MCSA/MCSE 2003 JumpStart

Using IPX/SPX

Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) is a proprietary protocol that Novell developed for use with its NetWare software product. Because it is proprietary to Novell, it is not as commonly used as TCP/IP.

IPX works primarily at the Network layer. Its main function is to route packets through an internetwork and to identify devices. If connection-oriented services are not needed, IPX is also used to send packets through the Transport layer.

SPX functions at the Transport layer. It provides connection-oriented, fully duplexed connections. For each packet that is sent, an acknowledgement is returned. In addition, SPX is responsible for segmenting data into packets and maintaining a sequence number for each packet. The receiving computer uses the number to reassemble the data.

Benefits of IPX/SPX

IPX/SPX shares similar benefits to TCP/IP in addition to its own, including:

• IPX addressing uses more bits per address, so there is a greater supply of addresses.

• SPX is a reliable, connection-oriented protocol.

• Upper-layer protocols can bypass SPX in some cases to improve performance.

• The MAC address of the NIC/interface is built into the IPX address, eliminating the need for logical to physical address resolution.

Disadvantages of IPX/SPX

Consider these disadvantages before implementing IPX/SPX:

• IPX/SPX is considered a chatty protocol, meaning it creates a significant amount of network traffic that does not involve transferring data.

• IPX/SPX does not work on the Internet.

• IPX/SPX is proprietary, meaning that it is not a standard that other companies can use.