OSI Model Layers

OSI Model

• The OSI model consists of 7 layers: Application, Presentation, Session, Transport, Network, Data Link, and Physical.

Application Layer

• Provides a set of interfaces for sending and receiving applications to gain access to and use network services.
• Responsible for providing services to the user, such as networked file transfer, message handling, and database query processing.

Presentation Layer

• Manages data-format information for networked communications.
• Converts data into a generic format for network transmission and converts data from the generic network format to a format that the receiving application can understand.
• Responsible for protocol conversions, data encryption/decryption, and data compression/decompression.

Session Layer

• Enables two networked resources to hold ongoing communications (called a session) across a network.
• Responsible for initiating, maintaining, and terminating sessions.
• Manages the transmission of data across a network, segmentation of long data streams into smaller data chunks, and reassembles chunks into their original sequence at the receiving end.

Transport Layer

• Handles the delivery of a message from one process to another.
• Responsible for addressing messages for delivery and translating logical network addresses and names into their physical counterparts.
• Decides how transmissions between computers are handled and handles packet switching and network congestion control to route.

Network Layer

• Responsible for the delivery of individual packets from the source host to the destination host.
• Handles special data frames (packets) between the Network layer and the Physical layer.
• Packages raw data from the physical layer into data frames for delivery to the Network layer at the receiving end.

Data Link Layer

• Reassembles data frames into their original sequence at the receiving end.

Physical Layer

• Handles conversion of data into raw formats that can be handled by the Physical Layer at the sending end.

Test your knowledge of the Open Systems Interconnection (OSI) model, a standard for networking and operating system interactions. Learn the 7 layers of the OSI model, from the Physical Layer to the Application Layer.