restoration, and maintenance activity. Distribution: Data filtered at the network manager or service logs created by aggregating multiple network level logs gets distributed to several service management modules and other network management modules. the distri- bution channel can lead to business level modules like order management and customer trouble management. Next let us look into quality assurance, which ensures that the service pack- age after activation meets the guaranteed performance levels as per the customer specific SLA. Quality assurance is handled by customer QoS/SLA management, service quality management, and network performance management modules. A set of attributes that are classified under network, service, and customer levels are defined for measuring quality. These attributes are monitored by the quality assur- ance management modules. Some of the attributes monitored by network performance management mod- ule are: Latency: It is the time delay between the initiation of an event and the moment the effect begins. There are different types of latency. - Propagation latency corresponding to time delay for travelling from source to destination. Again propagation latency can be calculated as one way or round trip. - Transmission or material latency is the time delay cased in transmission due to the medium used for transmission. The response from a system may not be instantaneous upon receiving the request. The delay in response caused due to processing of request leads to processing latency. - There are other forms of latency like synchronization latency, caused when communication occurs between two systems that have different processing capability due to factors like difference in buffer size or proces- sor speed. The latency caused due to the mismatch can lead to flooding of the system with lower capacity. Fundamentals of EMS, NMS and OSS/BSS Throughput: It is a measure of successful message delivery over a communication channel. The most popular unit of throughput is bits/sec. There are differ