Supervising the Network

7-12
Maintaining the NetWare Server
About NetWare Networking Protocols
the Open Systems Interconnection (OSI) model. This model specifies how
protocols should be defined in the future. The OSI model separates the
functions required for effective computer communications (such as error
checking and addressing) into the following seven catagories or layers.
These layers are Application, Presentation, Session, Transport, Network,
Datalink, and Physical.
The protocols used by NetWare do not all correspond exactly to the OSI
model definitions. NetWare uses a variety of protocols. Some were
developed specifically for NetWare; some are used throughout the
networking industry. The protocols required for communications between
NetWare workstations and file servers are as follows:
• Medium-access Protocols (MAC) provide bit-level (0,1) error checking.
• IPX provides the best connectionless transport.
• SPXII provides a guaranteed delivery, session-oriented transport.
• Routing Information Protocol (RIP) maintains routing information and provides
routing services to IPX.
• Service Advertising Protocol (SAP) provides dynamic service advertising on the
network.
• NetWare Core Protocol™ (NCP™) defines connection control and service
request encoding for client/server interaction.
Medium-Access Protocols (MAC)
MAC protocols (such as 802.5 Token-Ring or 802.3 Ethernet) provide bit-
level error checking through cyclic redundancy checking (CRC). This CRC
which is added to every transmitted packet, assures that 99.9999 percent of
the packets received are corruption free.
MAC protocols define the addressing for each node on a NetWare network.
This addressing is provided by each network interface card.
Internetwork Packet eXchange (IPX)
The IPX protocol is a datagram, connectionless protocol that does not
require an acknowledgement for each packet sent. Other NetWare protocols
such as SPXII, SAP, RIP, and NCP are built on top of IPX.