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Upload killing download speed

piplowe
Hooked
Posts: 9
Registered: 07-06-2015

Upload killing download speed

I understand that the upload speed can have an effect on the download speed with regards to ACK packets, but should it drop the speed dramatically.
Line Rate
Rate (Kbps):
Downstream 21435
Upstream 984
Speedtest
17.58 Mbps
0.86 Mbps
http://www.speedtest.net/my-result/4561600637
Attached is a graph of uploading a file to box.net and downloading itunes
As you can see the upload grabs the max bandwidth and slowly pulls the download down to a crawl of less than a 0.9Mbps
I've tested this on more than one pc (wired and wireless)
When gaming I can see the my upload is about 0.8meg and my download 0.3meg hence my poor gaming experience as I'm assuming UDP packets are being dropped.
Any insight would be appreciated.
Phil
3 REPLIES
Community Veteran
Posts: 38,460
Thanks: 1,030
Fixes: 62
Registered: 15-06-2007

Re: Upload killing download speed

If the upload is being saturated that is exactly what you will see
Superuser
Superuser
Posts: 12,605
Thanks: 3,878
Fixes: 25
Registered: 22-08-2007

Re: Upload killing download speed

Quote from: piplowe
I understand that the upload speed can have an effect on the download speed with regards to ACK packets, but should it drop the speed dramatically.

Hi Phil,
If you have something hammering the upload to the exclusion of other services on your network, then downloads will be slugged due to being unable to return ACKs (or for that matter NACKs).
What is hammering the upload so much?
Sight of the router stats might indicate which ADSL service you are on and if there is any possibility of getting a bit more US speed ... which will help a little.
Kevin
Community Veteran
Posts: 5,172
Thanks: 480
Fixes: 20
Registered: 10-06-2010

Re: Upload killing download speed

The 2704N seems to be particularly bad at managing the situation where you're fully utilising your upload for a while. Fixing this "bufferbloat" issue is finally getting a bit more attention, and measuring the issue has been added to the dslreports.com speedtest.
Edit: The last 3 threads I could find on the subject:
Uploading to YouTube Kills Downstream
HELP Uploading causes Slow internet
Downloads stop while uploading
These kind of threads seem to have started or become more common since the 2704N, unless that's just a coincidence and people are uploading more these days.
It shouldn't have to be like this, a router could manage the situation much better than many current ones do.