ROADM
Network and bandwidth planning should be as easy as in SDH/SONET networks in the past. Within the given ring bandwidth, for example STM-16 or OC-48 each node could provide as much bandwidth as needed. Access to the entire bandwidth was possible at every ADM. Network extension, for example, introduction of a new node in an existing ring, was relatively easy and did not require any on-site visits of the existing nodes. The network diagram on the left illustrates this: Digital cross-connect systems link up with multiple optical SDH/SONET rings. Reconfigurable optical networks act differently: Bandwidth can be planned on-demand and the reach is optimized as the optical power is now managed per WDM channel. The scalability goes up significantly. The key element for enabling such a reconfigurable optical network is Reconfigurable Optical Add-drop Multiplexer (ROADM) . It enables optical wavelengths to be redirected to client interfaces on just a click in the software. Other traffic remain