  We present a description of the type IIB NS-NS p-branes in terms of
topological solitons in systems of spacetime-filling brane-antibrane pairs.
S-duality implies that these spacetime-filling branes are NS9-branes, S-dual to
the D9-branes of the type IIB theory. The possible vortex-like solutions in an
NS9,anti-NS9 configuration are identified by looking at its worldvolume
effective action. Finally we discuss the implications of these constructions in
the description of BPS and non-BPS states in the strongly coupled Heterotic
SO(32) theory.
