  The self-interacting dark matter can affect various cosmological processes.
Such interactions can be number conserving (\emph{e.g.} $2 \rightarrow 2$) or
number violating (\emph{e.g.} $3 \rightarrow 2,\,4 \rightarrow 2$ etc.). The
latter processes where three (or more) dark matter particles undergo
self-annihilation/scattering to produce less number of dark matter is termed as
``Cannibalism'' process. In this work, the self-interaction of dark matter and
the strength of such interactions are investigated in the light of experimental
results of the global 21-cm spectrum of neural hydrogen from the era of cosmic
dawn. From the present work, it appears that $2\rightarrow 2$ process is much
more dominant over the $3\rightarrow 2$ process. It is also found that such
interactions affect the dark matter-baryon elastic scattering cross-section.
The study also indicates the presence of multi component dark matter of
different mass range in the Universe.
