[rfc-dist] RFC 6069 on Making TCP More Robust to Long Connectivity Disruptions (TCP-LCD)

rfc-editor at rfc-editor.org rfc-editor at rfc-editor.org
Mon Dec 13 12:32:49 PST 2010

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        RFC 6069

        Title:      Making TCP More Robust to 
                    Long Connectivity Disruptions (TCP-LCD) 
        Author:     A. Zimmermann, A. Hannemann
        Status:     Experimental
        Stream:     IETF
        Date:       December 2010
        Mailbox:    zimmermann at cs.rwth-aachen.de, 
                    hannemann at nets.rwth-aachen.de
        Pages:      23
        Characters: 59600
        Updates/Obsoletes/SeeAlso:   None

        I-D Tag:    draft-ietf-tcpm-tcp-lcd-03.txt

        URL:        http://www.rfc-editor.org/rfc/rfc6069.txt

Disruptions in end-to-end path connectivity, which last longer than
one retransmission timeout, cause suboptimal TCP performance.  The
reason for this performance degradation is that TCP interprets
segment loss induced by long connectivity disruptions as a sign of
congestion, resulting in repeated retransmission timer backoffs.
This, in turn, leads to a delayed detection of the re-establishment
of the connection since TCP waits for the next retransmission timeout
before it attempts a retransmission.

This document proposes an algorithm to make TCP more robust to long
connectivity disruptions (TCP-LCD).  It describes how standard ICMP
messages can be exploited during timeout-based loss recovery to
disambiguate true congestion loss from non-congestion loss caused by
connectivity disruptions.  Moreover, a reversion strategy of the
retransmission timer is specified that enables a more prompt
detection of whether or not the connectivity to a previously
disconnected peer node has been restored.  TCP-LCD is a TCP sender-
only modification that effectively improves TCP performance in the
case of connectivity disruptions.  This document defines an Experimental 
Protocol for the Internet community.

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

EXPERIMENTAL: 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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