wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

ISO/OSI Model 1-9
Layer 7 Layer 7
M7
Layer 6
Layer 6
M6
Layer 5
Layer 4
Layer 3
Management
Layer 5
Layer 4
Layer 3
M5
M4
M3
Management
Layer 2
Layer 2
M2
Layer 1
Layer 1
M1
FIGURE 1.11
Adding management units. Mn: management n {n: 1 to n}.
1.5 Extensions, Benefits, and Discussion
The ISO/OSI model is the first model of its kind. It provides a template for the design of protocols and
has proven useful over decades. Since its definition, many different protocols have been defined using
the ISO/OSI model. Telecommunication relies on it, just like fieldbus systems in automation use it. It
has been refined over the years, for example, by introducing a management for automatic handling of
different protocol layers as shown in Figure 1.11.
The developer has to decide how to add management systems. For smaller stacks, one management
for the whole stack will be sufficient, for bigger stacks each layer will get its own management, and additionally,
the whole stack will have an integral management. In such a system, it is necessary to introduce
priorities, since error handling has to be considered.
The main advantages as we see them today are modularity, a clear top-down design, independence
of the layers, the possibility to handle errors in each layer, the functional description, and the resulting
possibility to implement in either hardware or software. Disadvantages of a design according to
the ISO/OSI model are the overhead, which can become considerable, and the fulfillment of real-time
requirements.
References
[Hay 88] Hayes, J. P., Computer Architecture and Organization, McGraw-Hill Series in Computer
Organization and Architecture, 2nd edn, McGraw-Hill, New York, 1988, p. 500.
[Leo 00] Leon-Garcia, A. and Widjaja, I., Communication Networks, McGraw-Hill, New York, 2000, p. 51.
[Loy 05] Loy, D., Fundamentals of LonWorks/EIA-709, ANSI/EIA-709 protocol standard (LonTalk), in:
The Industrial Communication Technology Handbook, CRC Press, Boca Raton, FL, Zurawski, R.
(Ed.), 2005, p. 35-1.
[Ols 92] Olsen, A., Færgrgemand, O., Møller-Pedersen, B., Reed, R., and Smith, J. R. W., Systems Engineering
Using SDL 92, Elsevier Science B. V., Amsterdam, the Netherlands, 1994, ISBN 0-444-89872-7.
[Zur 05] Zurawski, R. (Ed.), The Industrial Information Technology Handbook, CRC Press, Boca Raton,
FL, 2005, p. 37-1.
© 2011 by Taylor and Francis Group, LLC