Networks

• Types of communication

  Carrier Pigeon: 1167

  Semaphore: 1791

  Telegram: 1837

  Telephone: 1876

  E-mail: 1961
• Benefits of Networks:

  Allows connection to Hardware

  File and resource sharing

  Increased storage capacity
• Computer Network Hardware:

  Network cable

  Hub

  Router

  Server
• Advantages of Wired Networks:

  Faster Connection

  Higher bandwidth

  Better security
• Disadvantages of Wired Network

  Cables form trip hazard and look unpleasant

  More expensive and time consuming to connect devices

  Devices are in a fixed position
• Advantages of Wireless Network

  No trailing wires (no trip hazard)

  Quick and cheap to connect new devices

  Allows portability
• Disadvantages of Wireless networks:

  Lower bandwidth

  Connections can be weakened by walls and ceilings

  Less secure
• Amitie:

  A undersea cable running between the UK and the USA. Runs for 6,792 km
• The Internet is a worldwide network of computers
• The structure of an IP address is 4 numbers ranging from 0 to 255, separated by dots
• TCP: a protocol that splits the messages sent across the internet into smaller pieces called packets
• VoIP: allows voice data to be sent over the internet
• Tim Berners-Lee invented the World Wide Web
• World Wide Web:

  Part of the internet that contains websites and webpages and the links between them
• Switch


  A switch is a component which is used within a computer network.

  A switch has a number of ports and it stores the addresses of all network devices that are directly or indirectly connected to it on each port.

  As a data packet comes into the switch, its destination address is examined and a direct connection is made between the sending and receiving machines.
• Hub


  A network hub is a hardware device that connects multiple computers in a network.

  It allows networked computers to share data packets.
• Local Area Network (LAN)


  A LAN is a network of computers which are connected together in a limited area, usually the same building or a couple of nearby buildings.

  LANs are usually high speed and they make use of connected periperhals such as printers.
• Data Packet?


  This term is related to transmitting data over networks.

  Rather than send a whole file the data is split into 'blocks' or 'packets' which are then sent separately to the destination computer.

  A 'packet' contains the data itself and also other information needed to handle that data. For example the packet may contain a destination address, a source address and an error checking section.

  The exact make-up of a packet depends on the protocol being used. For example Ethernet, as used in computer networks, has a very precise data packet format.
• Network


  In general a network is a word to describe a collection of parts joined together by links of some kind.

  A network is as basic as two computers being connected together.

  Computers are linked together in order for them to share and exchange data with each other. When this is the case, the computers are said so be NETWORKED.

  A network can be any combination of LANs or WANs.
• File Server


  A file server is a networked computer that stores and manages users files. When a user logs on, the server will find and present their files.

  A file server can also store application software for the network.
• WIFI


  A type of network that makes use of radio channels to connect either to a local area network (LAN) or a router linked to the Internet.

  Companies often have a Wi-Fi system installed inside their buildings. Then visitors and workers with laptops can instantly connect to their LAN.

  Wi-Fi is has not replaced hard-wired networks because of two limitations

  1. They are nowhere near as fast as standard networks, around half the speed (at best).

  2. There are only a limited amount of channels that can be used at any one time within a Wi-Fi network.
• Packet 


  A small parcel sent over the internet that contains data. Are used for moving information