Designing a Network
Knowing the number of users isn't enough, though. You need to know more about
the users. At a minimum, consider the following questions to determine if any of the
following will be important factors for the users generally or for subgroups of users:
Aside from the bandwidth required to save and
retrieve files, send and receive e-mail, and perform an average amount of
browsing on the Internet, do any users need significant amounts of bandwidth?
For example, will scientists download a fresh copy of the human genome from
the Internet once a week? Will groups of users need to exchange large quantities
of data among different sites? Will any users be running videoconferencing
software over your network connection? How much web browsing do you
expect the network's users to do? Will people be sending large e-mail attachments
Will any group of users need significantly more storage
capacity than the overall average you already determined? For instance, will
an electronic imaging group catalog millions of documents into image files on
a server? If so, how many people need access to that data? Will the accounting
group need to keep the previous ten years of financial information online?
Will the company use or install an executive information system where all the
managers have query capability into the company's accounting, distribution,
and manufacturing systems, and, if so, how much additional bandwidth or
server performance could that capability require?
Will any groups of users require additional network
services not needed by most users? For example, does part of the company do
work of such sensitivity that it should be separated from the rest of the local
area network (LAN) by a network firewall? Will a subset of users need direct
inward fax capability?
When examining user bandwidth requirements, remember to look at the timeliness
of the bandwidth needs. If certain known activities require a lot of bandwidth and must
be carried out during the normal workday, that high-bandwidth use might interfere
with the performance of the rest of the network. Therefore, make sure to estimate both
average and peak bandwidth needs.
Next, you should look at the services that the network must provide. These can vary
widely in different companies. A very basic network might need only file and print
services, plus perhaps Internet connectivity. A more complex network will need many
additional services. Consider which of the following types of services the network you
are designing will need to provide, as well as any others that are specific to the company:
File and print services
Backup and restore services