Optical networking is the technology of choice for high-bandwidth core networking. Several industry groups are defining interoperability standards between optical transportation networks and other devices such as edge and access routers and switches. Forums such as Optical Internetworking Forum (OIF) are defining User Network Interface (UNI)-based signaling protocols. Other bodies such as IETF are working towards interoperability through the GMPLS (Generalized Multi Protocol Label Switching) framework.