RFC 4138 on Forward RTO-Recovery (F-RTO): An Algorithm for Detecting Spurious Retransmission Timeouts with TCP and the Stream Control Transmission Protocol (SCTP)

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        RFC 4138

        Title:      Forward RTO-Recovery (F-RTO): An Algorithm for
                    Detecting Spurious Retransmission Timeouts with
                    TCP and the Stream Control Transmission Protocol
                    (SCTP)
        Author(s):  P. Sarolahti, M. Kojo
        Status:     Experimental
        Date:       August 2005
        Mailbox:    pasi.sarolahti@nokia.com, kojo@cs.helsinki.fi
        Pages:      23
        Characters: 55538
        Updates/Obsoletes/SeeAlso:    None

        I-D Tag:    draft-ietf-tcpm-frto-02.txt

        URL:        ftp://ftp.rfc-editor.org/in-notes/rfc4138.txt

Spurious retransmission timeouts cause suboptimal TCP performance
because they often result in unnecessary retransmission of the last
window of data.  This document describes the F-RTO detection algorithm
for detecting spurious TCP retransmission timeouts.  F-RTO is a TCP
sender-only algorithm that does not require any TCP options to
operate.  After retransmitting the first unacknowledged segment
triggered by a timeout, the F-RTO algorithm of the TCP sender monitors
the incoming acknowledgments to determine whether the timeout was
spurious.  It then decides whether to send new segments or retransmit
unacknowledged segments.  The algorithm effectively helps to avoid
additional unnecessary retransmissions and thereby improves TCP
performance in the case of a spurious timeout.  The F-RTO algorithm
can also be applied to the Stream Control Transmission Protocol (SCTP).

This document is a product of the TCP Maintenance and Minor Extensions
Working Group of the IETF.

This memo defines an Experimental Protocol for the Internet community.
It does not specify an Internet standard of any kind.  Discussion and
suggestions for improvement are requested.  Distribution of this memo
is unlimited.

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Joyce K. Reynolds and Sandy Ginoza
USC/Information Sciences Institute

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