Using the Novell Proprietary Protocols


The workstations and other machines and resources on your network communicate with the NetWare server by using communications protocols. A protocol is a set of rules that specifies how resources move data across the network. In a sense, the protocol is the language that the network and machines on the network use to communicate with each other. It's important that the client and the server speak the same language. Novell has several protocols designed specifically for use on Novell NetWare networks. These proprietary protocols include the following:

  • Internetwork Packet Exchange (IPX) that operates on the Network layer

  • Sequenced Packet Exchange (SPX) that operates on the Transport layer

  • Packet Exchange Protocol (PXP) that operates on the Transport layer

  • Novell Core Protocol (NCP) that operates on the Transport, Session, Presentation, and Application layers

  • IPX Routing Information Protocol (IPX RIP) that operates on the Network layer

  • NetWare Link Services Protocol (NLSP) that operates on the Network layer

  • Service Advertising Protocol (SAP) that operates on the Network, Transport, Session, Presentation, and Application layers

Although the following sections overview all the previously listed protocols, this chapter contains detailed discussion on IPX, SPX, and NCP. Most of the protocols that the following sections discuss are routing protocols. However, neither SPX nor NCP plays a direct role in routing.

When designing the IPX, PXP, and SPX subnet protocols, Novell used the Xerox Network System (XNS) as its springboard because the design of the XNS protocol lends itself readily to LAN (local area network) environments. The XNS design does not lend itself well to WAN (wide area network) environments or their large time delays; neither does its progeny ”the Novell subnet protocols ”work as efficiently as a WAN environment needs. Although the Novell protocols do overcome some of these limitations, they still work best in a LAN environment.

Both IP and IPX use the Routing Information Protocol (RIP), which is a distance vector routing protocol, but the implementations are slightly different. IP RIP and IPX RIP use similar processes for discovering, maintaining, and prioritizing routes. In addition, they both send route requests for obtaining routing information and send periodic route updates to synchronize the routing information tables. IP RIP and IPX RIP differ by virtue of the protocols with which they are associated, the way in which they prioritize routes, and their routing table update intervals.

Note

RIP is considered by the Internet Engineering Task Force (IETF) to be an "interior" routing protocol suitable for use within a specific business entity that uses routers to connect many different LAN segments. These protocols are referred to in the literature as Interior Gateway Protocols (IGP). Another commonly used IGP is the Open Shortest Path First (OSPF) Protocol. When it becomes necessary to connect this network to a larger internetwork, such as the Internet, other routing protocols called Exterior Gateway Protocols (EGP) are used. For more information about routing protocols and how they relate to each other and exchange information, see Chapter 37, "Routing Protocols."

NLSP is an IPX link state routing protocol that Novell developed to overcome limitations of using IPX RIP and SAP in larger internetworks, particularly over WAN links. Link state routers and servers exchange information about their routes to other devices on the network. Using this information, each router can construct the topology of the internetwork and derive routing information. NLSP converges router information tables faster, uses firsthand routing information, and generates less traffic than IPX RIP does. Because of these attributes, network managers can use NLSP to interconnect small or large IPX networks without routing inefficiencies .

SAP extends over the Transport, Session, Presentation, and Application layers. SAP allows file, print, and gateway servers to advertise their services and addresses. The Novell routers keep these services in a Server Information Table (SIT). The server address field includes the full internetwork address, network number, node address, and socket number of the server.

The NetWare Protocol Suite

A protocol suite is a group of protocols that have evolved together ”regardless of whether the same company created them ”or are used in the same environment. Protocol suites have definitions for the interface between protocols that occur at adjacent layers of the OSI (Open Systems Interconnection) model. One such relationship exists in the NetWare protocol suite between IPX in the Network layer and SPX in the Transport layer. The NetWare IPX/SPX protocol suite provides file, print, message, and application services.

For more information about the OSI Networking Reference Model, see Appendix A, "Overview of the OSI Seven-Layer Networking Reference Model."


IPX and SPX compose the Novell NetWare protocol suite. SPX resides in the Transport layer. When compared to the TCP/IP protocol suite, IPX provides routing and internetwork services similar to IP, and SPX provides Transport layer services similar to TCP. IPX and IP are connectionless datagram protocols, whereas SPX and TCP are connection-oriented protocols.

If you are running a mixed NetWare/Windows environment, you will most likely use Microsoft's NWLink implementation of the IPX/SPX protocols. NWLink is an IPX/SPX-based, routable transport protocol that you can use to establish connections between computers running any Windows operating systems. NWLink enables NetWare servers and Windows NT computers to send Novell NetBIOS packets to each other.

Note

NWLink is a useful tool to use when you are migrating an older Windows-based network that uses NetWare's IPX/SPX to a modern network based on TCP/IP. NWLink enables you to keep existing legacy servers that do not understand the IP protocol (such as NetWare 3.x systems) in your network until you can upgrade those servers to a newer version of NetWare, or dispose of the NetWare software entirely, and upgrade your Windows systems to use TCP/IP. In Part XI, "Migration and Integration," you will find that Microsoft has other packages, such as Services for NetWare, that can assist you in making these transitions.



Upgrading and Repairing Networks
Upgrading and Repairing Networks (5th Edition)
ISBN: 078973530X
EAN: 2147483647
Year: 2003
Pages: 434

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