Preface to the Current Edition Optical networking has matured considerably since the publication of the last edition of this book in 2002. A host of new technologies including reconfigurable optical add/drop multiplexers and sophisticated modulation formats are now mainstream, and there has been a significant shift in telecommunications networks migrating to a packet-over-optical infrastructure. We have incorporated many of these into this revised edition. In Chapter 2, we expanded the discussion on multimode fiber and added sections on photonic crystal and plastic fibers. Chapter 6 has been rewritten with new sections on Generic Framing Procedure, Optical Transport Network, and Resilient Packet Ring (RPR). The coverage of Synchronous Optical Networks (SONET) now includes Virtual Concatenation (VCAT) and the Link Capacity Adjustment Scheme (LCAS). There is also expanded coverage of Ethernet and Multiprotocol Label Switching (MPLS) that includes the development of these technologies to support carrier grade