DISCUS will analyse, design, and demonstrate a complete end-to-end architecture and technologies for an economically viable, energy efficient and environmentally sustainable future-proof optical network. It will provide a revolution in communications networks applicable across Europe and the wider world exploiting to the full the opportunity offered by LR-PONS and flat optical core networks to produce a simplified and evolvable architecture which will be the foundation for communications for the long term future. The architecture will be ultra energy efficient, simple to operate, robust to new technology introduction and providing universal availability of bandwidth and features regardless of geographic location.This ideal is obtained by a clean-slate approach to the architectural design by universal application of optical technologies throughout the fixed network eliminating traditional demarcations of metro, regional, core and access. Thus our essential concept is to use advanced optical technologies throughout giving rise to economies of scale and allowing bandwidths and flexibility hitherto unimaginable.Specifically the DISCUS architecture will: scale gracefully and economically, over a common physical infrastructure, as FTTP drives bandwidth growth by three orders of magnitude or more. It will evolve from today's architectures, adopting future technologies while co-existing with earlier generations. A unique feature will be a "Principle of Equivalence" whereby all network access points have equal bandwidth and service capability including core bandwidths (10Gb/s to 100+Gb/s) delivered to the access edge. It will seamlessly integrate wireless and fixed optical networks, fully exploiting both technologies. It will enable a competitive and simple regulatory environment controlled by customers and users rather than network operators and service providers.DISCUS is therefore fully aligned with the objectives of ICT-2011.1.1 and directly addresses its targets.