Survivable subwavelength switching optical metro networks: cost comparison of POADM and TWIN

In this paper, we compare the cost of the attrac- tive survivable optical transport solutions with subwavelength switching granularity. The focus is on Time-Domain Wavelength Interleaved Network (TWIN) and Packet Optical Add/Drop Multiplexer (POADM) network. Both technologies exploit the optical slot switching: TWIN on a physical mesh topology, and POADM - on a physical ring. The cost model accounts for the node architecture, the transponder cost and the cost of wavelength use per km of fiber. For the first time, a single network dimensioning model supporting protection is proposed for these competitive metro technologies. The network planning solution is based on linear programming, and addresses the routing and wavelength assignment problem (RWA) and the optimal scheduler calculation. We consider the dedicated protection, which consist in doubling the capacity of each operational connection in the network and the shared protection, in which the protection capacity is potentially shared between the multiple connections. By extensive simulations we study the impact of different protection models on the cost of networks in different configuration and identify the settings in which each of the technologies shows its advantages and disadvantages.