The RACK-TLP Loss Detection Algorithm for TCP
Y. Cheng, Neal Cardwell, Nandita Dukkipati, Pradeep Jha · 2021
This document presents the RACK-TLP loss detection algorithm for TCP. RACK-TLP uses per-segment transmit timestamps and selective acknowledgements (SACK) and has two parts: RACK (Recent ACKnowledgment) starts fast recovery quickly using time-based inferences derived from ACK feedback. TLP (Tail Loss Probe) leverages RACK and sends a probe packet to trigger ACK feedback to avoid retransmission timeout (RTO) events. Compared to the widely used DUPACK threshold approach, RACK-TLP detects losses more efficiently when there are application-limited flights of data, lost retransmissions, or data packet reordering events. It is intended to be an alternative to the DUPACK threshold approach.