Discuss the factors determining network specification for a small business.

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Introduction

The purpose of this assignment is to discuss the factors determining network specification for a small business. A small manufacturing and design company has recently moved to new premises and require a network to be implemented, successfully connecting two buildings together. My job is to recommend an appropriate networking specification, detailing the required networking media and technologies required.

Task 1. Networking Media

Table 1 (attached) describes the different types of networking media, drawing

comparisons, Depending on the factors:

* Maximum segment length (distance before attenuation)

* Cost

* Type of connector

* Advantages - such as cost, rate of data transfer

* Disadvantages - such as interference, usability

Analysing the different types of networking media will enable me to choose the appropriate cable configuration, as explained further on in task 2.

General Categories of Transmission Media: Coaxial, Twisted Pair, Fibre Optic

Refer to Table 1 for summary of information and comparison.

Coaxial Cable

Coaxial cable is inexpensive and offers similar features to UTP and STP, in that it can transmit data at up to 100Mbps. It is advantageous compared to UTP and STP in terms of the distance it can travel before attenuating - 500 metres. This is five times the distance of UTP and STP. Coaxial cable is not as cheap as UTP, but still remains fairly inexpensive. It is also fairly flexible which means it can easily fit round corners, making many twists and turns. So, why not use coaxial cable? Although coaxial has various benefits over UTP and STP, it also has major problems. Coaxial cable uses a larger form of connector than either UTP or STP, called a BNC connector. This results in coaxial media taking up more space for installation. Workstations are not ready-prepared for BNC connectors, meaning hardware would have to be upgraded.

The major problem with coaxial cable is that it has to be grounded prior to installation. Grounding is done by ensuring that there is a solid electrical connection at both ends of the cable. Because technicians often fail to do this, this results in poor shield connection and consequently, electrical noise that interferes with signal transmission. For this reason, coaxial is not appropriate for the proposed network.

Twisted Pair

UTP

Unshielded Twisted Pair is a type of cabling that is used for telephone communications and most Ethernet networks. The cable consists of a pair of wires which forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, which is the noise generated by adjacent pairs. Twisting the wires enhances the cancellation effect. This occurs when two wires are close together in a circuit a circular magnetic field is created. Because the two wires have opposite magnetic fields, they cancel each other out. The twisting of the wires is a 'self-shielding' method, which makes the wires less susceptible to noise.

Unlike STP, UTP does not have extra shielding, and therefore relies solely on the cancellation effect to reduce noise and limit signal degradation cause by electromagnetic and radio frequency interference.

UTP offers many advantages when used for an Ethernet network. Its small size makes cabling easier than other forms of cabling. UTP cable is easy to install and is less expensive than other types of networking media.

The only disadvantage associated with UTP when compared with STP is the fact that UTP does not have extra shielding. As described previously, this makes it more susceptible to noise and interference.

UTP is rated under different categories based on the number of twists and rate of data speed - Table 2.

STP

Shielded twisted pair is very similar to UTP, but combines the techniques of shielding, cancellation and wire twisting to improve its resistance to noise and interference. Each pair of wires is wrapped in a metallic foil and then the four pairs of wires are wrapped in a complete metallic braid or foil.

Although STP is more resistance to noise and interference, it does have its disadvantages. Due to the fact that the wire comprises additional shielding methods, it is more expensive than UTP. It is also more difficult to install as it is not as flexible, and has to be grounded at each end. This results in the installation of the media taking more time, thus increasing labour costs. If the media is improperly grounded, this results in more problems; the shield acts like an antenna and attracts unwanted signals.

Fibre Optic

Fibre Optic cable transmits data using modulated light transmissions. Compared to other forms of networking media, fibre optic is the most expensive. The reason it is more expensive is due to the fact that it is not susceptible to interference like coaxial, STP and UTP and is capable of higher data rates than any of the other networking media discussed. Fibre Optic is also resistant to environmental issues which make it a good choice for future growth.

Even though light is an electromagnetic wave, light in fibres is not considered wireless because the electromagnetic waves are guided in the optical fibre. Fibre optic is therefore considered a form of guided media, like STP, UTP and coaxial.

Fibre Optic is available as multi mode and single mode. Multi mode uses multiple streams of LED (laser emitting diode) light whereas single mode uses one stream of laser generated light.

In terms of material structure, a fibre optic cable consists of glass fibre and cladding (the light guiding parts) which are covered by a plastic shield, Kevlar reinforcing material and then an outer jacket. It is connected by a multimode connector which is fairly small. The Kevlar material is used as a protector.

Fibre Optic provides many advantages over the other forms of cabling, but is inappropriate for this situation due to the fact that it is expensive, difficult to install and difficult to terminate. The business does not require data rates as fast as fibre optic cable offers; it is therefore not justifiable to pay the extra money for improved security and better resistance to interference. However, the multi mode 100baseFX can be used as the backbone to connect the two buildings that are 150 metres apart. This will enable faster rate of data for access to the web servers, internet and email from the design and engineering workgroup server to main facility in the other building (PoP).

Cabling Configurations

After evaluating the information present in Table 1, I have concluded that the most appropriate type of networking media to be used for this particular scenario is UTP and STP. UTP and STP offer many of the same features, but STP is slightly advantageous by being more resistant to interference than UTP. UTP and STP are appropriate for the small manufacturing and design company for the following reasons:
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- UTP and STP are easy to install - they can fit around corners and are fairly flexible.

- The premises occupy 30x35m2 each. UTP and STP can cover up to 100 metres without attenuating.

- UTP and STP are fairly inexpensive, UTP being the cheapest. Obviously, reducing costs is a priority for any small business.

- They use RJ45 connectors which most workstations can accommodate without upgrades - this is providing each workstation has a network interface card.

- Operate at speeds of up to 10 - 100Mbps - this is ...

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