Networking performance

Justin Krejci jkrejci at
Wed Feb 11 17:17:25 UTC 2009

STG is a very simple windows real time snmp grapher

It is geared at interface throughput but can easily be used for things like
CPU utilization, firewall connection counts, temperature, etc.

-----Original Message-----
From: Joel Jaeggli [mailto:joelja at] 
Sent: Friday, February 06, 2009 12:59 PM
To: Deric Kwok
Cc: nanog at
Subject: Re: Networking performance

Deric Kwok wrote:
> Hi
> I would like to ask your professional experience about switch throughput
> I have Gig Switchs eg: H P3400 /3500, cisco c4 948../ dlink
> In their spec, they said that it can handles Gig
> So far, I couldn't see their ports are used up over 200M in mrtg graph
> when I try to transfer 3G size files to files between computers

So, first off there's the question of sample interval vs the actaul time
the transfer takes... I'd use an instrument other than mrtg to measure
the spead of the transfer for example bytes transfer/wall clock time.

Second, you're benchmarking a bunch of components other than the
network, like your disks for example, which are likely slower than the
125MB/s you're trying to measure... Switch to ttcp or iperf for your
throughput measurement and you'll probably get a lot closer to measuring
what you're in fact trying to measure.

> ls there any limitation in those switchs?
> or I have to do configuration eg: put it full duplex instead of auto

autonegotiation on gigabit interfaces should almost always produce the
desired result.

> Thank you for your help

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