Abstract: 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×32 seconds (n×256,000 frames).

Abstract: 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×32 seconds (n×256,000 frames).

Abstract: A SONET/SDH frame synchronization method uses one framing pattern to find the frame and a second framing pattern to monitor the frame after it is acquired. The first framing pattern uses twenty-four bits selected from the A1 and A2 bytes. After acquisition, the second framing, pattern uses only twelve bits, e.g. the last four bits of the last A1 byte and all of the first A2 byte. The framing pattern comparisons are made with a window of N+1 bytes or 2N bytes. The method of the invention meets the requirements of Telcordia GR-253 and eliminates aliasing in the last H2 bytes. The method can also be applied to enhanced framing in STS-192 and STS-768. An exemplary implementation of the method is realized in a state machine.