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.
Go-GBSAsked:
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JFrederick29Connect With a Mentor Commented:
Sorry, you need to go into config mode first:

enable
Password:
conf t
int ethernet0/0
ip helper-address x.x.x.x
end
wr mem   <--save changes
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JFrederick29Commented:
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
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Go-GBSAuthor Commented:
Question, the router located at the remote location points to a router at our main site, will I have to do this on both?
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JFrederick29Commented:
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.
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Go-GBSAuthor Commented:
How do I view the configuration of the router, such as the interfaces to be sure which one is the LAN interface?
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JFrederick29Commented:
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.
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Go-GBSAuthor Commented:
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
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JFrederick29Commented:
Yes, exactly.  x.x.x.x is the IP address of your DHCP server.
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JFrederick29Commented:
Or if it is truly "Ethernet0/0"

int ethernet0/0
ip helper-address x.x.x.x
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Go-GBSAuthor Commented:
When I type int ethernet0/0, I get the response, "% Invalid input detected at '^' marker.
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Go-GBSAuthor Commented:
That did it, won't actually be able to test it today, but thank you very much for the help.
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JFrederick29Commented:
No prob.  Let us know how it works out.
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Go-GBSAuthor Commented:
Sorry for the lack of an update, just waiting on a time to get over to the remote facility.
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JFrederick29Commented:
No sweat.  Thanks for the update.
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