Foreword

With the Internet continuing to expand, the need for robust and flexible IP routing protocols to sustain the expansive global routing system can never be overemphasized. Of all the IP routing protocols that evolved alongside the Internet, only three of them survived the test of time and are currently widely deployed: BGP for exterior routing, and OSPF and IS-IS for interior routing.

The IS-IS Protocol has emerged as one of the universally adopted and widely used Interior Gateway Protocols, besides OSPF. BGP remains the de facto Exterior Gateway Protocol for interdomain routing. IS-IS is used as an IGP by most of the Tier 1 and Tier 2 Internet service providers for both practical and historical reasons. The wisdom and insight of the original protocol designers and subsequent pragmatic contributions by the IETF manifest in the protocol's flexibility can be easily adapted for many emerging applications, such as MPLS Traffic Engineering and IPv6. The scalability and extensibility of the IS-IS protocol made it an obvious choice for IGP when I directed the design and deployment of one of the largest existing IP backbones several years ago. Our high confidence and comfort level allowed us to run both IP and ISO routing in a single instance of IS-IS.

Many networking professionals have longed for a readable tutorial and design guide on this popular protocol. The original specification of the IS-IS protocol, ISO 10589, is a tough indoctrination for most people interested in grasping fundamentals of operation of IS-IS. Additionally, several enhancements to the original IS-IS protocol, including RFC 1195 and many recent related RFCs and IETF drafts, are not captured in one place for easy access by interested readers.

This book provides the first, most extensive coverage of the IS-IS protocol, written and reviewed by networking experts with many years of practical experience designing, deploying, and troubleshooting IS-IS-based networks and also working with advanced routing systems. Having firsthand experience with the challenges and fun in deploying and using IS-IS to its full potential, I only wish this excellent book had been available sooner.

IS-IS Network Design Solutions by Abe Martey certainly augments the list of excellent literature on internetworking technology brought to many networking professionals worldwide by Cisco Press in fulfilling one of its primary goals ”sharing Cisco's networking expertise! This book is a key reference for anyone interesting in IGP deployment and evolution.

Tony  Bates,  VP/GM
Internet  PoP  Systems  Business  Unit
Cisco  Systems,  Inc.