3.5 - Computer Networks

Network

2 or more computers connected together to allow the transmission of data, and the sharing of resources

(eg. a printer shared between multiple computers that can access it) 

Advantages + Disadvantages of one?

Advantages 

• Users can share files + resources – can access files from any computer 

• Computers/servers can be centrally managed (eg. Updating software, fixing problems) by a network manager 

• Easier to work collaboratively 

Disadvantages 

• Can be targeted by hackers (unauthorised access to network files) 

• Malware + Viruses can be spread 

• Potential for a single point of failure 

• High traffic can lead to the network running slowly 

LANs vs WANs (differences)?

LANs

• focused on a single building or site 

• Eg. Homes, schools, small businesses etc. 

• Usually owned + maintained by the organisation using it 

• Wired, wireless or mixture of both

vs.

WANs

• covers large geographical areas 

• Lots of LANs connected together 

• Eg. Large organisations/3^rd party telecom companies in multiple locations (shared ownership) 

• Connected via fibre-optic cables, satellite links, radio waves etc. 

PANs?

• Often just two devices (centered around one person) 

• short-term - Normally only exists whilst it is needed

• Almost always wireless (bluetooth) 

Comparison of LANs vs. WANs (data transfer rates, transmission errors likelihood, Security?, Ownership)

2 Cables that could be used for wired networks? (How are wired networks connected)

Ethernet Cables (copper cables) - most commonly used

Fibre-optic cable (thin glass strands transmitting data as pulses of light)

Ethernet cables vs. F-O cables (advantages vs disadvantages)?

How are wireless networks connected/ how is data transmitted?

transmit data via Radio waves

WiFi and Bluetooth are most common network protocols/standards used (determine how data should be communicated over the radio waves - frequency used, power of transmission etc.)

Wired vs Wireless networks (advantages + disadvantages)?

What is a network topology?

The arrangement of devices within a network

Two types of topologies?

Bus - central backbone (the “bus“) which each node for a cable connects to it

means data sent from one node is broadcast to all other connected devices.

also means that only one device can communicate at a time (otherwise there will be collisions)

Star - central switch (or you could use a hub) that all devices individually connected to

when typically using a switch, has to learn the MAC address of each device to create temporary links between devices that are communicating.

so can also allow devices to exchange data with eachother simultaneously (no collisions happen).

Comparing advantages and disadvantages of each topology