As others have noted, the book is not a solid OSPF technical reference. There's lots of introductory networking info in here.The book is also absolutely FULL of errors. Figures and text that disagree, sample path cost calculations that are wrong, and on and on. I found myself keeping track of which I saw more of in each chapter: errors or pages.Oh, and for OSPF... Right off the bat the author launches into a bit-by-bit (literally) examination of all the different packets an OSPF process might generate. It was absolutely maddening to read the details of how OSPF accomplishes something without first getting an overview of WHAT was being accomplished.sigh.This is my first amazon review, written explicitly because of how frustrated I am with this book.