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How to configure a Cisco 2600 Router to forward DHCP requests.

Can someone instruct, or point me to a link on how to have a Cisco 2600 router forward DHCP requests from clients. I'll likely need to also do this on a Cisco 1700 as well. Basically, I want the DHCP server at our main site to server as the DHCP for a remote location connected by a dedicated T1.

JFrederick29

Use the "ip helper-address <dhcp server>" command on the LAN interface of the 2600/1700.

conf t
int fa0/1
ip helper-address x.x.x.x <--the DHCP server at the main site

Go-GBS

ASKER

Question, the router located at the remote location points to a router at our main site, will I have to do this on both?

JFrederick29

Nope, just on the "first hop" on the LAN as the router will unicast the DHCP request at that point so there is no broadcast forwarding necessary on any other router.

techsupportcpm

http://www.tek-tips.com/viewthread.cfm?qid=1195018&page=1

Go-GBS

ASKER

How do I view the configuration of the router, such as the interfaces to be sure which one is the LAN interface?

JFrederick29

On the remote LAN, determine the clients default gateway IP address. Once you have that, do this on the router:

enable
show ip int brief

You will see the interface that has the IP address configured as the LAN clients default gateway.

Go-GBS

ASKER

Ok, I've determined that to be Ethernet0/0, so would that affect the command I use, like this?

conf t
int fa0/0 (as opposed to int fa0/1)
ip helper-address x.x.x.x

JFrederick29

Yes, exactly. x.x.x.x is the IP address of your DHCP server.

JFrederick29

Or if it is truly "Ethernet0/0"

int ethernet0/0
ip helper-address x.x.x.x

Go-GBS

ASKER

When I type int ethernet0/0, I get the response, "% Invalid input detected at '^' marker.

ASKER CERTIFIED SOLUTION

JFrederick29

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