Communications

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Communications Networks

• By Shaun Campbell

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What is a network?

• A series of computers linked together so they can
  send and receive data between each other.
• Networks can be split into two types Local Area
  Networks and Wide Area Networks (LAN and WAN).

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Local Area Networks (LANs)

• Operate in small areas such as offices and
  schools. Even at home.
• Computers are joined using wireless transmitters
  or cables.

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Wide Area Networks

• Ability to communicate instantly world wide!
• Stretch from office to office or city to city!

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Multi-access Computers

• Allows many users to
• Access the system at the same time.
• Share available memory
• Display data held on the system.

• Below is a diagram of how the multi-access
  computer works. Computers are linked to one
  larger computer.

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Cables

• There are different cables you can use to connect
  to your network.
• Coaxial cabling the central cable transmits the
  data.
• Twisted-pair cabling used a lot in LANS. Simple
  type of cable made up of two copper cables
• Fibre-optic cabling Made of thin strands of
  glass. Light represents the data. This transmits
  at high speeds and is difficult to break. It also
  is not effected by electro-magnetic interference.

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What Do These Cables Look Like
Above is a coaxial cable.
Above is a optical fibre cable.
To the left is a twisted-pair cable.
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Warning!
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Networks Must Be Secure!

• All networks have to have security mesures in
  place. If not then the network can be hacked into
  and data can be stolen or changed.

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Securing Networks

• Physical Security
• Installing network computers with a lock.
• Security locks on rooms with computers.
• Installing computers without CD Drives etc.

• Software Security
• Password protect the network.
• Biometric systems can be used e.g. special smart
  cards.
• Encrypt the data held so it is useless to any
  hacker unless they can decrypt it.

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Electronic Communication
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Electronic Communication

• There are two ways of communicating
  electronically
• Text Messaging
• Electronic Mail (e-mail)
• There are many advantages and disadvantages to
  both of these.

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Advantages

• Email Advantages
• Email delivery is very fast, it can be almost
  instantly delivered.
• Email costs a lot less, some services offer free
  e-mail. All you need to pay for is your internet
  connection.
• Email is secure because you need and ID and
  password to access it.

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Disadvantages

• Disadvantages of Email
• Viruses can be hidden in e-mail attachments so
  you must be careful when opening attachments from
  people you dont know.
• You can often receive spam e-mail. Spam is
  unwanted adverts and offfers.

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Viruses

• Viruses received by email can cause a lot of
  trouble with your computer and you may need to
  have it repaired which could cost you a lot of
  money. You should have a anti-virus and a
  firewall to help protect against these viruses or
  you could be in for a very stressful time.

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Rules

• A few things which may help your network be more
  pleasant
• Dont start flame wars (arguing etc)
• Dont use bad language
• Dont post unwanted mail or spam
• Be patient to people who ask questions through
  e-mails and message boards.

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The End

• Stick to these rules and you should have no
  problems on your network whether it is LAN or
  WAN.