NETWORK DESIGN
The first step in designing a network is to decide
whether or not a network is needed. This decision is
made easier by soliciting network requests from the
command. Once the decision is made to design and
install a network, you need to look at the capacity and
reliability of the network and the design options.
Many design options are available for designing
and building a LAN. Four interrelated factors
contribute to this great flexibility. They are physical
layout (topology), access method (protocol), physical
connection (cabling), and networking operating system
(NOS). There is one additional factor to be considered
when designing a network, the need for security. This
need for security is met by the implementation of a
firewall.
NETWORK REQUESTS
Before committing the money to install a network,
you need to research the need for a network for the
command. The best way to conduct this research is by
using a network request. Always make sure you have
all the available information to guide your planning.
The following are some guidelines to use when
beginning to plan for a network:
Calculate your needs as completely as possible.
This will help you decide what components and
services will need to be included in the network.
Determine what resources are available at your
command for planning, implementing, and
running a network.
Determine who needs access to the network and
where these people are located. This
information will help determine whether a
network is a necessary or feasible solution for the
command’s needs. It will also provide
information regarding cabling requirements.
Get to know the current usage and needs in
detail. This information will also help decide
whether a network is the best solution.
Get a detailed drawing of office locations,
existing wiring, and possible server locations.
After gathering and evaluating the information, the
decision can be made as to whether or not a network is
the way to go. If it is decided to go with a network, it is
time to determine what resources are available.
CALCULATING NETWORK
CAPACITY
After you’ve determined the available resources,
use only a portion of these for your working
calculations. This downsizing will protect you against
the losses of these resources.
The amount by which you should decrease your
estimates depends on the possible costs if your network
is a failure and on how stable the resources are. A
general rule to follow is to assume that your available
resources will be anywhere from 10 to 50 percent less
than estimated. Let’s say, that you have 25 PC
workstations available to connect to the network. You
should plan on connecting 22 (12% less than available),
which would leave you with 3 spare workstations.
Another example would be: if your NOS is capable of
having 250 accounts, reducing this quanity by 10% (25)
will help reduce the time that the users will be waiting
for the network to respond to their request.
The opposite of this rule is applied when it comes to
the cost calculations. When you decide how much time
and money it is going to cost, it is a good idea to add an
amount or a percentage to the calculations. Projects like
networks never seem to be completed on time or at cost,
due to unforeseen circumstances.
LAN CONFIGURATIONS (TOPOLOGIES)
The physical arrangement of a LAN’s components
is called its configuration or topology. The three major
types of LAN configurations, or topologies, are the
star, the bus, and the ring. You can also create hybrid
topologies by combining features of these
configurations. For example, several bus networks can
be joined together to form a ring of buses.
Each topology requires LAN components to be
connected in a different arrangement. These
components are also referred to as nodes. Remember, a
node is any point on a network where data can be sent
(transmitted) or received—a workstation, server, and so
on.
The Star Network
In a star network, each component is connected
directly to the central computer or network server, as
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