System information

CHAPTER
Troubleshooting DECnet 11-249
11
Troubleshooting DECnet
Digital Equipment Corporation (Digital) developed the DECnet protocol family to provide a
well-thought-out way for its computers to communicate with one another. The first version of
DECnet, released in 1975, allowed two directly attached PDP-11 minicomputers to communicate.
In more recent years, Digital has included support for nonproprietary protocols, but DECnet remains
the most important of Digital’s network product offerings.
DECnet is currently in its fifth major product release (sometimes called Phase V and referred to as
DECnet/OSI in Digital literature). DECnet Phase V is a superset of the OSI protocol suite and
supports all OSI protocols as well as several other proprietary and standard protocols that were
supported in previous versions of DECnet. As with past changes to the protocol, DECnet Phase V is
compatible with the previous release (Phase IV, in this case).
Digital Network Architecture
Contrary to popular belief, DECnet is not a network architecture at all but is, rather, a series of
products conforming to Digital’s Digital Network Architecture (DNA). Like most comprehensive
network architectures from large systems vendors, DNA supports a large set of both proprietary and
standard protocols. The list of DNA-supported technologies grows constantly as Digital implements
new protocols. Figure 11-1 illustrates an incomplete snapshot of DNA and the relationship of some
of its components to the OSI reference model.