In MPLS and MPLS-TE environments pseudo wires use two unidirectional LSPs as PSN tunnels, the two PEs select LSP tunnels independently. In contrast the MPLS-TP environment supports both bidirectional and unidirectional LSPs and PWE may, therefore, use bidirectional LSPs as PSN tunnels. In order to use MPLS-TP bidirectional LSPs as a PSN tunnels for pseudo wires some modification of the pseudowire signaling procedures is required. This draft specifies an extension to LDP that ensures pseudo-wires are correctly constructed over bi-directional LSPs.