The Ethernet

This document, "The Ethernet: A Local Area Network: Data Link Layer and Physical Layer Specifications," is a comprehensive technical specification for the Ethernet protocol. Developed collaboratively by Digital Equipment Corporation, Intel Corporation, and Xerox Corporation, it details the Data Link and Physical Layers of the Ethernet architecture, aligning with the lowest layers of the ISO Model for Open Systems Interconnection.

The specification is structured into seven sections, covering an overall description, goals, functional model, and detailed specifications for both the Data Link and Physical Layers. It emphasizes simplicity, low cost, compatibility, addressing flexibility, fairness, progress, high speed, low delay, stability, maintainability, and a layered architecture as key design goals. It explicitly states that full duplex operation, advanced error control, security, speed flexibility, priority, and protection against malicious users are not goals of the design.

The document describes the Data Link Layer as medium-independent, responsible for framing, addressing, and error detection. The Physical Layer is medium-dependent, providing a 10 MBit/sec physical channel through a coaxial cable, handling data encoding and channel access. It outlines the interfaces between these layers and defines the frame format, including address fields, type field, data field, and frame check sequence.

The specification details transmission and reception processes, including handling of contention and collisions through CSMA/CD. It also provides a procedural model for the Data Link Layer using Pascal and describes the physical channel's characteristics, interfaces, configuration, and environmental requirements. Appendices offer a glossary, notes on address and type assignment, CRC implementation details, and circuit diagrams for typical transceiver cable drivers and receivers.