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Asked: 2015-09-06 08:13:46 +0800 CST

Create Separate Broadcast Domains on One Hyper-V Host

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I have two VMs running on a Windows Server 2012 R2 Standard Hyper-V Host. They're both DCs holding the PDC role for the same domain name, and therefore must not be able to communicate with each other via layer 2 (I'm manipulating DNS to make layer 3 connectivity OK I think).

They Hyper-V host has two network adapters; one dedicated to management traffic, the other to VM networking.

How can I configure Hyper-V's networking to put the two VMs into separate broadcast domains and both still have access to my external network, but permit routing between them? I don't care if the routing is handled by Hyper-V (if that's possible) or by an external router.

networking

1 Answers

  1. You can create different virtual switches (isolating the VMs at layer 2) or use the same virtual switch but different IP subnets (isolating the VMs at layer 3); you can also use both options: two virtual switches, and a different IP subnet on each switch; this is the cleanest solution.

    If you want routing between the VMs, you'll need to use different IP subnets; you'll also need something to act as a router between the two networks; you can use a third VM with two NICs, and enable the Routing and Remote Access Service to perform routing between them.

    Sample configuration:

           Virtual Switch 1
       |              |
VM1 10.0.1.10       Router NIC1 10.0.1.1
                              |
                          Router VM
                              |
VM2 10.0.2.10       Router NIC2 10.0.2.1
       |              |
       Virtual Switch 2

    If you also need external connectivity, this could be managed by creating a third virtual switch configured as "external" (i.e. connected to a physical NIC):

           Virtual Switch 1 (Internal)
       |              |
VM1 10.0.1.10       Router NIC1 10.0.1.1
                              |
                          Router VM --- Router NIC 3 --- Virtual Switch 3 (External)
                              |
VM2 10.0.2.10       Router NIC2 10.0.2.1
       |              |
       Virtual Switch 2 (Internal)

    On the third NIC, you would use an IP address appropriate for your LAN; in the router VM, you can enable NAT and this will allow both internal networks to share the external access.

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