Alcatel This document is a companion to the Generalized MPLS (GMPLS) signalling documents [GMPLS-SIG], [GMPLS-RSVP] and [GMPLS-LDP]. It describes the G.709 [ITUT-G709] technology specific information needed to extend GMPLS signalling to control Optical Transport Networks (OTN); it also includes the so-called pre-OTN developments.