IPX/SPX
The Internetwork Packet Exchange is a NetWare communications protocol used to route messages from one node to another. IPX
packets include network addresses and can be routed from one network to
another. An IPX packet can occasionally get lost when crossing networks, thus IPX does
not guarantee delivery of a complete message. Either the application has to
provide that control or NetWareÆs SPX protocol must be used. IPX provides services at layers 3 and 4 of the OSI model (network and transport layers).
The Sequenced Packet Exchange is the NetWare communications protocol used to
control the transport of messages across a network. SPX ensures that an entire
message arrives intact and uses NetWareÆs IPX protocol as its delivery mechanism. Application programs use SPX to
provide client/server and peer-to-peer interaction between network nodes. SPX
provides services at layer 4 of the OSI model.