Exemplos de aplicação:
- Agente do ArcServe Backup para NetWare
- NetWare Pervasive.SQL v7
- Servidor Lotus Domino
SPX (analogous to TCP) was optimised for LANs, and used per-packet NACKs (packets were assumed to be received instead of explicitly acknowledged) and had no concept of a transmission window.
Compare this with TCP, which uses an ACK for every byte; this also implies that you will buffer all the unacknowledged data and re-send after a lost packet.
However, IPX was not suitable for the WAN. For example, it couldn't cope with different frame sizes. I.e. two networks with different frames (say, Ethernet and Ethernet with jumbo frames) couldn't interoperate without a proxy server or some form of encapsulation.
Additionally, packet reordering in WANs is common but it plays hell with SPX (at least with Novell's implementation) causing a lot of spurious NAKs. Note 1
Finalmente, o IPX / SPX suporta no máximo 20 soquetes em um único nó. Compare isso com o TCP, que suporta o endereçamento de milhares de soquetes simultâneos.
Nota 1 : Desempenho do IPX / SPX e TCP / IP