Taken from my response in ServerFault
Use Route Tables
Your route table will be where this is indicated. You should be able to ping either IP on a separate ping operation, without issue, if your PC is aware of where those networks are. If the routes aren’t already there, you should be able to add them yourself.
route add -p < network > mask < subnet mask > < gateway >
route add -p 192.168.1.0 mask 255.255.255.0 10.100.98.25 route add -p 192.168.0.0 mask 255.255.255.0 10.100.98.87
Note: The exact command may differ for your operating system, but there is a synonymous command for any networked operating system; as they all use route tables.