NS5 brane can be considered as 1/2 BPS solution in supergravity (with other solutions to compare):
This branes of Type IIA/B supergravity are expected to extend to solutions of the full Type IIA/B string equations.
The NS5 brane indeed very much behave as large size semi-classical solitons, whose energy depends on the string coupling via $1/g^2_s$, as is familiar from solitons in quantum field theory.
In contrast, in the weak-coupling limit, the D-brane solution of supergravity reduces to a localized defect in flat space-time, that gives us boundary condition on the string dynamics.
But I wanna to understand more about NS5 branes.
What is role of such objects in string theory?
Which d.o.f. are related to such objects?
Is some effective theory, that describe dynamics of such objects? Is it Namby-Goto action for brane or some kind of DBI action?