| 摘要 |
A large network switch has switch elements distributed across several chassis separated by perhaps several hundred meters. A generated sync pulse arrives at different switch elements at different times, creating skew. The latency of data through the network switch is set to match the frame period of SONET frames. SONET frames are adjusted at the ingress ports to align the data pointer to the beginning of the frame. The frame is divided along row boundaries into separate cell-packets that are routed across the switch fabric to the egress port. The packets are held in a buffer at the egress port until the next frame begins with the next sync pulse. Upon receiving the next sync pulse, the frame is transmitted. No pointer adjustment is needed by the egress port. A row number is used as a sequence number for the cell-packet to allow the egress port to re-order the cell-packets when transmitting the frame. Since no pointer manipulation is needed at the egress port, pointer management is simplified.
|
