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.