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Title:Understanding OSI

Author: John Larmouth
Pub: International Thompson Computer Press

ISBN: 1-85032-176-0
Price: 24-95
Disk: N/A


This is one of those companion books that fills in all the background and reasons that bare standards and technical books tend to leave out. To write an OSI stack or comms system you will need other books but to understand why the standard does some “silly” things you will need this book. Then you will see why the “silly” thing was in fact the right idea or in some cases the least wrong option. It explains how the seven layer model came about (and why seven layers in the first place). It explains how the OSI standards generation and documentation works and differs from the CCITT (as was) and the UIT. I can now see why it usually takes a decade to get a standard (and why it will never be less than 6 years).


The part I found particularly useful was the history and developments of ASN.1 There are also examples of X.25, X.400 and X.500. On very useful aspect are the explanations that crop up of other standards where they touch and overlap the OSI system. It is also very good at putting more than just a three word explanation to the TLAs that abound OSI and the industry in general. (TLA = Three Letter Abbreviation)
I would say that this book would be useful to anyone working in the area of comms not just OSI.


The text builds the picture stage by stage explaining the steps and decisions. It is part history and part tutorial without getting to heavy. This makes it readable as a book rather than a reference book one dips into. The style is readable anyway which helps. The many insights will help with tuning ones application to get the most out of the comms. It will also help put one in the correct frame of mind and understanding when faced with the programming standards and specs. I shall be keeping this book on my shelf.