Optical mesh network

Optical mesh networks are a type of telecommunications network.
Transport networks, the underlying optical fiber-based layer of telecommunications networks, have evolved from DCS (Digital Cross-connect Systems)-based mesh architectures in the 1980s, to SONET/SDH (Synchronous Optical Networking/Synchronous Digital Hierarchy) ring architectures in the 1990s. Technological advancements in optical transport equipment in the first decade of the 21st century, along with continuous deployment of DWDM systems, have led telecommunications service providers to replace their SONET ring architectures by mesh-based architectures. The new optical mesh networks support the same fast recovery previously available in ring networks while achieving better capacity efficiency and resulting in lower capital cost.
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 infrastructure, but also support efficient routing and fast failure recovery of high-bandwidth services. This was made possible by the emergence of optical network elements that have the intelligence required to automatically control certain network functions, such as fault recovery.
Optical mesh networks enable Quality-of-Service protection and a variety of dynamic services such as bandwidth-on-demand, Just-In-Time bandwidth, bandwidth scheduling, bandwidth brokering, and optical virtual private networks that open up new opportunities for service providers and their customers alike.


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.