Survivable MPLS over optical transport networks: cost and network resource usage analysis

In this paper we study various options for the survivability implementation in MPLS over optical transport networks (OTN) in terms of the network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single layer and multilayer survivability and present different methods for spare capacity allocation (SCA) to reroute disrupted traffic. The comparative analysis shows the influence of the traffic granularity on the survivability cost: for high bandwidth LSPs, close to the optical channel capacity, the multilayer survivability outperforms the single layer one in terms of the configuration cost, whereas for low bandwidth LSPs the single layer survivability is more cost-efficient. For the multilayer survivability we demonstrate that by mapping efficiently the spare capacity of the MPLS layer onto the resources of the optical layer one can achieve up to 22% savings in the total configuration cost and up to 37% in the optical layer cost. These results are based on a cost model with actual technology pricing and were obtained for networks targeted to a nationwide coverage.