A Glossary of Networking Terms - Part 3

English: wireless access point (Photo credit: Wikipedia)

In the final instalment of this trilogy of articles highlighting some of the more common computer networking terms, the three terms concerned are all common and integral to small home networks as well as enterprise levels. As such they are terms with which it is useful for many people outside of the IT industry to be familiar.

Firewall
The concept of a firewall in computing takes its name from the idea of the physical construct used to prevent fire spreading between buildings and rooms or compartments. In computing therefore, firewalls perform an analogous function preventing packets of data that may harm a computer or network from passing through - an obvious example of such packets would be viruses. In practise firewalls are therefore software applications or hardware based systems which sit on the connection points between LANs or individual devices and public WANs like the internet. They will monitor all traffic attempting to enter or leave the LAN/device and grant or deny access to it based upon rules that the user is able to predefine and control.

Gateway/Router
What is now referred to as a router was originally, and in some contexts still is, termed a gateway. It can be thought of as the hub at the heart of a network through which all communications (data packet transfers) pass. The routing element describes the process of receiving data packets from one device, determining its destination address, comparing that to a list of known devices, whether it be games consoles or dedicated hosting servers fro websites, and then forwarding the packets to that destination. Whereas the term ‘router’ has become more commonplace, the term ‘gateway’ is used more specifically to describe devices which allow communication between networks/computers/programs that use differing protocols.

Routers can take the form of physical devices or software applications and in practice many, like those used in home networks, can also provide the functions of a number of network elements such as network switches, modems (to connect to the rest of the internet), firewalls and wireless access points. They therefore also act in the more generic sense as ‘gateways’ to the local networks that sit behind them for any traffic being transferred to or from wider networks such as WANs and the internet.

Wifi/Wireless
Wifi is short for wireless fidelity and is used in general to describe technologies that deliver digital communications between devices using radio waves. Networks that utilise WiFi can interchangeably be referred to as wireless networks or wireless local area networks (WLANs). As with the wired Ethernet, the technologies are standardised by the Institute of Electrical and Electronics Engineers Standards Association (IEEE), however the actual term “Wi-Fi” is a trademark of the Wireless Alliance, who are the trade association that certify that products adhere to those standards.

WLANs are created using a Wireless Access Point (WAP) which takes wireless data and forwards it, through a wired connection, to or from a router - often WAPs are integrated into routers themselves. The areas in range of WAPs are called a wireless hotspot and are now commonplace in peoples homes as well as throughout business premises and public spaces. Often in the latter two areas, WAPs can be positioned so that hotspots overlap to provide extensive networks. The Wi-Fi standards ensure that any enabled device will be able to connect to a WAP, and, although transfer speeds across wireless networks will generally be slower than wired counterparts (and can be disrupted further by interference where competing signals use the same frequency channels) newer standards are still capable of delivering data thirsty services, such as streaming for video conferencing, without the restrictions of fixed wiring.

One of the major concerns with WLANs is security because any device within range of a WAP can see the network and pick up the signal. Consequently, there are a number of measures that are used to restrict access to private WLANs and to keep transmissions on those networks secure. Initially WEP (Wireless Equivalent Privacy) and latterly WPA (Wi-Fi Protected Access) and WPA2 have been implemented to this end to ensure that transmissions are encrypted and passwords are required in order to connect to the network. In addition, networks can be configured to only allow connections from predefined devices by using their unique MAC (Media Access Control) addresses.