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Chapter 15:
Designing a Network
Your first order of business is to determine just how the common applications will
be used. Determine whether all users need to have the entire suite installed, how often
different users plan to use the different applications, how many files they will create and
store, how large those files might be, and how those files will be shared among users.
For example, in a 1,000-user population, you might determine that 90 percent will
use word processing to generate an average of ten documents a month, with each
document averaging 100KB, and the users probably will want to keep two years'
worth of documents on hand at any given time. Yes, these will be educated guesses,
but it's important to come up with reasonable estimates. Experience with similar user
populations and companies can pay off handsomely in determining these estimates.
With this information alone, you know immediately that you need about 24MB of
storage per user, or 21.6GB for the word processing population of 900 users, just for
word processing documents. For applications where users frequently will share files,
you might need to factor in that most users keep personal copies of some files that they
also share with others.
TIP You can help reduce overall network storage requirements by establishing shared directories in
which different groups of people can store and access shared files.
Then you come up with the same estimates for the other applications, taking into
account their expected size, frequency of creation, and long-term storage requirements.
After determining the common applications, move on to department-specific
applications. This step gets trickier for new networks in new companies, because you
might not know which applications will be used. For existing companies, you have the
advantage of already knowing which departmental applications you must support.
Different departmental applications can have wildly different impacts on the network.
For example, an accounting system designed around shared database files needs a
different network design than one using a client/server database design. The former
relies more on file server performance and is more likely to be bandwidth-sensitive than
an efficient client/server application that runs on a dedicated server. If a departmental
application is not yet selected, talk with the managers of that department to get their best
estimates and then proceed.
Following are common departmental applications you should consider:
Accounting
Distribution and inventory control
Manufacturing/material requirements planning (MRP)
Information
technology
Electronic
commerce
Human
resources
Payroll and stock administration