Definition: The OSI model defines internetworking in terms of a vertical stack of seven layers. Upper layers of the OSI model represent software that implements network services like encryption and connection management. Lower layers of the OSI model implement more primitive, hardware-oriented functions like routing, addressing, and flow control.
Data communication in the OSI model starts with the top layer of
the stack at the sending side, travels down the stack to the sender's
lowest (bottom) layer, then traverses the physical network connection to
the bottom layer on the receiving side, and up its OSI model stack.
The OSI model was introduced in 1984. Designed to be an abstract
model and teaching tool, the OSI model remains a useful for learning
about today's popular network technologies like Ethernet and protocols like IP.
Examples: Internet Protocol
(IP) corresponds to the Network layer of the OSI model, layer three.
TCP and UDP correspond to OSI model layer four, the Transport layer.
Lower layers of the OSI model are represented by technologies like
Ethernet. Higher layers of the OSI model are represented by application
protocols like TCP and UDP.
1. Short for Open System Interconnection, OSI is a network model developed by ISO in 1978
where peer-to-peer communications are divided into seven layers. Each
layer performs a specific task or tasks, and builds upon the preceding
layer until the communications are complete. Below are the purposes of
each of the seven layers.
1 - Physical layer - responsible for the electrical, mechanical, and timing across the link. 2 - Data link layer (also known as the link layer) - responsible for transmitting data across a link. 3 - Network layer - responsible for routing information through the network and allowing systems to communicate. 4 - Transport layer
- responsible for transferring information between endpoints on the
network and deals with errors such as lost or duplicate packets. 5 - Session layer - responsible for managing a session between two applications. 6 - Presentation layer - responsible for the data formatting and display, allowing for compatibility. 7 - Application layer - responsible for user interaction. An example of an OSI application is the FTAM.
2. Short for Open-Source Initiative, OSI is a non-profit corporation dedicated to managing and promoting Open Source.