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From Marc Slemko <>
Subject Re: draft-faber-time-wait-avoidance-00.txt
Date Sun, 14 Sep 1997 17:13:08 GMT
On Sun, 14 Sep 1997, Roy T. Fielding wrote:

> Is relevent to us.  It also mentions a patch is available for Apache.

Mmm.  While the authors (well, I an only speak for one) know much more
than I do... I am concerned that they only briefly mention various server
side solutions to the problem that may completely work around it, and
their tests are done using SunOS 4.x which isn't the most modern operating
system.  BSDI's changes are quite effective, and there are other solutions
(similar to have BSDI does SYN flood attack prevention) which use minimal
state on the server and improve the algorithm to something better than
linear search.  You can store an obscene number of TIME_WAITs in a trivial
(compared to the memory required for normal server functioning at that
level) amount of memory.

Their HTTP solution would appear to add a RTT or two to the time required
to close a connection and it is not really commented on how to implement
it in a backwards compat. way. 

> ....Roy
> ------- Forwarded Message
> From:
> Subject: I-D ACTION:draft-faber-time-wait-avoidance-00.txt
> Date: Fri, 12 Sep 1997 14:00:18 -0400
> Message-ID:  <>
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> 	Title		: Avoiding the TCP TIME_WAIT state at Busy Servers
> 	Author(s)	: J. Touch, T. Faber, W. Yue
> 	Filename	: draft-faber-time-wait-avoidance-00.txt
> 	Pages		: 14
> 	Date		: 11-Sep-97
>    This document describes the problems associated with the accumulation
>    of TCP TIME_WAIT states at a network server, such as a web server,
>    and details two methods for avoiding that accumulation.  Servers that
>    have many TCP connections in TIME_WAIT state experience performance
>    degradation, and can collapse.  One solution is a TCP modification
>    that causes clients to enter TIME_WAIT state rather than servers.
>    The other is an HTTP modification that allows the client to close the
>    transport connection, maintaining the TIME_WAIT state at the client.
>    The goal of both approaches is ensure that TIME_WAIT states accumu-
>    late at the less loaded endpoint.
>    The document also presents initial performance data from reference
>    implementations of these solutions, which suggest that the modifica-
>    tions improve HTTP connection rates at the server by as much as 50%,
>    and allow servers to operate at small transaction throughputs that
>    they cannot sustain their default configuration.
> Internet-Drafts are available by anonymous FTP.  Login wih the username
> "anonymous" and a password of your e-mail address.  After logging in,
> type "cd internet-drafts" and then
> 	"get draft-faber-time-wait-avoidance-00.txt".
> A URL for the Internet-Draft is:
> ------- End of Forwarded Message

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