dtj v01-03 sep1986

This Digital Technical Journal (Number 3, September 1986) from Digital Equipment Corporation provides a comprehensive overview of the company's networking products, primarily focusing on the evolution and implementation of its Digital Network Architecture (DNA) and DECnet.

The document details how Digital's networking strategy progressed from early, limited systems to a robust, large-scale distributed computing environment. Key areas covered include:

1. Digital Network Architecture (DNA) Overview: The journal outlines DNA's design goals (common user interface, wide range of facilities/topologies, availability, extensibility) and traces its evolution through four phases (Phase I to IV), culminating in Phase IV's support for Ethernet, X.25, and hierarchical addressing, enabling networks of thousands of nodes.
2. Performance Analysis and Modeling: Articles discuss how analytical modeling, simulation, and measurements were critical in optimizing DECnet's performance across various layers, including physical (adapter placement), data link (buffering), network (path splitting), and transport (flow control, timeouts).
3. Cross-Vendor Networking: The DECnet/SNA Gateway Product is presented as a case study, explaining how Digital's network products interact with IBM's Systems Network Architecture (SNA), addressing challenges in architecture, protocols, and network management for cross-vendor communication.
4. Extended Local Area Network (LAN) Architecture: The LANBridge 100 is introduced as the first product implementing the Extended LAN Architecture, designed to expand the physical extent, number of stations, and throughput of LANs, while transparently connecting different LAN technologies.
5. Terminal Servers on Ethernet LANs: The Local Area Transport (LAT) protocol is highlighted as a solution for flexible, cost-effective connections between terminals and hosts over Ethernet, detailing its unique directory service, load balancing, and efficient character transport.
6. Operating System Implementations of DECnet: Dedicated articles describe the integration of DECnet software into Digital's major operating systems:
   • DECnet-VAX: Emphasizes tight coupling with VMS for transparency, allowing remote services to appear local.
   • DECnet-ULTRIX: Focuses on incorporating DNA capabilities into UNIX, expanding the socket interface, and building network management structures compatible with the UNIX environment.
   • DECnet-DOS: Details the challenges and solutions for bringing full DECnet functionality to MS-DOS personal computers, including background tasking and network programming services.
7. Network Management Products: The journal covers the evolution of network management, culminating in the NMCC/DECnet Monitor design. This system provides centralized monitoring, fault diagnosis, performance analysis, and configuration management for complex, diverse DECnet networks.

In essence, the document serves as a testament to Digital's leading role in developing and implementing robust, high-performance, and interoperable networking solutions in the mid-1980s, showcasing how these technologies were transforming computing.