On Thursday 31 July 2003 05:00, Martin A. Brown wrote:
> Good questions Damion,
>
> : I've noticed as of late, everyone saying 'you can't shape incoming
> : traffic' but the best solution is to use the imq device.
>
> Well....(you'll love this) the reason everyone is saying "you can't shape
> incoming traffic" is because you can't shape incoming traffic (without
> IMQ).
>
> Well, in short, what we're really saying is that you can't control what
> you receive (without IMQ). As the recipient of frames/packets, you have
> no control over how fast they arrive in your device's input queue.
You can shape outgoing packets because they are queued in a buffer before they
are sended out. You can shape because you can reorder packets in that
buffer. Incoming packets are not buffered, so you can't change the order.
> : what happened to ingress /policer usage? is this not recommended
> : anymore?
>
> There's nothing at all wrong with using an ingress policer. I don't
> believe it's possible to attach any classes to the ingress qdisc*. That
> is, the ingress qdisc only exists to allow the user to police inbound
> traffic.
>
> So, using the ingress qdisc as a dummy qdisc against which to attach a
> policing filter (which drops traffic over a given rate) is the only use of
> the ingress qdisc.
Indeed. And policing is not shaping. Policing is rate limiting while shaping
can do more. For example, shaping can borrow unused bandwidth in a
controlled way between different flows.
Stef
--
stef.coene@xxxxxxxxx
"Using Linux as bandwidth manager"
http://www.docum.org/
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