en, S. Jain et al., Broadband Infrastructure BusinessEdge Solutions Inc. 2003 The Ultimate Guide to Building and Delivering OSS/BSS modular, scaleable and re-usable OSS components that can be quickly developed and assembled, and easily integrated. Since the next-generation OSS may never completely replace the existing systems, new applications must co-exist with the legacy environment, and this will present its own challenges. In the past the old systems were modified, albeit in a non-optimized manner, to support new features functions. As a new breed of OSSs are developed to support new networks, and since the old network and its supporting systems are not going away anytime in the near future, integration of OSS functions across these systems will be a key challenge. Answers to questions such as how do we integrate inventory data housed in a legacy system with inventory that was auto- discovered by a next-generation inventory module, and how do we correlate faults across legacy and new systems - one managing the traditional SONET physical layer and the other the IP layer - will define success or failure. THE DRIVING FORCE: THE NEXT- GENERATION NETWORK (NGN) Multiple forces are causing a fundamental evolution in networking today, transforming the network, as we now know it, into a next-generation network. Some of the key trends include more intelligence in the network elements, a move to a packet/cell based network model, an evolution towards an IP-based network core, the delivery of QOS-enabled services, and convergence of the telecom, enterprise and internet network domains. Figure 30 illustrates this evolution. Chapter 8 - Next-Generation OSS Intelligent Network Network ATM and IP Core FR Core Circuit Packet Switched Switched Guaranteed Best-Effort Separate Telecom Converged Enterprise Networks Networks Internet Figure 30. The Network Evolution 1.1 Driving Intelligence into the Network The network elements of the past were primitive compared to those of today and those that are on the horizon. The "old" netwo