Internetwork Packet Exchange
lastmod 2018-08-17created 2018-07-311 edits
IPX (short for Internetwork Packet Exchange) is an OSI model network layer protocol in the IPX/SPX protocol stack. The IPX/SPX protocol stack is supported by Novell's NetWare network operating system. As NetWare became popular from the late 1980s to the mid-1990s, IPX became well known as an internetworking protocol. Novell derived IPX from the Xerox Network Services IDP protocol.
With the popularity of TCP/IP driven by the Internet boom, IPX went into decline. Because computers and networks can run multiple network protocols, almost all IPX sites came to run TCP/IP as well for Internet connectivity. Also, as NetWare moved to version 5 and above and came to support both IPX and TCP/IP, Novell's products can also run without IPX.
IPX addressing
- Logical networks are assigned a unique 32-bit hexadecimal address. (Range 0x1 to 0xFFFFFFFE)
- Hosts have a 48-bit node address. By default it is set to the MAC address of the LAN card. This node address is appended to the network address to create a unique authenticator for the network host.
- The network address 00:00:00:00 means the current network address.
- The broadcast (sent to all) address is FF:FF:FF:FF.
Similarity to IP
An IPX network address is conceptually identical to the network part of an IP address. (The part where the netmask bits are set to 1) The node address has the same meaning as "the bits of the IP address where the netmask bits are set to 1". Because the node address is usually the same as the MAC address of the network adapter, the Address Resolution Protocol is not needed.
For routing, entries in an IPX routing table are similar to those in an IP routing table. Routing is done by network address, and for each network address the network:node of the next router is specified in a way similar to how the IP address/netmask is specified in an IP routing table.