DECnet-20 System Manager's and

This document serves as the "DECnet-20 System Manager's and Operator's Guide," updated in June 1983. It provides a comprehensive overview of the operational, control, and monitoring functions for DECnet-20 and the TOPS-20 Packetnet System Interface (PSI) product, which together enable DECSYSTEM-2040S/2060 computers to communicate with DIGITAL's corporate DECnet and Public Packet Switching Networks (PPSNs).

The manual is intended for system managers and operators, detailing the Digital Network Architecture (DNA) model, its layered structure, and the specific implementation of DECnet-20 Version 3.0 (Phase III). It covers key network concepts such as nodes, data links, the PSI Gateway (for X.25 PPSN access), and adaptive routing.

Key areas of focus include:

• System Operations: Detailed procedures for automatic and manual startup and restart of DECnet-20 components (e.g., DN20 communication front end, ORION, NMLT20, X29SRV, DN200). It also explains downline loading, upline dumping, and methods for identifying and resolving network problems using tools like SPEAR and loopback tests.
• Network Control Program (NCP): A thorough explanation of the NCP command language, which is the primary interface for network management. Commands are categorized by their processing mechanisms (OPR, NCP/NML, NML) and cover a wide range of functions for configuring, monitoring, and controlling network entities (nodes, circuits, lines, and event logging).
• DECnet-20 Options and Compatibility: Information on the RJE-20 Version 2.0 (Remote Job Entry) and PSI Version 1.0 (X.25 Packet Switching Network Interface) options, including their hardware requirements and co-existence limitations. It also addresses compatibility between Phase II and Phase III DECnet nodes.

The document is supplemented with appendices that summarize DECnet parameters, counter statistics (including X.25 specific counters), network-related messages, recognized line devices, and X.29 file definitions.