IEEE Standards for Local Area Networks

The Carrier Sense Multiple Access with Collision Detection (CSMA/CD) media access method is the means by which two or more stations share a common bus transmission medium. This is a comprehensive standard for Local Area Networks employing CSMA/CD as the access method. This standard encompasses several media types and techniques for signal rates from 1 Mb/s to 20 Mb/s. IEEE Standard 802.3-1985 provides the necessary specifications and related parameter values for a 10 Mb/s baseband implementation. In order to achieve greater clarity and flexibility, this document is organized along architectural lines, ie emphasizing the logical divisions of the system and how they fit together. It describes the large-scale separation of the system into two parts: the Media Access Control (MAC) sublayer of the Data Link Layer, and the Physical layer. These layers correspond closely to the lowest layers of the ISO Model for Open System Interconnection (OSI). The LLC sublayer and the MAC sublayer together encompass the functions intended for the Data Link Layer as defined in the OSI model.