IPX and SPX are derived from Xerox Network Services' IDP and SPP protocols, respectively. IPX is a network layer protocol (layer 3 of the OSI Model), while SPX is a transport layer protocol (layer 4 of the OSI Model).
A D V E R T I S E M E N T
The SPX layer sits on top of the IPX layer and provides connection-oriented services between two nodes on the network. SPX is used primarily by client/server applications.
IPX and SPX both provide connection services similar to TCP/IP, with the IPX protocol having similarities to IP, and SPX having similarities to TCP. IPX/SPX was primarily designed for local area networks (LANs), and is a very efficient protocol for this purpose (typically its performance exceeds that of TCP/IP on a LAN). TCP/IP has, however, become the de facto standard protocol. This is in part due to its superior performance over wide area networks and the Internet (which uses TCP/IP exclusively), and also because TCP/IP is a more mature protocol, designed specifically with this purpose in mind.
- SAP - Service Advertising Protocol packets are used by file and print
servers to periodically advertise the address of the server and the services
available. It works at the application, presentation, and session levels.
- NCP - NetWare Core Protocol provides for client/server interactions such
as file and print sharing. It works at the application, presentation, and
- SPX - Sequenced Packet Exchange operates at the transport layer
providing connection oriented communication on top of IPX.
- IPX - Internetwork Packet Exchange supports the transport and network
layers of the OSI network model. Provides for network addressing and
routing. It provides fast, unreliable, communication with network nodes
using a connection less datagram service.
- RIP - Routing Information Protocol is the default routing protocol for
IPX/SPX networks which operates at the network layer. A distance-vector
algorithm is used to calculate the best route for a packet.
- ODI - Open Data-link Interface operates at the data link layer allowing
IPX to work with any network interface card.
NetWare frame types
Novell's original NetWare client was written for DOS. Initial versions required a hard-linked protocol stack, where a separate executable would be created by the network administrator for each network card configuration on the network. This executable would be loaded at boot time, and remain resident in memory until the system was shut down. Later implementations allowed the network stack to be loaded and unloaded dynamically, using pre-existing modules. This greatly simplified maintenance of client workstations on the network.