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Bandwidth has been defined as the amount
of information that can flow through a network in a given time. The
idea that information flows suggests two analogies that may make it
easier to visualize bandwidth in a network. Since both water and
traffic are said to flow, consider the following analogies:
- Bandwidth is like the width of a
pipe.
A network of pipes brings fresh water
to homes and businesses and carries waste water away. This water
network is made up of pipes of different diameters. The main water
pipes of a city may be two meters in diameter, while the pipe to a
kitchen faucet may have a diameter of only two centimeters. The width
of the pipe determines the water-carrying capacity of the pipe.
Therefore, the water is like the data, and the pipe width is like the
bandwidth. Many networking experts say that they need to put in bigger
pipes when they wish to add more information-carrying capacity.
- Bandwidth is like the number of
lanes on a highway.
A network of roads serves every city or
town. Large highways with many traffic lanes are joined by smaller
roads with fewer traffic lanes. These roads lead to even smaller,
narrower roads, which eventually go to the driveways of homes and
businesses. When very few automobiles use the highway system, each
vehicle is able to move freely. When more traffic is added, each
vehicle moves more slowly. This is especially true on roads with fewer
lanes for the cars to occupy. Eventually, as even more traffic enters
the highway system, even multi-lane highways become congested and
slow. A data network is much like the highway system. The data packets
are comparable to automobiles, and the bandwidth is comparable to the
number of lanes on the highway. When a data network is viewed as a
system of highways, it is easy to see how low bandwidth connections
can cause traffic to become congested all over the network.
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