| C.O. | Telephone Company Central Office |
| DSL | Digital subscriber line. In this document either symmetric (SDSL) or asymmetric (ADSL) lines are referred to as DSL. |
| IP Address | The method in which computers are identified on the Internet or private TCP/IP networks. Example: 192.168.10.1 |
| Dynamic IP | An IP address which can change. Whenever the computer logs on the Address internet is assigned an address by a host computer (DHCP server). This also happens periodically when your "lease" on the address expires. |
| Static IP | An IP address which is fixed. If it's an Internet Address, then it is set by Address your ISP. For a private TCP/IP network, it is set by the network administrator. In our discussion, that is YOU. |
Typical single computer installation: This is a simplified view. I have left out the NID, POTS splitter, DSLAM and C.O. connection to the Internet. However from a LAN to Internet viewpoint, this is all we need. The service provider will do the rest. The computer IP address is either dynamically assigned or a static address.
Each computer must either get its IP address dynamically assigned or have an individual static IP address assigned by the ISP. The diagram shows only 2 computers, but we can add as many as we have open hub ports and addresses. This is the simplest way of sharing the DSL line with multiple computers. But also it is the most expensive. Many ISPs charge extra for each computer.
In this scenario, only the Gateway Computer must either get its IP address dynamically assigned or have an individual static IP address assigned by the ISP. The ISP assigned address is associated with the Ethernet port connected to the DSL Modem. The Ethernet port connected to the hub will have a static private IP address given to it. Just pick one of the available classes of private IP addresses. For our example, lets assign it 192.168.1.1. The diagram shows only 2 other computers, but we can add as many as we have open hub ports. Each of them will also have to have an private IP address, let's say 192.168.1.2 and 192.168.1.3. The TCP/IP gateway in each of these computers (#1 and #2) is the private IP address we gave to our Gateway Computer (192.168.1.1). Additionally, we must have NAT , Proxy, or similar Internet sharing software loaded on the Gateway Computer.