Multiple Subnet Routing

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• Tuesday, July 17, 2012 6:58 AM

   

   
  

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    DHCP knows nothing about domains! It can handle different scopes for different networks using DHCP relay. If the non-domain machines are in a different network, they will receive addresses froma different scope. Which scope is used depends on what network the machine broadcasts the request in. If the DHCP server receives the broadcast directly it makes on offer of an IP in the subnet it is in itself. If the request is received by a DHCP relay agent in another network, the DHCP will offer an IP (via the relay agent) from the scope covering the IP address range of the network where the broadcast was recieved (ie in the same IP subnet as the relay agent.

  RRAS works fine as a router in a vm. As far as network design is concerned, work out your network diagram ignoring the fact that you have virtual networks and virtual machines. It doesn't matter. Note that using a segmented network adds a bit more complexity to your Internet routing. Your Internet gateway only kows about the subnet it is directly connected to.

   

   

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  Bill

  • Marked As Answer by David Donovan Wednesday, July 18, 2012 1:29 PM
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• Tuesday, July 17, 2012 6:31 PM

   

   
  

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  David Donovan wrote:

  Hi,
  
  I have a Hyper-V server running on Windows Server 2008 R2 SP1.  One
  of my VMs is a DC with DHCP and DNS roles.  Currently I have one
  subnet setup 10.1.1.0/24 that is handling all DHCP assignment as of
  right now.
  
  I have a mix of servers joined to the domain and clients that are
  connected to the network but are not a part of the domain.  I wanted
  to have machines that are part of the domain to have their DHCP
  assigned IP addresses in the 10.1.1.0/24 subnet while all non domain
  machines get their DHCP assigned IP address to go on a second subnet
  (10.1.2.0/24).  We are a little scarce on proper network equipment as
  of right now.  I do not think the small router they have can act as a
  relay agent.
  
  Did a little research and was wondering if in the interim, I could
  set up another VM in Hyper-V to act as a relay agent or if I need to
  install RRAS on a new VM.  Although I have no clue how you would
  specify only domain machines using a DHCP scope for subnetA and non
  domain machines using the DHCP scope for subnetB.  Is this even
  possible?  Any documentation/guides would also be helpful if so.
  
  Looked briefly at a few things:
  
  http://technet.microsoft.com/en-us/library/cc771390
  
  http://technet.microsoft.com/en-us/library/dd469685.aspx
  
  Thanks. <http://technet.microsoft.com/en-us/library/dd469685.aspx>
  <http://technet.microsoft.com/en-us/library/cc771390>

  As Bill already has outlined you cannot do this easily. BUT if you are
  willing to spend enough time on it you can do this easily, if you only
  set static DHCP assignments. E.g. if you define static entries for all
  your domain machines in your desired subnetA you could let the DHCP
  server only hand out addresses in the subnetB for all dynamic
  assignments. You then could use a 10.1.x.x/16 (or 22) subnet for all
  your PCs and servers, thus avoiding the need for additional routing
  devices but being able to discern between domain and no-domain PCs
  based on IP-addresses.

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  Wolfgang
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• Wednesday, July 18, 2012 1:29 PM

   

   
  

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  After some consideration, I have decided to hold off the multiple subnets until we get a few more switches.  Thanks.

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  My Blog: http://www.montavesta.net

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