NonIP

Non-IP refers to communications protocols and networks that do not use the Internet Protocol (IP) for addressing and routing. In contrast to IP-based networks, non-IP systems rely on their own network and transport layer technologies, often built around vendor-specific architectures. Non-IP networks were common in many enterprises during the 1980s and 1990s, particularly in local area networks and some WANs, before TCP/IP achieved widespread dominance.

Common examples of non-IP networking include IPX/SPX used by Novell NetWare, AppleTalk used on Apple devices, and DECnet developed by Digital Equipment Corporation. Other non-IP approaches include X.25-based networks and other era-specific protocols that provided routing, error handling, and flow control without IP. These systems typically employed distinct addressing schemes and custom transport methods, sometimes providing tight integration with specific operating systems or hardware.

In practice, many non-IP networks were used alongside IP or gradually migrated to TCP/IP. Gateways and protocol translators were developed to interconnect non-IP networks with IP networks, enabling broader communications and Internet connectivity. The migration was driven by the universality, scalability, and wide ecosystem of IP, as well as standardized TCP/IP services such as HTTP, DNS, and email.

Today, non-IP networks are largely historical or specialized, surviving mainly in legacy or niche environments where legacy hardware and software require non-IP protocols. They are studied for historical insight into network evolution and for understanding multi-protocol interoperability in mixed-network environments. See also AppleTalk, IPX/SPX, DECnet, and X.25 for related non-IP technologies.