Understanding Ip Routing And Rip - Bay Networks 5390 Administering

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Internet Protocol (IP) Routing

Prerequisites

This chapter assumes that:

Your Model 5390 server is attached to the network and both are operational.

Any hosts you want to reach are attached to the Ethernet or the Model 5390 server and links

to them have been proven to work.

Any modems you intend to use have been tested in the conﬁguration in which you intend to

use them. For example, testing a modem for dial-in and thereby assuming dial-out works is

not sufﬁcient.

RIP is the primary routing application on your network and you know which routers are

running it; you also know which RIP version (1 or 2) the routers are running.

You understand RIP. Read the remainder of this chapter, and if you need more information,

consult the sources cited at the end of the chapter.

Understanding IP Routing and RIP

IP routing is the process of determining the best path to follow to deliver a piece of data, contained

in an IP datagram, to its destination on a

TCP/IP network. Only a simple network, in which all systems directly attach to a single LAN, does

not require routing. But a simple network can easily grow into an internet—a collection of multiple,

interconnected networks —where routing is required to reach hosts on distant networks. Special

machines called routers connect two or more networks to each other and route packets from one to

Routers use routing applications to learn and generate routing information. The Model 5390 server

uses RIP, an application that runs on top of the transport-layer protocol UDP (User Datagram

Protocol), for this purpose. Through information broadcast by other RIP routers, the Model 5390

server maintains a routing table containing up-to-date routes to various destinations on local and

remote networks. (This table also contains AppleTalk routes.)

Deﬁnition of a Route

The information a RIP router broadcasts contains the network addresses in the router's routing table

and the number of routers (including itself) that must be crossed to reach these addresses. Each