OSI model Flashcards
Layer 1
Physical Layer. responsible for the transmission and reception of unstructured raw data between a device and a physical transmission medium. It converts the digital bits into electrical, radio, or optical signals.
Layer 2
Data link layer. provides node-to-node data transfer—a link between two directly connected nodes. It detects and possibly corrects errors that may occur in the physical layer. It defines the protocol to establish and terminate a connection between two physically connected devices. It also defines the protocol for flow control between them.
Layer 3
Network layer. provides the functional and procedural means of transferring variable length data sequences (called packets) from one node to another connected in “different networks”.
Layer 4
transport layer. controls the reliability of a given link through flow control, segmentation/desegmentation, and error control
Layer 5
Session layer. controls the dialogues (connections) between computers. It establishes, manages and terminates the connections between the local and remote application
Layer 6
Presentation Layer. transforms data into the form that the application accepts, formats data to be sent across a network
Layer 7
Application Layer. User interacting with software application
PDU
Protocol Data Unit
PDU of physical layer
bit
PDU of data link layer
frame (Series of bits)
PDU of network layer
packet (source & destination address)
PDU of transport layer
segment w/ TCP header and data
PDU of session layer
data passed to network connection
PDU of presentation layer
data formatted for presentation
PDU of application layer
data received or transmitted by software
