>From what I understand is it the TCP/IP Stack in solaris's Kernel. Here is
the message that I got, and a few URL's that will help
> ---------- Forwarded message ----------
> Date: Tue, 21 May 96 08:41:06 UTC
> From: Hank Nussbacher <hank@ibm.net.il>
> To: nanog@merit.edu
> Subject: Solaris retransmission bug eats Internet links
>
> If you can think of a better list to post this, please forward it...
>
> The following TCP bug has been measured to consume as much as
> 15% of Internet links. ISPs who run heavily congested links
> and/or satellite links will lose 15% of their bandwidth as we
> have due to this error by Sun.
>
> Please distribute this announcement to those running Solaris 2 as often as
> possible.
>
> Thanks,
> Hank Nussbacher
> IBM Israel
>
> --------------------------------------------------------------------
> During the last few weeks we were conducting a survey of our internet
> communication performance. As a result of the survey we have discovered
> that your host is involved in a large portion of TCP/IP retransmissions.
> This phenomena significantly decreases the communication performance.
>
> If your host is a Sun running Solaris 2, than we think we know what is the
> source of the problem. It appears that Solaris 2 has a bug in the TCP/IP
> implementation, causing excessive retransmissions to occur. The following
> is an excerpt from the May 3rd Solaris 2 FAQ:
>
> -----------------------------------------------------------------------------
> +5.49) Solaris 2.5 and Solaris 2.4 patch 101945-34+ have poor TCP performance
> over slow links.
>
> Solaris 2.5 and Solaris 2.4 kernel patch 101945-34 and later have
> a bug in their TCP retransmission algorithm that cause excessive
> retransmissions over slow links, Sun's bug ID is #1233827.
>
> A work around for this bug is running the following commands
> at system boot, e.g., by adding them to /etc/init.d/inetinit
> (values are in milliseconds):
>
> /usr/sbin/ndd -set /dev/tcp tcp_rexmit_interval_min 3000
> /usr/sbin/ndd -set /dev/tcp tcp_rexmit_interval_initial 3000
> -----------------------------------------------------------------------------
>
> Please note that the above mentioned patch (101945-34) included a "fix"
> to the retransmission problem, but apparently, the fix is not good enough
> (see "http://www.sun.com/sunworldonline/common/cockcroft.letters.html"
> section: "How can I improve my Web server's http performance?").
>
> To summarize, it seems that all Solaris 2 versions suffer from this problem!
>
> We recommend that you apply the above workaround until the problem is
> resolved in a future Sun release. Please note that the problem affects
> mainly your host and users accessing it over large latency links, such as
> satellite links (as we do), or over slow links (e.g. dialup lines) or a
> congested network .
>
> We will appreciate if you let us know how do you intend to proceed with this.
>
> Thanks for your cooperation,
>
> Oded Comay (comay@post.tau.ac.il)
> Operating Systems group
> Computing Center
> Tel Aviv University
+-------------------------+------------------------+
| Shawn Freeman | GoodNet, LLC |
| (602) 303-9500 Ext. 259 | Network, LAN, and UNIX |
| goggles@goodnet.com | System Administration |
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| 'Funny... I've never seen it do THAT before....' |
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