Moving DHCP to a new server

[leco]

The story so far is that I am systematically moving, migrating or installing, applications and services from a W2K3 server to a number of W2K8R2 servers.

 

OK so I've got a variety of articles and How to's for DHCP, as that's the next service to migrate. As I understand it I can export the database and import on the new server. Or backup the database and restore on the new server. However, as far as I can see none of the papers mention doing this in a live network. Does the network have to be non-operational for the move to take place? I'm a little confused as to what happens to clients during the move. Also after (or before?) the move, what will I need to look at to ensure that all clients are pointing to the new server?

[SYNACK]

You are fine to do it live if you want to, just use the migration tools and it will do it all for you. Both can run in parallel for a short time untill the migration of settings is complete then just turn off the old dhcp server service. Just make sure you don't tell it to move the server ip addresses over from the old one to the new one unless you are decommisioning the old one right away.

 

There is a video here that goes through it quite well:

Migrating DHCP using the Windows Server 2008 R2 Migration Tools | Media | TechNet Edge

 

To check that it is all going after you have moved the service and switched off the old one just do an ipconfig /release then ipconfig /renew to see if it can grab an ip, you can use the ipconfig /all command to see what server it got it from.

 

The existing clients will be fine and will just keep running with whatever setting they had untill they are restarted or the DHCP lease runs out. At this point they will just find the new DHCP server and use it.

 

The only thing that would likely cause problems is if you have a layer 3 network with muultiple VLANs and DHCP helpers/fowarders setup on your switches. In that case you would need to point the switches to the new ip address.

Edited May 18, 2010 by SYNACK

[leco]

Thanks didn't find that one in my trawling. Also hadn't realised that 2K8 had a migration tool. By server addresses do you mean the IPs of the actual servers?

[SYNACK]

Yes thats correct, it has an option to move over the ip addresses from the old server to the new server but I have never used it. The migration tools include support for most of the services so if you have any others to migrate it can be quite handy.

[leco]

Thanks, that's tomorrow taken care of then. Let's hope I have more luck with this than I have done so far with Exchange migration.

[SYNACK]

Yes I saw your blog posting about that, unfortunatly I have not done a 2010 migration yet so don't have any answers to offer regardign the permissions issue. The only thing that I can think of is making sure that the send connectors/routing groups are setup properly for both the 2003 and 2010 servers as it needs those to talk properly.

Upgrade Exchange 2003 to Exchange 2010

[leco]

That's one of the articles I followed, I've left it for now so my brain clears a little. Sometimes can't see the wood for trees. Thanks again, no doubt my blog will be growing this weekend.

[Firefox]

Can't see you having any issues with this, we successfully did exactly the same task, by exporting the database to a file and importing back in on a new 2008 server. After the forwarders had been set it all worked seemlessly

[leco]

Well I've spent all day on this - to no avail:( I used the Migration Tool mentioned above and successfully put it on the 2003 server. After downloading and reading all the articles from MS I began the task. Trouble is when doing something for the first time - messages that pop up have little or no meaning, so I probably missed some vital instructions. After exporting I imported on the new box only to get lots of "this hasn't been done because it already exists" verbosity. When opening DHCP on the 2010 server there is nothing there.

 

At that point the IT suite filled up - with lots of people unable to logon!! I swiftly reinstated DHCP on the old server and all was well again. Think I need some peace and quiet to absorb what it is that I'm actually trying to achieve and why what I have done has not worked. More grey hair appearing by the minute - is it half term yet?

[leco]

:) Success at last yippee. DHCP is now set up on new server and servicing clients. Oh that's after I sent an ipconfig /release command to a machine - that I was remoted into - . Still I tested another machine that's on Hyper-V and that worked OK. (Note to self must reset the 'stuck' machine first thing)

 

However, I have an IP showing up to be a DHCP server, that's not even in my range. Think it must be a throw-back from a previous range (the LA changed all the schools' ranges when they changed ISP) Is there a way of getting rid of it?

[SYNACK]

I have done that (ipconfig /release) on a remote system before, you hit enter then wonder why you loose the connection for a second or two before it clicks.

 

Where is the other DHCP server displaying? In the authorized DHCP servers list? If so and it is no longer active you will need to use the netsh commands to remove it.

How to Use Netsh.exe to Authorize, Unauthorize and List DHCP Servers in Active Directory

 

If that does not work you may need to use ADSI edit and remove it manually from the AD database in CN=NetServices,CN=Services,CN=Configuration,DC=domain

http://forums.techarena.in/active-directory/393412.htm

Edited May 19, 2010 by SYNACK

[leco]

Have tried the netsh command to remove it but it stubbornly refuses to go. ADSI edit mm my learning never stops, will have a look at that thanks.