  In this article we study the relation between the bubbling construction and
the Mathur's microscopic solutions for the D1/D5 system. We have found that the
regular near horizon D1/D5 system (after appropriated constraints are imposed)
contains all the bubbling regular solutions. Then, we show that the features of
this system are rather different from the bubbling in $AdS_5\times S^5$, since
the perimeter and not the area plays a key role. After setting the main
dictionary between the two approaches, we investigate on extensions to
non-regular solutions like conical defects and/or naked singular solutions. In
particular, among the latter metrics, closed time-like curves are found
together with a chronology protection mechanism enforced by the AdS/CFT
duality.
