LO3

• A leased line is a dedicated connection between two networks, usually between a business and its internet service provider.
• Leased lines are typically more expensive than other types of connections due to the cost of installing and maintaining the physical infrastructure required for the dedicated link.
• benefit of leased lines = security, offer a private and secure connection between two locations, protects private data being stolen
• Advantages of leased lines are:

  • improves speed of network as less people are interfering with it because its uncontended
  • Very secure as its a private network
  • High bandwidth due to a full-duplex network
  • highly reliable
• disadvantage of leased lines are:

  • expensive
• Why are leased lines expensive? They are expensive because they are dedicated to one company and they are not shared with other companies
• What is an advantage of using a leased line over ADSL? Leased lines have lower latency (the time taken for information to travel from your computer to another) compared to ADSL
• Why are leased lines better than ADSL?

  • highly reliable as they use fibre optic cables so don't suffer interference rather than using copper wires that do
  • Leased lines have lower latency than ADSL
• What is an ADSL connection? A connection that uses a copper telephone line to transmit data over the internet
• What does ADSL stand for?

  Asymmetric Digital Subscriber Line
• ADSL provides high transmission speeds for video and voice for homes over copper telephone wires
• What are the advantages of ADSL?

  Faster internet speeds, always-on connection, and ability to use existing phone lines.
• What are the disadvantages of ADSL?

  Limited bandwidth, distance limitations, and susceptibility to interference due to copper wiring
• What is ISDN connection?

  allow digital transmissions of voice and data over a single line connected to the PSTN/ landlines.
• What is the difference between ISDN and ASDL?


  ISDN is a digital telephone network technology that supports voice and data transmission, while ADSL is a broadband internet connection technology that provides high-speed internet access over existing telephone lines.
• What are the advantages of ISDN?

  Faster data transfer, simultaneous voice and data transmission, and better call quality.
• What are the disadvantages of ISDN?

  Limited bandwidth, high cost, and outdated technology.
• What is PSTN stand for?

  Public Switched Telephone Network
• What is a PSTN network?

  calls are connected by digital devices called a 'switch' to transfer the call to the correct reciever
• What can PSTN send?

  Data and voice communications
• Advantages of PSTN?

  Clear

  reliable
• Disadvantages of PSTN?

  Limited scalability, high cost, lack of flexibility, vulnerability to natural disasters.
• Why is PSTN better than ADSL?

  PSTN is better for voice communication, while ADSL is better for high-speed internet access.
• Why is ADSL better than PSTN?

  Faster
• Why is ISDN better than PSTN?

  faster data transfer.
• What is an ethernet cable used for?

  To connect devices in a local area network (LAN) and transmit data.
• LAN's cabling allows messages to travel in either direction
• Half duplex ethernet LAN’s allow communication in both directions but only in one direction at a time.
• Advantages of a wired ethernet LAN are:

  • high bandwidth
  • quick data transfer
  • harder to intercept data as its wired
• Many Advantages of a LAN network:

  • Allows for easy sharing of files and data between computers
  • Allows for easy communication between computers
• Disadvantages of LAN networks:

  more expensive to set up and maintain than WANs.
• Advantages of MAN networks are: Higher bandwidth, Lower latency than LANS, Lower cost than WANS, Higher reliability
• What do ADSL's need at both sending and receiving end of the connection?

  modems
• Why are leased lines better than ADSL?

  uncontended where as ADSL are contended so speed is slower as you add more devices on the network.
• How does a ring topology work?

  connects devices in a circular network where data travels in one direction. Each device receives and forwards data until it reaches its destination.
• Star Topologies connect all devices to a central hub or switch which then sends data out to other connected devices.
• Bus Topologies have a single cable running through the centre of the network connecting all devices together. Data flows along this cable from one device to another.
• In a peer-to-peer network every computer acts as both a client and server meaning that files can be shared across the entire network. There is no dedicated file server so there is no centralised control over accessing files.
• Mesh Topologies use multiple cables between devices allowing them to communicate directly without having to go via a central point like a star topology. This means that if one link fails then communication can still take place using an alternative route.
• A client/server topology has at least two computers, with one acting as a server (storing information) and others acting as clients (requesting information). The server controls access to resources on the network and manages security. Clients are able to share resources such as printers and storage space.