Interfaces between network and application software. Includes authenticatin services.
Defines format and organization of data. Includes encryption.
Establishes and maintains end-to-end bidirectional flows between end points. Includes managing transaction flows.
Provides a variety of services between two host computers including connection establishement and termination, flow control, error recovery, and segmentation of large data blocks inter smaller parts for transmission.
Logical addresssing, routing and path determination.
Formats data into frames appropriate for transmission onto some physical medium. Defines rules for when medium can be used. Defines means by which to recognize transmission errors.
Defines electrical, optical, cabling, connectors and procedural details required for transmitting bits represented as same form of energy passing over a physical medium.