Poor quality - increased latency with internet usage



  • I have been watching the quality rrd graphs and when the internet is idle I see a consistent 10ms ping. As soon as someone begins downloading or uploading, the latency to our gateway increases to 40 or 50 on average and sometimes spikes in the hundreds.

    My ack queues are set to real-time 30% and 5% and I believe that's sufficient for my connection - it's DSL 5000/800. The default LAN queues have upper limits of 80% upstream and 90% downstream, but my qwanroot is set to 600kbps instead of 800 anyway. Besides, when I see the increased latency, it's NOT when the connection is at capacity - even when uploading at perhaps 100k or downloading at 1000 we still see the problem.

    40-50 ms ping isn't too bad but that's just to the gateway. My brother plays WoW and says sometimes it will spike to several thousand ms and screw up his game - but only for a moment so it doesn't show up in a one-minute average on the rrd graph.

    my dsl modem indicates that it is sync'd at 5085/800 so no problem with line quality. I would guess that it's an issue with the way I have the traffic shaper set up - especially because I really don't know how this shaper works or how to use it correctly.

    can anyone help me troubleshoot this problem? It would be much appreciated.

    let me just give you a bit of history:

    I previously had a cable connection and it would always stay constant around 15ms with regular usage, and the only time it would ever increase is when we turn on bit torrent, and then the latency would remain at a consistent 500ms - the cable company had their traffic shapers in effect. So we switched to a small DSL company that promises they do not use any sort of traffic shaping  - Teksavvy inc. (and I'm confident they are telling the truth after monitoring it for a while). But do you think it could just be an issue with the quality of their own network?



  • You're seeing a problem where one likely doesn't exist.

    First, your cable company probably didn't "shape" traffic. They may have, but from what you describe that doesn't seem to be the case.

    Your cable company was likely limiting traffic basically the same way your DSL is limited to 5000/800. On cable networks, the cable modem is where your throughput cap resides. When you're pegging your connection, queuing occurs in the modem, which causes latency to increase substantially.  500 ms with a pegged connection isn't bad at all. If I really hammer my cable modem (15/1.5 Mb) I can get gateway ping times in excess of a second. That's normal, especially if you're uploading heavily.

    DSL works basically the same way.

    The goal of traffic shaping is to move the queuing up to where it can be more controlled - your firewall. Once the traffic gets to your modem, if you reach your cap, it's too late. Things queue and they go out in FIFO (first in first out) fashion. Traffic shaping basically orders that traffic so the important traffic goes before the less important traffic. It's a lot more complex than that, but this post is long enough without a dissertation on traffic shaping.  :)

    Back to my point - your ping times from pfsense will suffer when your link is loaded to capacity, regardless of the type of connection (not just cable and DSL, T1's do it, fiber connections do it, wireless really does it, it's just how networks work). The only way to keep ping times from pfsense low would be to shape your traffic at a lower speed than your actual connection speed. Then you'll ensure at least relatively good response times. But what's the point? All you're doing is making your graphs pretty and keeping yourself from using your full Internet connection speed.

    I'm not familiar with the pfsense traffic shaper as I don't use it, so I won't offer any specific recommendations on configuration.


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