 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 network element. An SNMP (simple network management protocol) agent is used for collecting data from a network element that supports SNMP. The agent will issue commands Data collection components XML/TL1 mediation mediation mediation agent agent agent Figure 11.2 Data collection blocks for specific protocols. Fundamentals of EMS, NMS and OSS/BSS like "Get" and "Get-Next" to browse the data in the network element. It should be kept in mind that not all network elements can respond to SNMP queries from the agent on the NMS. The network element should be maintaining a MIB (manage- ment information base) with configuration details and also generate logs