An optical network is configured to optimize network resources. The optical network includes multiple optical nodes, light paths between the multiple optical nodes, and a network monitoring device. The network monitoring device monitors the optical network to identify a failure in the optical network. When the failure is a fiber failure, light paths are re-routed around the fiber failure while maintaining the required bandwidth for the optical network. When the failure is a transponder card failure within one of the multiple nodes, a floating spare card may be provisioned to service a particular light path associated with the transponder card failure. When the failure is a node failure, transponder cards in some of the multiple optical nodes are provisioned to reconfigure some of the plurality of light paths to route traffic around the failed node.

The invention relates to an optical communication network (1) comprising a plurality of nodes (2) connected to each other by means of optical fibers (3) in a ring structure, wherein optical signals are transported at working wavelengths (.sub.w) in a first direction in said ring structure and wherein optical signals are transported at protection wavelengths (.sub.p) in a second direction that is opposite to the first direction in said ring structure, wherein for each node (2) at least one wavelength assignment table (WAT) is provided, wherein to each working wavelength (.sub.w) a corresponding protection wavelength (.sub.p) is assigned, wherein in case of a detected connection failure in said ring structure each node (2) which loses at least one connection performs for all working wavelengths (.sub.w) affected by said connection failure a lookup in its wavelength assignment table (WAT) to determine the respective protection wavelength (.sub.p) and tunes lasers of transceiver units to the determined protection wavelengths (.sub.p).

A device includes a threshold setting unit that sets a threshold for an input optical power monitor to detect the input optical power to the optical transmission line of an active system; a threshold deciding unit that decides whether the input optical power to the optical transmission line of the active system detected by the input optical power monitor is not greater than the threshold set by the threshold setting unit or not; and an attenuation controller that carries out, when the threshold deciding unit decides that the input optical power is not greater than the threshold, system switching by controlling first variable optical attenuators so as to gradually reduce attenuation of the signal light rays input from the optical transmission line of one backup system, and to gradually increase attenuation of the signal light rays input from the optical transmission line of the active system.

A method, in a node operating in a network with a control plane, to optimize wavelength retuning on service redials, includes detecting a failure on a link associated with the node; and, for each affected connections on the link, sending a respective release message to an associated originating node via the control plane, the release message including a protect path and a wavelength, wherein the release message is utilized by the associated originating node to redial the affected connections with the protect path and the wavelength determined by the node, to minimize wavelength retuning on the affected connections.

A network management device monitors an optical network that is configured for a required bandwidth. The optical network includes multiple optical nodes and a plurality of light paths between the multiple optical nodes. The multiple optical nodes include transport cards with a majority of the transport cards provisioned as active cards to receive a traffic load of up to full capacity of the transport cards, and with a minority of the transport cards provisioned as floating spare cards for the active cards. The network management device identifies an unused first floating spare card and an unused second floating spare card in a pair of the multiple optical nodes and automatically provisions, by the network management device, the first floating spare card and the second floating spare card to service a light path for best-effort traffic between the pair of the multiple optical nodes.

An optical path route design device includes a transmission/reception route selection unit, a candidate selection unit, an existence judgement unit, a maximum resource 3R selection unit, and a new 3R selection unit. The design device selects relay stations in which two transmission/reception end points are arranged, selects a route pair of an active system-0 route and a standby system-1 route, which connects the transmission/reception end points with each other and does not overlap each other, and a backup third route detouring from the route pair via one or more relay stations, and arranges a resource amount of predetermined wavelengths in a shared 3R which is on the third route and shared by a plurality of route pairs.