Internetwork Packet Exchange (IPX) is the network-layer protocol in the IPX/SPX protocol suite. IPX is derived from Xerox Network Systems' IDP. It also has the ability to act as a transport layer protocol.

The IPX/SPX protocol suite was very popular through the late 1980s and mid-1990s because it was used by Novell NetWare, a network operating system. Due to Novell NetWare's popularity, IPX became a prominent protocol for internetworking.

A big advantage of IPX was a small memory footprint of the IPX driver, which was vital for DOS and Windows up to Windows 95 due to the limited size at that time of conventional memory. Another IPX advantage was easy configuration of its client computers. However, IPX does not scale well for large networks such as the Internet. As such, IPX usage decreased as the boom of the Internet made TCP/IP nearly universal.

Computers and networks can run multiple network protocols, so almost all IPX sites also ran TCP/IP, to allow Internet connectivity. It was also possible to run later Novell products without IPX, with the beginning of full support for both IPX and TCP/IP by NetWare version 5 in late 1998.

A big advantage of IPX protocol is its little or no need for configuration. In the time when protocols for dynamic host configuration did not exist and the BOOTP protocol for centralized assigning of addresses was not common, the IPX network could be configured almost automatically. A client computer uses the MAC address of its network card as the node address and learns what it needs to know about the network topology from the servers or routers – routes are propagated by Routing Information Protocol, services by Service Advertising Protocol.

A small IPX network administrator had to care only

Each IPX packet begins with a header with the following structure:

The Packet Type values are: