reley dhcp through cisco 1600 router

Posted on 2006-04-06
Last Modified: 2010-04-17
I Was wandering how i could reley dhcp through my cisco 1600 router.

My main office got dhcp server on a windows2000 server.  Then I got a Branch office that is connected with private line to my cisco 1600 router in my main office with 2mb of bandwith.
I want the branch offiice to get Ip adresses from the dhpc server in the main office.

it looks some thing like this

Win2K server and dhcp server(main office) -> cisco 1600 <- private line <- cisco 1600 <- branch office (currently on a private subnet) .

Ok how can i configure the routers to relay dhcp to the branch office.
Question by:Finnbogi80
    LVL 50

    Accepted Solution

    On the LAN interface of the branch office router, use the command:

    ip helper-address x.x.x.x (ip address of the DHCP server)

    LVL 15

    Expert Comment

    >>branch office (currently on a private subnet)

    by private subnet do you mean this subnet is different from the main office subnet?  If so, you will need to either A) put the branch office on the same subnet as the main office, or B) put a DHCP server on the same subnet as the branch office.

    you could set DHCP on the branch office router if you want to have seperate subnets.  read this document for complete details on how to do it on a Cisco IOS:

    LVL 79

    Expert Comment

    Don is correct in the syntax for the command on the router to forward DHCP requests from local lan to the remote DHCP server.
    I'd like to point out that the DHCP server has to have an appropriate scope set up with the same IP subnet as the LAN interface of the 1600.

    Sorry, nprignano, but you do not have to have a local dhcp server, and the only way to be on the same subnet on both sides of the router is to set up bridging. I certainly would never recommend bridging across a WAN connection unless absolutely necessary for other protocol reasons.
    However, the link that nprignano posted shows you how to setup the 1600 router itself to be a dhcp server for the remote site - but only if you have the proper IOS version on the router.
    "This command first appeared in Cisco IOS Release 12.0(1)T"
    The "T" is important in the release designation.
    LVL 15

    Expert Comment

    thanks for the correction, lrmoore, i will keep that in mind in the future :)


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