 architectures and technologies, but recently most have been implemented by deploying DWDM systems and securing OC-x links (for example, OC-3s, OC-12s, and OC-48s) to overlay data networks onto the bearer transport network. In MANs and WANs, there is a nontrivial deployment of telco-managed fiber-optic rings for narrowband services. These rings are currently using telephony-centric protocols (such as TR-303) that do not scale to the demands of packet networks in general and broadband in particular. These demands include reducing equipment and operational cost, improving the speed of deployment, supporting bandwidth allocation and throughput, and providing resiliency to faults. Emerging optical products must be optimized for the metro-edge portion of the network, where commercial buildings (typ- ically in the range of several thousand per city, or about 735,000 nation- wide, as of 2000) need to be connected in an effective and high-speed manner to the carrier's SNs. Chapter 1 There has been a lot of hype in the recent past about metro DWDM. When the long-haul industry saw major retrenchments at the turn of the decade, optical vendors took the easy course of taking the equipment that they had developed for long-haul applications and pasting a metro DWDM label onto the equipment. This was done while generating new marketing collaterals rather than redeveloping equipment that is optimized for metro access/metro core applications (as would have been appropriate). We have argued that the window of opportunity of metro DWDM is very limited. Finally, the following quotes bring some satisfaction: "With SO much unused fiber, when will metro nets really need WDM? What are the requirements for 40-Gbps systems? What are the new economic trade-offs between trans- parency and grooming? And which of the new service providers will suc- ceed?"10 Some brandname vendors have products that would cost several hundred thousand dollars per building. This is totally untenable because carriers generally need to keep their in-building cost