I'm an IT administrator in school. I use a windows 2003(also have a windows 2008 server ready for testing) file server with 2 NICs. At the moment only one NIC from file server is connected to the Science Labs Network. For simple security purposes the school has **2 separate physical networks**: Science Labs and School Administration. For convenience each network has 1 router with **same IP address 192.168.1.244** and each router get's internet from different ISP. Rarely when internet goes down on one network I simply switch the cable from the router with no internet to the other, as a result for this down time 2 physical networks become one with the internet from one ISP only and when internet is back on the other ISP I revert the changes. **My question is how can I have one file server with 2 NICs connected to these both networks and still keep them separated?** I don't need the server to have internet access I just use it for file sharing. To understand my question better here is a diagram of what I wan't to do:

[![School Network](https://i.stack.imgur.com/lVgVq.png)](https://i.stack.imgur.com/lVgVq.png)

I still want to keep routers on the same IP because it's convenient for me to switch the cable without changing any other settings on computers. And having two physical networks separate is secure without much of the hassle.

The purpose of this is to schedule on the school administration computers an automatic image backup to a network path on the file server.