local area networks Flashcards
what is a network
- 2 or more devices connected by some type of communications channels.
-exists to share hardware and software resources between devices
node
any device connected to a network
LAN
local area network
networking capabilities of computers near each other that share resources and connect to other LANS + the internet
what are the basic requirements of a network
hardware as source/sender
connection
hardware as destination/receiver
eg. of nodes
PCs, servers, printers
server
central network computer that provides various resources
eg. connecting devices
switches,bridges,routers
bounded connection media
signals are confined to the medium + dont leave it
cables carry signals between computers and peripheral devices
twisted pair cable
2 insulated strands of copper wire twisted around each other - prevents electrical interference
STP
shielded twisted pair
more expensive/bulkier - twisted pairs enclosed in protective foil
less affected by interference than UTP
UTP
unshielded twisted pair
most widely used network cable
easy to install,expand + trouble shoot
UTP variations
UTP Cat 1- traditional telephones
UTP Cat 5e- most popular
disadvantages of twisted pair
attenuation, cross talk, eavesdropping, electro magnetic interference
length cant exceed 100m
unbounded connection media
source +destination devices connected w/o physical connection
eg infrared,bluetooth,microwaves
advantages of twisted pair
low cost
easy to install
fibre optic cable
carry digital data pulses in the form of light
cable- extremely thin cylinder of glass surrounded by cladding
includes 2 strands in separate sheaths - 1 transmits and 1 receives
advantages of fibre optic cable
high speeds of data transmission
secure transmission over long distances
disadvantages of fibre optic cables
more expensive than UTP
expertise needed to install + connect
wireless technologies
allow for transfer of data over short + long distances
used mostly for long rage communications (radio + microwave communication, light, infrared)
bluetooth
wireless technology used to send data over short distances
uses short wavelength radio transmissions from 2400 - 2480MHz
inexpensive, automatic
versions of bluetooth
1.0 max transfer speed of 1Mbps
2.0 backwards compatible, max 3Mbps
3.0 24 Mbps
4.0 + 5.0 Bluetooth Low Energy (BLE) applications with lower power consumption
advantages of bluetooth
can handle data + voice transmissions simultaneously
NFC
near field communication
wireless connection between 2 devices in close proximity
2 way communication (used in contactless payment systems)
radio waves
electromagnetic wave used in communication technologies + data transfer
used in radio,TV and mobile phones
long wavelengths in EM spectrum(1mm to 100km +)
EM spectrum
electromagnetic spectrum
7 regions in order of decreasing wavelength + increasing energy + wavelengths (higher frequency =shorter distance)
broadcast
communication channel shared by all devices in a network
signal heard by multiple parties
eg radio stations
point to point communication
directly connects 2 nodes of a network
eg telephone call
topology
physical set up of a network and how nodes are connected