On Sat, 04 Nov 2006 02:09:03 +0200
Graham Leggett <minfrin@sharp.fm> wrote:
> Hi all,
>
> I have been trying to investigate traffic shaping in an effort to solve
> the "unfriendly network apps" problem on a test network.
>
> I have a basis by which I'd like to shape traffic, but studying the
> howto doesn't uncover and existing qdisc that seems to fit what I would
> like to do.
>
> The problem I would like to address is to prevent an IP address opening
> 10 simultaneous streams from drowning out another IP address that opened
> 1 stream.
>
> I would like to penalise IP addresses where two or more simultaneous
> sessions are in effect, by adding a delay to the streams such that the
> total bandwidth used by the IP address is capped at a declining curve.
>
> In other words, assuming that the data you are sending is constrained
> behind you by a 1mbps bottleneck.
>
> When an IP has one session detected, their traffic is passed through,
> and normal rules apply.
>
> When an IP has two sessions detected, their combined sent traffic
> towards the IP is delayed and shaped down to say 800kbps.
>
> When an IP has three sessions detected, their combined sent traffic
> towards the IP is delayed and shaped down to say 600kbps.
>
> The starting point of how many sessions can be open before penalising
> takes effect, the starting point of the curve and the gradient of the
> curve would obviously be subject to lots of experimentation and would be
> set by the admin.
>
> The nett effect I am looking for, is that a user who chooses to open
> multiple simultaneous streams, should see a noticable decrease in
> maximum throughput, in an effort to discourage them from swamping the
> network with sessions.
>
> My question is, does a qdisc exist that implements something like this?
>
> Is this a reasonable thing to do, or will a strategy like this not work,
> and if not, why not? (for the purposes of me better understanding the
> issues).
>
> Regards,
How about making a modified version of RED that works by doing:
enqueue(skb) {
if (qlen < min) {
skb_queue(q, skb);
return;
}
if (qlen > threshold) {
drop(skb);
return;
}
skb1 = queue[random() % qlen];
if (skb->protocol == IP && skb1->protocol == IP &&
skb->src.ip == skb1->src.ip) {
drop(skb);
drop(skb1);
return;
}
skb_enqueue(q, skb);
}
There will be issues since the queue is no longer work conserving.
But it will penalize overloaders.
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