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Extending LANs
Often the range of a Local Area Network (LAN) needs to be extended. Here we look at why and then how.
by
Matthew Martin
Content
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Often the range of a Local Area Network (LAN) needs to be extended. Here we look at why and then how.
by
Matthew Martin
The electrical pulses travelling through a copper wire or the pulses of light travelling through a fibre optic cable get weaker as they move along. This causes the signal that they represent to become less clear, a situation known as signal degradation.
In the case of electrical signals travelling in a copper wire, electrical interference from the fields of other electrical equipment in the environment cause introduce a random element called noise. In the case of pulse of light travelling in a fibre optic cable, imperfections in the cable also introduce noise. The greater the distance the signal travels the greater the ratio of noise to signal. Eventually the noise makes it impossible for the signal to be carried any further. This process of increasing noise is called signal degradation.
Signal degradation of longer distances can be avoided by using a combination of slower transmission rates and special equipment.
There are a number of devices for extending a LAN. These provide portals, regulating the flow of traffic into and out of the network with the outside world.
Repeaters are devices that are able to regenerate signals, effectively extending the range over which signals may be carried. This can be important where the LAN has to cover a large area. Repeaters work at the physical layer of the OSI model. It is worthwhile noting that networking hubs are a type of repeater, but typically when using the term repeater we refer to something that extends the reach of a LAN, rather than an actual hub.
A bridge connects different areas of the network and is discriminating in terms of what it will allow to pass through it. Only certain types of traffic will be allowed to pass through the bridge, from one area of the network to another. In this way security can be maintained. Bridges typically operate at the data-link layer of the OSI layer, using information provided by network device firmware.
A router connects LAN segments but has far greater capabilities for regulating what network traffic can flow through it. Routers use information about the network layer protocols for the regulation and directing of traffic.