Hardware RDMA Transport with Selective Recovery for Packet Loss

The patent implements selective acknowledgment (SACK) mechanism that allows the receiver to identify and acknowledge specifically which packets have been received correctly. When packet loss is detected, only the lost packets are retransmitted rather than forcing retransmission of all subsequent packets. This selective recovery approach recovers from packet loss while minimizing unnecessary retransmissions of already-received data.

The patent implements explicit feedback mechanisms through acknowledgment (ACK) and negative acknowledgment (NAK) packets. The receiver sends ACK packets to confirm receipt of packets and NAK packets to indicate packet loss. This feedback loop enables the sender to make informed retransmission decisions without requiring complex network-wide congestion control mechanisms like PFC, thereby reducing device complexity while maintaining reliability.

The patent extends the feedback mechanism to include resource status reporting. When the receiver's out-of-order tracking resources are depleted, the system can send appropriate feedback signals to the sender. This enables the sender to adjust its transmission strategy, such as reducing the rate of out-of-order packets or implementing flow control, thereby preventing information loss while maintaining high throughput through continued out-of-order placement.

The patent implements dynamic retransmission timeout adjustment based on network conditions and packet characteristics. Rather than using a fixed static timeout, the system adapts the timeout values dynamically. When tail drops occur, the dynamic timeout mechanism can adjust to avoid premature retransmission attempts that would fail, thereby maintaining reliability guarantees while preventing goodput degradation through intelligent retry timing.