embedded in these new optical transport equipment, which allows recovery to be automatic and handled within the network itself as part of the network control plane, without relying on an external network management system. Optical mesh networks Optical mesh networks refer to transport networks that are built directly off the mesh-like fiber infrastructure deployed in metropolitan, regional, national, or international (e.g., trans-oceanic) areas by deploying optical transport equipment that are capable of switching traffic (at the wavelength or sub-wavelength level) from an incoming fiber to an outgoing fiber. In addition to switching wavelengths, the equipment is typically also able to multiplex lower speed traffic into wavelengths for transport, and to groom traffic (as long as the equipment is so-called opaque - see subsection on transparency). Finally, these equipment also provide for the recovery of traffic in case of a network failure. As most of the transport networks evolve toward mesh topologies utilizing intelligent network elements (optical cross-connects or optical switches ) for provisioning and recovery of services, new approaches have been developed for the design, deployment, operations and management of mesh optical networks. Optical switches build by companies such as Sycamore and Ciena (with STS-1 granularity of switching) and Tellium (with STS-48 granularity of switching) have been deployed in operational mesh networks. Calient has built all-optical switches based on 3D MEMS technology. Optical mesh networks today not only provide trunking capacity to higher-layer networks, such as inter-router or inter-switch connectivity in an IP, MPLS, or Ethernet-centric packet infrastructure, but also support efficient routing and fast failure recovery of high-bandwidth point-to-point Ethernet and SONET/SDH services. Several planned satellite constellations such as SpaceX Starlink intended for global internet provisioning aim to establish optical mesh networks in space. The constellations consisting of several hundred to thousand satellites will use laser communication for high-throughput optical inter-satellite links. The interconnected network architecture allows for direct routing of user data from satellite to satellite and enables seamless network management and continuity of service. Recovery in optical mesh networks Optical mesh networks support the establishment of circuit-mode connection-oriented services. Multiple recovery mechanisms that provide different levels of protection or restoration against different failure modes are available in mesh networks. Channel-, link-, segment- and path- protection are the most common protection schemes. P-cycles is another type of protection that leverages and extends ring-based protection. Restorationis another recovery method that can work on its own or complement faster protection