BUPT University BUPT University BUPT University This document describes a new mechanism for the label allocation of co-routed bidirectional point-to-point paths in MPLS Transport Profile (MPLS-TP) networks, which is called the bidirectional label allocation mechanism. The nodes on co-routed bidirectional point-to- point paths will not need to record the label pairing relationship of the forward and the backward directions in this mechanism because the labels are symmetrical. In addition, the compression of the LIB becomes possible because of the existing of symmetrical elements.