MinCost - An Improved Offline Strategy for Multipath Provisioning of Connections in Survivable OFDM based EONs

Survivability is a vital issue to address in Orthogonal Frequency Division Multiplexed (OFDM) Elastic Optical Networks (EONs) which forms the Internet backbone. So it is important that a fiber-cut (link-failure) does not disrupt the established connections. Since spectrum is allocated to connection requests using subcarriers available in fiber-links, connection requests get blocked when subcarriers are not available. If we assume that the subcarriers in a link are indexed, then the efficiency of Survivable Routing and Spectrum Allocation (SRSA) algorithm can be estimated by its cost, which is the highest used subcarrier index over all links. Lower the cost, higher the efficiency. So an SRSA algorithm which aims to minimize request blocking must minimize its cost to the extent possible. Existing research has shown that ensuring survivability with multipath provisioning of connection requests can reduce blocking by saving more spectrum than providing survivability with a primary and backup paths. In this paper, we propose a polynomial-time multipath SRSA algorithm, Minimize Cost (MinCost) to minimize cost to the extent possible in OFDM based EONs for an offline scenario. Performance comparisons with two well-known heuristics show that over all experiments conducted, an average 27.92% reduction in request blocking is achieved using MinCost.