[TriLUG] migrate win server DHCP to OSS

[gregbrown at mindspring.com]

As best I can tell Company X (I can't use the real name in public e-mails for some reason) has a fairly interesting DHCP setup which I'd like to migrate Linux or BSD (BSD only if Linux can't get done what I need to).

Okay, here's the scenario:

Company X is big.  Like HUGE, but I am only concered with the US Operations at this point (which is at least 150 /24 networks alone).  They have recently migrated to a routed network where each communication room has between one and three large switches all on different /24 subnets each with roughly 200 IP addresses reserved for DHCP.

Each router with a /24 range has a "helper address" which, I think, forwards DHCP requests from each /24 subnet to one of two DHCP servers, both running older versions of Windows Server.  These servers are quite aged and l'd like to replace them with something OSS (mostly so I can manage these boxes from the command line via SSH and not have to worry about having a broadband connection each time I need to do something to them at night).

My understanding of the way Linux's DHCP server works is you can only have one DHCP server per system (i.e. even with four ethernet cards you can still only have one DHCP server in one range).  Is this wrong?  If so please let me know.

What I'd like to do is have one IP address (the helper address on the routers) assigned to one card on the "new" machine.  I'd like that one interface to handle DHCP assignments for up to 200 /24 networks.  I imaigne this could be done with virtual interfaces where each virtual interface is assigned a network address in each of the /24 networks (so I would have eth0, eth0:1, eth0:2, eth0:3, and so on).

My FreeBSD based m0n0wall runs multiple DHCP servers with no problem so at least I know there must be a way to configure this using FreeBSD but, as previously stated I'd like to use Linux simply because that is the OS where I am most comfortable.  Running 2 DHCP servers on one box is one thing, but 200 and perhaps more?

Has anyone done this type of enterprise sized DHCP server?  How did you make it work?

Greg