Networks

Networks

1. Advantages and disadvantages of dial up and broadband

   • Dial up can be used on a phoneline
   • dialup-can be used anywhere there is a phoneline
   • Dialup is very slow and limits its use- a download on dialup can take minutes compared to broadband
   • Broadband is a faster at downloading information
   • broadband makes videoconferencing possible
   • Broadband does not tie up phone line

2. factors which would influence the choice of a network

   • Cost of network-Initial purchasing of equipment
   • size of the organisation-needs can range from a small LAN to a global WAN
   • How the system will be used- what applications do users require?
   • existing systems to integrate-more often networks are not developed from scratch but need to fit in with existing systems. sometimes an extension is required e.g when a new branch office opens
   • Performance in terms of reliability- different parts of the organisation may have different performance requirements

3. user accounts and logs

   • who logged on
   • what files they accessed
   • when they logged on and off
   • User accounts -Everyone who uses a network is given a user account. The user account is set up by the network manager. The network will allocate the user certain rights . All users of the network are able to: change their password, Change desktop settings, manage their own files in their storage area

4. advantages and disadvantages of using a wireless network

   • can use a variety of devices such as tablets and mobile phones
   • health and safety- tidier desktop with no trailing cables
   • there may be health problems in using wifi
   • transmission speeds slower than cable

5. Network topologies

   • Physical configuration of a network and how it is linked together
   • The ring network is a peer to peer network because there is no server. all the computers are arranged in a circle. Data sent by one computer passes around the ring until it reaches the correct computer
   • The star topology uses a central connection point to connect all the devices on the network together. The central connection point can be a hub, a switch or a router
   • The bus topology has all the devices connected to the network by a common shared cable called the backbone. Signals are passed in either direction along the backbone
     • Cost effective because of the small amount of cable needed
     • Simple cable runs makes it easy to install
     • easy to add extra devices to the network
     • If more than about 12 devices are connected to the network, then the performance of the network is degraded
     • If there is a break in the backbone cable, then the network cannot be used

6. Remote management

   • guide users through problems
   • Log off users who have forgotten to do so
   • Shut down stations
   • Clear printer queues
   • send instant messages

7. Ring and star

   • Advantages and disadvantages
     • Ring
       • Network not dependent on central computer
       • Each computer has the same access as others so no one computer can hog the network
       • Faults are difficult to locate
       • If there is a break in the connection then the whole network fails
     • Star
       • Easy to add extra computers- extra computers can be added without disturbing the network
       • Load tolerant-extra computers can be added without much loss in performance because all computers have their own path to the server
       • higher cost-the large amount of cabling needed makes it more expensive
       • Dependance on the central server
   • Compare and contrast
     • The ring is a lan which means it can only be accessed from within the building or organisation. Messages are pass around all devices on the ring and repeated on to the next if not at the destination address. The star can be a LAN or a WAN linking networks via gateways and a classic example of this is the internet or when large banks link u their branches with the HQ computers
     • A ring network is a peer to peer network with the file server and all peripherals and work stations on a ring. In the star network is a client server network and the file server is the centre of the spokes with peripherals and workstations on the end of each node
     • There may be more than one file server on the ring network and if one goes down the ring can still function by redirecting network traffic to the functioning server. In the star network if a spoke goes down the others can still function but if the central file server goes down then the network cannot function

8. Wireless networking

   • Many computers are now able to connect to the internet or communicate with other computers in a local area network wirelessly. With wireless communication the data transfer medium is the air through which the radio waves travel
   • Many people, especially people who travel a lot, need access to the internet regularly. There are many public places where the internet can be accessed wirelessly using a persons laptop or other portable devices
   • To set up WIFI you need: a broadband connection to the internet, a Router, wifi enabled computers, you can buy wireless adapters for older computers

9. How Wifi works

   • 1. The router is connected to the internet by a high speed broadband connection
   • 2. The router receives data from the internet
   • 3. It transmits the data as a radio signal using an antenna
   • 4. The computers wireless adapter picks up the signals and turn the radio signal into data that the computer can understand

10. Network management software

    • If you were a network manager responsible for a network consisting of several hundred computers, you would need help looking after them all to keep the network running
    • network management software would help with...
      • Making sure that all the computers have up to date software with the latest security patches, so that hackers cannot get into the network.
      • Keeping track of the software being run on each computer and checking that there are licences for all the software being used
      • check that bandwidth is being used correctly

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