Efficient shared subconnection protection in mixed-line-rate optical WDM networks

Mixed-line-rate (MLR) networks have been proposed recently to support emerging traffic demands with diverse capacity requirements. In such networks, wavelength channels of the optical paths can have a variety of capacities (10/40/100 Gbps). It has been shown that this feature enables new paradigms for protection in optical wavelength-division-multiplexing (WDM) networks. In this paper, we propose to design transparent MLR networks with shared subconnection protection (SSP). SSP in an MLR network, compared with other more classical approaches (dedicated or shared protection), can also address the cost-versus-capacity trade-off in providing shared protection in a transparent network. The design problem is solved by a two-step approach that formulates part of the problem as an integer linear program (ILP). Our results show that SSP enables higher sharing of backup capacityin an MLR network in that the design cost is up to 37% less than a single-line-rate network with SSP and around 40% less than MLR with dedicated protection.