OSI Model 1

Layer 7

Application Layer - Human interaction layer, where applications can access the network services - Details: Protocols: HTTP, SMTP

Layer 2

Datalink Layer - Defines the format of data on the network. Details: Like the network layer, the data link layer is also responsible for flow control and error control in intra-network communication

Layer 4

Transport Layer - Transmits data using transmission protocols including TCP and UDP. Details: The transport layer on the receiving device is responsible for reassembling the segments into data the session layer can consume.

Layer 3

Network Layer - Decides which physical path the data will take. Details: The network layer also finds the best physical path for the data to reach its destination; this is known as routing.

Layer 1

Physical Layer - Transmits raw bit stream over the physical medium. Details: The physical layer of both devices must also agree on a signal convention so that the 1s can be distinguished from the 0s on both devices.

Layer 6

Presentation Layer - Ensures that data is in a usable format and is where data encryption occurs. Details: The presentation layer is responsible for translation, encryption, and compression of data.

Layer 5

Session Layer - Maintains connections and is responsible for controlling ports and sessions. Details: The session layer ensures that the session stays open long enough to transfer all the data being exchanged, and then promptly closes the session in order to avoid wasting resources.