Today, it is the main protocol used in all Internet operations. TCP/IP also is a layered protocol but does not use all of the OSI layers, though the layers are equivalent in operation and function ...

"OSI transport services" include layers 1 through ... The most ubiquitous example is the IP protocol in TCP/IP (see TCP/IP). IPX, SNA and AppleTalk are examples of earlier routable protocols ...

While some people may argue that the OSI model is obsolete (due to its conceptual nature) and less important than the four layers of the TCP/IP model, Kumar says that “it is difficult to read ...