Tail Loss Probe (TLP): An Algorithm for Fast Recovery of Tail Losses

Document Type Expired Internet-Draft (individual in tsv area)
Last updated 2015-10-14 (latest revision 2013-02-25)
Stream IETF
Intended RFC status Experimental
Expired & archived
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Stream WG state (None)
Document shepherd No shepherd assigned
IESG IESG state Expired (IESG: Dead)
Consensus Boilerplate Unknown
Telechat date
Responsible AD Martin Stiemerling
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


Retransmission timeouts are detrimental to application latency, especially for short transfers such as Web transactions where timeouts can often take longer than all of the rest of a transaction. The primary cause of retransmission timeouts are lost segments at the tail of transactions. This document describes an experimental algorithm for TCP to quickly recover lost segments at the end of transactions or when an entire window of data or acknowledgments are lost. Tail Loss Probe (TLP) is a sender-only algorithm that allows the transport to recover tail losses through fast recovery as opposed to lengthy retransmission timeouts. If a connection is not receiving any acknowledgments for a certain period of time, TLP transmits the last unacknowledged segment (loss probe). In the event of a tail loss in the original transmissions, the acknowledgment from the loss probe triggers SACK/FACK based fast recovery. TLP effectively avoids long timeouts and thereby improves TCP performance.


Nandita Dukkipati (nanditad@google.com)
Neal Cardwell (ncardwell@google.com)
Yuchung Cheng (ycheng@google.com)
Matt Mathis (mattmathis@google.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)