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1.4 Hardware & Data Transmission (Network Hardware (Wireless Access…
1.4 Hardware & Data Transmission
Data Packets
Split up into pieces called packets
Packets may travel via different routes and reassembled at destination
Data transmitted across network piece by piece
Each Packet contains
IP ADDRESS OF SENDER
IP ADDRESS OF RECEIVER
IT'S POSITION IN SEQUENCE
HOW LONG THE PACKET IS ALIVE (TIMEOUT)
CHECKSUM WHICH VERIFIES THE DATA ARRIVED WITHOUT CORRUPTION
IP Addressing
IPv4 (version 4 of the IP Address format) = 4 octets
Written as four numbers separated by dots
eg; 76.74.128.90
01001100.01001010.10000000.01011010
Each client has unique IP Address
Network Hardware
Specific hardware is needed to connect clients to a network and to allow them to communicate and transfer packets correctly without loss of data
Wireless Access Points (WAPs)
Usually connects to router via wired network
Relays data between wireless & wired devices
Usually uses Wi-Fi or Bluetooth
Allows wireless devices to connect a wired network (LAN or WAN)
ADV
No building work required
Visitors can access network easier
Quick installation and easily moved around
DISADV
Slower and less secure
Routers
Forwards Data packets between networks
Reads destination IP Address
Looks up route for destination in routing table
Receives data packet
Directs packet to the next network
Repeats until data reaches final destination
Switches
Used to join segments of a network together
A network cable can only take one data packet at a time; two computers place a packet onto a network at the same time a DATA COLLISION OCCURS
A switch connects two or more devices together and solves this problem
As packet arrives at the switch, it's destination address is examined and the switch creates a direct connection to that device
Network Interface Card (NIC)
Allows a computer to connect to a wired network
Where the ethernet cable plugs in
Provides a unique, hardware address (MAC address) for each client
Transmission Media (Cables)
Ethernet ( Cat5e / Cat6)
Copper wires for fast data transmission
Maximum length about 100m
4 pairs of twisted wires
Flexible networking standard
Fibre Optics Cables
Very fast but expensive
Huge bandwidth ( 1 optical fibre can carry over 3 million voice calls or 90,000 TV Channels)
Transparent fibres of silica or plasitc
Immune to electromagnetic interference
Transmit over large distances
Coaxial Cable
Inner conductor surrounded by insulation, then a tubular conducting shield
Mostly used to carry TV signals into houses
An older networking standard - no longer used
Network Performance
Number of users
Too many users can cause the network to slow if the bandwidth is insufficient
Transmission Media
Wired connections have higher bandwidth than wireless
Fibre optic cables have higher bandwidth than copper cables
Bandwidth
Not how fast but how much data that can be sent in a given time
Measured in bits per second (bit rate)
Error Rate
Poor connections increases errors resulting in data being sent again
eg poor grade of copper
Latency
A delay between transmitting data and receiving it
Latency is caused by bottlenecks in the network that can be avoided by proper network planning
eg using more switches to further segment work
Latency can also arise when different hardware such as switches and cables operate at different speeds