This document describes extensions to Multi-Protocol Label Switching (MPLS) signaling required to support Generalized MPLS. Generalized MPLS extends the MPLS control plane to encompass time-division (e.g.@ Synchronous Optical Network and Synchronous Digital Hierarchy@ SONET/SDH)@ wavelength (optical lambdas) and spatial switching (e.g.@ incoming port or fiber to outgoing port or fiber). This document presents a functional description of the extensions. Protocol specific formats and mechanisms@ and technology specific details are specified in separate documents.