Control flow reduction in selective repeat protocols.

摘要

In the Checkpoint Mode Protocol (CPM), checkpoint frames are transmitted at regular intervals for acknowledging received information frames and individually requesting retransmission of missing information frames. The disclosed invention reduces the flow of checkpoint frames in situations where their information is not required. This is achieved by either sending a Stop Checkpointing frame from sender to receiver in particular situations, or by inserting, in the case of duplex transmission (i.e. both stations are sending and receiving), Request-Reply bits into normal checkpoint frames for suppressing the flow of checkpoint frames when they are not necessary. In each case, provisions are made to resume the transmission of checkpoint frames as soon as they are required again.