  Elastic Optical Networks (EON) emerge as a viable solution to supply the
current growing demand for bandwidth. With the application of multi-core fibers
(MCF) in EON links, it is possible to increase the availability of spectral
resources. An EON network with MCF enables Space-Division Multiplexing (SDM),
allowing the use of more resources in the fibers and increasing the capacity of
attending circuit requests. However, the use of SDM brings some problems of
interference between the circuits of a fiber, with greater emphasis on
crosstalk interference. In this paper, some important concepts around EON are
presented, along with the characterization of SDM technology. The Routing,
Modulation, Spectrum and Core Allocation (RMSCA) problem is also characterized,
and some solutions currently found in the literature are cited. After, the
impact of crosstalk interference is discussed, and which elements are
responsible for its occurrence. The paper is concludes with an evaluation of
the state of the art, and the discrimination of the main points found from the
study of papers related to the SDM-EON scenario.
