The Network Appliance: A Go Between For Computer PartsWhen I say the word appliance the first thing that comes to mind is a refrigerator or maybe a washer and dryer. Well, it may surprise you to know that computer networks have appliances also. A network appliance is a device that acts as a physical connectivity device for computer data. These appliances include parts such as hubs, routers, switches and repeaters. Depending on the type and size of network you have, it may include just a few or all of these items. All of these appliances have their own specific purpose. One common network appliance is the repeater. Just as its name implies, this is a device that takes a signal from one appliance and then repeats the signal to other devices. The purpose for a repeater is to receive a low signal that may be weak, such as that from a wireless Internet router, and amplifies it so it becomes stronger and can travel longer distances. The repeater is an important piece of network hardware. Another network appliance you may have heard of is the network hub. Price wise, these devices are preferable to network switches, but they do have problems associated with them. A network hub does not identify any of the data that it receives. It passes all data to all ports and it is up to the correct computer with the IP address the data is intended for to deliver the data. Because of the way they function, information "collisions" often occur. Network integration suffers as collisions cause erratic transfers of data, rather than a smooth flow. Designers are quickly replacing network hubs with network switches because they allow for smoother transfer of data. A switch is preferable to a hub because switches send information only to a named port while, as mentioned before, a hub will send any information it receives to every port. This causes data "collisions". Use of a switch will cut down on this particular problem almost because the switch assigns the ports to each computer. It then remembers the ports' location and the computer attached to it. A router is another network appliance that works well in computer systems. A router connects two or more computer networks and acts as a liaison between the two. A router transfers the data between the two networks and creates a bridge between the networks, maintaining the integrity of the data as it is passed between them. Network appliances have been around for many years. The first Internet, called ARPANET, which was used by the US Department of Defense in the early 70's, had network appliances. These appliances were slow however, most ran at a whopping 2400 baud and only connected about five universities together. Modern network appliances are much more sophisticated. They allow instant interaction between computers separated by hundreds of miles. |