Changes from First Edition

There are several factors influencing the changes contained in this second edition. The first factor is the CCIE itself. When I (Jeff) wrote the first edition of this book, the CCIEspecifically what is now called the Routing and Switching specialty of the CCIEwas the only certification Cisco Systems offered. Now, there is a series of certifications creating a path to the CCIE at the pinnacle. Moreover, the typical networking professional is more knowledgeable than in 1997. Given this, we have eliminated the first chapter of the original book, which covered such very basic concepts as the definition of bridges and routers and network addresses. (When was the last time you even saw a bridge in a network?)

The second factor influencing the changes in this edition is the changes in the Cisco Systems IOS. IGRP, which was frequently used when the first edition was written, is now a legacy protocol whose main significance is as the ancestor of EIGRP. Therefore the IGRP chapter of the first edition has been eliminated and IGRP is covered for historical perspective early in the EIGRP chapter. The IOS command suite itself has expanded to accommodate new functions and options; we have made every effort to include the commands and protocol extensions that did not exist in the late 1990s.

Lastly, a protocol that existed mostly only in proposal form in 1997IPv6is now in the early stages of worldwide deployment. You can expect to need a detailed knowledge of this protocol and the extensions to IP routing protocols that support it in the near future, if not already, so this second edition delves deeply into routing IPv6.

Other changes in this edition are semantic. For example, in the first edition, I (Jeff) made a point of differentiating between a "network" as a data link and an "internetwork" as a set of networks connected by routers. Although that terminology is certainly accurate, it is clumsy, and "internetwork" is seldom used these days. Instead, "network" usually refers to everything from a local link to worldwide autonomous systems operated by the likes of Level 3, NTT, and Sprint. We have attempted to bring the terminology in this edition up to modern, common usage.