Hyper-V Internet Routing with 2 NIC

Hi,

I have problems adding internet routing to an existing Hyper-V network running on Windows Server 2008 R2. I am using the following setup:

1) Virtual Hyper-V network bound to NIC
2) Second NIC bound to internet router

A couple of VMs run on Hyper-V. They are using fixed IP addresses. The virtual network is configured as external an bound to the first NIC. A DHCP server is bound to the NIC to assign addresses to devices connected to this network.

So far so good. This setup itself works fine but I need a way to route all internet traffic to the secondary NIC. I tried to activate RRAS NAT but in this case external addresses were still not reachable (whereas DNS lookups work fine) and the DHCP server was suddenly sending broadcast to my internal LAN and therefore competing with the existing DHCP server of the internet router.

Some more details about the interface setup:

a) virtual network: IP 192.168.20.2, netmask 255.255.255.0
b) NIC 1: IP 192.168.20.1, netmask 255.255.255.0
c) NIC 2: acquire from DHCP server (could also use static IP)

Any ideas how I can correctly configure the routing?

Regards,
Christoph