Subject: Why do large downloads fail ?

From: Martin Lorang <[email-masked]>
Date: Thu, 21 Oct 1999 07:43:36 +0200 (METDST)

Hi
    Why is it that we encounter problems of
connections breaking off when downloading large files.

Thanks in advance,
Arkesh

=====
R. S. Arkesh Kumar	
Research Engineer,
Centre for Development of Telematics(C-DOT),
71/1, Miller Road,
Bangalore-560 052, India.
Ph : 91-80-2263399 Ext:329
Fax : 91-80-2263256
__________________________________________________
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Bid and sell for free at http://auctions.yahoo.com

-----------------------------------------------------------------------------
 Martin Lorang                          Universitaet Stuttgart
                                        Institut fuer Nachrichtenvermittlung
 Phone: +49 711 685 7991                und Datenverarbeitung
 Fax:   +49 711 685 7983                Pfaffenwaldring 47 
 [email-masked]            D-70569 Stuttgart
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From: Vernon Schryver <[email-masked]>
Date: Thu, 21 Oct 1999 07:56:06 -0600 (MDT)

> From: Martin Lorang <[email-masked]>
> To: [email-masked]
> Cc: [email-masked]

> connections breaking off when downloading large files.

I've noticed something odd with the WINSOCK2 in Windows 98, both original
and 2nd Edition.  On a TCP connection that should have an RTT of about
500 ms (measured by `ping`) and that breaks (I disconnect a router), Windows
does a total of 5 retransmissions and then kills tells the application
WSAECONNRESET or "Connection reset by peer" instead of "connection timed
out.  As seen by third party on the same 10BASE-T segment, the
retransmissions are at 1.561 ms after the 1st transmission, then again
3.199 seconds later, after 6.400 seconds more, 12.800 sec, and finally
after 25.595 sec.  That last or fifth retransmisssion is a total of 49.552
seconds after the original transmission.

50 seconds is less than the values for R2 suggested in 4.2.3.5 of RFC 1122,
although they do get more than the suggested 3 retransmissions.

From what I've seen of the Internet in recent years, 50 second hiccups
are very much other than uncommon.  If what I've observed about
Microsoft's WINSOCK2 is reasonable and if R. S. Arkesh Kumar or Martin
Lorang are using Windows 98, this might be related to that problem.

The WSAECONNRESET error bugs me as much as the short timeout, because it
misleads me into thinking that the TCP peer got unhappy (e.g. terminated
the connection) and sent an RST.

Vernon Schryver    [email-masked]