Residential gateway is a term that has been used widely to identify any device that acts as a single access point to or from a home or home computer network. It is much like any other network gateway or border device, with the exception that its functionality can vary significantly. The term, therefore, has been used for anything from a simple modem to more robust equipment that provides routing and security features for a home network.
A wireless router can be used as a residential gateway.
A device used as a residential gateway is similar, in essence, to a border gateway device used for a larger organization such as a corporate network that controls how two networks interact with each other. Depending to some extent on its capabilities, it allows for the creation of what is known as an autonomous system (AS), or a network of computers separated from the Internet as a whole by this gateway device. The residential gateway has its own address that it advertises to the world, while the computers and devices that make up the home network have their own internal address structure. While the device can join a home’s local area network (LAN) with the Internet as a whole, it is also sometimes used when joining a home’s LAN with a community wide area network (WAN). The larger WAN then has its own gateway to the larger Internet.
Coaxial cable – typically used when installing cable TV – can also be used for computer networks.
In its simplest form, the residential gateway is a modem, such as those used by an Internet Service Provider (ISP) to connect to the provider’s service network. In this case, it is only able to send network traffic from a personal computer over a specific type of connection, such as a telephone line, coaxial cable, radio frequencies, and so on, converting the data into a signal. This type of device does not allow the creation of a home LAN, however, if multiple computers within the home need to access the modem, it will be necessary to configure a computer to share its Internet connection, or a small switch or hub connected to the modem. The residential gateway type of modem also lacks protection or networking.
Other devices, however, are sometimes sold separately and provide the other useful gateway services for home networks. Those with routing capabilities will be able to handle tasks such as establishing a LAN via an explicit Internet Protocol (IP) addressing scheme and running Dynamic Host Configuration Protocol (DHCP) services to make networking easier. To further aid the network, these residential gateways will provide Network Address Translation (NAT), which allows modification of certain packet addresses in order to route those packets entering the LAN through an address to a specific internal address. For security, some devices also offer packet filtering firewall functionality that further protects the home network from malicious intent.