Preface

Sitting in my office at Cisco on the third floor of building K, I read an e-mail from Kathy Trace from Cisco Press asking if I was interested in writing a book. She had read my technical tips that I had written for Cisco Connection Online and said that she wanted me as an author for Cisco Press. I was very enthusiastic about it and said to myself , "Yeah! It's a great idea! Let's write a book!" But on what subject?

One of the topics that I had in mind was OSPF. Johnson used to sit right in front of my office at that time. I asked him, "Hey, Johnson! You want to write a book with me?" He screamed, "A book!" I said, "Yeah, a book! What do you think?" He thought for a minute and said, "Well, what is left for us to write a book on? Cisco Press authors have written books on almost every routing topic ‚ . But there is one subject that has not been covered in one single book ‚ troubleshooting IP routing protocols."

Apparently, Johnson got the idea to write a troubleshooting book from his wife. Whenever Johnson's wife calls him at work, he has to put her on hold because he is busy troubleshooting a customer's problem. His wife, whose name is also Cisco, then gave him the idea of writing a troubleshooting book so that customers would have a troubleshooting guide on routing protocols that they can refer to so that they can successfully solve their problems before opening a case.

The idea was indeed great. No books had been written on this particular subject before. I then called Zaheer, who was attending IETF 46 in Washington, D.C., and told him about this; he also agreed that the idea was a good one. So now we had a team of three TAC engineers who had spent the last three to four years in TAC dealing with routing problems ‚ and each one of us was an expert in one or two protocols. Our manager, Raja Sundaram, used to say, "I want you to pick up a protocol and become an expert in it." My area of expertise was OSPF, Johnson was a guru of EIGRP and multicasting, and Zaheer shone with his BGP knowledge. Very soon, we realized that we were missing one important protocol, IS-IS. Our exposure with IS-IS was not at a level that we could write a whole chapter on troubleshooting IS-IS, so Zaheer suggested Abe Martey for this job. Abe was already engaged in writing a book on IS-IS with Cisco Press, but after seeing our enthusiasm about this book, he agreed to become a member of our author team.

When we started working on these chapters, we realized that we were working on something that a routing network administrator had always dreamed of ‚ a troubleshooting book that contains solutions for all the IP routing protocol problems. The data that we collected for this book came from the actual problems we have seen in customer networks in our combined 20 years of experience in troubleshooting IP networks. We wanted to make it a one-stop shop for troubleshooting guidance and reference. So, we provided the "understanding protocols" chapters along with troubleshooting to help you, the reader, go back to a specific protocol and refresh your memory. This book is also an excellent resource for preparation for the CCIE certification. This book should teach you how to tackle any IP routing problem that pops up in your network. All possible cases might not be discussed, but general guidelines and techniques teach a logical approach for solving typical problems that you might face.

Syed Faraz Shamim