Networking: A Beginner's Guide
Other line-of-business applications specific to the company's industry
For each of the departmental applications you identify, you need to ask several
questions: How much storage will they consume? From where will the applications
be run (from local computers with data on a server or completely centralized, where
both the data and the application run on a central computer)? Will they have their own
dedicated servers? How much network bandwidth will the application need? How will
all these factors change as the company grows?
Finally, while you might not formally include them in your plan, consider user-specific
applications that might be run. For example, you might estimate that the people in
the company's research and development group are likely to run two or three unknown
applications as part of their job. If you decide that user-specific applications will have a
significant impact on the network, then you should estimate their needs, just as you have
for the other types of applications. If you believe they will have minimal impact, then you
might decide either to include a small allowance for them or none at all.
TIP Don't get bogged down in "analysis paralysis," worrying about whether you can scientifically
prove that your estimates are accurate. Instead, make sure the estimates are reasonable to other
network professionals. At a certain point, you need to justify the network design and cost and, to do
this, having reasonable estimates is necessary. Just avoid overdoing it.
Once you know the applications that the network must support, you can estimate how
many users need to be supported and which applications each user will use. Estimating
total users will likely be easier because the company should already have a business plan
or long-range budget from which you can derive these estimates. Your user estimates
should be reasonably granular; know the number of users in each department in the
company as well as the company's total number of users.
You should estimate how many users will need to be supported immediately, in
one year, in three years, and in five years. Even though five years is a distant horizon
to use for an estimate, this information is important to know during the design process.
Different growth rates suggest different network designs, even at the inception of the
network. A company estimating that it will have 100 users immediately, 115 users in
one year, 130 users in three years, and 150 users in five years needs a different network
design than a company estimating 100 users immediately, 115 users in one year, 300 users
in three years, and 1,000 users in five years. In the latter case, you must invest more in a
design that is more quickly scalable, and you are likely to spend much more at inception
to build the network, even though the network will have the same number of users in the
first two years.