This book is about problems and methods in managing communication networks. The kinds of networks under consideration include enterprise networks (i.e. those that are typically owned and managed by businesses) and service networks (i.e. those that are owned by service providers but leased to businesses). Given the increasing dependence of human activities and business on networking, the topics of managing them and keeping them healthy are especially important. The book is divided into three parts. The first part describes the special characteristics of business and service networks, standards and common practices in managing networks, architectures of network management systems, and a close look at one popular network management system. The second part consists of three case studies: managing a micro city network, managing a service provider network, and managing an Internet2 GigaPoP network. The third part discusses future directions of network management. It looks at current research activities in network management, current practices in the field, the problem of combining research and practice, and finally discusses directions towards a comprehensive network management system.