IT Applications Theory Slideshows

1
IT Applications Theory Slideshows
Networks

• By Mark Kelly
• McKinnon Secondary College
• Vceit.com

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What you dont need to know

• Topologies
• Protocols
• Neither of these are in the study design for ITA.
  They are, however, applicable to year 11 and
  Software Development.
• They wont be covered here, however.

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What is a network?

• Two or more computers that are interconnected so
  they can exchange data.

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Types of networks

• Type is vague could be categorised by
• 1. Size
• 2. Server configuration

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Types of networks part 1Categorised by Size

• LAN Local Area Network
• Geographically limited in size.
• Usually in a single building or on a single site.
• Spread limited to a few hundred metres.
• e.g. the computers in the McKinnon branch of the
  Commonwealth bank

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Size 2

• WAN Wide Area Network
• Geographically widespread (e.g. across cities,
  states, countries)
• Usually made up of interconnected LANs
• E.g. the interconnected LANs of every branch of
  the Commonwealth Bank in Australia.

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Size 3

• The Internet
• What you get when WANs join together
• There is nothing that is the internet except
  for the computers that are interconnected at any
  single moment

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A standalone computer
PC
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A LAN
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A WAN
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An internet
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Types of Networks part 2Categorised by server
configuration

• File server a computer at the heart of a LAN
  that controls the operations of the network
• What it does
• Authenticates users as they log in to keep out
  villains
• Allocates privileges such as printer access, home
  directory, access to certain shared folders
• Allocates IP addresses to allow internet access
• Runs virus-scans, caches downloads, does backups,
  controls email, manages print queues etc

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Types of Networks part 2Categorised by server
configuration

• P2P Peer-to-peer LAN has no file server
• Client-Server LAN has a server

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File Server

• Rugged, powerful, but expensive (e.g. 5,000 -
  10,000)
• Requires considerable knowledge to set up and
  maintain
• Used for LANs with many computers
• Used if users are not trustworthy or network is
  used by staff and non-staff (e.g. libraries,
  schools, internet cafés)

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File Server
Note the large number of hard disk drives. File
servers need lots of disk space and
bandwidth. Servers often use multi-disk arrays
(RAID) and two NICs.
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File Server

• Runs the Network Operating System (NOS)
• The NOS does for a network what the local
  operating system (e.g. Windows Vista, Mac OSX,
  Linux) does for a single PC
• Controls the networks operations
• Expensive, complex software

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Network Types

• A LAN with a server is called Client-Server. The
  workstations are clients, controlled and served
  by the server.
• A LAN without a server is called Peer-to-Peer
  (P2P)

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P2P

• Every operating system has P2P features to allow
  small numbers of PCs to
• Share an internet connection
• Use email
• Share a printer
• Share documents

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P2P Good

• Saves money on expensive equipment (1 shared
  printer far cheaper than a printer on each PC)
• Far cheaper and easier internet access with one
  connection
• Suitable if there are only a few users, and all
  are trustworthy
• Free!

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P2P Bad

• Little power to control users who misuse or hog
  resources
• Stops working well if there are more than a few
  concurrent users

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Technology Ethernet

• The standard networking technology
• The Ethernet rules specify
• How networking hardware must work (e.g. cables,
  network cards, switches)
• How networking software must work
• Such standardisation lets any Ethernet computer
  communicate with any other, regardless of
  manufacturer, operating system etc.

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Some basic terms

• Bandwidth how much data can be conveyed per
  second
• Bandwidth measured in bits per second
• Not bytes per second! (1 byte 8 bits)
• Standard network speeds 10, 100 or 1000 Mbps
• Mbps Megabits per second
• Megabit 1,000,000 bits (rounded off)
• Gigabit 1000 Mbps
• Note small b indicates bits. Capital B
  bytes.

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Basic Hardware - Cables

• Unshielded twisted pair cable (UTP)
• Types Category 6 (CAT6)
• Maximum cable length 100m
• Metal core, electrical signals
• Only one network signal can travel along a cable
  at a time
• Poorly shielded from electromagneticinterference
• Bandwidth 10, 100, 1,000 Mbps
• End connectors RJ45

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Basic Hardware - Cables

• Fibre Optic Cable (FOC)
• Glass or plastic core
• Optical (laser light) signals
• Max length kilometres (no electrical resistance
  little signal fade)
• Immune to EMI (electromagneticinterference)

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Basic Hardware - Cables

• Each thread is hair-thick
• Many threads used in a cable
• Many simultaneous signals on a thread using
  different wavelengths of light
• MASSIVE bandwidth!
• MASSIVE speed (speed of light)
• Expensive connectors needed ateach end to
  convert betweenoptical/electrical network signals

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Uses

• CAT6 for the final connection to a computer from
  a data point
• FOC for l-o-n-g distances (over 100m), across
  oceans, between distant sites.
• FOC for extreme bandwidth needs (e.g. internet
  lines between continents, TV phone companies)

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Do not worry about coaxial cable

• Used to be standard, rarely if ever seen now
  except for cable internet.
• Cant even buy the necessary equipment any more!

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Wireless Good

• Wifi local wireless networking
• Uses Wireless Access Point (WAP) to convert
  electrical network data into radio signals
• Most laptops now have wireless antennae and
  wireless network cards built in
• Very useful for flexible or temporary networking.
  No expensive cable laying.

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Wireless Bad

• Not as fast as a cabled connection (54 Mbps max
  compared to a cabled 1000 Mbps max)
• Affected by obstacles (walls, bookshelves, filing
  cabinets, concrete, metal roofs) which reduce
  signal distance
• Affected by interference (e.g. next doors
  wireless equipment on the same channel)
• Very restricted range (tens of metres)
• Insecure!

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Wireless Weak

• Cant tell radio waves to stop at the fence
• Can be eavesdropped by outsiders data can be
  read or stolen
• Can be piggybacked people passing by can use
  your internet connection
• Must be encrypted to make signals unreadable to
  outsiders e.g. WPA2. Both WAP and laptop must
  use same encryption method and encryption key.

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Other Wireless

• 3G, HSDPA Wireless / mobile phone broadband.
• Good for workers on the move
• Long range
• Expensive per megabyte

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Other Wireless

• Microwave point-to-point fast wireless
• Very expensive to set up, but very fast
• Line-of-sight no obstacles between dishes
• Usually corporate use only

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Basic Hardware - NIC

• NIC network interface card
• In every networked device
• CAT cable plugs into it
• Manages a computers communication with the rest
  of the network
• Most computers now have them built in
• Most work at up to 100 Mbps. Many now run up to
  1000 Bbps.

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Basic Hardware - Switches

• Switches (switching hubs) are boxes that let
  devices be interconnected.

PC
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Server
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CAT cable
switch
Here, 3 PCs connect to a switch which lets them
all communicate with each other and with the
server.
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Switches
Rack-mounted 24-port switch
4-port switch for a SOHO (Small Office Home
Office) LAN
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IT APPLICATIONS SLIDESHOWS

• By Mark Kelly
• McKinnon Secondary College
• vceit.com

These slideshows may be freely used, modified or
distributed by teachers and students anywhere on
the planet (but not elsewhere). They may NOT be
sold. They must NOT be redistributed if you
modify them.