  We report inelastic neutron scattering measurements of the magnetic
excitations in SrFe2As2, the parent of a family of iron-based superconductors.
The data extend throughout the Brillouin zone and up to energies of ~260meV. An
analysis with the local-moment J_1-J2 model implies very different in-plane
nearest-neighbor exchange parameters along the $a$ and $b$ directions, both in
the orthorhombic and tetragonal phases. However, the spectrum calculated from
the J1-J2 model deviates significantly from our data. We show that the
qualitative features that cannot be described by the J1-J2 model are readily
explained by calculations from a 5-band itinerant mean-field model.
