What is Wifi? - How Wifi Routers Work at Home and in Business
written by: allychevalier•edited by: M.S. Smith•updated: 5/4/2010
To many computer users, wifi routers are a strange and esoteric piece of technology that somehow creates a wireless network in a little box. This article attempts to remove some of the opacity and provides a basic explanation as to how wi-fi routers work.
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What Does a Wifi Router Do?
First, it's important to know what exactly the purpose of a wi-fi router is. Wi-fi routers relay packets (the data) back and forth between a wired network to a series of wi-fi-enabled devices in a wi-fi network. This is a specific kind of wireless router, one that only uses the wi-fi standard.
A wi-fi router uses highly specialized software, usually unalterable, in the form of firmware. While some high-end research routers use Linux or Unix, most wi-fi router manufacturers develop their own independent code, albeit with a certain debt to Unix.
The wired network side tends to be connected to the ISP, or Internet Service Provider. For many individuals this involves either DSL or cable connections. The wired network may either connect to the Internet at large, a private network (for instance, within a company while at work), or some combination of the two. Most wi-fi routers often have additional LAN Ethernet ports so that they can service other devices that may need a direct wired connection to the network, a function known as an Ethernet switch.
To transmit and receive wifi signals from other devices in the wifi network, a wi-fi router also has an antenna. This is often adjustable so that you can perfect your wifi reception.
What goes on in the device, however, is a bit more complicated than it might seem:
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Forwarding and Routing
This involves two processes, routing and forwarding. Routing is the process of selecting the path in the network that the data will follow. This path that the data follows is what is known as forwarding, or more specifically in this case, packet forwarding.
On a micro level, you can think of the processes being run along one of two planes, a control plane and a forwarding plane.
In the control plane, the router decides which outgoing interface will work best for sending any given packet to its destination, or rather, the most efficient way to route it. This involves drawing a sort of network map, or a routing table, with all the different destination addresses listed on it. The actions along the control plane are directly controlled by a series of routing protocols.
It is in the forwarding plane where packets are then transferred. So, this is also known as the "data plane" or “transport plane", because this is where all the data is transported through. Once the destination address of the incoming packet has been deciphered, the data then passes through what is known as the forwarding fabric of the router. One of the most important functions of the forwarding plane is what to do when there is traffic congestion, that is, where there are more packets than the router can handle.
For more information about wi-fi and wireless technology in general, check out the What is wi-fi? series. For advice on purchasing the right wireless router, check out this article. For an introduction to router configuration, check out this article.