Abstract: Aspects of the disclosure provide techniques for retransmitting transaction layer packets (TLPs) for which a negative acknowledgment (NACK) is received without retransmitting previously transmitted TLPs that are correctly received, yet out-of-sequence, by a receiver. A receiver (e.g., a receiving link partner) can provide a transmitter (e.g., a transmitting link partner) with a NACK that includes a starting sequence number (SSN) and an ending sequence number (ESN), which can notify the transmitter about the packets for retransmission and/or packets that can be purged from a transmit buffer of the transmitter.