Sequenced Packet Exchange (SPX) is a protocol in the

IPX/SPX IPX/SPX stands for Internetwork Packet Exchange/Sequenced Packet Exchange. IPX and SPX are networking protocols used initially on networks using the (since discontinued) Novell NetWare operating systems. They also became widely used on netwo ...

protocol stack The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the ''suite'' is the definition of the communication protoco ...

that corresponds to a

connection-oriented Connection-oriented communication is a network communication mode in telecommunications and computer networking, where a communication session or a semi-permanent connection is established before any useful data can be transferred. The establish ...

transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end ...

protocol in the

OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...

. Being reliable and connection-oriented, it is analogous to the

Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly ...

(TCP) of

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

, but it is a datagram protocol, rather than a stream protocol.

SPX packet structure

Each SPX packet begins with a header with the following structure: The Connection Control fields contains 4 single-bit flags: The Datastream Type serves to close the SPX connection. For this purpose two values are used:

External links

SPX, Sequenced Packet Exchange

IPX / SPX Packet Structures
Novell NetWare Transport layer protocols {{network-stub