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Some context:

Currently all devices in our remote sites are setup on 1 VLAN. We have 400 remote sites.

A project wants to split our sites into multiple VLAN's which on the whole seems like a good idea because they will be able to prevent PC's from talking to POS devices and so on.

In the current proposal, they have 5 VLAN's per site that will require DHCP.

We have 2 centralized DHCP servers for the entire environment which means I will go from having 400 scopes to 2000 scopes. Each scope is part of a Windows Server 2012 R2 DHCP Failover cluster so the numbers actually double in each case.

My questions are:

  1. Is there a limit to the number of DHCP Scopes I can deploy to a Windows Server 2012 R2 server? If there is, I'll need to consider adding more DHCP servers now.
  2. Is there another way to do my DHCP config so I can cut down on the number of scopes?
  3. Am I over thinking this considering we can now manage DHCP via PowerShell? We use PowerShell to manage the scopes already so we do have a level of automation we can apply.

Any advice or guidance will be appreciated. Please let me know if I need to clarify anything.

Thanks,

Chris

  • A project wants to split our sites into multiple VLAN's which on the whole seems like a good idea - Well I'd say they better have some pretty solid justification for it, not just because it seems like a good idea. Don't implement things just because you think you should or because someone tells you that you should. What are the technical/business reasons for taking on a project of this size? This is going to require changes to your entire network infrastructure. – joeqwerty Mar 26 '14 at 15:59
  • It'll be phased over 18 months or more and all that equipment is being refreshed so now is the time. PCI and other local governance requirements are the one driver and some other business requirements are the others. – Chris.ZA Mar 27 '14 at 17:01
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1 - Is there a limit to the number of DHCP Scopes I can deploy to a Windows Server 2012 R2 server? If there is, I'll need to consider adding more DHCP servers now.

According to this: http://social.technet.microsoft.com/Forums/windowsserver/en-US/759becd0-9fbe-44e6-aac8-6f50036294c2/windows-2008-r2-x64-dhcp-server-maximum-scope-?forum=winserverNIS

There is no limit.

2 - Is there another way to do my DHCP config so I can cut down on the number of scopes?

This depends on your requirements. Do all sites have the same 5 VLAN's (Globally, 5 VLAN's), or are they separate each? (5x 400)? Do all sites need their own IP Space? How exactly are they connected? Depends on a lot of stuff.

3 - Am I over thinking this considering we can now manage DHCP via PowerShell? We use PowerShell to manage the scopes already so we do have a level of automation we can apply.

I'd definitely use PS in favor of Point on Click on this task :) And it should not be that complicated to do this using a script.

  • Thank you - you answered my main question. To answer your question - it's 5 X 400 and each needs it's own IP space. 3 VLAN's in each site need DHCP. I'm feeling a lot more comfortable now. – Chris.ZA Mar 27 '14 at 17:02
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As answered earlier there no limit on number of scopes that may be added.

Microsoft DHCP server has been tested up to a maximum of 50,000 scope.

But again it depends on hardware capacity of your server. Please check following link more information regarding scalability options.

https://blogs.technet.microsoft.com/teamdhcp/2012/12/15/scalability-test-results-for-windows-server-2012-dhcp-server/

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