OSI

Open System Interconnection. Interconnection of open systems. Reference standard recommended by ISO (V.) for the connection of systems using telematic networks (V.). The model, independent of the hardware, identifies seven layers or levels. In particular: 1 – Physical layer, establishes the physical elements to make connections (connectors, modems, cables, etc.); 2 – Link layer, organizes the information to be transmitted in packets, or plots, with standard content format (address, sender, messages, controls, etc.); 3 – Network layer, manages the information packets through the network protocols, then sorts them to their destinations; 4 – Transport layer, manages the ordering and delivery of packages to the recipient; 5 – Session layer, checks and corrects communication errors, prepares the information received to be treated locally; 6 – Presentation layer, manages the information already processed to be viewed and printed by the user; 7 – Application layer, user environment in which processing takes place and information exchanges are managed with other users