Computer Networks KO

communication

All ________ is via the hub Advantages Greater security as data are only sent to the intended recipient.

What is a network?

A network is a set of computers that are connected to one another.

Standalone computers

Standalone computers are isolated from other devices.

greater speeds

Wired methods have ________ than wireless methods.

LANs

LANs are usually managed by a single organisation, covering a quite small geographical location, for example a school site.

Worms

Worms can spread from one computer to another A problem with any shared resource, (eg file server goes down) can impact the whole network.

Local Area Network

A LAN covers a relatively small geographical area typically extends over the range of a single organisation such as a university campus, school site.

Bluetooth PAN

A Bluetooth PAN uses radio waves to communicate wirelessly between devices over a range of a few metres.

Star Network Topology

Star Network Topology includes all devices, clients, servers, printers
that are connected to a central hub or switch.

What are fibre optic cables?

Fibre optic cables are glass or plastic and use use pulses of light
to transmit data.

How can computers be connected through wired methods?

Wired transmission methods use cables to communicate.

How can computers be connected through wireless methods?

Wireless transmission use radio waves communicate (eg Wi-Fi).

What is bus network topology?

All devices are connected to a cable called a bus. All communication is through the shared bus. At either ends of the bus is a terminator.

What are the advantages of a network? (3)

• Share resources, such as software applications, files and
hardware
• Allows communication and can transfer files easily.
• Easier network management

What are the disadvantages of a network? (3)

• Greater security risk as computers can be hacked if they are
connected to the internet.
• Worms can spread from one computer to another
• A problem with any shared resource, can impact the whole network

What is a WAN?

A WAN is made up of many local area networks and covers a much wider geographical area.
For example the Internet

What are the advantages of a star network topology? (3)

• Greater security as data are only sent to the intended recipient.
• If any of the connections fail only a single node will be affected.
• Fewer collisions between data packets

What are the disadvantages of a star network topology? (2)

• If the central hub fails then every computer on the network is
affected.
• Expensive as extra cable and hardware hubs are needed.

What are the advantages of fibre optic? (3)

• Higher bandwidth than copper so can transmit more data
• Less attenuation (degrading) of the signal so fibre optic is more
suitable over long distances
• Less “cross talk” interference between fibres compared with
copper so the quality of the signal is better

What are the disadvantages of fibre optic? (2)

• Expensive
• Difficult to install

What are the advantages of copper cables? (2)

• Cheaper than fibre optic
• Reliable because a telephone is powered from the copper cable
and does not rely on a separate electrical power supply

What are the disadvantages of copper cables? (4)

• Slow
• Low capacity
• Can only be used over short distances
• Interference can occur

What are the advantages of bus network topology? (2)

• Easy and cheap to install and does not require much cable
• Easy to add more computers

What are the disadvantages of bus network topology? (4)

• If the main cable fails then then the whole network fails.
• Less secure as data are broadcast to all devices on the network.
• Can be slow as there are collisions between data along the
shared bus.
• Will get slower as more computers are added.

What are the three main types of copper cables?

• Coaxial cable – the signal loses strength over long
distances
• Unshielded twisted pair – A pair of copper cables are
twisted together and allows data to be transmitted over
longer distances
• Shielded twisted pair – Shielding around the twisted
cables means the signal is less susceptible to interference