In one embodiment, a method includes generating a trace request at an initiator node configured for segment routing, the trace request comprising an FEC (Forwarding Equivalence Class) query corresponding to a label in an FEC stack with an unknown FEC, transmitting the trace request on a path with the unknown FEC, and receiving a response to the trace request, the response comprising FEC information including an identifier associated with a label and a forwarding path and representing a class or category of packets. An apparatus is also disclosed herein.