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Date:      Thu, 20 Feb 2003 11:08:26 -0600
From:      Dan Nelson <dnelson@allantgroup.com>
To:        Will Saxon <WillS@housing.ufl.edu>
Cc:        questions@FreeBSD.ORG
Subject:   Re: network tuning
Message-ID:  <20030220170826.GO13096@dan.emsphone.com>
In-Reply-To: <0E972CEE334BFE4291CD07E056C76ED8DB2B69@bragi.housing.ufl.edu>
References:  <0E972CEE334BFE4291CD07E056C76ED8DB2B69@bragi.housing.ufl.edu>

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In the last episode (Feb 20), Will Saxon said:
> I am trying to use ntop in the 'border filter' mode to get some
> statistics on that link, which is a gigE link typically seeing
> 40-120Mbps sustained traffic (varies throughout the day). The
> capturing interface is an intel pro/100+ server adapter, plugged into
> another port on the switch set to mirror the gigE interface.
> 
> Obviously there ought to be some drops due to serialization
> differences, etc. But ntop is reporting upwards of 2/3 packets
> dropped in the kernel and running tcpdump on that interface for any
> length of time reports usually 50% drops in the kernel.

You first need to determine what is being overloaded.  Run top.  Is
ntop running at 100% cpu?  If so, you'll need a faster machine.  If
it's close to 100%, bumping debug.bpf_bufsize might help.  What are the
user/system/irq CPU percentages while ntop is running?

-- 
	Dan Nelson
	dnelson@allantgroup.com

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