The Open System Interconnection (OSI) reference model was developed by the International Organisation for Standardisation (ISO) as a model for a computer protocol architecture and as a framework for developing protocol standards. The OSI Model includes 7 layers which are Physical, Data Link, Network, Transport, Session, Presentation and Applications (Ince 2004 p.41).
The TCP/IP Protocol Architecture is a result of protocol research and development conducted on the experimental packet-switched network, ARPANET, funded by the Defense Advanced Research Projects Agency (DARPA), and is generally referred to as the TCP/IP protocol suite. It has 5 independent layers which are Application, Transport, Internet, Network Access and Physical (Stalling 2005 p.106).
Stalling (2005) points out that the overall OSI model has been never flourished due to the following reasons:
- The key TCP/IP protocols were mature and well tested at a time when similar OSI protocols were in the development stage.
- When business began to recognize the need for interoperability across networks, only TCP/IP was available and ready to go.
- Compared with the TCP/IP Protocol Architecture, the OSI model is unnecessarily complex with 7 layers.
Today Internetworking has highly adopted the TCP/IP architecture. The TCP/IP network has been dominating the market while there are many communications choices available, standardising on one particular protocol can make administration easier and reduce costs and complexity. Reduced complexity can also translate into increased up time and reduced configuration time. Sometimes we would still maintain more than one protocol in a network owing to some legacy systems and applications. For examples, keeping TCP/IP, AppleTalk and IBM Systems Network Architecture (SAN) protocols in a network will incur a lot of costs for translating data which can be accepted and communicated among all of them.
References
Ince D 2004, ‘Developing Distributed and E-commerce Applications’, 2nd edn, Pearson Education Limited, Edinburgh Gate Harlow Essex CM20 2JE, pp.41-42.
Stallings W 2005, ‘Business Data Communications’, International Edition, 8th edn, Pearson Education, Inc., Upper Saddle River, NJ 07458, pp.97-128.
