Building Local Area Networks

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Ray Nimmo  HND 2

Building Local Area Networks

Assessment 3 – Outcome 2

Scenario 2:

Analysis:  

Summary of requirements

SweetCo Ltd wishes to computerise their stock control system in their warehouse. Their intention is to connect portable barcode readers (via USB) to laptop PC’s. They plan to use these to track incoming and outgoing stock as well as stock movements within their warehouse. These PC’s will then connect to a small local server using wireless links.

Current provision

The company has already purchased some of the hardware for this task:

  • Six PIII laptops – Windows 98 - 128MB RAM – 2 No. Type II PCMCIA slots.
  • Barcode readers with appropriate software.
  • Server unit – Windows 2000 server – 10/100mbps PCI NIC.

The warehouse is a rectangular room measuring 50m long by 30m wide and 4m high. The stock shelving consists mainly of wooden racks with a few of them having steel frames. On the shelving, the stock is mainly in the form of cardboard boxes and plastic wrappings. There is an unused cupboard at one corner of the warehouse; this would be ideal for the placement of the server as it has adequate lighting and power sockets.

- Drawing 1 - Existing warehouse layout -

Proposal for solution

The company only needs to purchase a minimal amount of hardware to implement this network as they have the majority of the requirements already. All that is needed is a method of interconnecting the laptops to the server whilst allowing the employees to carry out their work efficiently. The best solution for optimising this network is to implement a wireless local area network within the warehouse. To accomplish this, the Server Unit will need to be wireless enabled, as will the laptops.

Specification of hardware/software required

To enable wireless connectivity amongst all the required hardware the company will need to purchase hardware with the following capabilities;

  • A minimum of six type II PCMCIA wireless LAN cards – able to transmit/receive up to 50m.

(May wish to purchase more as spares to allow for any breakdowns)

  • Wireless access point for the server – again able to transmit/receive up to 50m.
  • Length of appropriate cable for connecting the Server to the Wireless Access Point.

(Purchasing a ready-made cable, no need for RJ45’s and necessary tools)

Design:

Each of the laptops will be wireless enabled with the barcode readers attached, then the employees will be able to go about their daily tasks from anywhere in the warehouse. As the shelving system consists mainly of older wooden racks with a few newer steel framed ones, the laptops should have no problem communicating with the server. Blackspots may be a problem at the ends of the shelving racks to the left, mainly because the signal strength will be slightly weaker at that point. The presence of blackspots could potentially cause irreversible data loss, as users roam within the WLAN infrastructure. The signal strength of an individual waveform will diminish according to the distance traveled. The loss of signal strength should follow the 1/d2 law, where d is the distance between the transmitter and the receiver. In actuality, the loss will be much greater (between 1/d3 to 1/d6). This is mainly caused by the variety of reflective surfaces in WLAN environments. In our warehouse the loss due to reflective surfaces will be negligible, as only the exterior walls have this quality and will result in a signal bounce. The stock shelving is constructed in such a material that there should be no interference with the signal. Only the steel framed shelving may be problematic, but again it should be negligible.

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Below is shown a rough network drawing indicating signal strength boundaries every 10m, shown by the concentric circles.

-Drawing 2 - Wireless signal patterns -

Description of proposed hardware and cabling:

Research into the optimum Wireless Access Point to allow this WLAN to operate efficiently brought a number of different products to my attention. Through careful consideration and a comparison of the main characteristics of each product, the most appropriate WAP to install is the NETGEAR WG602. This access point boasts many features, the choice was made mainly due to its high access speed, the impressive ...

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