Networking / Beginners

The Internet Model

The OSI model was very successful at getting people to concentrate on the specifics of a network implementation. However, implementations based directly on it were not popular, principally because they were complex and quite slow. By sticking too rigidly to the layers and following the principle of insulation between the layers it is difficult to get any real speed from an implementation.

Another model, the TCP/IP Reference Model, also called the Internet Reference Model and the Department of Defense Four-Layer Model, was developed by DARPA in the 1970 with the principles of the Internet in mind: namely, resilience to damage and flexibility of application.

This is a four layer model, in contrast to the OSI model's seven (Figure below).

OSI vs. TCP/IP
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In this tutorial:

  1. Layering Models
  2. The Seven Layer Model
  3. The Physical Layer
  4. The Data Link Layer
  5. The Network Layer
  6. The Transport Layer
  7. The Session Layer
  8. The Presentation Layer
  9. The Application Layer
  10. How the Layers Fit Together
  11. Why Layers and Encapsulation?
  12. The Internet Model
  13. The Link Layer
  14. Models and Protocols
  15. Comparing OSI and Internet Models