Ping and traceroute in inter-autonomous system (AS) segment routing (SR) networks without requiring headend router or path monitoring system (PMS) controller knowledge of topology outside of origin as

Ping or traceroute functionality is supported in a path spanning multiple autonomous systems (ASes) having segment routing (SR) enabled, the path including an ingress node in a first autonomous system (AS) and an egress node in an AS other than the first AS, using a reverse path label pair including (1) a node segment identifier (SID) corresponding to an AS Border Router (ASBR) of the second AS (second ASBR), and (2) an egress peer engineering (EPE) SID corresponding to a segment between the second ASBR to an ASBR of the first AS (first ASBR). Responsive to receiving a ping or traceroute request by a router in the second AS, the router generates a ping or traceroute reply including the reverse path label pair. The ping or traceroute reply is forwarded to the second ASBR using the node SID of the reverse path label pair. The ping or traceroute reply is then forwarded from the second ASBR to the first ASBR using the EPE SID of the reverse path label pair. Finally, the ping or traceroute reply can be forwarded (e.g., using standard IP forwarding) from the first ASBR to the headend router.