Reorganizing Windows Server 2003 DHCP server

Question

Currently we are running a pair of DHCP servers at a medium-sized high school with about a 60/40 split. The problem is that over the years the address reservations have become more and more disorganized. We want to reorganize the address leases so that things are grouped better by type.

The issue arises when we want to move a group of devices from one range of IPs to another, which is already taken by a second group that we want to move to another area, and so on. I was thinking of simply doing the moves slowly, moving a group to an unused area, then shifting things into the hole it left behind, then moving the first group back to where we want it to end up, however this approach is long and tedious, and could lead to several errors and conflicts, if not properly planned.

Is there any better way to do this, avoiding any potential problems that would likely arise?

Answer 1

Since you are working at a high school, why not use the summer break, and a weekend, to take everything down and rebuild it the way you want it?

You wouldn't actually be unplugging anything. You would be just moving leases.

With most (if not all) your users gone for three months now would be a perfect time. That is assuming you live in an area that observes summer vacation.

My answer still stands even if you have a full user base: move them on the weekend.

Answer 2

If you're using DHCP and you want to clean it all up you have many choices. If you're using private IP addresses you can just move them to different private addrsses in a new DHCP orderly fashion. If you're using public addresses the problem is slightly trickier, but not impossible. The trick is all in lease management. Even if you aren't planning on making the changes soon you can shorten up your leases now, so that they will all churn much faster when the time comes. This is especially important to do early if you have very long lease times.

When your change time comes, Set your leases to a VERY short lease time, like an hour. When the leases expire make sure that the new range you want for the area is in effect there. This will let you roll your DCHP changes over a weekend. The problem is all the machines have to be on for this to work, and your existing leases have to be pretty short. It won't actually require rebooting everything.

As soon as all your machines have refreshed onto new leases in the correct subnets then you can extend your leases back out to something more reasonable for your environment.

This will avoid disruption of users work, as they never notice their own DHCP addresses.

For our campus wide re-iping plan I am have suggested that we move all our IP addresses into a private range for a short while then move them back to where we want them as soon as everyone is over, avoiding the rolling update method you are trying to avoid.

Also reboots DO NOT always cause leases to be checked, or refreshed.