Multi Service OTN Design and Optimization of a Germany Wide Scale Example Network

Service evolution and cost pressure motivate operators to converge networks to a packet-over-OTN architecture. In fact, the major part of the services requires packet routing and switching transport. However, multi-service carriers face a strongly increasing demand of wavelength services which impact the OTN design. In pure packet services networks the OTN design may be regarded as trivial, it may consist just of a tree of point-to-point connections between routers/switches. Even in such networks economical and ecological reasons exist to consider an active photonic layer. Energy consumption and cost per bit are by factors lower for those portions of the traffic which are bypassed on the photonic layer where routing and packet switching is not essential, as e.g. for storage and data centre connectivity. The focus of this paper, however, is on large multiservice OTNs not only interconnecting the carrier’s own packet layer devices but as well carrying a significant amount of carrier’s carrier and business leased lines services. Those services exhibit an explicitly different geographic distribution pattern compared to router interconnections, suggesting a different OTN architecture. They also imply different OTN networking requirements in terms of resilience and dynamic operations. Two basic OTN architectures for a Germany-wide multi service network have been modelled and investigated. The topology of the first follows the one of the superposed packet services network, the second is optimized considering the leased lines characteristics and the capabilities of present-day OTN technology. Service demands expected in the near future were applied to these models. Dimensioning the networks accordingly and analyzing the required resources indicates benefits of the optimized architecture both in terms of network costs and power consumption. The analysis further shows that the benefits grow with increasing bandwidth demands and network load. Some key parameters of the OTN optimization are outlined and discussed.