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.