Hi Nico,

90% of the bandwidth hogs we see are folks using well-behaved OSs. And
for the evil-doers out there that decide to craft a special
mass-mailer that somehow bypasses their OS TCP stack to ignore the
window size, then there's nothing to do there but use standard QoS
drops. But that's a rare occurrence. The more common issue are
impolite clients that need to be elegantly shaped down.

-J

On 2/21/07, Nicolas Williams <[EMAIL PROTECTED]> wrote:
On Wed, Feb 21, 2007 at 02:37:34PM -0700, Jason J. W. Williams wrote:
> >I'm not sure that I understand what you're talking about here,
> >can you expand on what problem you're having and how you would
> >like to address it?
>
> Say for example you've got a heavily utilized SMTP server. 100
> different clients connect that you haven't seen before. 20 of them
> start transmitting 20 MB files concurrently, which completely
> saturates your 20 Mb/s link for 106 seconds (assuming each client is
> limited on their end to a T1). In this case, what I'd like to be able
> to do is tell the OS when the connection is built up only allow this
> sender to consume 100 Kb/s. If the after 3 MB they're still sending
> data then I'd want to ratchet them down again to probably 20 Kb/s. The
> reason being, these 10 senders otherwise prevent the other 80 from
> getting connections...or cause them to time out.

But you don't need to muck with the MSS to make this happen -- nor can
you since it's a connection establishment-time thing.

It's important to note that you can't actually stop bad peers from
sending packets at their line rate, but you can slow down well behaved
peers.

Nico
--

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