network monitoring and control is performed by a network management system. The monitoring and control of a network or service has a subset of the functions performed by its management system. It mainly involves monitoring the health of the system and controlling the system with corrective actions in trouble scenarios. The network monitoring system discovers the state of the elements in the network at regular intervals of time. A trouble condition identified with a fault log can initi- ate a discovery to find the status of the element. There are multiple network monitoring tools and systems that are available even as open source products. The basic monitoring tool follows server-agent architec- ture with a single monitoring server and multiple agents connecting and sending information to the server. The communication will be based on a predefined pro- tocol that is supported in NMS. Some of the popular protocols are SNMP, CMIP, XMLP, SOAP, NETCONF, and SO on. Some of the protocols will be handled in detail later in this book. Network monitoring can also be seen as a specialized function in NMS. For example a security monitoring system would collect security logs, provide access permissions, create roles, and groups and performs the set of activities to ensure security in an NMS. Likewise, a fault monitoring system is a specialized fault han- dler that collects fault logs, helps to program actions for specific fault scenarios, allows the creation of user-defined logs and performs a set of actions that would be of importance from a fault perspective. As a result of the various functionalities, monitoring solutions or specialized functions are available as stand-alone tools. Control functions associated with monitoring are usually simple controls like in security monitoring, the control function might involve preventing the user to log in by locking the account if there are three consecutive failed attempts with a wrong password or in a fault monitoring tool there controls to selectively clear certain faults. These 