The internet is on the way of becoming the principle means of telecommunication. The growing demand for better and reliable on-line services raises issues for managerial and strategic decision processes that often call for sound technical and theoretical solutions. For the last two decades, internet traffic engineering techniques prove to resolve these problems. In this book, we propose efficient mathematical techniques and software tools to solve some critical problems in internet networks. We have designed and developed three generic tools for intra-domain traffic engineering, which we have implemented in an open source software. This software can be downloaded, used and modified freely for general and customized network related purposes. We evaluate the performance of our methods and software using a range of problem instances, in which we demonstrate promising and fruitful results for better and more reliable management of internet networks. This book will be of interest to researchers and graduate students in the area of network optimization and to practitioners, such as internet service providers and large network administrators.