Tsinghua University Tsinghua University Tsinghua University Tsinghua University China Academy of Telecom. Research A stateful Path Computation Element (PCE) maintains the information of Label Switched Path (LSP) and resource availability within a domain, so multiple stateful PCEs are able to provide traffic engineering inter-domain routing through cooperating with each other. This document introduces the applicability of cooperative stateful PCE for establishing inter-domain inter-vendor LSP which is initiated by PCE.