omposes the original request into multiple service-provisioning requests for each domain manager. Domain managers then use the inventory in the NMS database to design the service within the domain, assigning NEs to be traversed, ports to be used and channels to be allocated. Domain managers may also implement appropriate routing to calculate path based on source, destination and QoS requirements. For example, an ATM domain manager is capable of assigning VPI/VCI values and QoS parameters; an optical domain manager will be able to assign wavelengths and setup appropriate protection mechanisms; and an IP domain manager will be able to create routing entries, assign IP addresses and setup IP-QoS variables. Once the path is designed, NE configuration commands are sent to each EMS managing the target NEs. The EMS then uses the native device protocol to configure the resources on the NE. This multi-level provisioning process is transactionally controlled at each level by domain and inter-domain managers. Vendor provided packages and legacy systems can be positioned The Ultimate Guide to Building and Delivering OSS/BSS at appropriate levels of this architecture framework to create a system blueprint. Trouble Ticket System Trigger Service Ticket for Reconfiguration Service Fault Fault Customer Service Service User- Correlation Design Info Provisioning Defined Rules Root Network Fault Inventory Fault Events Fault Fault Root Cause Filtering Aggregation Analysis Logical Integrated NMS Database Fault Fault Fault Legacy Events Events Events Performance Fault Violations Management Fault Fault Fault Performance Collection Collection Collection Manager SNMP Trap, Syslog, etc. Legacy DSL Access Core IP and Optical Transport Network ATM Switching Figure 42. Multi-Domain Service Provisioning Framework 3.1.3 Fault Management Fault Management is an important OSS function since it monitors and detects network failures and allows providers to take appropriate actions to fix them SO as to keep the network running and customer services f