Need help with the IP-Helper address address

[Dan Loring]

                   We recently went from 2003 DHCP server to 2008.  In 2003 the server relay agent broadcast dhcp requests accros our subnets, but with 2008 only our primary subnet is receiving addresses.

So we have our main location at 192.10.10.0, and we have have 7 remote sites accross our MPLS that each have there own subnet 192.10.20.0, 192.10.30, 192.10.30.0.....and so on.  The majority of our remote sites have dhcp servers, but 2 of the sites get there scope from our main DHCP server.

So lets say 192.10.40.0 and 192.10.50.0 need there dhcp requests sent to them from our primary DHCP server with the IP of 192.10.10.27. 

There are two routers that sit between each site(see attached diagram)

Would I just need to put the command for IP-Helper address 192.10.10.27 on the interface S0 on the 2800 router, or would I need to add that command to the E0 interfaces on the 1841 routers as well, or any subnet that I wanted to broadcast dhcp requests??

Any help wouyld be great.

Thanks,

Dan

[Alessio Andreoli · Accepted solution]

Hi Dan,

you need that command where you terminate the VLAN, and on each vlan you need to address to the DHCP WIN 2K8 server. A workaround is to set loca dhcp pool with the subnet you want (e.g. 192.168.40.0)

Alessio

[cadet alain · Accepted solution]

Hi,

you need the command on the 1841 only then they will unicast the DHCP Discover to your DHCP server which needs a route to the remote subnet through the 2800 and the 1841 need a route to the DHCP server.

Regards.

Alain

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[Dan Loring]

Thanks Guys!