Publisher Summary Network management is essential to operate and maintain any network. Operating costs dominate equipment costs for most telecom networks, making good network management imperative in ensuring the smooth operation of the network. The main functions of network management include configuration (of equipment and connections in the network), performance monitoring, and fault management. In addition, security and accounting are also management functions. Most functions of management are performed through a hierarchy of centralized management systems, but certain functions, such as restoration against failures, or the use of defect indicators to suppress alarms, are done in a distributed fashion. Several management protocols exist, the main ones being transaction language-1 (TL-1), simple network management protocol (SNMP), and common management information protocol (CMIP). Interoperability between equipment from different vendors is a major issue facing the industry today. Initially the focus was on trying to get interoperability between vendors at the wavelength division multiplexing (WDM) level, but that has been recognized now as being very complex. The level of transparency offered by the optical network affects the amount of management that can be performed. Key performance parameters such as the bit error rate can only be monitored in the electrical domain. Fast signaling methods need to be in place between network elements to perform some key management functions.