DNA: The Digital Network Architecture

Recognizing the need to share resources and distribute computing among systems, computer manufacturers have been designing network components and communication subsystems as part of their hardware/software system offerings. A manufacturer's general purpose network structure must support a wide range of applications, topologies, and hardware configurations. The Digital Network Architecture (DNA), the architectural model for the DECnet family of network implementations, has been designed to meet these specific requirements and to create a communications environment among the heterogeneous computers comprising Digital's systems. This paper describes the Digital Network Architecture, including an overview of its goals and structure, and details on the interfaces and functions within that structure. The protocols implementing the functions of DNA are described, including the motivations for the specific designs, alternatives and tradeoffs, and lessons learned from the implementations. The protocol descriptions include discussions of addressing, error control, flow control, synchronization, flexibility, and performance. The paper concludes with examples of DECnet operation.