Question : Basic Gateway Address

I have a basic question about the Gateway Address programmed into a small router such as a LinkSys.  I understand that Gateway Address is the one used by LAN clients for routing of IP addresses not on the local LAN but the question is what is its implementation?

I have a client with a LAN (10.1.10.x addresses) that we are planning to attach through a router to another areas LAN (192.168.1.x addresses) for access to the Internet through their connection.

What Gateway Address do I program into the router?  Is the Gateway Address one that exists on the network somewhere, or is it one allocated to the router so it will respond to traffic addressed to that address.  There are no other systems acting as a gateway on the LAN currently.  Simply put, is the programming of a Gateway Address into the router (such as 10.1.10.1) a non-existent pseudo-address the router uses to recognize traffic that it needs to route to the WAN, or is it an existing address somewhere?  If it's an address that must exist how do I identify it?  Is it something I can get using IPConfig or tracert on systems that currently have Internet access?

Thanks in advance.

Answer : Basic Gateway Address

Pick a number within the internal lan (i.e 10.1.10.1 or 10.1.10.254) that is not currently being used.  Make sure to pick a number that is not part of the 10.1.10.x DHCP pool (if DHCP is being used).  The gateway address is used for internal traffic (10.1.10.x) to route to outside netwrok whenever an external address (anything other than 10.1.10.x) is being requested.  Your router, on the setup, must also indicate how your router is being identifid to the 192.168.1.x network.  So, if the 192.168.1.x network is using DHCP, then just set your router to be a DHCP client and automatically get an ip address on the 192.168.1.x network.  If you can dedicated an IP address (STATIC) to your router (i.e. 192.168.1.253), then it will make it easier for you access the admin function of your router, regardless whenever you are working in the 192.168.1.x network or the 10.1.10.x network.