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Many networking textbooks are guilty of propagating this conundrum of networking. This is unfortunate. It's also almost as bad as Microsoft continuing to include detailed coverage of Ethernet barrel connectors, terminators and the like in its Networking Essentials test-training material. There simply is no excuse for it -- nor for a networking giant like Cisco to include material in its networking industry certification exam that serves no purpose but to confuse and bamboozle.

So why do network-certification exams and college textbooks continue to exhibit such mindless loyalty to the OSI model? One argument is that it helps us understand the important concepts of layering, modularity and encapsulation of network protocols. These concepts are indeed fundamental to comprehending how networks function -- which is my point exactly. Why make it more confusing than necessary?

My decision to ignore Layers 5 and 6 has served me well. I've been successfully engineering, troubleshooting and managing networks for about 15 years and have spent countless hours with developers to diagnose difficult problems with multilayered, networked-based client/server applications. Layers 5 and 6 have never been an issue. Sure, things happen on a network that fit somewhere between the application and the transport layers, but that doesn't mean we should attempt to force them into the contrived explanations of Layers 5 and 6 in college textbooks and CCNA prep materials.

My advice to Cisco: Remove requirements for knowledge of Layers 5 and 6 from the CCNA test immediately. You have no excuse for distracting future network engineers with this drivel. And for those of you writing a textbook that covers the OSI layers, replace the usual contrivances that attempt to make sense out of Layers 5 and 6 with the following: Historical artifacts; no longer relevant.