What are the layers of the OSI reference model?
OSI stands for Open Systems Interconnection. It is a reference model for how applications can communicate over a network. It describes the communication functions of a system; so that a product or software program can define how it will interoperate will other products and software programs.
The OSI reference model breaks down the functions into seven layers, which are as follows:
Layer 1: Physical Layer – Transmission and reception of raw bit streams over a physical medium
Layer 2: Data Link Layer – Reliable transmission of data frames between two nodes that are connected by a physical layer
Layer 3: Network Layer – Structuring and managing a multi-node network, including addressing, routing and traffic control
Layer 4: Transport Layer – Reliable transmission of data segments between points on a network, including segmentation, acknowledgement and multiplexing
Layer 5: Session Layer – Managing communication sessions, i.e. continuous exchange of information in the form of multiple back-and-forth transmissions between two nodes
Layer 6: Presentation Layer – Translation of data between a networking service and an application; including character encoding, data compression and encryption/decryption
Layer 7: Application Layer – High-level APIs, including resource sharing, remote file access