1 Opportunities and Application Scope Because of its costs, DWDM is more suited to longer-reach applications at this time. This situation could change in the future if developers begin to grasp what the real requirements are in the metro access/metro core space. For long-haul applications, DWDM offers a cost-effective complement to OC-48/OC-192 time-division multiplexing (TDM) technology that is embod- ied in SONET/Synchronous Digital Hierarchy (SDH) systems. Assuming a decent-quality fiber plant, WDM methods enable the planner to maximize network capacity and address service scalability needs. In addition, because it defers-or eliminates-the capital outlays and long lead times associated with deploying new fiber cable, DWDM is a useful solution for high-growth routes that have an immediate need for increased bandwidth. Carriers that are building or expanding their long-haul networks could find DWDM to be an economical way to incrementally increase capacity, rapidly provision needed expansion, and "future proof" their infrastructure against unfore- seen bandwidth demand. Network wholesalers can take advantage of DWDM to lease capacity rather than entire fibers either to existing opera- tors or new market entrants. However, in aggregate, DWDM technology is not cheap. Systems can cost from $50,000 to $100,000 per lambda, particu- larly when redundant and long-reach applications are considered. Further- more, these figures do not include the cost of the repeaters. Systems costing from $0.5 million to $1 million or more are not unusual. Power consumption and floor space requirements are usually high, and unless tunable laser sys- tems are available, complex design/engineering and sparing disciplines are involved, requiring plug-ins that are specific to the given lambdas. Further- more, future proofing may in fact imply that after a route upgrade, there is no need for additional equipment for several years; this is, therefore, bad news for equipment suppliers. The proponents typically present diagrams similar to the r