Subject: [Tsvwg] I-D ACTION:draft-ayesta-to-short-tcp-00.txt

From: Urtzi Ayesta <[email-masked]>
Date: Wed, 23 Oct 2002 14:56:13 +0200

Dear Members of TSVWG,

Please find below an abstract of a new InternetDraft on reducing timeouts in 
Short TCP transfers.

All comments and suggestions are very welcome.

Kindest regards,
Urtzi Ayesta and Konstantin Avrachenkov

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.

	Title		: On reducing the number of TimeOuts for short-lived TCP
                          connections
	Author(s)	: U. Ayesta, K. Avrachenkov
	Filename	: draft-ayesta-to-short-tcp-00.txt
	Pages		: 5
	Date		: 2002-10-21
	
This document shows that short TCP sessions are prone to timeout. In
particular, one single segment loss will provoke TCP to timeout if the
document size is below certain threshold. This document analyzes the
benefit of TCP modifications such as Limited Transmit Algorithm
[RFC3042] and Increasing Initial Window [RFC2414] in the context of
short-lived TCP transfers. However TCP remains vulnerable to the losses
at the very end of the transmission. Therefore we suggest complementary
modifications to Limited Transmit Algorithm to recover effectively from
losses at the end of the TCP transfer.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ayesta-to-short-tcp-00.txt

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From: Jeffrey Hsu <[email-masked]>
Date: Wed, 23 Oct 2002 14:37:02 -0700

Is this modification applicable for dynamically generated data when the
currently remaining amount of data to send is less than TO-THRESH, or,
is this really meant only for statically sized data?

							Jeffrey

---

From: Urtzi Ayesta <[email-masked]>
Date: Thu, 24 Oct 2002 15:12:04 +0200

Hello,

TO-THRESH was defined for statically sized data, in particular if the file 
size is smaller or equal to TO-THRESH, the TCP will inevitably timeout if a 
segment is lost.

Limited Transmit Algorithm sends new segments upon reception of the 
first two duplicate ACKs. In this way the likelihood the TCP receiver will 
receive three duplicates increases and as a consequence the posibility of
timeout is reduced.

In cases when the TCP sender receives a duplicate ACK and no more new data 
queued, the TCP sender will wait for the reception of three duplicates 
corresponding to the already sent segments.  In particular, when either one 
of these three segments is lost, TCP will inevitably timeout. In this 
circumstance, we suggest the possibility of retransmitting immediately upon 
reception of one duplicate ACK. 
This could benefit applications that generate data dynamically in on-off 
pattern withing the same TCP connection (Telnet and Network games).

thanks for your interesting comment.
Urtzi