Efficient link layer retry protocol utilizing implicit acknowledgements

摘要

Methods, apparatus, and systems for implementing a link layer retry protocol utilizing implicit ACKnowledgements (ACKs). Peer link interfaces are configured to facilitate confirmed error-free delivery of link-layer packets through use of implicit ACKs, while also providing retransmission of packets for which errors are detected and guaranteeing the link control data is either successfully received or data transfer over the link is prevented. In conjunction with transmitting packets, reliable packets are copied into sequential slots in a replay buffer. Each link interface tracks the slot at which each reliable packet is buffered, and in response to detection of an error, a retry request is sent to the transmit-side to retransmit the errant packet. The previously buffered copy of the errant packet is retrieved from the replay buffer and retransmitted. Through use of a link roundtrip detection mechanism, absence of a retry request by the time a replay buffer has returned to the slot of a reliable packet (plus a predetermined number of additional transfer cycles, if applicable) provides an implicit ACK that the packet was received without error.

主权项

1. An apparatus, comprising:
a link interface configured to support bi-directional communication with a link interface of a link peer when the apparatus is coupled to the link interface of the link peer via a link and operating, wherein the link interface for each of the apparatus and link peer includes, a receive port; and a transmit port comprising a replay buffer and circuitry and logic to,
temporarily store a copy of each of a plurality of reliable packets to be transmitted over the link to a receive port of the link peer in the replay buffer;transmit packets including the reliable packets over the link to the receive port of the link peer;determine that the reliable packets have been received without error at the receive port of the link peer without use of an explicit Acknowledgement (ACK) from the link peer; andoverwrite copies of previously transmitted reliable packets for which it has been determined were received at the receive port of the link peer without error.