Fiber Distributed Data Interface System Level Description

This document, titled "Fiber Distributed Data Interface System Level Description," published by Digital Equipment Corporation in May 1991, provides a comprehensive overview of the Fiber Distributed Data Interface (FDDI) standard and Digital's specific implementation of it.

Targeted at users familiar with basic networking concepts, the manual introduces FDDI as a 100-Mb/s, timed-token ring, fiber optic local area network defined by ANSI standards (PMD, PHY, MAC, and SMT). It highlights Digital's recommended "dual ring of trees" network topology, emphasizing its benefits in reliability, scalability, and maintainability.

The document details the various FDDI components:

• Concentrators: Central to Digital's topology, providing connection points for stations and other concentrators, and offering fault isolation capabilities.
• Bridges: Devices connecting FDDI LANs to other LAN types (e.g., 802.3/Ethernet), focusing on a translation process rather than encapsulation.
• Adapters: Connect end-user devices to the FDDI ring, typically as single attachment stations (SAS) through concentrators.

Key technical concepts covered include data encoding (4B/5B and NRZ/NRZI), clock recovery, ring operation (token handling, claiming, beaconing), and addressing schemes. It also describes Digital's enhancements, such as the Frame Content Independent Stripping and Ring Purger algorithms, which improve network robustness by reliably removing "No Owner Frames."

Furthermore, the manual outlines Digital's network management capabilities, based on its Enterprise Management Architecture, detailing functions like configuration, fault detection, performance monitoring, accounting, security, and troubleshooting tools for effective network administration. Practical planning and configuration guidelines for implementing FDDI networks with Digital's products are provided throughout.