A network gateway is an internetworking system that joins two networks together and it can be configured in software, hardware or both. Network gateway can operate at any level of OSI layers model.
The gateway has two sides: The WAN side connects to your cable DSL modem and LAN side connects to your private network via a hub or switch. The main function of it is to route the traffic from computer to the Internet and back to the computer. A computer with the two NIC cards can act as a gateway. It routes the network traffic between two logically and physically different networks.
In its configurations, you first configure the public side of the gateway and the IP address, which is assigned to you by your ISP. The public side configurations generally includes, assigning the IP address, DNS server, subnet mask, ISP gateway IP address and host name. Additionally, if your ISP uses PPPoE, you simply have to enable PPPoE in your gateway.
On the other hand to configure the private side , you have to enable DHCP. By enabling this feature each computer in your network, will automatically pick the settings from the DHCP server that are required for a computer to be a part of the network and communicate.
The last step in the configurations, is to configure each PC in such a way that it automatically gets the all the settings from the DHCP server. Make sure that TCP/IP protocol is properly installed in each computer of your network. After configuring each PC in your network perform a reboot.
After rebooting the each PC in your network, you will see a blinking underneath network icon on the right side of the task bar. If everything is done then you can access the internet, share the printer and data in your network.
The firewall can also be configured with it to put a check on the unauthorized network traffic from the internet to your computer or network.