DSL bandwidth always starts low and climbs?

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dsalch
Posts: 123
Joined: Wed Jan 06, 2016 2:09 pm
Location: Tx

DSL bandwidth always starts low and climbs?

Post by dsalch »

I have been toying with the QOS inside gargoyle for a few years. great stuff! But There is one consistent finding on my own DSL line that I just dont understand. I will explain as well as I can:

router: gargoyle 1.8.2 on netgear wndr 3700
ISP: centurylink dsl 10M/768K
QOS: 3 basic rules, ACC active
Test mechanism: many, virtually ALL (dslreports, ookla, centurylink, mlabs, etc)

Summary: Whenever a new stream of bandwidth starts up, the ping times increase dramatically for a few seconds, then drift down to normal. During this time, the bandwidth is also limited but increases as ping time decreases.

For instance, an example session:

normal ping times, 15 to 18 ms
start stream
1 second - ping time 400ms bandwidth = 3M
2 seconds - ping time 800ms bandwidth = 1.5M
3 seconds - ping time 600ms bandwidth = 2M
4 seconds ping time 300ms bandwidth =4M
5 seconds ping time 100ms bandwidth = 6M
6 seconds ping time 50 ms bandwidth = 8M

final average bandwidth = 6M

Those numbers are not exact, but an average over multiple tests. the "curve" is always the same. repetitive tests show less pronounced dip. waiting longer between tests increases the dip again.

I have tried various ping targets inside centurylink and the effect is the same. It is a little less pronounced as the ping target moves deeper into centurylink, away from my own WAN gateway.

The bandwidth always tracks the ping times, so it seems that the problem is not within the router, but within centurylink.

What this does to ACC is to artificially lower the bandwidth that gargoyle passes. The fair link limit decreases faster than it increases if there are successive short bursts like this. I have seen most morning after running regular automated tests, the ACC fair link limit drops to about 3M.

What could be the cause inside of centurylink for this phenomena?

ispyisail
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Posts: 5180
Joined: Mon Apr 06, 2009 3:15 am
Location: New Zealand

Re: DSL bandwidth always starts low and climbs?

Post by ispyisail »

screen shot of the speed test?

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