Short for Sequenced Packet Exchange,
a transport layer protocol
(layer 4 of the OSI Model
) used in Novell Netware networks
. The SPX layer sits on top of the IPX
layer (layer 3) and provides connection-oriented services between two nodes on the network. SPX is used primarily by client/server
Whereas the IPX protocol is similar to IP, SPX is similar to TCP. Together, therefore, IPX/SPX provides connection services similar to TCP/IP.