The main network protocols (see Layer 3 of the OSI Model) are TCP/IP, NetBEUI, AppleTalk and IPX/SPX. In the early 1990’s, no one was sure which of these protocols would prevail, since the Internet, though in existence, hadn’t really "happened" yet and was not fully understood or appreciated by PC OS manufacturers.

As the Internet developed, and as programs like Mosaic and later Netscape came onto the scene, the need to provide world-class, robust networking exploded and TCP/IP’s place was secured. TCP/IP had been developed by military and academic researchers throughout the 1970’s and 80’s. It was very robust and proved early on to be an efficient protocol that could be scaled up to the needs of massive networks, eventually to become what it is today, the primary protocol of the Internet and most all large LANs. TCP/IP has less layers than the OSI Model, but manages to handle the traffic of the Internet and very large campus LANs.

Although Novell’s IPX/SPX protocol was powerful, its proprietary nature kept it from being widely adopted outside the small business LAN market. NetBEUI is less robust and was mainly limited to smaller business LANs.

AppleTalk is a protocol (not to be confused with the Signaling Scheme of LocalTalk) that was not well thought out when scaled to larger sized networks. Originally conceived to handle no more than 256 total nodes, Apple foolishly created AppleTalk Phase II in July of 1989 which permitted this inefficient, chatty protocol to be used on a network of (256)²⁵⁶ nodes. This led to its adoption on large campus LANs where it reeked havoc in the early to mid 1990’s, bringing entire campus LANs to their knees with its inefficiencies.  Since that time, AppleTalk has become a non-routed protocol on most large networks (more than 800 nodes), usually relegated to reside within a TCP/IP Class C size (256 node) network.