to avoid future confusion.

Chris

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gatlin007 · ‎09-09-2010