Thesis: This paper
looks at designing a Small-Medium Enterprise (SME)
network. Important factors that will be considered
are: performance, security, capacity and scalability.
The use of LAN and WAN will be considered, along
with customer needs, business and political restraints.
Designing of an SME network is largely dependent
on the number of computers and the number of users.
Network design for 50 computers will not be the
same as that for 300 computers. Apart from the
initial number of users, scalability should also
be taken into consideration. Scalability refers
to not only adding more computers to the network,
but inclusion of other devices such as Printers
etc. An organization which starts of with say
50 computers is likely to have plans of expanding
its network. Hence, scalability of the network
is dependent on planning for the right number
of present and future users.
The number of users usually decides the type of
network - LAN or WAN. Local Area Networks (LANs)
are typically used for sharing resources like
files, printers, games or other applications in
small networks like homes, schools and offices.
Wide Area Networks (WANs) can be thought of as
a geographically-dispersed collection of LANs.
A router connects the LANs to the WANs. WAN technology
is different and they use technologies such as
ATM, Frame Relay and X.25 for connectivity. [McCarty,
2000]
Once the initial number of users on the network
is known, and the design developed accordingly,
the next step involves studying the nature of
activity on the network.
This is where customer needs have to be accounted
for. A business with 50 users sharing the network
only for word-processing can make do with a 10
Mbps shared network. But if 50 users are to work
on intensive 3D animation, nothing less than a
10/100 Mbps switched network will do. At this
point it is important to note the basic difference
between using a hub and switch for interconnectivity,
and their effects on the capacity of the network.
While the switch provides dedicated point-to-point
bandwidth to each of the nodes connected to it,
the hub shares the bandwidth amongst all the nodes
it is connected to. Switches, which are obviously
a better option, are available at 10/100 and up
to 1 Gbps throughputs. Hubs and switches can be
used in combination too.
Once an SME network is set up, security becomes
an important issue. Network security is incomplete
without taking into consideration all of these
six elements – security-firewalls, patches
and update management, anti-virus/anti-spam, intrusion
detection, security policy, and the human factor.
[Chopra, 2003]
The choice of Operating System (OS) is also important.
It is not advisable to use Operating Systems like
Windows 98 which are no longer supported by Microsoft.
(This means that no security patches will be available
for this OS). The OS from the Linux and the Macintosh
family can also be used, and many a times it becomes
feasible to combine different operating systems
on the same network because of business and financial
restraints.
Encryption is one of the well known methods of
making a computer network secure. Encryption becomes
crucial when confidential data flows through the
network. Network security can be compromised by
tapping of lines, introduction of forged message,
replay of valid messages etc. [Popek, Kline, 1979]
However, encryption of data invites government
censorship as seen by the Clinton administration’s
Clipper Chip proposal.
The PATRIOT Act and newly formed Department of
Homeland
Security have sought to make Internet surveillance
of both content and transactional records easier,
and has also made it mandatory to introduce transparency
and traceability within networks using certain
encryption methods. Hence, use of encryption is
not without political restraints.
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