Computing - 5 Fundamentals of Computer Networks - 2 Network Topologies and Transmission

LAN stands for...

Local Area Network

Local Area Network

local computer network for communication between computers

Network advantages [3]:

- resources such as printers can be shared
- files can be accessed through any networked computer
- data is easily backed up as it is stored centrally in a server

Network disadvantages [3]:

- network hardware is expensive
- managing a large network is complicated
- viruses that infiltrate can infect every device

LAN vs. WAN [4]

- LAN is over a local area like an office or school
- WAN is over a large geographical area
- LAN hardware is owned by the manager
- WAN hardware is leased infrastructure

Topology

physical layout of computers on a network

Star topology

topology where all nodes are connected to one central switch, which is connected to a server

Advantages of star topology [2]:

- fast data transfer as wires aren't shared between nodes
- cable failure does not cause system failure

Disadvantages of star topology [2]:

- additional hardware required (network cables, central switch)
- central switch failure causes network collapse

Bus topology

topology where all nodes are connected to a central cable with terminators either end

Terminator

device that absorbs signals to prevent them reflecting

Advantages of bus topology [2]:

- cheaper and easier to install due to less hardware
- devices are added easily as they connect to the central cable

Disadvantages of bus topology [3]:

- single cable causes data collisions
- cable failure causes network failure
- all devices can view all information (security risk)

Modem

device that allows computers to communicate over telephone lines

Network hardware [5]

- NIC
- Switch/Hub
- Modem
- Router
- Wireless AP

Ethernet

communication technology that connects computers in a network via a wired connection

Ethernet protocols

family of standard local networking 'protocols' or rules. It describes how devices should format data ready for transmission between nodes on the same network

Examples of ethernet protocols [2]:

- nodes wait until connection is quiet to transmit
- if two nodes attempt to transmit simultaneously, they will wait a random period of time before attempting again

How is data transmitted using ethernet? [3]

- divide data into frames
- frames are broadcast to all nodes on a network, but only the intended recipient will open it (otherwise it is discarded)
- frames containing errors are dropped or resent

Frame

chunk of data similar to a packet

Frame contents [3]:

- source address
- destination address
- error checking data

Ethernet cable

twisted copper cable connecting computers to the LAN allowing nodes to communicate

Fibre optic cable

cable that carries data transmitted as light

Advantages of copper cables [2]:

- adequate speed for low bandwidth applications
- low cost cable and cheaper routing hardware

Advantages of fibre optic cables [3]:

- high speed and bandwidth
- signals not affected by electromagnetic interference
- less signal loss over distance

Disadvantages of copper cables [2]:

- signals affected by electromagnetic interference
- significant signal loss over distance

Disadvantages of fibre optic cables [1]:

- expensive cable and routing hardware

PAN stands for...

Personal Area Network

Personal Area Network

a computer network used for communication among computer devices close to one person

Bluetooth

wireless PAN technology that transmits signals using radio waves over roughly 10m between devices

Bluetooth pairing

process of establishing a persistent link between two Bluetooth‐based devices for communication

Pairing process [3]:

- a passkey must be entered to pair initially
- passkey is remembered by networked devices
- a persistent link is formed