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 From:  Chris Hoy Poy <chrishp at dugeo dot com>
 To:  Mark Ryan <markryan at cfl dot rr dot com>
 Cc:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] traffic shaper borrowing
 Date:  Wed, 25 Oct 2006 09:42:56 +0800
no, its *extremely* effective at smoothing the traffic when you have it set 
near the right bandwidth. Dont forget that the traffic shaper can only have 
limited effect on incoming traffic anyway, as those packets are sent from the 
upstream provider.

I had a few problems with ADSL routers that had low buffers, and normal 
traffic to them would flood them so much they'd disconnect from the net (so 
the net connection would see-saw under load). The traffic shaper effectively 
stopped this, and under load the traffic would be nicely smoothed (and still 
responsive, so the acks/nacks were getting thru in a timely fashion etc).


On Wednesday 25 October 2006 09:00, Mark Ryan wrote:
> Chris Hoy Poy wrote:
> > hello again ;)
> >
> > You've got pipes and queues.
> >
> > my understanding is this:
> >
> >  Queues represent possible slices of a pipe. The shaper will try to allow
> > each queue its *minimum* % bandwidth of a pipe, but the queue is allowed
> > to use all of the pipe if its available.
> >
> > But pipes represent a hard limit, to my knowledge, and wont borrow from
> > other pipes. You need to do that allocation at the queue level.
> >
> > Rules then allocate actual traffic to each queue.
> >
> > so looking at your question again : if FTP is in the low priority queue
> > and everything else is in the high priority queue, then FTP will use the
> > maximum pipe speed, but will drop back down to its minimum when something
> > else happens.
> >
> > Note the one "semi" issue I have seen is where you allocate a pipe to be
> > less then the bandwidth you have available - it seems to use a bucket
> > system to allocate the pipe, so if you allocate a really small pipe (like
> > 512kbit) and you actually have 2mbit of bandwidth there, the pipe will
> > flood the bandwidth for 1/4 of the time available and the actual usage
> > will be very jagged. That may not apply, but I've done it a few times
> > without thinking and found the behaviour (though it makes sense when I
> > think about it) at the time was a bit bizarre. There might be some way to
> > change the interval that the traffic shaper uses? It seems to be set at
> > like 5 or 10 seconds. Having smaller intervals would make the flow a bit
> > smoother, I assume.
> >
> > does that make sense? ;)
> >
> > On Tuesday 24 October 2006 09:44, Mark Ryan wrote:
> >> I've been evaluating whether the m0n0wall traffic shaper will work for
> >> me and I have to say wow!  It seems very nice.
> >>
> >> I do have 1 question:
> >>
> >> Does the traffic shaper use borrowing?  Such as if i have 2 upload ques,
> >> ftp assigned to low priority que and everything else assigned to high
> >> prio que.  Will the ftp consume the maximum available pipe speed until
> >> something in the high prio ques needs it, then i would assume the ftp
> >> traffic would slow down until the bw is available again?
> >>
> >> Sorry for the cryptic question there.
> >>
> >> Mark
> >>
> >> ---------------------------------------------------------------------
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> Yes, makes sense.  That jagged use of bw bothers me though.  Does that
> happen if you set the pipe close to the bw available?
> Thanks for the explanation!
> Mark

Chris Hoy Poy
System Administrator
DownUnder GeoSolutions