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Industrial Communications Handbook
By Mick Crabtree
Chapter 4: Internet Protocol
Today, the almost universally used protocol stack of choice is what is officially designated the ‘Internet Protocol Suite’ – more commonly referred to as TCP/IP. The TCP/IP protocol stack is a complete suite of protocols, named after its two most important protocols:
• Transmission Control Protocol (TCP)
• Internet Protocol (IP)
The TCP/IP architecture is based on a four-layer model that was originally developed as part of a military project commissioned by the Advanced Research Projects Agency (ARPA) – later known as the Defence Advanced Research Projects Agency (or DARPA). The communications model used to construct the system is still known as the ARPA model. When compared with the seven-layer Open Systems Interconnection (OSI) model, it can be seen that although they were developed by different bodies at different points in time, both serve as models for a communications infrastructure with a high degree of similarity.