Abstract: The first step in isolating a soft fault within a transparent network is to determine which OMS trail is causing the fault. This can be accomplished by forcing regeneration at a flexibility point, which permits the estimation of the signal quality using a BER measurement. The preferred mechanism for segmenting Och faults to an OMS/trail is eavesdropping, using dedicated tunable filters and receivers or spare test tunable filters and receivers at network flexibility sites. Once the fault has been isolated to a specific OMS trail, analog tools are used to further isolate the fault down to a single replaceable module or fiber, using rapid measurement and correlation of relevant measured and pre-calculated expected performance data. In case of hard faults, to avoid superfluous alarm reports at connection termination points, the optical channel fault detector provides fault indications to downstream nodes using Forward Defect Indications (FDI) over the optical supervisory channel (OSC).

Abstract: The path selection and wavelength assignment to a selected path are performed by mapping the wavelength reach to the demand distribution (agile reach) resulting in a 50-60% increase in the network reach. The network reach is further increased (about 2.2 times) when on-line measured performance data are used for path selection and wavelength assignment. The connections may be engineered/upgraded individually, by optimizing th eparameters of the entire path or of a regenerator section of the respective path. The upgrades include changing the wavelength, adjusting the parameters of the regenerator section, controlling the launch powers, mapping a certain transmitter and/or receiver to the respective wavelength, selecting the wavelengths on a certain link so as to reduce cross-talk, increasing wavelength spacing, etc.

Abstract: The architecture for a photonic transport network provides for separation of passthru channels form the drop channels at the input of a switching node. A wavelength switching sub-system then switches the passthru channels, without OEO conversion. The drop channels are directed to broadband receiver of choice using a broadcast and select drop tree. The add channels are inserted at the output side of the node, using tunable transponders. In addition, a passthru channel may be OEO converted if signal conditioning and/or wavelength conversion are necessary. The transponders, regenerators and transceivers are not wavelength specific, allowing flexible and scaleable network configurations. This structure provides for fast provisioning of new services and ‘class of service’ network recovery in case of faults.

Abstract: A n×n transparent photonic switch TPS for an optical communication network uses wavelength selective elements connected in the switch fabric, to allow channels to pass, or to block channels from passing according to a network-wide routing connectivity data. The WSE may be a two-port blocker, in which case all input and output ports of the TPS are provided with 1:(n−1) splitters/combiners for providing internal routes between all pairs of input I(i) and output O(j) ports. The WSE may be assembled using wavelength selective switches WSS, or combinations of WSSs, splitters/combiners and circulators.