[OMPI users] How to establish communication between two separate COM WORLD

[Ali Eghlima]

 Hello,

I have read MPI-2 documents as well as FAQ. I am confused as the best way 
to establish communication
between two  MPI_COMM_WORLD which has been created by two mpiexec calls on 
the same node.

mpiexec -conf  config1
     This start 20 processes on 7 nodes

mpiexec -conf  config2 
      This start 18 processes on 5 nodes

I do appreciate any comments or pointer to a document or example.

Thanks

Ali,