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Date:      Wed, 10 Apr 2002 09:18:29 -0400
From:      Bill Vermillion <bv@wjv.com>
To:        freebsd-net@freebsd.org
Subject:   Re: Need help. A system stops responding to network requests periodically.
Message-ID:  <20020410131829.GA40130@wjv.com>
In-Reply-To: <OPEKLGNIBDIHJCIEIOPFGEJFCPAA.ank@bigpond.net.au>
References:  <OPEKLGNIBDIHJCIEIOPFGEJFCPAA.ank@bigpond.net.au>

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On Wed, Apr 10, 2002 at 11:06:09PM +1000, Arkadi Kosmynin spewed forth:

> I really can not explain this. We are stress testing a server. We
> use the following configuration: the server runs on a FreeBSD box
> (or Linux, with a similar effect). A multithreaded tester program
> runs on a Win2K box and emulates random multiuser activity. The
> FreeBSD box stops responding to network requests every 20-30
> minutes. I can't even connect to its FTP server. If I don't
> touch it, it does not "unstuck" for quite a while. But, if I do
> something with it, like start a Web browser on it and access the
> server, or just do netstat, it became active again shortly.

> Can anyone explain this? Is it some form of protection from denial
> of service attack? The tester program generates a lot of requests,
> and does it very fast, so, it does look like an attack.

You didn't say a thing about your network.  Sometimes the plain
stopping can be a result of automatic-sensing and
automatic-negotiation if you do not have everything fixed.

Take a look at this and understand the failure modes

http://www.cisco.com/warp/public/473/46.html

While it is targeted to the Cicso switches the same advice applies
to most things.  

I'm not saying this IS the problem you are having but since it is
on the same HW with two OSes this needs to be verfied.

Bill

-- 
Bill Vermillion - bv @ wjv . com

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