An explanation of my OSI (Open Systems Interconnect) Halloween costume.

routEing
IS-IS=0
presentation
session
TP4 with dual connections
interoperability in a circle-slash
H.323
waterfall specs

=====================

COMMITTEE FIRST
IMPLEMENT LATER

The biggest mistake OSI made. Software is designed *without* working
models. THe IETF (Internet Engineering Task Force) doesn't allow
this; proposers *must* have working model systems. Only through actual
experience are most protocol deficiencies discovered.

This can also be described as using the "waterfall" model for specifications.

=====================

COPYRIGHTED $$$ SPECS

Which is why there are no freeware versions of OSI stuff,
and no textbooks describing the protocols in detail.

=====================

ROUTEING [SIC]
IS-IS = 0

OSI likes to spell "routing" with an extra e. That's the British
spelling, rather deprecated in the United States.
IS-IS is the "Intermediate Systems - Intermediate Systems"
routing protocol that OSI likes to use; intermediate systems
are basically like TCP/IP routers. The transformation to an
equation, IS minus IS = 0, was from a famous joke T-shirt
at an Internet meeting at which IS-IS was defeated as an
Internet protocol.

(There is actually nothing wrong in principle with IS-IS.)

=====================

PRESENTATION & SESSION LAYERS

OSI introduced these layers. TCP/IP gets along without them.
To this day, they have no clearly defined uses.
(*Maybe* the TLS layear is a Presentation layer; see the Intro chapter)

=====================

NONINTEROPERABILITY

Back in the 1980's and early 1990's, many OSI applications
failed to interoperate, because vendors were so legalistic
about the specifications.  Failure to interoperate was often taken
to be a sign that ones own product was *so* strictly written
that it showed up bugs in the other guy's stuff.

Unfortunately, "strictly" written is not the same as "well" written.

=====================

LEGALESE

OSI documents are *full* of this.

=====================

Scary, eh?  ;-)