Multi-subnet DHCP

[Jeffrey Hutzelman]

--On Friday, August 22, 2008 04:11:00 PM -0600 Jeff Anderson 
<jefferya at programmerq.net> wrote:

> Hello,
>
> I have an existing network with several subnets/vlans/whatever.
>
> Up until recently, we kept track of all the hosts by mac address and
> assigned leases that way. It worked beautifully.
>
> We now want to add a couple subnets that will need dynamic addresses
> (think guests that get on a wifi during a presentation).
>
> We added the first dynamic range and it appeared to work fine. The
> bahaviour that we're seeing is any piece of hardware that is connected
> anywhere on any subnet is getting an address from this dynamic pool
> because it doesn't match any of the mac addresses defined in our config
> file. This is mostly an annoyance, but it really would be nice to assign
> an address from a dynamic range that gets forwarded through the
> corresponding router. It appears that the dhcp server is aware of (and
> logs) how each request is forwarded to it. Is there a way to force the
> behaviour of our server to only give out useful dynamic addresses based
> on the router it is received through?
>
> If an example or clarification is needed, let me know.

You haven't provided a copy of your dhcpd.conf, but it sounds like you have 
a shared-network containing a number of subnets that aren't really on the 
same wire.  If you do that, the DHCP server believes they are the same 
network, and will assign dynamic addresses from pools on that network to 
any client booting there.

-- Jeffrey T. Hutzelman (N3NHS) <jhutz+ at cmu.edu>
   Carnegie Mellon University - Pittsburgh, PA