The Question is:
I had heard that TCP/IP services in os versions earlier than v5.5-2 were
unstable and unreliable, but many of these problems were fixed in later
versions. Is this correct?
The Answer is :
The OpenVMS Wizard encourages the use of the current releases and the
current ECOs of all products, except where specific local requirements
prevent this use.
As part of the typical software development process, problems that are
identified in older releases are typically fixed in later releases.
This means that problems that have been encountered in earlier product
releases are normally addressed by ECO kits and (more commonly) by new
product releases -- there is a limit to the complexity of a problem that
can be addressed by an ECO kit. If you choose to use an older product
release, you may well spend time and effort resolving problems that have
been addressed by more recent product releases.
The OpenVMS New Features and Release Notes manuals for releases after
V5.5-2, as well as the various ECO kits for OpenVMS and for TCP/IP
Services, will provide you with some general information on problems
that have been resolved in later product releases. There are other
fixes and there are also product enhancements available in later
product releases, obviously.
OpenVMS and layered products typically provide good upward-compatibility.
This means that user-mode code -- and kernel-mode code on OpenVMS VAX
V6.0 and later -- is expected to be upward-compatible across OpenVMS
upgrades. A need to rebuild user-mode code not expected and not typical.
(Assuming the code lacks latent bugs, uses documented interfaces, etc.)
The software upgrade process is of course itself not entirely without
some risk -- once in a while, a new product release does provide a new
The earliest OpenVMS VAX release with Prior Version Support (PVS) is
V5.5-2, with the current release (as of this writing in August 2001)
being V7.3. Prior Version Support contracts for TCP/IP Services
require particular versions for particular OpenVMS releases -- the
OpenVMS FAQ has pointers to PVS information.