Abstract: An apparatus and method for efficiently managing shadow stacks.

Abstract: A method and apparatus to insert control blocks into a stream of data user blocks. Data user blocks are transmitted onto a network during transmission slots. One of the data user blocks is buffered during one of the transmission slots. Instead of transmitting the buffered data user block during this transmission slot, a control block is transmitted onto the network in the data user block's place. Transmission of the data user block is delayed until the next transmission slot. The control block is inserted at a required position into the stream of data user blocks at a transmit engine, as opposed to a queue manager, leaving the queue manager unconcerned with the insertion details of the control block. Insertion of the control block by the transmit engine enables the queue manager to handle frames containing large numbers of user blocks as a single unit (e.g., such as is the case with AAL-5) and avoid complications related to inserting the control block in the midst of these frames.