How do you route between 2 ip networks

1. I assume you are using tcp/ip as your network protocol.

1a. If you use the same tcp/ip network address locally as the county uses you just have to make sure the node addresses (the last part of the address) don't overlap. You don't need a router in this case. You just need a media converter to plug the fiber into your hub.

1.b If you use (or can change to) a different network address than the County uses you need a router. One way to do this is to purchase a fiberoptic network card compatible with the other end of the link and install it in one of your NT machines.
You need to assign the fiber-optic NIC an address in the County-wide network.

Turn on IP forwarding on the machine with both network cards. This is done in the control panel/network/protocol/tcp window. This will make the machine pass traffic between the two networks. This is an acceptable solution if inter-network traffic isn't too heavy.

(You can also purchase a stand-alone router for this purpose)

Now you need to tell your other machines that their default router is the local address of the machine with both network cards.

Note: It is a good idea to run a firewall on the routing machine so that you can monitor and control network flow.

2. Is your local office NT domain the same name as the County-wide domain? That would be bad. You can't have two PDC's in the same domain. If this is the case you should set up your NT server as a BDC or change the name of your domain. You might want to "trust" the County domain. Unfortunately, the PDC/BDC/Standalone choice is made early in the NT Server installation process and cannot be changed. You'll have to reinstall NT Server. There is a decent writeup on distributed serversand trusting in the NT Server Resource Kit.

Answer 3 gives you the 90% solution. One exception: You can change the name of your domain (on your PDC) without re-installing NT (if indeed you are running two domains with the same name): Disconeect from the county-wide WAN. Promote (if needed) your PDC to PDC. From Network Neighborhood Properties select rename. Type in the name of the new domain. It'll move your PDC into the new domain - i.e., change the name of your domain on the PDC. Then, for each BDC in turn: Promote to PDC and change the domain to the new domain. On member servers / workstations just delete their accounts from the (new) PDC in server manager, and then from the server/workstation, using a domain admin user name/password, join the new domain.

Do you needa router? You'll need either a router or a switch. A router can be either a separate box (a "cisco router", e.g.) or a server (NT or UNIX) performing the router functions in addition to its normal server duties. The later - for small LANS - is the most economical solution. Go back to answer 3. If answer 3 doesn't work as posted, drop me a line. Answer 3 will work in perfect world situation. If you have any unadvertised features in LAN/WAN setup you may need additional steps to trouble shoot.

When you are connecting 2 ip networks located in different places, you need a router(gateway), high-end modem. This is default.
I think you are connecting your NT server to a Hub/Switch using a cross UTP cable.Connect even the router to the same Hub/Switch with a direct UTP cat5 cable.