Dear Dinesh,
The question and the words are not clear. Still trying to answer your questions.
All the activities you define in routing will be performed in any of the work center. The work center contains the capacity. One work center can contain multiple capacity.
At the time of MRP run it is being considered infinite capacity for any of the work center. So order will be planned. But you can see the overloading scenario with respect to the work center/order with all CM.., related transaction and you can level as well to over come the problem of overloading.
Regards,
Krishnendu.