Generalized Multiprotocol Label Switching (GMPLS) can be used to control a wide variety of technologies including packet switching (e.g.@ MPLS)@ time division (e.g.@ Synchronous Optical Network / Synchronous Digital Hierarchy (SONET/SDH) and Optical Transport Network (OTN))@ wavelength (lambdas)@ and spatial switching (e.g.@ incoming port or fiber to outgoing port or fiber). In some of these technologies@ network elements and links may impose additional routing constraints such as asymmetric switch connectivity@ nonlocal label assignment@ and label range limitations on links. This document describes Open Shortest Path First (OSPF) routing protocol extensions to support these kinds of constraints under the control of GMPLS.