e foresee- able future, as anecdotal information18 tends to show. The camp that sup- ports native data interfaces asks the following rhetorical question: Given that WAN traffic from the enterprise into the metro network is primarily Ethernet data today and it is likely to continue to dominate in the future, should the conventional view that legacy private line services are the most efficient means for metro optical networking be challenged? In the long term (three to five years out), metro optical networking based on Ethernet native LAN interfaces is likely to become prevalent. This is because there is addi- tional cost for Ethernet router vendors to adapt native data interfaces into Chapter 5 private-line interfaces (DS1, DS3, and OC-x) using what are referred to as telecom adapters. The additional cost translates into private-line interfaces costing as much as three to four times more than native LAN interfaces (100Base-T and GbE). In addition, the cost of GbE interfaces is expected to drop rapidly as their deployment rises in enterprise networks. Bandwidth growth has been limited to private-line-like bandwidth increments such as DS1, DS3, or OC-x. Because these private-line interfaces are provisioned as physical connections from the customer premises onto the metro network, incremental bandwidth needs require new physical connections to be estab- lished. However, as noted, the reality is that the legacy interfaces will be around for a number of years. Clearly, most carriers have invested billions of dollars in SONET optical products, ATM switches, and digital crosscon- nect system (DCS) crossconnects; hence, they are highly motivated to price and design these services right in order to achieve a return on their invest- ment, particularly in the new telecom economics market. Eventually, carri- ers will migrate to new technologies. The challenge is making a graceful migration from the embedded network to a network based on data-oriented interfaces. 5.3.2 Network Management in DWDM A critical yet often understudi