The key to
building the best network is to achieve a balance of these characteristics.
Networks can be described and compared according to network performance and structure,
as follows:
?– Speed: Speed is a measure of how fast data is transmitted over the network. A more
precise term would be data rate.
?– Cost: Cost indicates the general cost of components, installation, and maintenance of
the network.
?– Security: Security indicates how secure the network is, including the data that
is transmitted over the network. The subject of security is important and constantly
evolving. You should consider security whenever you take actions that affect the
network.
12 Chapter 1: Building a Simple Network
?– Availability: Availability is a measure of the probability that the network will be
available for use when required. For networks that are meant to be used 24 hours a day,
7 days a week, 365 days a year, availability is calculated by dividing the time it is
actually available by the total time in a year and then multiplying by 100 to get a
percentage.
For example, if a network is unavailable for 15 minutes a year because of network
outages, its percentage availability can be calculated as follows:
([Number of minutes in a year ??“ downtime] / [Number of minutes in a year]) * 100 =
Percentage availability
([525600 ??“ 15] / [525600]) * 100 = 99.
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