Distance-awareness gains in flexible ring topologies

As elastic networking approaches maturity, it is relevant to evaluate the spectral gains that may be achieved in specific survivable topologies. This paper discusses gains that may be achieved by advanced modulation schemes in distance-aware connections embedded in survivable rings. Two classical ring topologies are discussed under uniform, homogeneous traffic. The paper introduces a method to evaluate the achievable gains as a function of ring size and signal power. The method is applied to two selected protection ring architectures and a representative set of modulation schemes. The examples show that large rings do not benefit from distance-awareness, but smaller rings do, with spectral gains increasing with decreasing ring size.