DELNI ETHERNET Local Network Interconnect Technical Manual

This document is a Technical Manual for the DELNI (DIGITAL Ethernet Local Network Interconnect), a hardware communications device developed by Digital Equipment Corporation in July 1984.

The manual provides comprehensive information for field service engineers on the DELNI unit, which is designed to create various types of Local Area Networks (LANs) for Ethernet-compatible stations using the Carrier Sense Multiple Access/Collision Detect (CSMA/CD) protocol.

Key areas covered include:

• Overview: Describes the DELNI as a hardware device for interconnecting Ethernet stations and its nine communication interfaces (eight local, one global).

• Operational Modes: Details the two selectable modes:

  • LOCAL Mode: Communication occurs solely among devices connected to the DELNI's local connectors.
  • GLOBAL Mode: Communication involves both local and global connectors, allowing connection to larger Ethernet networks.

• Network Configurations: Explains how DELNI units can be used to form:

  • Standalone DELNI LANs (up to 8 stations).
  • Two-Tier DELNI LANs (up to 64 stations, by cascading multiple DELNIs).
  • Connected DELNI LANs (up to 8 stations connected to a broader Ethernet via a single transceiver).

• Functional Description: Outlines the DELNI's core functions, including signal transmission and reception, heartbeat signaling, and collision detection and signaling in both operational modes.

• Physical and Electrical Specifications: Provides dimensions, weight, power requirements, environmental conditions, and detailed electrical characteristics of its communication interfaces (transmit, receive, collision presence, and power pairs), including signal levels, impedance, and timing relationships.
• Functional Theory of Operation: Describes the internal circuitry and how various components (like data concentrators, routers, and collision detectors) contribute to the unit's overall operation.
• Maintenance: Includes procedures for logic module and connector board removal and replacement.

The document serves as a detailed guide for understanding the design, operation, and servicing of the DELNI unit.