DECnet Digital Network Architecture Phase IV Maintenance Operations Functional Specification

This document, titled "DECnet Digital Network Architecture Phase IV Maintenance Operations Functional Specification," describes the structure, functions, interfaces, and protocols essential for low-level maintenance of a DECnet network (Phase IV).

It focuses on maintenance operations that do not depend on high-level network software, instead relying directly on data link services. The key functional areas covered are:

1. Communications Testing: To determine if the data link path is operational (e.g., Loop Tests).
2. System Console Access: Providing low-level remote access for tasks such as identifying processors, reading data link counters, booting systems, and general console input/output.
3. System Load/Dump: Facilitating the copying of processor memory to (loading) or from (dumping) a remote system.

The document details:

• Models: How these low-level maintenance operations fit within the DECnet Network Management Layer and directly interact with the Data Link Layer, outlining "requester" (active) and "server" (passive) roles.
• Interfaces: Programmatic interfaces for basic data link functions (open, close, transmit, receive), user-level maintenance operations (Dump/Load, Loop Test, Remote Console), and network management controls (enabling/disabling functions, setting parameters).
• Operation: The algorithms and procedures that govern these functions, often compatible with the Maintenance Operation Protocol (MOP) version 2.1.
• Protocol Messages: The binary formats for the messages exchanged to perform these maintenance tasks.

Appendices provide predefined values for various communication devices, data link types (DDCMP, LAPB, Ethernet), implementation-specific characteristics for PDP-11 dump/load programs, and a detailed section specifically on Ethernet Loop Testing.