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[altq 291] Re: Ingress traffic shaping?
Can't you use a traffic conditioner element to pass ingress traffic
coming over fxp0 to some acceptable rate and dropping the excess?
> Karl Pielorz wrote:
> > We're running AltQ-2.1 on FreeBSD 3.3, and we have a config which sets up fxp0
> > to be an interface with a forwarding rate of 512kbs, i.e.
> > interface fxp0 bandwidth 512k cbq
> > Outoing traffic seems to be pretty much kept to this overall 512k limit...
> > However, incoming traffic (fxp0 connects via a cisco to a higher speed link,
> > i.e. 2mb) doesn't seem to be limited... I remember reading somewhere that
> > whilst you can schedule / shape outgoing traffic you can't do the same to
> > incoming traffic?
> That's right.
> > - If this is true, surely the traffic coming 'in' from the
> > router is going to 'out' of the FreeBSD AltQ machine, and thus could be
> > shaped?
> Managing incoming traffic is tricky:
> - when congestion occurs, packets are dropped at the other side of
> your bottleneck link. you can't do much about it.
> - if incoming traffic is all adaptive (e.g., tcp), there is a chance
> to control incoming traffic to some extent.
> but, for packet scheduling to work, packets need to be backlogged
> in the queue.
> if the link is 512Kbps and you shape it to 512Kbps, packets are
> never backlogged.
> so, you have to shape it at a slightly lower rate in order to
> create a bottleneck for the packet scheduler.
> > ps. We do actually have valid reasons for wanting to shape 'incoming' requests
> > :-)
> So does everyone :)