Redundancy structure in a digital switch

A redundancy system for a digital switch with switch inputs and switch outputs and switch equipment therebeteween, that comprises a switch core and functional entities, a connection path for data flow between a switch input and a switch output being able to include a number of such functional entities on both sides of the core, said redundancy system including switch planes working in parallel and having mutually substantially identical switch equipment and majority vote functions, spreading means for spreading a data flow coming in from the outside to the equipment of the switch planes, and assembling means for assembling the data flows coming from the switch planes, wherein

• the redundancy system is distributed to at least a plurality of the functional entities on each of said connection paths, in a way that each such functional entity has its own redundancy subsystem with planes working in parallel and comprising means for spreading from the equipment of each plane a respective passing-by data flow to the equipment in parallel therewith, and wherein
• each plane and each switch output has a unit for maintenance functions including
• a majority vote function that receives the data flows of a plane and the planes in parallel therewith and compares these on a bit level for creating a majority voted data flow,
• a plane condition sensing function, that indicates if links of the planes have meaningfull information and synchronism and as a result emits a link condition indicating signal for each plane, that forms an indication thereof, and
• a priority select function, that is connected to receive the majority voted data flow and the link condition indicating signals and if the latter do not indicate a fault condition, lets through the majority voted data flow as an outgoing data flow from the functional unit, but in case of indication of a fault condition in one or more of the link condition indicating signals selects the data flow from one of the planes as an outgoing data flow on the basis of a determined priority order.

A method for providing a redundancy structure for a functional entity in a digital switch, comprising the step of

• at least triplicating the functional entity in planes working in parallel,
• spreading from each plane a respective passing-by data flow to each plane in parallel therewith, and
• performing in each plane the following steps:
• the data flows of a plane and the planes in parallel therewith are compared on a bit level for creating a majority voted data flow,
• indication is performed of whether the links of the planes have meaningful information and synchronism and as a result a link condition indicating signal is emitted, and
• the link condition indicating signals do not indicate a fault condition, the majority voted data flow is emitted as an outgoing data flow, but in case of indication of a fault condition in one or more of the link condition indicating signals, the data flow from one of the planes is selected as an outgoing data flow on the basis of a determined priority order.

A method for providing a redundancy structure for a digital switch with switch inputs and switch outputs and switch equipment therebetween, that comprises a switch core and functional entities, a connection path for data flows between a switch input and a switch output being able to comprise a number of such functional entities on both sides of the core comprising the step of

• distributing the redundancy system to at least a plurality of the functional entities on each of said connection paths, in a way that each such functional entity obtains its own redundancy subsystem with planes working in parallel, and spreading from the equipment of each plane a respective passing-by data flow to each equipment in parallel therewith, and performing
• in each plane and each switch output the following further steps of
• comparing data flows of a plane and the planes in parallel therewith on a bit level for creating a majority voted data flow,
• indicating whether links of the planes have meaningful information and synchronism and as a result emitting a link condition indicating signal for each plane, that forms an indication thereof, and
• letting through, if the link condition indicating signals do not indicate a fault condition, the majority voted data flow as an outgoing data flow, but selecting, in case of indication of a fault condition in one or more of the link condition indicating signals, the data flow from one of the planes as an outgoing data flow on the basis of a determined priority order.