The value of tnOamPingHistoryReturnCode is an integer that indicates the OAM return code received in the OAM ping response. The return codes are test specific and can vary for different types of pings. LSP-PING and VCCV-PING use return codes values from RFC4379 with the following meanings and suggested text descriptions. Value Meaning 0 No return code (NoRtnCode) 1 Malformed echo request received (MalformedReq) 2 One or more of the TLVs was not understood (UnknownTlv) 3 Replying router is an egress for the FEC at stack-depth (EgressRtr) 4 Replying router has no mapping for the FEC at stack-depth (NoFECMapping) 5 Downstream Mapping Mismatch (DSMappingMismatched) 6 Upstream Interface Index Unknown (USIntfIdxUnkn) 7 Reserved (Reserved) 8 Label switched at stack-depth (DSRtrMatchLabel) 9 Label switched but no MPLS forwarding at stack-depth (DSNoMplsFwding) 10 Mapping for this FEC is not the given label at stack-depth (DSRtrUnmatchLabel) 11 No label entry at stack-depth (DSNoLabelEntry) 12 Protocol not associated with interface at FEC stack-depth (DSProtoMismatched) 13 Premature termination of ping due to label stack shrinking to a single label (DSPreTermination) 14 See DDMap TLV for rc and sub-rc (seeDDMapForRetCodeSubCode) 15 Label Switched with FEC Stack Change (LabelSwitchedWithFecChange)