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The Silent Scream: The Sad Story of Aborted Connections

daemon@ATHENA.MIT.EDU (Simon E Spero)
Mon Dec 12 23:27:57 1994

Date: Tue, 13 Dec 1994 05:00:25 +0100
Errors-To: listmaster@www0.cern.ch
Reply-To: ses@tipper.oit.unc.edu
From: Simon E Spero <ses@tipper.oit.unc.edu>
To: Multiple recipients of list <www-talk@www0.cern.ch>

Executive summary:

	Preliminary results show that Netscape aborts 8 times as many
	connections as NCSA Mosaic, and that  nearly a quarter of all 
	Netscape conceptions result in abortion.

-----	
A while ago I posted a message to www-talk describing problems caused by
aborted connections, and the difficulties involved in getting reliable 
statistics on how often this problem was occuring.

Because it's so hard to gather these statistics through existing logs, 
I made some minor modifications to tcpdump to add some HTTP 1.0 protocol
analysis, and ran a trace on all http traffic going over the primary 
sunsite network. I only ran the trace for a relatively short period of time;
I'll be running a longer trace later this week. A brief analysis of the data
did yield some extremely interesting results. 

I classified an aborted transaction as one in which the client sends a packet
containing a RST flag, and a successful transaction as one where the client
sends a packet containing a FIN flag. 

The two most common clients as identified by a User-Agent flag in the HTTP
header were Mosaic (NCSA), and Mozilla(Netscape). 

RESULTS:

Browser		LIVE BIRTHS	ABORTIONS	TOTAL	ABORTION %age
---------------------------------------------------------------------
NCSA Mosaic	1,194		36		1,230		 3%
Mozilla		1,004		313		1,317		24%

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