Patent ID: 8149871
Filing Date: 2012-04-03
Classification: H04J,H04L

Abstract:
1. A method of demapping a SONET synchronous bit frame from received Ethernet frames comprising: reading received SONET frame data from a first reassembly FIFO at a first clock rate, with the received SONET frame data including transport overhead (TOH) bytes including pointers that indicate the beginning of SONET frame payload bytes and SONET frame payload bytes, with the TOH bytes and SONET frame payload bytes extracted from payloads of the received Ethernet frames; writing only received SONET frame payload bytes to a second reassembly FIFO at the first clock rate; reading received SONET frame payload bytes from the second reassembly FIFO at a reference clock rate; indicating the number of bytes stored in the second reassembly FIFO; comparing the number of bytes stored in the second reassembly FIFO to a target value; generating a negative justification signal if the number of bytes held in the second reassembly FIFO is greater than the target value; generating a positive justification signal if the number of bytes held in the second reassembly FIFO is less than the target value; reading a received pointer value, included in the TOH bytes of the received SONET frame, from the first reassembly FIFO; forming a new pointer value by decrementing the received pointer value if the negative justification signal is generated or incrementing the received pointer if the positive justification signal is generated; and inserting the new pointer value into H2 and H3 locations of transport bytes of the TOH in an outgoing SONET frame being reassembled in the second reassembly FIFO.