Abstract: A method of transmitting packet traffic between first and second network nodes in a shared protection optical transmission network, the method comprising defining first and second traffic paths between said nodes, at least one of said paths being a shared protection path, and allocating traffic along said paths utilising link aggregation.

Abstract: A system for hybrid electronic/photonic switching of traffic in a node of a communications network includes a plurality of interfaces; an electronic cross-connect (EXC); and a photonic cross-connect (PXC). Each interface is designed to translate a respective traffic stream between corresponding electronic and optical signals. The EXC selectively maps an electronic signal through a selected one of the interfaces, and the PXC selectively couples an optical signal between the selected interface and a selected one of at least two optical channels of the communications network.

Abstract: To provide improved protection bandwidth efficiency for a fast recovery from a fault in an optical network, a protection ring for sharing between some of the protection paths has a pre-configured route so as to overlap on a given one of the links, with other protection paths or other rings. A selector for the given link selects which of the overlapping secondary paths is allocated to the given link at any time. Thus, two types of sharing of protection paths are combined to achieve more efficient use of protection bandwidth. The link selector can be controlled locally and so can operate more rapidly. The local control, essentially independent of the switches used to set up the secondary path through the network, makes the combination easier to scale to larger, more complex networks than shared rings alone.

Abstract: An optical switch comprising switching means arranged to switch an optical signal by redirection of the optical beam path of said signal, wherein said optical switch is arranged to misalign the optical beam path so as to provide a predetermined optical output power. Thus a switch can be directly used to attenuate a signal, instead of utilising separate attenuators.

Abstract: A system for hybrid electronic/photonic switching of traffic in a node of a communications network includes a plurality of interfaces; an electronic cross-connect (EXC); and a photonic cross-connect (PXC). Each interface is designed to translate a respective traffic stream between corresponding electronic and optical signals. The EXC selectively maps an electronic signal through a selected one of the interfaces, and the PXC selectively couples an optical signal between the selected interface and a selected one of at least two optical channels of the communications network.

Abstract: In optical communication switching equipment there is a need to set up optical paths through the switch before there is an optical signal present. The present invention provides an optical switching apparatus comprising: an optical switch having a number of optical paths for switching optical channels; a demultiplexer coupled to said switch; a broadband light source coupled to said demultiplexer which distributes said light in said channels to enable correct alignment of said optical paths.

Abstract: An optical switch comprising at least two segments, each segment having a respective input and a respective output, arranged such that in use if a first segment is removed, a second segment can operate as a pass-through device.

Abstract: Telecommunications switch architectures and switching methods based on the principle of replication/broadcasting some or all of the incoming data from each input-switch port to all output switch ports. The replicated data is transferred to the output ports either by the respective output port reading directly from a relevant address in an input memory, or by transferring the content of all or part of the input memory data simultaneously en bloc and in parallel to a plurality of output memories, with each output port then taking the data intended therefor. The input and output data is in serial form but transferred in parallel form. The data can be replicated optically or electronically. In particular, the input data can be formatted as spatially arranged pages in the optical domain by spatial light modulators (SLM) and switched by an image replicating optical switch, such as a matrix-matrix switch, to an output plane at which a second SLM device converts the data back to serial form.