13.1 INTRODUCTION

This chapter reviews a routing protocol for an IPv6 Internet. It is rooted in both the protocols and algorithms that are extensively used in the IPv4 Internet. This specification depicts a new version of the Inter-Gateway Routing Protocol (IGRP) which will be used with IPv6 as well as other protocols.

When dealing with a very large network like the Internet, it is improbable that one routing protocol will be employed for the whole network. Instead, the network is organized as an aggregate of Autonomous Systems (AS) administered by one individual; it has its own routing technology that may vary with each AS. The routing protocol employed within an AS is called an Interior Gateway is referred to as an Exterior Gateway Protocol (EGP) used to transfer routing information among the ASs. IGRPng is created to work as an IGP in moderate to large size ASs operating IPv6. IGRPng is not appropriate for very large complex networks. In this event, OSPF is a superior routing protocol.

IGRPng integrates many of the useful features of IGRP. This is particularly intended to yield stable routing in large networks. This stability is accomplished by preventing routing loops from happening. IGRPng employs a vector of metrics to distinguish how good a path to a destination really is. This allows physical characteristics to be integrated into the routing decision regarding what path to choose for any given destination. The ability to associate physical characteristics with routing data assists in managing complex configurations in large...