Packet switched based network architectures exhibit a high degree of resource sharing and consequently make very efficient use of the available bandwidth. On the other hand, they experience a great amount of transit traffic in IP routers, increasing costs. Wavelength switched based concepts can reduce this transit traffic, but have limited resource sharing and consequently need more resources (wavelengths) to avoid losses. We present a new hybrid network architecture, Overspill Routing In Optical Networks (ORION), which combines the benefits of wavelength switched networks and packet switched networks. An example node hardware design and corresponding control architecture is presented. A case study quantifying the benefits of ORION when com...