Integrated memory for storing egressing packet data, replay data and to-be egressed data

摘要

An integrated egress/replay memory structure is provided with split rate write and read ports and means for managing at least three types of data moving into, through and/or out of the integrated memory structure, namely: (1) currently egressing packet data; (2) replay data; and (3) to-be egressed data. Additionally, a shared free space (4) is managed between the storage areas of the (2) replay data and (3) the to-be egressed data. The to-be egressed data (PdBx) is allowed to enter into (to be written into) a front-end raceway portion of the integrated memory structure at a rate which can be substantially greater than that allowed for corresponding egressing packet data (PdUx). Thus, even when egressing packet data that is ahead in line is shifting out toward a slow rate egress port; this slowing factor does not slow the speed at which the to-be egressed data (PdBx) can be shifted into the front-end raceway portion. A shared free space memory area is maintained between the storage areas of the replay data (PdAx) and to-be-egressed data (PdBx). When a positive acknowledgement (ACK) is received from the destination of already-egressed data (of the After-Transmission Data, or PdAx), the corresponding replay storage area (the area storing the acknowledged PdAx data) can be reallocated for use as an empty part of the raceway portion.