viders (ASPs), and web-hosting sites are in the tens of gigabits per sec- ond, rivaling the rates carried in core systems and prompting the use of optical networking in such high-rate LANs. Simultaneously, applications such as site and/or server mirroring and corporate intranets require these high rates to be supported over new or existing MANs. 11 1.2 The Panoply of Technologies and Architectures MANs play a vital role in connecting users to WAN services. Traditionally, MANs have been circuit-switched networks that are optimized for voice traffic using the SONET/SDH circuit-switched layer. LANs, on the other hand, are packet-switched networks that are optimized for data traffic using Ethernet technology. This is quickly becoming the dominant traffic source driving bandwidth demands in MANs and WANs. The consequence of carrying packet traffic on circuit-switched networks is that it is ineffi- cient at the bandwidth level. New packet-switched MAN and WAN archi- tectures and technologies are needed that are optimized for data traffic with carrier-class operational performance attributes. Will this new archi- tecture be Ethernet at the core metro or next-generation SONET with Eth- ernet handoffs? Planners need to understand the trade-off between efficiency, complexity, transparency, flexibility, manageability, and cost effec- tiveness. More specifically, metrics might include security, reliability, speed, throughput, access/backbone cost, equipment cost, sustainability, and mar- gins (which also factor in operations/management costs). Figure 1-6 exem- plifies such trade-offs. Chapter 1 Security Figure 1-6 An example of a Margins Reliability multidimensional Architecture/ trade-off space for a Technology 1 carrier's deployment Architecture/ of broadband Technology 2 services. Architecture/ Technology 3 Architecture/ Sustainable Technology 4 Speed Service Throughput Equip. Cost Access/ Backbone cost Industry groups, such as the Institute of Electrical and Electronics Engi- neers (IEEE), are now developing new metropol