I-D ACTION:draft-ietf-tcpm-tcp-dcr-04.txt

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		: Improving the Robustness of TCP to Non-Congestion Events
	Author(s)	: S. Bhandarkar, et al.
	Filename	: draft-ietf-tcpm-tcp-dcr-04.txt
	Pages		: 17
	Date		: 2005-6-3

This document specifies Non-Congestion Robustness (NCR) for TCP.  In
   the absence of explicit congestion notification from the network,
   TCP's loss recovery algorithms treat the receipt of three duplicate
   acknowledgments as an implicit indication of congestion in the
   network.  This is not always correct, notably in the case when
   network paths reorder segments (for whatever reason), resulting in
   degraded performance.  TCP-NCR is designed to mitigate this degraded
   performance by increasing the number of duplicate acknowledgments
   required to trigger loss recovery, based on the current state of the
   connection, in an effort to disambiguate true segment loss from
   segment reordering.  In addition, we specify an option, Aggressive
   Limited Transmit, where the TCP sender does not reduce its sending
   rate until a segment is actually retransmitted; this would delay the
   reduction of the sending rate by roughly one round-trip time compared
   to current TCP implementations.  This document specifies the changes
   to TCP, as well as the costs and benefits of these modifications.

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