This document describes extensions to Generalized Multi-Protocol Label Switching (GMPLS) Resource ReserVation Protocol - Traffic Engineering (RSVP-TE) signaling required to support mechanisms for the establishment and maintenance of GMPLS Traffic Engineering (TE) Label Switched Paths (LSPs), both packet and non-packet, that traverse multiple domains. For the purpose of this document, a domain is considered to be any collection of network elements within a common realm of address space or path computation responsibility. Examples of such domains include Autonomous Systems, IGP areas and GMPLS overlay networks.