>>All of a sudden tonight my web browsing and ssh performance is
>>terrible. I'm on a cable connection and I'm wondering if it could be
>>due to evening bandwidth contention or ISP throttling. If so, I
>>suppose tcdevices numbers are out the window. Can anything be done?
>
> First thing you can do is look at your TC numbers and see where the
> packets are queuing up - if your TC isn't throttling it, then it must
> be external.
>
> As I wrote in another thread ("Traffic Shaping Newbie", 20th Jan),
> unless you have a guaranteed minimum bandwidth then you have to
> compromise. If you configure your TC when there is no contention (in
> the local cable network, or in the ISPs backhaul) then it will fail
> to function once contention kicks in and your available bandwidth
> drops. All you can do is compromise :
>
> Reduce your inbound and outbound rates to allow for the contention.
>
> The downside is that unless you throttle yourself down to the worst
> case situation, then you are still going to have periods where your
> tc doesn't work properly. And any reduction in rates you specify will
> restrict you for the other 22 hours of the day.
>
> Over here in the UK, ADSL used to be sold on contention ratio but
> virtually all ISPs have dropped that and no longer mention it.
> Typical for home use was 50:1, so a 2Mbps ADSL service could cut you
> down to just 41kbps ! Not many people realise this, and I think the
> best way to deal with some of the complaints would be to force the
> ISPs to quote minimum rates (aka CIR, Committed Information Rate)
> which is common in business environments - but that's another thread !
>
> So if you had such a 50:1 2M service, to guarantee effectiveness of
> your tc, you would need to set your inbound rate to just under 41kbps.
>
> In the real world, the other 49 won't be using there 2M all the time
> - that's why the ISPs can (or at least could) get away with it. Now
> torrenting and watching video is so common, more people are using
> more bandwidth for more of the time and congestion in the backhaul
> (or local segment in cable networks) is more of a problem.
Thank you for taking the time to explain. That's what I was afraid
of. How can I look at my TC numbers and see where the packets are
queuing up? Is that done in tcdump?
- Grant
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