A computer-implemented method for testing a static label-switched path "LSP" over which packets belonging to a forwarding equivalency class "FEC" are forwarded, the computer-implemented method comprising: a) generating , by an ingress router of the static LSP, a multi-protocol label switching "MPLS" echo request message including a target FEC stack type-length-value "TLV", the target FEC stack TLV having a Nil FEC sub-TLV; b) sending , by the ingress router, the MPLS echo request message with a label stack corresponding to the FEC for forwarding over the static LSP, wherein the MPLS echo request message further includes a downstream detailed mapping TLV "DDMT"; c) receiving, by a transit router of the static LSP, the MPLS echo request message; and d) responsive to receiving the MPLS echo request message, checking for validity, by the transit router, label information in the DDMT against information in a local routing table of the transit router; e) responsive to a determination, by the transit router, that the label information in the DDMT checked against information in a local routing table of the transit router is invalid, - generating an MPLS echo reply message addressed to said router of the LSP that generated the MPLS echo request message and including information encoding that there is no label entry in its local routing table corresponding to the information in the DDMT, and otherwise, responsive to a determination, by the transit router, that the label information in the DDMT checked against information the local router table of the transit router is valid, - generating an MPLS echo reply message addressed to said router of the LSP that generated the MPLS echo request message and including information encoding that the label was switched. a) generating , by an ingress router of the static LSP, a multi-protocol label switching "MPLS" echo request message including a target FEC stack type-length-value "TLV", the target FEC stack TLV having a Nil FEC sub-TLV; b) sending , by the ingress router, the MPLS echo request message with a label stack corresponding to the FEC for forwarding over the static LSP, wherein the MPLS echo request message further includes a downstream detailed mapping TLV "DDMT"; c) receiving, by a transit router of the static LSP, the MPLS echo request message; and d) responsive to receiving the MPLS echo request message, checking for validity, by the transit router, label information in the DDMT against information in a local routing table of the transit router; e) responsive to a determination, by the transit router, that the label information in the DDMT checked against information in a local routing table of the transit router is invalid, - generating an MPLS echo reply message addressed to said router of the LSP that generated the MPLS echo request message and including information encoding that there is no label entry in its local routing table corresponding to the information in the DDMT, and - generating an MPLS echo reply message addressed to said router of the LSP that generated the MPLS echo request message and including information encoding that there is no label entry in its local routing table corresponding to the information in the DDMT, and - generating an MPLS echo reply message addressed to said router of the LSP that generated the MPLS echo request message and including information encoding that the label was switched. <EOS>