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wjw

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  Reply # 500681 2-Aug-2011 10:13
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GeoffisPure: Setting a max download speed of 500K  and 250K  still resulted in the unusual pattern and only made the downloads take longer.  :(






Are you still doing these downloads on wireless? 

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  Reply # 500801 2-Aug-2011 14:29
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wjw:

Are you still doing these downloads on wireless? 


This ^ 

 
 
 
 




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  Reply # 500915 2-Aug-2011 16:54
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Okay, have disabled wireless and downloaded some files with an ethernet connection. 
The annoying download pattern is still happening.  :-(










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  Reply # 501082 2-Aug-2011 22:37
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have you attempted to hack your TCP parameters - like MTU, RWIN etc - to make your connection better in the past?

do you still get ping drops from a wired connections?

have you a spare DSL router that you can swap to and re-test?

what dsl router are you using?




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  Reply # 501148 3-Aug-2011 08:49
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Thanks for your response, Regs.

Regs: have you attempted to hack your TCP parameters - like MTU, RWIN etc - to make your connection better in the past? 


No, I've not heard of this before and don't know how to do it.

do you still get ping drops from a wired connections?


No, and not from a wireless connection either. That issue has been resolved. But to be sure, any test results I'm posting here will be done with a wired connection.

have you a spare DSL router that you can swap to and re-test?
what dsl router are you using? 


The router I'm using is a Netgear DG834G v4 Wireless ADSL2 Modem Router.  I purchased it just a few months ago.  I think I will have to swap with a friend's and investigate.  I will do that over the next couple days and report back.

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  Reply # 501368 3-Aug-2011 14:31
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Since this is normal behaviour to some extent because its the nature of TCP, I wonder if there is anything else we have missed by focussing only on the TCP backoff issue. This behaviour would certainly be more apparent if something else was slowing down the throughput. What speed is your ADSL connection syncing at?

Also, does your download program measure speeds in kBytes/sec? In which case your 500kB/s download translates to 4000kbits/s ? quite a reasonable speed that implies your issue only occurs with international traffic at the 4pm peak time that you measured it. Traffic to Oz has lower latency than other international, so it may be caused by international latency as much as anything.




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  Reply # 501425 3-Aug-2011 15:39
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webwat: Since this is normal behaviour to some extent because its the nature of TCP, I wonder if there is anything else we have missed by focussing only on the TCP backoff issue. This behaviour would certainly be more apparent if something else was slowing down the throughput. What speed is your ADSL connection syncing at? 


just how 'normal' is this though?  i get an aggregate download speed of a constant 800KB/sec when i download items via HTTP/FTP over the home adsl connection.  No sawtooth here... at least nothing as visible as this




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  Reply # 501429 3-Aug-2011 15:44
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I'd have to agree, since the OP has been able to cap his download, this should essentially eliminate the chance that this is due to the TCP backoff algorithm.

I'm strongly suspecting an ISP issue in this case. I'm normally the last person to actually suggest this - expecially in the case of Snap, but I really think it's worth pointing Snap at this thread via twitter and asking them to confirm that it's 100% not them.

Cheers - N

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  Reply # 501444 3-Aug-2011 15:58
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Mine doesnt do that on snap, but without a time scale on the graph its pretty meaningless.




Richard rich.ms

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  Reply # 501448 3-Aug-2011 16:00
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richms: Mine doesnt do that on snap, but without a time scale on the graph its pretty meaningless.


It would be fair (and probably almost exactly right) to assume one pixel per second, even if I am out by a factor of 2-3 times (which I doubt), the pattern is still damning.

I'm also sure this won't be affecting ALL customers on Snap... There are many places this could be happening - I'm just saying it doesn't look like a local issue anymore.

Cheers - N




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  Reply # 501680 3-Aug-2011 22:49
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webwat: Since this is normal behaviour to some extent because its the nature of TCP, I wonder if there is anything else we have missed by focussing only on the TCP backoff issue. This behaviour would certainly be more apparent if something else was slowing down the throughput. What speed is your ADSL connection syncing at?


I've been told by Snap that my sync speed is good.  I hope i'm copying the relevant figures here:
DownStream Connection Speed
15238 kbps
UpStream Connection Speed
1177 kbps


webwat: Also, does your download program measure speeds in kBytes/sec? In which case your 500kB/s download translates to 4000kbits/s ? quite a reasonable speed that implies your issue only occurs with international traffic at the 4pm peak time that you measured it. Traffic to Oz has lower latency than other international, so it may be caused by international latency as much as anything. 


The speeds in the image above are KB/sec.  I agree that 500KB/sec isn't too horrible,  but without the speed dropping to nothing every 20 seconds, I would be getting average speeds of 800+ KB/sec, which is obviously preferable.

Talkiet: I'm strongly suspecting an ISP issue in this case. I'm normally the last person to actually suggest this - expecially in the case of Snap, but I really think it's worth pointing Snap at this thread via twitter and asking them to confirm that it's 100% not them.


Very interesting to have your opinion - thanks.  I'm still in touch with Snap via email and they say they are still trying to diagnose where the problem might be.  Tomorrow I am taking my modem to a friends house and testing that,  and then bringing his modem to mine to test that.  This will rule out my modem, anyway.

  richms:  Mine doesnt do that on snap, but without a time scale on the graph its pretty meaningless. 


The total time for each download is listed in the picture above. I included this to give people an idea of the time scale.   Roughly speaking, it appears that there is usual activity for 30 seconds,  and then a reduction to almost nothing for 15 seconds,  which repeats over and over.




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  Reply # 502386 5-Aug-2011 12:19
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I conducted a number of tests yesterday.  I borrowed my friend's modem and cables,  and tested both his and my equipment at both of our houses.  Interestingly, his modem actually dropped connection altogether a couple of times (during the speed drops).

This first image shows that both of our modems show  the frustrating speed drops every thirty seconds at my house:







This second image shows what happens when I try both of our modems at his house  (he is also on ADSL2 on an Xtra connection).  This shows the regular fluctuations I would expect.







So what can I conclude?
There is nothing wrong with my new modem, but there is something wrong with either my internal wiring or somewhere on the Telecom or Snap networks.  Upon sharing these results with Snap (who acknowledge something is wrong as they could see my friend's modem dropping off), I was told that this could be due to jackpoint or power-plug issues,  so I also tried  both modems in two other rooms in my house.  The problem still occurred everywhere.

I believe this means the problem can only be my internal wiring,  or somewhere on Telecom or Snap's network.  But here's the crappy part:  Snap say they could dispatch a technician, but they would likely say there's no problem with the things they check for, and therefore charge me a $200 no fault found fee.

Feels like I'm stuck between a rock in a hard place.  I could pay for my own technician to come round and check my internal wiring, but even if they can rule that out, it feels like Snap or Telecom will keep saying there's no problem and not be of any help :(

Please give me advice, fellow geeks.  What should I do?

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  Reply # 502388 5-Aug-2011 12:23
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GeoffisPure: [snip]

Please give me advice, fellow geeks.  What should I do?


You've done a heap of detailed testing and have eliminated a large number of variables. It's time for Snap to step up and do some real investigation.

Snap normally have pretty decent support. I'm surprised you're seemingly getting the runaround.

What about it Snap? Anyone watching? Helloooooo?

Cheers - N

ps. Please note I am definitely not saying the issue is with Snap... it could still be in part of the Telecom network - but it's up to Snap to deal with the issue now - at least IMHO.

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  Reply # 502428 5-Aug-2011 13:32
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you could drop Ralph from Snap a PM and see if he/she could help you

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