ay's closed systems are disaggregated into separate hardware and software components; the network equipment is simplified by removing functionality from it and moving those functions to a central controller, and this simplification is used as an enabler to creating open systems. The initial open specifications targeted metro applications. The distances in metro are shorter relative to the nationwide intercity network, enabling system performance to be traded for openness. The open ROADM program will overcome the vendor lock-in inherent in the deployment of today's closed optical systems. It creates a new sourcing model and intense competition among sup- pliers who will invest in improving the price/performance and functionality of their products. This model has obvious benefits for service providers but also creates opportunities in the supplier space as service providers will be more amenable to using products from new market entrants as the need to pick an established supplier with strong staying power is removed. There are other efforts to define open optical systems using "alien wavelengths." In this approach, the ROADMs must be sourced from a single supplier but the transponders can come from a third party. But there is one big catch-the transponders on either end of a wavelength must be book- ended and need to come from the same supplier. In contrast, the open ROADM effort allows com- plete flexibility in mixing and matching ROADMs and transponders from different suppliers. A requirement to bookend transponders would translate to a need to segment transponders into sup- plier pools, hence restricting the value of having flexible rearrangements. The OpenROADM.org specifications include the common data models (device-level, network- level, and service-level templates) that enable uniform control and management of a multivendor optical network. The models include the "hooks" that allow for supplier-specific extensions across the multiple vendor implementations. The data models are specified using the YANG [8] 