Management function components Data collection components Figure 11.1 Legacy NMS building blocks. What Is NMS? North bound interface (NBI) components: These components provide man- agement data to the north bound interfaces like another NMS or operations support systems (OSS). GUI components: These provide user interaction screens that enable a user to perform operations on the various modules in the NMS. These building blocks and the open source components that can be used in making these blocks are discussed in detail in the sections that follow. The data col- lection components can collect data directly from the network elements or from an EMS. In legacy NMS, solutions and products available from leading NMS vendors, the data collection was done usually from the network elements with interfaces that permit collection of data from an EMS or other NMS solution. Use of standard interface and shared data models as in next generation has led to much reuse of the NMS functional components. A network management system will also have a database for storing the raw or formatted data. The presence of a database avoids re-query for historical data from an NMS to the network element. The historical data can be stored into a full- fledged database to which SQL-based commands are executed to send and receive data or it can be maintained as flat files or compressed flat files. 11.4 Data Collection Components The data collection components collect data from the network elements using a specific protocol (see Figure 11.2). The protocol used can be a proprietary protocol specific to the company implementing the network element and the management application, but in most scenarios a standard management protocol is used. Use of a standard protocol promotes flexibility, SO that the data collection agent imple- mented for the specific protocol can be reused to collect data from another network element that supports the same protocol. Also a standard protocol will allow agents from different vendors to be used to collect data from a