WLAN as an alternative to leased line'

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WLAN as an alternative to leased line.

• Stewart Sharpe.

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Vendor neutral supplier.
Mobius Technologies Ltd. can supply solutions
from a huge range of vendors on an impartial
basis. These include -

• Cisco Systems.
• 3Com.
• BreezeCOM.
• Culubris.

• Lucent.
• Enterasys.
• SpectraLink.
• Intersil.

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Basis for choice of solution.

• Reliability.
• Application suitability including security.
• Expandability.
• Upgradeability and investment protection.
• Customer support.
• Cost effectiveness.

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Solutions to be highlighted.

• Cisco Systems Aironet.
• 3Com Airconnect.

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2 different applications to be studied.

• Huge number of scenarios available to us for each
  solution.
• We have chosen straightforward scenarios for
  demonstration.
• Case studies later, will expand up on this basic
  representation.

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2 different applications to be studied.

• Cisco Systems Aironet.
• Point-to-point/multipoint link between buildings.
• Applications with specific or extended coverage
  requirements.
• 3Com Airconnect.
• Office environment LAN.

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Scenario 1.

• Multi-building LAN extension.

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Scenario 1.

• 1. Main office building.
• Centralised location of -
• File servers.
• Mail server.
• Internet connection.

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Scenario 1.

• 2. Sub-office within the main campus.
• Office uses all facilities of main office.
• 15 network users.

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Scenario 1.

• 3. Sub-office within main campus.
• Office uses all facilities of main office.
• 30 network users.

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Scenario 1.

• 4. Sub-office outside main campus.
• Office uses all facilities of main office.
• 15 network users.
• Public road between office and main campus.

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Scenario 1.
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Options for extending network. Campus buildings
1, 2 3.
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Options for extending network. Campus buildings
1, 2 3.

• Wire between buildings.
• Fibre between buildings.
• Wireless bridge between buildings.

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Characteristics of options.Wire/fibre between
buildings 1, 2 3.

• Benefits.
• Limitless bandwidth possibilities.
• Permanent link with little maintenance.
• One off installation costs.

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Characteristics of options.Wire/fibre between
buildings 1, 2 3.

• Drawbacks.
• Typically would be buried in ground.
• Huge upheaval to existing features e.g. car
  parks, footpaths, landscaping etc.
• Time consuming and costly installation.
• No benefit in relocation.

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Options for extending network. Buildings 1 4.
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Options for extending network. Buildings 1 4.

• Dial-up connection between buildings.
• Leased line between buildings.
• Wireless bridge between buildings.

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Characteristics of options.Dial-up connection.

• Benefits.
• Easy quick installation using existing lines.
• Adequate for occasional usage.
• e.g. Weekly submission or update of files.
• Can be used in multiples to increase bandwidth.
• No office relocation issues.

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Characteristics of options.Dial-up connection.

• Drawbacks.
• Very slow for all but most basic tasks.
• Multiple connections increase unit costs.
• Inconvenience of repeated reconnection.
• High relative costs.

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Characteristics of options.Leased line.

• Benefits.
• Permanent link.
• Huge bandwidth availability.
• Reliable connection.

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Characteristics of options.Leased line.

• Drawbacks.
• Not always possible to install.
• Expensive installation costs.
• High periodic costs for higher bandwidth.
• Long lead times for installation.
• Relocation requires re-installation.

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Characteristics of options.Wireless bridge.

• Benefits.
• Very quick and simple installation.
• No periodic charges.
• 11Mbps bandwidth.
• Permanent link.
• Easily relocated.

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Characteristics of options.Wireless bridge.

• Drawbacks.
• Requires clear line of sight between points.
• Bandwidth diminishes as distance increases.
• Site survey necessary as a pre-requisite.

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Site survey.

• Necessary to ensure the following -
• That no unforeseen circumstances render system
  unsuitable - prior to purchase.
• Highlight precisely what will be available.
• Accurately specify equipment required for
  quotation purposes.
• A clear picture of physical layout in advance.

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Costings.Scenario 1.

• Suggested.
• Point-to-multipoint link between 1 2, 1 4.
• Point-to-point link between 1 3.

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Costings.Scenario 1.

• Allows 11Mbps to be shared between the 1 - 2
  link and the 1 - 4 link.
• Allows a full, separate 11Mbps link between 1 3.

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Costings.Scenario 1.

• Site survey.
• 2 people on-site for 2 days.
• Point-to-multi-point link.
• Bridge and omni antenna for building 1, bridge
  and yagi antenna for each of building 2 4.
• Point-to-point link.
• Bridge and yagi antenna for buildings 1 and 4.

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Costings.Scenario 1.

• Installation.
• 2 people, 5 days.
• Additional equipment.
• Lightning arrestor per location.
• Antenna mounts and connectors.

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Costings.Scenario 1.

• Additional costs (unknown.).
• NEMA enclosure per location.
• Electrical contractor to provide supplies to
  enclosures and earth lightning arrestors.
• Any masts required to gain line-of-sight.

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Summary of benefits.

• Bandwidth adequate for most applications.
• No periodic costs.
• Quick and easy installation.
• Short lead times.
• Ideal in difficult situations.
• Easily relocated with the business.
• No license required.