OSI model.txt

OSI model 
networking : allow two hosts to share data with one another

hosts must follow a set of rules

Physical : data exits in the form of bits ( 0 and 1)
transporting bits between hosts
transmission of raw data bits over a physical medium
l1 technologies : cables , wifi, repeaters, hubs


data link : interacts with wire
reliable transfer of data between two directly connected nodes, error detection, framing of data packets.
ensure that data transferred without error with the same network
sent bits on the wire and retrieve bits from the wire
hop to hop delivery uses addressing scheme mac address
switch allow to comm data to many devices
often comm bet hosts required multiple hops

network : end to end
manages the routing of data packets betn diff networks ensuring reaching to correct destionation
ip address allow to go data end to end 
routers hosts

Transport : service to service
distinguish data streams
insure that right program received right data
it provides error recovery, data segmentation, flo control for comm bet device

Session layer : manager connection betw appln
maintaining the state and ensuring comm remains open or closed as required

presentation layer :
translate, encrypts and compresses data bet appln n transport layer
so it can be understood by receiver

Appln layer : provide the service directly to end users