I have several old DHCP servers scattered throughout my environment. Mostly 2003, one or two that are 2008. I've already built out and defined all of my scopes in a pair of active/active 2012 DHCP servers, and carried what few reservations we have over.
At the moment, DHCP relay / helper addresses still point to the old servers and the new server's scopes are deactivated.
My trouble comes in at the actual moment of cutover and migration. Renewing all client addresses in our sites is just not a feasible option. We have very limited staff and in most cases will not even be on-site when we perform these migrations. This task is complicated by the fact that the site migrations are not occurring all at once, but staggered over the course of several weeks (implemented as a part of a WAN carrier change).
I could just shut every port on my switches off and back on and hope everything shoots out DHCP requests, but this is really my last resort.
What I'm trying to do is generate a script that I can use to export the lease information for a particular subnet from the source server, then import that data in to the 2012 pair. I've found many references to using netsh to export the data, however I haven't been able to get it to give me only lease information in a format that I can then import. My goal would be to execute this script in the minutes leading up to the cut over, effectively syncing the old and new server's lease information. So far the only thing I've found that gives me this information is a total DB dump, which I can't import as I don't want to change any of the scope details / options / etc in the new servers - I only need the lease information.
Is it possible there's an argument I'm missing to import or export only the lease information?
Making this situation even more fun is the fact that we are migrating domains at the same time, and I have not been able to get cross-domain authentication working, eg; using something like export-dhcpserver in powershell from the 2012 servers (new domain)
to export data from the old servers (old domain), although that may also be a problem with 2003 not understanding the request.
I'm completely happy with an export script to execute on the old server, manual file copy out to a share, then an import script to execute from the new servers.
Any suggestions?