[tcpm] I-D Action:draft-ietf-tcpm-tcp-lcd-01.txt

Internet-Drafts@ietf.org Tue, 30 March 2010 14:00 UTC

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Subject: [tcpm] I-D Action:draft-ietf-tcpm-tcp-lcd-01.txt
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A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the TCP Maintenance and Minor Extensions Working Group of the IETF.

	Title           : Making TCP more Robust to Long Connectivity Disruptions (TCP-LCD)
	Author(s)       : A. Zimmermann, A. Hannemann
	Filename        : draft-ietf-tcpm-tcp-lcd-01.txt
	Pages           : 26
	Date            : 2010-03-30

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 revert 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 case
of connectivity disruptions.

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