NSP

This document is the "Network Services Protocol (NSP) Functional Specification, Version 3.1," published by Digital Equipment Corporation in March 1978, detailing a core component of their DECnet Digital Network Architecture (DNA).

It comprehensively describes the syntax and semantics of NSP, which is responsible for establishing interprocess communication mechanisms among nodes in a DECnet network. NSP provides a set of network services, including the management and routing of data, operating under the assumption that underlying physical channels are error-free.

The specification covers:

• The establishment, operation, and termination of logical links between dialogue processes, ensuring guaranteed delivery, sequentiality, and flow control.
• Detailed formats of all NSP messages, including data, interrupt, link service, acknowledgment, and various control messages.
• The interfaces NSP presents to the higher-level dialogue layer and the lower-level physical link control layer.
• Network management functions, such as routing between adjacent and non-adjacent nodes, process identification, access control, node initialization, and handling of node/link failures.
• The various logical link states and their transitions.

This specification serves as a guide for individuals implementing NSP and for those seeking general information about the protocol.