Recommendation ITU-T G.8112/Y.1371 specifies the interfaces for the Multi-Protocol Label Switching (MPLS) Transport Profile (MPLS-TP) layer network. The interfaces for the MPLS-TP layer network use various server layer networks, like the plesiochronous digital hierarchy (PDH), synchronous digital hierarchy (SDH), optical transport hierarchy (OTH) and the Ethernet MAC layer network (ETH).