US Patent 8976682 Connection verification for MPLS label switched paths and pseudowires

In one embodiment, a maintenance intermediate point (MIP) receives a packet traveling along a multi-protocol label switching (MPLS) label switched path (LSP) that extends from a first maintenance end point (MEP) to a second MEP. The receiving MIP decrements a time-to-live (TTL) value in a header of the packet. In response the TTL value in the header of the packet equaling a particular value, the receiving MIP examines an associated channel header (ACH) field in an operations, administration, and maintenance (OAM) message stored in a payload of the packet, and determines a particular OAM function to perform based on a code in the ACH field. The receiving MIP performs the particular OAM function.