Question : A single PC with one physical NIC, one virtual NIC (two IP addresses)

I need to configure a PC to communicate mainly on network 10.11.0.0, however one piece of software on this PC (GE Fanuc Proficy iFix MBE [MODBUS over ethernet] driver) needs to communicate with a MODBUS gateway with address 10.12.17.17 on network 10.12.0.0.

All equipment shares the same physical network. The IP address of the MODBUS gateway (10.12.17.17) must stay the same.

I want to do this with a single physical NIC, and I can't simply add a second IP address to the NIC via the usual way (TCP/IP .. Properties .. Advanced) because the software seems to get confused when it's pointed to a NIC with two IP addresses.

This leaves me to think of other possibilities, such as:
* Can I install some kind of virtual NIC driver/application which operates through the physical NIC?
* Can I add some kind of static route to get around this?
* Perhaps software NAT could be configured on this PC?

Is there a neat way to do this, or should I just install a second physical NIC & patch it to the same switch?

Thanks.

Answer : A single PC with one physical NIC, one virtual NIC (two IP addresses)

I suspect that whatever problem the software has with a second IP address on the current NIC will probably rear its ugly head again with whatever you try (virtual or physical NIC).  Any chance we can get more details on that to try to fix the underlying problem?

Hmm ... something has just occurred to me while looking back over your numbers.  I assume you're using a subnet mask of 255.255.0.0.  Are there any other subnets connected to this network, either physically or via VPN (or anything else)?  If so, what are their ranges?

I'm thinking we could solve this with a bit of supernetting - change the subnet mask to 255.248.0.0 (just on the machine in question, for now, and possibly the MODBUS gateway), and the subnet would then include the range 10.8.0.1 - 10.15.255.254 so that the MODBUS would then be on the same subnet with the PC.

Of course, there might be unintended consequences related to this ... we'd need to make sure this won't cause conflicts with the rest of the network first.  It's food for thought, though.

:)