  We present results for meson masses and decay constants measured on 24^3x64
lattices using the domain wall fermion formulation with an extension of the
fifth dimension of L_s=16 for N_f=2+1 dynamical quark flavors. The lightest
dynamical meson mass in our set-up is around 331 MeV, while partially quenched
mesons reach masses as low as 250 MeV. The applicability of SU(3)xSU(3) and
SU(2)xSU(2) (partially quenched) chiral perturbation theory will be compared
and we quote values for the low-energy constants from both approaches. We will
extract the average light quark and strange quark masses and use a
non-perturbative renormalization technique (RI/MOM) to quote their physical
values. The pion and kaon decay constants are determined at those values from
our chiral fits and their ratio is used to obtain the CKM-matrix element
|V_us|. The results presented here include statistical errors only.
