Design of Resilient Transparent OFDM Optical Grids/Clouds: A Blocking Aware Approach

Owing to flexibility in spectrum allocation, Orthogonal Frequency Division Multiplexing (OFDM) based grids/clouds are replacing traditional Wavelength Division Multiplexed (WDM) based grids/clouds. Optical grids/clouds execute jobs/services that need to be completed and delivered within predefined deadlines. So, protection against a fiber cut is of paramount importance. In this paper, we address the problem of designing resilient transparent OFDM optical grids/clouds that can withstand any arbitrary link failure. Anycast feature of grids/clouds is efficiently used to minimize spectrum usage. Further Shared Backup Path Protection (SBPP) is used to minimize use of backup resources to the extent possible. Random arrival and departure of requests in a dynamic environment cause spectrum fragmentation, which leads to blocking of new requests. So, in this paper we also propose schemes to minimize fragmentation. To the best of our knowledge, this paper is the first to address the issue of survivability in OFDM optical grids/clouds with the joint objective of minimizing spectrum usage and spectrum fragmentation in routing paths. A polynomial-time algorithm, Survivability with Relocation and Fragmentation Minimization (SRFM) is proposed. Performance comparisons with an existing algorithm show significant reduction in bandwidth blocking ratio.