order of assign MPI_rank to nodes

[Federico Paladin]

Hi,
  I have an MPI application that generate data locally to nodes in which
it is dispatched. More, another part of this application will
collect/use this nodes.

The two part have to dispatched in the same order, that is, the same
MPI_rank have to go in the same nodes (as with mpirun -pgfile).

Is that garanteed by mpiexec?
If not, there is a way to force mpiexec to do it?

We have to use mpiexec under pbs to launch the 2 part, in the same pbs
session or, worst case, in 2 separated pbs session (in this case, we
have obviusly to use pbs keywords to force to go in the same nodes)

Thanks!