Module 4 Flashcards
Components of an access point
- The wireless antennas
- Several Ethernet switchports
- An internet port
NIC
Network interface card
Ethernet NICs for wired connection
WLAN NICs for wireless
Three functional areas of the physical layer
Physical Components
Encoding
Signaling
Terms used to measure the quality of bandwidth
Latency
Throughput
Goodput
Latency
The amount of time, including delays, for data to travel from one given point to another
Throughput
Throughput is the measure of the transfer of bits across the media over a given period of time
Usually lower than the bandwidth
Goodput
The measure of usable data transferred over a given period of time
Throughput minus traffic overhead from acknowledgements, encapsulation etc
UTP cable
Unshielded twisted - Most common network medium
Four pairs of twisted color-coded wires
Outer jacket protect wires from physical damage
Twisted pairs protect signal from interference
Insulation isolates wires and identifies each pair
STP
Shielded twisted pair
Four twisted pairs, each wrapped in a foil shield
All wrapped in an overall metallic braid or foil
Covered with a cable jacket to prevent minor physical damage
Wireless
Uses patterns of microwaves to represent bits
Fiber-optic
Uses light to represent bits
Copper
Uses electrical pulses to represent bits
Bandwidth
The capacity of a medium to carry data
EMI
Electromagnetic interference
RFI
Radio frequency interference
Potential sources of EMI and RFI
Radio waves and electromagnetic devices, e.g. fluorescent lights or electric motors
Crosstalk
A disturbance caused by the electric or magnetic fields of a signal on one wire to the signal in an adjacent wire.
Coaxial cable
Single copper conductor surrounded by a layer of flexible plastic insulation, a woven copper braid, and a cable jacket
Coaxial cables are used for:
Wireless installations
Cable internet installations
UTP limits crosstalk by:
When two wires in a circuit are twisted togehter, their magnetic fields cancel each other out
Twisting each braid a different number of times
Ethernet Straight-Through
Used to interconnect a host to a switch and a switch to a router
Ethernet Crossover
A cable used to interconnect similar devices (considered legacy)
Pros/cons of fiber-optic cable
Expensive
Transmits data further and at higher bandwidths than any other networking media
SMF
Single mode fibre
Very small core, uses a laser to send a single straight ray of light
Travels ~100km
MMF
Multimode fibre
Larger core, uses LED emitters to send light pulses at different angles
Travels ~500m
Commonly used on LANs
Four uses of fiber-optic cabling
Enterprise networks
Fiber-to-the-home (FTTH)
Long-Haul Networks
Submarine Cable Networks
Limitations of wireless
Coverage area limited by building materials
Interference by common devices
Security
Shared medium - half-duplex
Wireless Standards
WiFi
Bluetooth - Distance 1-100m, used for Personal Area Networks
WiMAX - Point-to-multipoint topology
Zigbee - Low-data, low-power, commonly used for IoT and industrial environments
Devices required for WLAN
Wireless Access Point - connects wireless to copper
Wireless NIC adapters - provides wireless capability to network hosts
