|This tutorial reviews the evolution and the advancements of converged WDM architectures, initially in the multi-service metro networks, and currently into an IP-over-WDM core. We analyze the functionality, characteristics, and challenges of these networks. We also discuss the key applications that motivated these networks to scale levering WDM transport. The tutorial then focus on the emerging intelligent WDM converged transport layer which improves significantly the network capital and operational cost. We evaluate the interplay among the network architectures, and the enabling technologies, most notably including OADM and switching, optical amplification and dispersion compensation, electronic processing (FEC, EDC) etc. Unlike traditional WDM transport where the main design objective has been to maximize the capacity and reach of networks with typically well-defined (often simple point-to-point) topologies, converged WDM networks call for cost-sensitive, “open” architectures that allow for service flexibility. We discuss in detail the innovation in WDM system design, and the most important performance characteristics of the current and emerging optical technologies that enable high performance metro-optimized fiber transmission digital systems, that cost-effectively scale to multiple 10 Gb/s wavelengths and more than 1000 km, meeting the diverse needs of current and future enterprise and residential applications. We further review the future evolution in metro networks, along with the important related research topics. We then review the currently emerging converged IP-over-WDM core network architectures, and identify the related promise in CapEx and OpEx efficiencies. For these core networks, flexibility remains the primary motivation but scalable 40 Gb/s WDM transport for thousands of km becomes also important. We review the future evolution in these networks, along with the important related research topics.
Loukas (Lucas) Paraschis is Technical Leader in the Advanced Technology and Network Planning team of Core Routing at Cisco Systems, responsible for the next generation optical technologies, R&D, and network architectures. At Cisco, he has primarily worked on WDM networks, multi-service metro and IP-over-WDM core architectures, network availability and techno-economical analysis. Prior to Cisco, Loukas completed his graduate studies at Stanford University (PhD 1999, MS 1998), and worked as an R&D engineer. He has (co)authored more than 40 peer-reviewed technical publications, multiple invited, keynote, and tutorial presentations, technical reports, and three patent disclosures. He has been editor for optical networks in JCN, guest co-editor for JLT (Nov. 2004), panelist in National Science Foundation (NSF), and member of conference organizing committees, IEEE, and SPIE. Loukas was born and raised in Athens, Greece, where he completed his undergraduate studies.