networks

  • Created by: cal14
  • Created on: 22-02-18 18:11
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  • networks
    • network typoligys
      • bus
        • a back bone with individual connections to each computer
          • cheap, if the cable breaks no computers have access
      • star
        • a central switch with individual connections to each computer
          • cheap, if one connection breaks only the connected computer is disconnected
      • ring
        • one connection that loops to all the computers
          • cheap if the ring breaks all computers cant communicate
      • partial mesh
        • most computers are connected to most others
          • it is cheaper than full mesh and if one connection breaks then it  is OK
      • full mesh
        • each computer has a switch connected to each outer switch
          • expensive but if one connection breaks all computers still have access
    • wired networks
      • transmission media
        • fiber optic cables
          • fastest transmission media
        • twisted copper pairs
          • supports full duplex used for ethernet
        • coaxal
          • original wires
      • LAN hardware
        • router
          • send data between WAN's uses IP
        • switch
          • routs packets in a LAN only sends it where it is needed uses mac
        • wap (wireless access point)
          • allows wireless access to the network
        • nic (network interface card)
          • lets computers access a network
        • transmission media
          • fiber optic cables
            • fastest transmission media
          • twisted copper pairs
            • supports full duplex used for ethernet
          • coaxal
            • original wires
        • hub
          • a dumb switch which just broadcasts data to all its connections
      • network models
        • peer to peer
          • all peers have equal power and have own files
            • no specialist needed
            • no single point of failure
            • cheap to setup
            • less secure
            • have to backup themselves
            • can be difficult to maintain files
        • client sever model
          • a central sever that controls files and network traffic etc
            • more secure
            • easier to manage
            • easier to backup
            • easier to update and install programs
            • can be expensive
            • requires specialist
            • a single point of failure
    • wifi
      • wireless fidelity
        • frequency and channels
          • each channel has a range of 22mhz
          • channels overlap and there are 14 channels in the 2.4mhz range
        • advantages and disadvantage
          • allows for free movement
          • easy to set up
          • slower speeds
          • convinient
          • relies on signal strength
          • can handle large numbers of users
          • can be obstructed
          • easy transfer of infomation
          • less secure than lans
        • encription
          • a device can listen into your wifi traffic
          • the wifi creates a key and uses this to encrypt data the key can be used to decrypt data
          • hand shake protocal
    • layers
      • layer 2
        • data link layer
          • creating and routing on a LAN error checking
            • Ethernet , mac
      • layer 5
        • session layer
          • Untitled
            • Untitled
      • layer 3
        • network layer
          • routing packets on a lan
            • ipv4 ,ipv6
      • layer 6
        • presentation layer
          • encription
            • ssl
      • layer 1
        • physical layer
          • methods of encoding bits
            • coax, fibre , wireless
      • layer 4
        • transport layer
          • creating and sequencing packets on a wan, error checking
            • tcp,
      • layer 7
        • application layer
          • web browsing, email, file management
            • http, https, ftp, pop, smtp, imap

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