Provider Backbone Transport (PBT, known as well as PBB-TE and progressed in IEEE as 802.1Qay [802.1Qay]) provides a mechanism where native Ethernet point-to-point tunnels can be configured or signaled across a provider-based Ethernet network [FEDYK]. PWE3 architecture defines a mechanism, called pseudowires, that emulates the essential attributes of a layer-2 and layer-1 service over a Packet Switched Network (PSN). This draft describes the architecture and procedures where Pseudowires are carried across PBT tunnels. In this proposal PBT tunnels are used as the PSN.