Stephan Balmer wrote at 2010-02-12 11:55 -0600: > > An automatic detection of down/up bandwidth would be great, but it is not > > necessary. Hmm, is there a way to set up something to test > > pseudo-automatically, like try wget download while the box is booting... > > Doing it just once would be fairly unreliable. If for some reason the > initial download was slow, the system will limit itself way below a feasible > rate. Not that I have a quick solution. When I tinkered with this stuff I > figured that there are basically two parameters you can watch: > 1. ping round-trip time to the router on the other side of the bottleneck > 2. fill state and flow rates of the queues > > The ping round-trip tells you how long it takes to get through the > bottleneck up and down. You could monitor that and when it starts going over > half a second your script would gradually squeeze the bandwidth choke. That > way the system would try to keep latency low in the face of congestion. > > One problem with this is that you get only compound time up+down, and you > don't know for sure which one is congested. This is where the second part > comes in. By monitoring flow rates the gateway could learn correlation > between flow rates and round-trip times and thus determine the maximal link > capacity, and even adapt to changing capacity. > > I've got it all figured out, I'm just too lazy to implement it. :-) I wish all that was implemented in Linux shaping somehow... > > So, I just need to do ingress policing on WAN interface at 10% less than tested > > down bitrate... > > Yes. You'll need IMQ for this. Huh? Why not just this? tc qdisc add dev eth0 handle ffff: ingress tc filter add dev eth0 parent ffff: protocol ip prio 50 u32 match ip src \ 0.0.0.0/0 police rate ${DOWN}kbits burst 10k drop flowid :1 > > ...And egress shaping on WAN interface. I see another message with some more > > tips for that, and of course examples online also. > > Do this first, it's a lot simpler. Chances are you'll decide you don't need > ingress shaping after all. And use those "great big FIFO ISP queues" I have heard about? But yeah, if ingress shaping does not help significantly (for interactivity), then I certainly am better off without it. And then I would not need to test down bandwidth.
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