Transwitch Corporation

Intel Corporation

Sachin Mathur

Chitra Wadhwa

Daniel C Upp

Jiaxiang Shi

Suvhasis Mukhopadhyay

Kumar Shakti Singh

Ashis Maitra

Pushkal Yadav

Yudhishthira Kundu

Diljit Singh

Ravindar Attineni

Amandeep Singh Gujral

Bart Brosens

Kris Van Aken

Ramses Valvekens

A phase alignment system for aligning clocks is disclosed. The system includes a calibration circuit and a phase locked loop (PLL). The calibration circuit is configured to receive a variable clock and a reference clock; determine phase alignment based on metastability; determine phase misalignment and generate a phase shift upon determining phase misalignment. The PLL is configured to generate the variable clock and incorporate the phase shift.

Systems and methods for dynamic phase alignment of clocks

Time multiplexed processing of multiple SONET signals uses the same shared circuitry for framing, descrambling, maintenance signal processing, control byte processing and extraction, pointer tracking, retiming, and alarm indication. The signals are deserialized and multiplexed onto a byte-wide bus from which they are processed in a shared pipeline. Additional pipelines allow scaling up to higher capacity SONET signals. Each pipeline is provided with means for communicating with the other pipelines so that information derived from the processing of one stream can be shared with the processing of other streams when necessary. According to the presently preferred embodiment, bytes pass through the pipeline in five clock cycles.

Time multiplexed SONET line processing

Methods for retiming SONET signals include demultiplexing STS-1 signals from an STS-N signal, buffering each of the STS-1 signals in a FIFO, determining the FIFO depth over time, and determining a pointer leak rate based in part on FIFO depth and also based on the rate of received pointer movements. According to the presently preferred embodiment, each FIFO is 29 bytes deep. If FIFO depth is 12-17 bytes, no leaking is performed. If the depth is 8-12 bytes or 17-21 bytes, a slow leak rate is set. If the depth is 4-8 bytes or 21-25 bytes, a fast leak rate is set. If the depth is 0-4 bytes or 25-29 bytes, pointer movements are immediate. The calculated leak rates are based on the net number of pointer movements (magnitude of positive and negative movements summed) received during a sliding window of n&#xd7;32 seconds (n&#xd7;256,000 frames).

SONET/SDH SPE/virtual container retiming with adaptive dual pointer leak rate computation

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Bengaluru, India

Sachin Mathur