Comparison of Various Reliable Transport Architectures for Long-Haul Networks

The advent of Flex-grid enabled Elastic Optical Networks brings a new dimension of flexibility for transport network architectures at the optical layer. This is aided in part by the capability to support multiple modulation formats as well as the ability to switch at different granularities in the optical layer. At the digital layer, network cost and efficiency are still heavily influenced by the types of digital node architectures and switching capabilities that are deployed in the network to carry services. We look into three network architectures capable of varying levels of switching in the optical and digital layers. These architectures are namely Muxponder, OTN Switching, and Hybrid. We study network efficiency metrics of each architecture in the context of Elastic Optical Networks using flexible grid ROADMs and Sliceable Bandwidth Variable Transponders (SBVTs). We propose methods for reliable network designs when SBVTs are deployed. We compare them by quantifying the benefits of optical and digital switching. We observe that a hybrid architecture consisting of a judicious mix of switching at both the digital and optical layers provides the best overall network efficiency.