Best practice on removing IP Scopes(subnets)

Peter Laws plaws at
Fri Apr 24 15:03:04 UTC 2009

Jeremy Phillips wrote:
>   We are currently in the process of moving our IP space.  I’m trying to 
> remove the old IP subnets from the dhcp server without effecting
> Customers or having our helpdesk have 1000’s of calls from customers 
> that need to get a new IP.  Essentially we will be moving 20+ class C’s.
> I was just wondering how some of you went about this very procedure 
> without effecting service. 

Heh.  We're just in the midst of doing exactly that (Wiis, and iP*** are 
giving us a run for our money on the wireless side).

We've got some overhead in the pool, so we're taking a slice out of the 
existing server, waiting an hour or so, then enabling it on the new server.

Seems to be working so far and we hope to go to bigger slices of the pools 
possibly as soon as today.

Make sure all your firewalls and routers know that there are two valid 
servers for DHCP and, if you're doing wireless, make sure the controllers 
know where to point as well.


Peter Laws / N5UWY
National Weather Center / Network Operations Center
University of Oklahoma Information Technology
plaws at
Feedback? Contact my director, Craig Cochell, craigc at Thank you!

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