3Com 2500 manual Elements, Intranetwork, Service Advertising Protocol SAP

6-8 CHAPTER 6: ROUTING WITH IPX

The Elements of	IPX routers use the following elements to transmit packets over an
IPX Routing	intranetwork:
■	Router interfaces
■	Routing tables
■ Service Advertising Protocol (SAP)
Router Interfaces	A router interface is the connection between the router and the network
	number (address). In traditional routing models, the interface would be the
	same as the port, because only one interface can exist per port.

In the LANplex system’s IPX routing, more than one port can be connected to the network number. Therefore, the router interface is the relationship between the ports and the network number (address) in your IPX network.

Each router interface has a network address. This address defines the network number to which the router interface is attached. The router interface’s IPX address serves two functions:

■It is used when sending IPX packets to or from the router itself.

■It defines the network number of the segment connected to that interface.

Routing Tables A routing table holds information about all the network segments. It allows a router to send a packet toward its ultimate destination using the best possible route. The routing information table contains an entry for every network number that the router currently knows exists. A router uses the routing information table when the destination network number of the packet it is sending is not on a network to which it is directly connected. The routing information table provides the immediate address of a forwarding router that can forward the packet toward its destination.

The routing table consists of the following elements:

■Interface — Identifies the number of the router’s interface that will be used to reach the specific network segment.

■Address — Identifies the addresses for segments that the router currently knows exists.