data transmission Flashcards
what is data
anything in a form suitable for use with a computer.
typically meaningless lol.
packet
a small unit of data used in network communication
make up of a data packet
1 source adress
2 target adress
3 priticol
4 data
why are protocols neccessary
protocols are the set of rules computers follow when communicating across a network - without them no information can be properly transmitted (without an agreed language two persons cannot communicate verbally)
their functions are:
- ensuring integrity
- managing flow control
- manage congestion
- perform error checking
why is data integrity important?
it is about overall completeness, accuracy and consistency of data
why is flow contorl important
flow control is the mechanism that ensures the rate at which a sender is transmitting is in proporiton with the reciever’s receiving capabilities. it is utilised especiall in cases where the sending device can send data much faster than the receiver can digest.
(huffing package)
what is deadlock
a situation where two nodes or processes are trying to acces the same nodde at exactly same moment causing neither to be able to proceed (playing only one song in spotify)
what is the congestion control
it refers to a network state where a node or link carries so much data that it may deteriorate network service quality - resulting in queuing delay, frame or data packet loss and the blocking of new connections
what is error checking?
detection - techniques used to detect noise or other impairments introduced into the data while it is transmitter from source to destination.
error detention often makes use of parity bits
why the speed of data transission across the network can vary (network in general aka not only internet)
1 traffic. if you’re downloading a game from internet expect images that you search up to take longer to load.
2 time of day - “network rush hours”
3 infrastucture - “bad cable management”
4 teriary causes - temperature, infrastructure limitations due to financial reasons, the type of data being transmitted (a text will take less than a stream)
why compression of data is often neccessary when transmitting across a netwrok?
compression is encoding information to use fewev bits than the original data entity
main reason is time, as it tkese less time to transfer a smaller data and also less space.
it is useful for making backups/archiving, faster file trnsfer, and protection.
lossy vs lossless compression
lossless makes it small, lossy makes it tiny. lossy loses some details but it is still generally ok for music files and such.
outline characteristics of different transmission media
there are two main focused groups:
wireless - radio waves, microwaves, and infrared lights (tv remote)
and wired - twisted pair cable, coaxial cable (isolated copper wire) and fiber-optic cable
STATS twisted pair
SECURITY - ok if encrypted
RELIABILITY - susceptible (easily affected) by electromagnetic inductions
COST - cheap as fuck
SPEED - slower but ok for short differences
STATS fiber optic
SECURITY - very secure (works as spaghetti)
RELIABILITY - generally very fragile
COST - costy.
SPEED - turbo!! literal speed of light!
