Elastic Optical Networking: Roles and Benefits in Beyond 100-Gb/s Era

Emerging technologies such as spectrally efficient multicarrier higher order modulation and bandwidth variable wavelength selective switches have led to a change in the optical network architecture from rigid and homogeneous to flexible and heterogeneous in terms of the bit rate, center frequency spacing, modulation format, and optical reach. The elastic optical network (EON) is a network architecture toward beyond the 100-Gb/s era. This tutorial paper reviews elastic opticalnetworking technology and presents its roles and benefits in a new era, where major line rates in metro/core optical networks are 100 Gb/s and beyond. The main features of the EON are that it increases the spectral efficiency in a network manner through rate-adaptive superchannels and distance-adaptive modulation, and it provides cost- and energy-efficient traffic grooming in the optical domain. The EON concept has been widely accepted by industry and academia. Significant standardization efforts have yielded great advances evidenced by the flexible grid and the flexible OTUCn frame format recommendations. Hardware virtualization such as a sliceable multiflow transponder in cooperation with emerging flexible clients will be key to achieving more flexible and cost-effective next generation optical networks.