LU4 - Local Area Networks Flashcards
Local Area Network(LAN)
Networking capabilities of group of computers which are found near each other
- Nodes - PC’s
- Network Interface Cards (which network media connects)
- Connecting devices ( Switches, Repeaters, Bridges)
Bounded Connection Media
Network Transmission medium
Signals are confined to the medium and do not leave it
Twisted Pair Cable
Consists of 2 insulated strands of copper wire twisted around each other
Unshielded Twisted-Pair(UTP)
Widely used
Advantages:
Low cost
Easy to install, expand, troubleshoot
Disadvantages:
Length cannot exceed 100m
Copper cables are inherently weak
Eavesdropping
signals travelling copper cable can be intercepted
Attenuation
Signal loses strength over a distance
Crosstalk
Two cables next to each other, may interfere with each others signals
Electro-magnetic Interference (EMI)
Nearby signals from machinery may corrupt signals travelling in copper cables
Shielded twisted-pair (STP)
Cable wrapped in protective outer layer
Fibre Optic Cable
Carry digital dat signals in the form of pulses of light
Advantages:
Data can be transmitted at very high speed
Data can be transmitted over long distances
Disadvantages:
More expensive than copper cables
Need to be installed by expert
Wireless - Unbounded Connection Media
Allow the transfer of data over short and long distances
Useful for long range comms, that cannot be achieved by bounded media
- Radio Communications
- Microwave Communications
- Light, visible and infrared(IR) such as remote controls
- Electromagnetic induction provides short range communication and power
Near Field Communications(NFC)
Provides wireless connection between two devices within close proximity
- commonly used near payment stations
Radio Waves
Type of electromagnetic wave which is known for their use in communication technologies and dat transfer
- Higher frequency means shorter distance travelled
Point-to-point connection
Directly connects two nodes in a network
Broadcast
Is a communications channel that is shared by all the devices
Topology
The physical setup of a network, way it is connected
Star Topology
Cable connect to computer has its other end in a port on central switch
Advantages:
- Easy to setup and maintain
- A problem on one computer does not disturb the rest
- Adding/removing nodes does not affect network
-Most common
Disadvantages:
- A large amount of cabling needed
- Switch adds cost
- If switch fails, network fails
Bus Topology
All nodes are connected to a single cable, with terminator at each end to stop signal bouncing
Advantages:
- Requires less cabling than star(Reduces cost)
- No switch needed(less cost)
Disadvantages:
- Faults are difficult to trace since nodes use same cable
- A fault in main cable, can shut down entire network
- Can get Congested
Ring Topology
All nodes are connected in a closed loop, data follows around a loop
Advantage:
- Orderly network, each device can transmit
- Each node duplicates data signal, so very little signal degradation occurs
Disadvantages:
- Malfunctioning workstation can cause problem for entire network
- Moves, changes and additions can disrupt network
- slower that star topology