Residential gateway

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This article is about the types of network routers and modems found in many homes, known colloquially as "residential gateways".

There are multiple devices that have been described as "residential gateways," each with a quite different function. Each type of device allows the connection of a LAN (used in the home) to a WAN (wide area network). The WAN can be the "Internet" or can merely be a larger LAN of which the home is a part (such as a municipal WAN that provides connectivity to the residences within the municipality).

The term "residential gateway" was originally used to distinguish the inexpensive networking devices designated for use in the home from similar devices used in corporate LAN environments (which generally offered a greater array of capabilities). In recent years, however, the less expensive "residential gateways" have gained many of the capabilities of corporate gateways and the distinctions are fewer. Many home LANs now are able to provide most of the functions of small corporate LANs.

Therefore the term "residential gateway" is becoming obsolete and merely implies a less expensive, lower capability networking device.

Multiple devices have been described as "residential gateways":

• DSL modems
• Cable Modems
• Routers or wireless routers
• Combined router/modems
• Wireless access points

[edit] Types

• A router provides:

• IP address routing
• network address translation (NAT)
• DHCP functions
• firewall functions
• LAN connectivity like a network switch

Most routers are self-contained components, using internally-stored firmware. They are generally OS-independent (i.e. can be used with any operating system).

However, PCs can also provide the same functions as a router. A PC using the Linux OS, for example, is able to provide all the functions of a router (an external router is optional). (Some self-contained routers use a small version of Linux within their firmware, in fact.)

• Wireless routers perform the same functions as a router, but also allows connectivity for wireless devices with the LAN, or between the wireless router and another wireless router. (The wireless router-wireless router connection can be within the LAN or can be between the LAN and a WAN.)

• A modem (or ADSL modem) provides none of the functions of a router. It merely allows digital Ethernet data traffic to be modulated into analogue information suitable for transmission across telephone lines, cable wires, optical fibers, or wireless radio frequencies. On the receiving end is another modem that re-converts the transmission format back into digital data packets.

This allows network bridging using telephone, cable, optical, and radio connection methods. The modem also provides handshake protocols, so that the devices on each end of the connection are able to recognize each other. However, a modem generally provides few other network functions.

• A USB modem plugs into a single PC and allow connection of that single PC to a WAN. If that PC uses a Linux OS, then that PC can also function as the router for a home LAN.
• An internal modem can be installed on a single PC (e.g. on a PCI card), also allowing that single PC to connect to a WAN. Again, if that PC uses a Linux OS, then that PC can also function as the router for a home LAN.

• A wireless access point can function in a similar fashion to a modem. It can allow a direct connection from a home LAN to a WAN, if a wireless router or access point is present on the WAN as well.

[edit] Manufacturers

There are a number of manufacturers of networking devices that have been used as residential gateways:

[edit] See also

• Home network
• Home server
• Technological convergence

[edit] External links

• Home Gateway Initiative, which proposes specifications for residential gateways
• The Residential Home Gateway on About.com