The RACK-TLP Loss Detection Algorithm for TCP
RFC 8985, “The RACK-TLP Loss Detection Algorithm for TCP”, is a Proposed Standard document published in February 2021 by Y. Cheng, N. Cardwell, N. Dukkipati, P. Jha. The canonical text is published by the RFC Editor.
Abstract
This document presents the RACK-TLP loss detection algorithm for TCP. RACK-TLP uses per-segment transmit timestamps and selective acknowledgments (SACKs) and has two parts. Recent Acknowledgment (RACK) starts fast recovery quickly using time-based inferences derived from acknowledgment (ACK) feedback, and Tail Loss Probe (TLP) leverages RACK and sends a probe packet to trigger ACK feedback to avoid retransmission timeout (RTO) events. Compared to the widely used duplicate acknowledgment (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.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
The canonical text of RFC 8985 is hosted at rfc-editor.org. Available in HTML,TXT,PDF,XML.
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