an apparatus comprising a path computation element configured to communicate with a path computation client and compute a point - to - multipoint path across an autonomous system domain . also included is a network component comprising at least one processor configured to implement a method comprising obtaining a computation request for a p2mp path across a plurality of as domains , attempting to calculate the p2mp path across the as domains , thereby generating a computed path or a failure reason , and transmitting a reply comprising the computed path or an indication of the failure reason . included is a method comprising exchanging a request message and a reply message about a p2mp path across an as domain between a pcc and a pce .