Redundant link delay maintenance circuit and method
AssigneeNortel Networks Limited
InventorsDavid William Denike, David G. Martin
Life of this patent
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Abstract
A system and method for maintaining a constant delay when a switch between two or more possible input data streams is made. Data received on a selected stream is buffered as it is received, the timing of this buffering being based on link timing recovered from the selected stream. Stable local timing information is generated from the link timing. It is stable in the sense that it is subject to only a very small shift when a switch in the selected data stream is made. Data is then read from the buffer on the basis of the local timing information thereby producing an output stream with a constant delay.
Claims28
An apparatus comprising:
- a data buffer;
- a link receiver for receiving an input data stream and for recovering link timing information from the input data stream, and for writing the input data stream to the data buffer on the basis of the link timing information;
- local timing circuitry for generating stable local timing information from the recovered link timing information and for reading data from the data buffer on the basis of the local timing information and for outputting this in an output data stream.
A method of maintaining a stable delay variation in a circuit which is connected to receive an input data stream which is subject to delay variation, the method comprising the steps of:
- receiving data from the input data stream;
- generating link timing information on the basis of the selected data stream;
- writing the received data to a data buffer on the basis of the link timing information;
- generating relatively stable local timing information on the basis of the link timing information;
- and
- reading data from the data buffer on the basis of the local timing information and outputting the read data in an output data stream.
An apparatus comprising:
- a link select circuit adapted to receive two redundant input data streams and output a selected data stream;
- a data buffer adapted to provide delay compensation for any delay variations between the two redundant input data streams;
- a link receiver for receiving the selected data stream and for recovering link timing information from the selected data stream, and for writing the selected data stream to the data buffer on the basis of the link timing information;
- and
- local timing circuitry for generating stable local timing information from the recovered link timing information and for reading data from the data buffer on the basis of the local timing information and for outputting this in an output data stream;
- whereby when a switch in the selected data stream from one of said two redundant input data streams to another of said two redundant input data streams occurs, the output data stream is substantially unaffected notwithstanding the delay variations.
Dependencies are inferred from the claim text.