Re: performance of libnet-based tools

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Hey Steven,

I'm not 100% familar with that error under ISIC, but sounds like libnet
is filling up the socket buffer faster then the network card can empty
it.

Those network cards you have prolly aren't the fastest in the world
which is probably one problem.  Intel/Pro 100 or 1000 cards generally
seem to do pretty well.  Other high-end or "server" cards should do
well.

You can also increase the buffer size, but that's not going to make your
computer send packets any faster, it may remove the error though.  On
*BSD increase the side of NMBCLUSTERS.  Check out options(4) for
details.

- -Aaron


On Fri, Feb 25, 2005 at 11:07:12PM -0800, Steven Alexander Jr. wrote:
> I've been experimenting with a few different
> libnet-based tools such as Packit and ISIC.  If I try
> to generate a high-volume of traffic using these
> tools, with various options and protocols, the error
> rate is extremely high.  ISIC says:
> 
> Failed to send packet: No buffer space available
> 
> The synflood tool that comes as a libnet sample works
> for several seconds and begins reporting:
> 
> libnet_write: libnet_write_raw_ipv4(): -1 bytes
> written (Host is down)
> 
> I'm not sure where the problem lies and I would love
> to hear any suggestions.  I'm using a 3.0Ghz P4 with
> 1.5G RAM and a $20 Linksys FA311 card on FreeBSD 5.3
> and a 1.3GHZ AMD laptop with 512MB RAM and a built-in
> Realtek RTL8139C+ card on FreeBSD 4.9.  
> 
> Do I need to tune the OS?  Do I need a better network
> card?
> 
> I'd like to be able to perform various stress testing
> exercises on my test network.  
> 
> Thanks.
> 
> -Steven

- -- 
Aaron Turner <aturner at pobox.com|synfin.net>  http://synfin.net/
They that can give up essential liberty to obtain a little temporary 
safety deserve neither liberty nor safety. -- Benjamin Franklin
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