 services The key benefit of the service is that users hand us an Ethernet signal directly. They do not need SONET equipment or expertise WorldCom has Ethernet service plans of its own These authors are publishing a companion set of two books that explore rapidly evolving architectures, products, technologies, and business mod- els, particularly from a metro access/metro core perspective, where all the action now is. The two books will prove useful to planners in carrier, ser- vice provider, and enterprise environments. It will also prove useful for decision-makers, technology developers, and for students. It also should prove useful to Venture Capitalists who wish to deliver some profits to their investors. Within the two books, one book looks at traditional-but-fast-improving architectures while the other looks at evolving architectures. Architec- tures, technologies, and services for high-end commercial applications are explored in detail in both books. This book looks at Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH) and the power- ful new Next-generation SONET, while the other book looks at Ethernet- based metropolitan area and wide area architecture such as Virtual LAN (VLAN), Rapid Spanning Tree Algorithm (RSTA), Resilient Packet Ring (RPR), wide-area 10 Gigabit Ethernet, and other Ethernet-based systems. The two books contrast these architectures to multilambda rings. Ring- versus-mesh-architectures are also studied. This book, SONET-Based Metro Area Networks: Planning and Design- ing the Provider Network, focuses on the significant advances in optics and Next-generation SONET approaches, with features and services that can rival what the new Ethernet architectures can offer. Can Ethernet- based architecture scale in size, robustness, reliability, and carrier OAM&P capabilities as the Next-generation SONET systems? Chapter 1 sets the stage for an assessment of the advances in SONET systems that enable them to compete with new architectures. Chapter 2 provides a short primer on opt