ROADM expansion and its cross-layer applications

In today's converged network environment, a rapid transition to unified packet-based core/edge network architecture is occurring. Core architecture becomes a two-layer network structure based on IP/MPLS (Internet Protocol/ Multi Protocol Label Switching) transport over DWDM (Dense Wavelength Division Multiplex) bandwidth pipes, which is the most effective way of providing sharing network capacities, enabling efficient protection schemes, and delivering guaranteed end-to-end performance. The edge network is recognized as a place for an intense manipulation of both data streams and services, through traffic grooming, exchange, and service convergence. Three major groups of the end-to-end services are voice, data, and video. Today's reality is that current network structure is in transitional phase, where a number of legacy services, delivering voice and data, are still in place, while packet based services are being rapidly introduced. Optical ROADM (Reconfigurable Optical Add/Drop Multiplexer) deals with the wavelength bandwidth pipes and provides flexible handling of wavelength paths (amplification, add/drop, and wavelength switching). In-service upgrade is needed at any particular location, which means that in line-amplifier site can be converted to ROADM site. In addition, the ROADM site should be upgradeable to full wavelength crossconnect functionality, which is required in a number of application scenarios. The ROADM functionality is not limited to wavelength related functions, but rather handles the key functions related to multiservice environment by accommodating Layer 1&2 features from a blade. Herewith, we will analyze the role of ROADM in converged network environment, its functions, and expansion over cross-layer applications, and present a structure that is the most appropriate to multiservice packetized. environment.