In reply to dave_59:
yes, it’s an enum.
how this line generated?: # B C
the constraint don’t allow it
foreach(portA_Type[i]) if(portA_Type[i] == C) portB_Type[i] dist{C:= 1, D:= 1};
foreach(portB_Type[i]) if(portB_Type[i] == C) portA_Type[i] dist{C:= 1, D:= 1};
and back to my question
in my runing always it C or D for both portA_Type and portB_Type for each I