Rethinking ACKs at the Transport Layer

Acknowledgements are a core component of transport protocols. They can send control information and be used to receive feedback about transmission progress, to measure responsiveness and capacity of the network path, and numerous other purposes. This paper takes a long look at the way acknowledgements are used across different transports and what ACK information is actually needed in new protocol designs. TCP's use of ACKs has inspired the design of other Internet transports and was used as a model for QUIC.