In Lecture #2, we saw a
layered network architecture model which provided
the conceptual framework for the first part of the subject.
We will briefly extend this model today by looking at the
Open Systems Interconnection Reference Model
(OSIRM, or just "OSI").
What is OSI? ...and why do I need to know about it?
Because it's an important part of the history of computer
networks. It's also something you're likely to get asked about
in job interviews, which is where it really
matters...:-)
It's a genuine International Standard (ISO/IEC IS 7498:1993) of
the International Organisation for Standardisation and
International Electrotechnical Committee(ISO/IEC)
Mechanism: working draft --> committee
draft --> draft IS
--> IS, with ballots at each stage.
Was adopted (in part) as the definitive standard for network
architectures by most western governments: GOSIP
National policy to mandate an OSI subset (or profile) for
government systems, discontinued in 1994/5.
Huge and complicated, never fully implemented anywhere
(see GOSIP, as above) although some portions are still (?)
commercially available.
Has had some influence on the Internet community: some upper
layer OSI protocols (eg X.500, X.509, ASN.1) have been adopted in
the Internet.
Lecture 25: The OSIRM
in Brief, also Revision and Exam Preview