NMS/EMS

NMS (Network Management System) – responsible for end-to-end management of a network composed of network elements from multiple suppliers. Instead of directly managing network elements, it relies upon the capabilities of the EMS(s).it may contain only network management layer functionality to manage one or more EMS(s).

EMS (Element Management System) – typically provided by a network element supplier and capable of managing multiple network elements of that supplier. An EMS may communicate with one or more NE(s) on an individual or collective basis.
 

Fault management (FM) is usually mentioned as the first concern in network management. Its main role is to ensure high availability of a network.

The functions of FM can  be broadly divided in to three parts

• Event Collection
• Event/Alarm Processing
• Generating Info/Reports

All the faults in the system/network are notified as events. Events are the source of information for all the management happenings that take place within the FM system.

An alarm is characterized by a sequence of related events (having same alarmKey), such as port-down and port-up.  The last event in the sequence determines the severity and state of the alarm. An alarm that ends with an event that has a severity of cleared is called a cleared alarm. 

Normally the management systems(EMS/NMS) notifies the events to the interested parties through SNMP/Corba/TCP mechanisms.