Networking Self-Teaching Guide: OSI, TCP/IP, LANs, MANs, WANs, Implementation, Management, and Maintenance

Chapter 8. The Upper Layers

	Protocol is everything.
	--Francois Giuliani[278]

The above quote is truly succinct, a real economy of words. This quote is not only true at the United Nations but also is easily applied to the networking environment. When you think of the mix of various equipment, wiring, networking operating systems, computer operating systems, programs running on servers as multiuser platforms, programs running on local computer workstations (which includes pretty much anything a person can hang off a network segment), the ability to communicate is essential. The United Nations uses translators to ensure that all the representatives from the many varied nations can understand the procedures. A network protocol also acts as a translator between the many subcomponents that we lump together under the word "network."

We would hate to think what a General Assembly meeting of the United Nations would look and sound like without the translators they employ. There is only one word that comes to mind: chaos. How would you ever be able to get anything done? The same goes for networks, except things move much faster than the world's fastest talker can utter even a single word. So protocol is truly everything in the networking world.

This chapter investigates the upper layers of the OSI reference model: the Application layer, the Presentation layer, and the Session layer. We will identify the "translators" being used so that information can flow smoothly and without error between ...