IRIS aims at fabricating a highly integrated, scalable, transparent and high capacity WDM Photonic Switch used as an Transponder Aggregator (TPA),a novel function which will be added to existing ROADM nodes without disrupting their architecture while adding attributes such as colourless, directionless and contentionless. For Metro networks, this switch will provide flexibility, energy efficiency, very small footprint,low cost and faster reconfigurability (microsecond regime) as they are particularly required in this segment of the network and, in conjunction with an intelligent control and management plane, it will empower future software defined networking (SDN).This novel integrated switch architecture is also suitable for Data Center networking due to its capability to manage large throughput in a single chip with low cost, low footprint and low power consumption.The new TPA will be based on a fully integrated electro-photonic device realized by using Silicon Photonics with an unprecedented density of photonic components (>1k on <30 mm2 chip area) controlled by >2k electronic building blocks. The TPA target product is an optical sub-system for Metro applications driving 48 optical channels, with 100 GHz spacing in the C-band, 4 different directions and 12 add/drop channels. A fully packaged prototype will be implemented with 12 wavelengths, 4 directions and 8 A/D ports, it will be integrated with a commercial transport node and tested with 10G and 100G signals. The TPA proposed has the competitive advantage, with respect to existing solutions, of more than an order of magnitude lower cost (few hundreds $) and overall device volume a factor of 60 smaller (only a few cubic centimetres). IRIS is strongly oriented toward industrialization as it is led by a major European telecom equipment manufacturer (Ericsson) and participated by a major European Silicon manufacturing company (STMicroelectronics), already committed to the industrialization of Silicon Photonics.