Perle Systems IOLINK-520 manual IPX Routing and The IOLINK-PRO & 520 Routers, IPX Addressing

Introduction

IPX Routing and The IOLINK-PRO & 520 Routers

The IOLINK router may be used to route between IPX networks.

Novell Netware uses a suite of protocols for LAN communications. The Novell protocols include IPX, SPX, RIP, SAP, plus others, and operate at layers 3 and above. These protocols, their relationship with each other, and the general operation of a Novell network are discussed in this section.

The Netware Network Operating System implements the concept of “Client-Server” computing. In this system, there are various Servers, such as File Servers, Print Servers, and Fax Servers, to name a few. The Client stations, where the users work, connect to these servers to retrieve files, get application software, or submit print jobs. Most of the interaction between the Clients and Servers is invisible to the users. These operations rely on the transfer of packets between Clients and Servers using the IPX/SPX protocols.

IPX Addressing

The IPX protocol is based on the Xerox XNS protocol. The IPX header contains all the IPX addressing information, and not much else.

Network Layer Addressing vs. MAC Addressing

An Ethernet frame has at least two levels of addressing. The MAC addresses for both the source and destination are contained in the MAC header. The MAC addresses are essentially physical port addresses, and are globally unique. Hardware vendors encode the port MAC address as part of the manufacturing process. All Ethernet devices have the same MAC address format. The MAC address is used to communicate frames between LAN ports regardless of protocol.

The Network layer addressing is assigned by the network administrator, in a format prescribed by the layer 3 protocol, for example IPX. The network address is used to structure the network system and for communications between ports operating the same protocol.

Note that it is possible for a single network port to have several different network addresses, but it can have one and only one MAC address. An example of this is a computer acting as an IPX File Server, an IPX Router, and an IP Router. In this case the port would have a MAC address, an IPX address for its IPX functions, and an IP address for the IP Routing functions.

IPX Address Format

The IPX Address is made up of three components: the Network Number, the Node Number, and the Socket Number. These components are fixed length (unlike the IP addressing) and function.

Figure 1 - 3 IPX Address Format

Network Addresses

The Network Number addresses the network. All stations on the same “network” will have the same Network Number. Note that a network could be a single segment, or multiple segments joined by either bridges or repeaters. In IPX internetworks, routers must be used to join different networks together.

1.8— IOLINK-PRO & 520 Reference Manual