Sequenced packet exchange (SPX) protocol

Sequenced packet exchange (SPX) protocol

SPX is a connection-oriented, reliable, sequenced transport protocol. SPX provides a packet-level service, while enhanced SPXII provides a message-level service.

SPX guarantees packet delivery to the destination endpoint and notifies the user if any errors occur during data transmission. Upon encountering a data transmission error, SPX retries a given number of times before closing the connection and notifying the connection user. SPX also notifies the user if a disconnection indication is received from the remote connection endpoint.

SPX also provides flow control. This regulates the speed with which packets are sent and received by both the sending and receiving processes.


NOTE: The SPX information in this topic provides a baseline from which to understand SPXII, the enhanced protocol. The NetWare® protocol stack does not include an SPX driver. However, the SPXII driver provides backward compatibility with SPX, both on the wire and in the programming interface.


© 1999 The Santa Cruz Operation, Inc. All rights reserved.
UnixWare 7 Release 7.1 - 19 March 1999