In Elastic Optical Networks (EONs), overcoming spectrum contiguity and continuity constraints is a challenging task while allocating spectrum slots (SS) to an incoming traffic demand. The frequent setup and release of SS over spectrum paths (SP) lead to unused isolated non- contiguous SSs. These isolated SS becomes unusable for future connections and causes significant fragmentation of spectral resources and degrades the network performance. This paper presents a spectrum assignment (SA) strategy that allocates SS based upon the relative difference between the required SS width and available SS width. The performance of proposed SA technique is evaluated in terms of Network Blocking Probability (NBP) by carrying out simulations under variable load conditions. The comparative analysis shows that the proposed strategy reduces spectrum fragmentation effectively as compared to existing SA strategies.

EONs, Routing and Spectrum Assignment (RSA), SS, NBP, Orthogonal Frequency Division Multiplexing (OFDM), SP, National Science Foundation Network Topology (NSFNET)

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