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 From:  Lee Sharp <leesharp at hal dash pc dot org>
 To:  "m0n0wall at lists dot m0n0 dot ch" <m0n0wall at lists dot m0n0 dot ch>
 Subject:  Re: [m0n0wall] Traffic Shaping
 Date:  Thu, 10 Sep 2009 22:05:26 -0500
Chris Buechler wrote:
> On Thu, Sep 10, 2009 at 8:28 PM, Paul Dugas <paul at dugasenterprises dot com> wrote:
>> On Thu, Sep 10, 2009 at 6:29 PM, Lee Sharp <leesharp at hal dash pc dot org> wrote:
>>> Joey Morin wrote:
>>>  Or, do I need to get the ISP to setup shaping rules on [Rtr1] to make this
>>>> work?
>>> You can do it all at your end.  You will need to set limits slightly below
>>> your full bandwidth, but it will work fine.
>> So, where can I learn more about the mechanism?  How does the local router
>> influence how the remote router chooses one packet over another to stuff in
>> the saturated link?
> It doesn't. The shaper can queue things in such a way that it will
> slow downloads because of TCP's congestion control mechanisms. If you
> can queue on both ends though, that's preferable. Most of the time
> that isn't an option.

And it really isn't absolutely necessary.  If you keep your "shaped" 
pipe smaller than your available download, it will be able to 
accommodate priority traffic very well.  If you have a very high volume 
of states, you just have to leave more headroom between the shaped and 
actually bandwidth to accommodate short bursts before the congestion 
mechanisms kick in.  The difference really is amazing.