Networking Devices and the OSI Model

For a network support person, a basic understanding of the implications of the OSI Model makes the difference between frustration and smooth operations. It is very difficult to maintain and troubleshoot a network without understanding the boundaries created by repeaters, bridges, routers, and switches.

Not separately described here, Layer 7 gateways used to be fairly common, but due to the prevalence of TCP they are not often seen now. A Layer 7 gateway completely reinterprets traffic at Layer 7 to allow communications between dissimilar network operating systems.