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Drop in responsiveness when uploading

StewartM
Hooked
Posts: 5
Registered: 02-08-2016

Drop in responsiveness when uploading

I'm getting quite a drop in responsiveness when browsing when uploading files.

From Speedtest, Ping is usually around 20–30ms, but during uploads Ping is typically about 850ms.

 

The download speed is normally around 13–14Mbps, but during uploads the download speed is typically around 5Mbps (and peaky over the duration of the test, opted falling below 1Mbps).

And the upload speed is normally just over 1Mbps, dropping to typically 0.3–04 Mbps during uploads (presumably to be expected, as uploading is going on).

 

So is there any way reduce the drop in responsiveness during uploads?

 

This is with a Plusnet Sagemcom F@st270N, connecting using Apple laptops, iPhones and iPads.

4 REPLIES
Community Veteran
Posts: 5,079
Thanks: 1,200
Fixes: 30
Registered: 16-10-2014

Re: Drop in responsiveness when uploading

This is correct as in order to upload the servers 'talk' to each other in both directions so this will have an effect on the download both in speed and responsiveness.

StewartM
Hooked
Posts: 5
Registered: 02-08-2016

Re: Drop in responsiveness when uploading

Hi Mook. Yes, I understand what you say, but it’s a question of degree. When an upload is in progress, the download speed is dropping to about 35% of normal, and the latency is increasing by over 4,000%! That can’t be right, can it?

Community Veteran
Posts: 5,079
Thanks: 1,200
Fixes: 30
Registered: 16-10-2014

Re: Drop in responsiveness when uploading

@StewartM - Those numbers do seem a bit large to be honest, but I'm no expert in this field, but you do need to take into consideration where you are uploading to. If the service in question was popular there may well be in issue with contention, along with the quality of the route used and of course the protocol used in the process can have an effect.

P.S. Apologies for the late response, didn't realise you'd posted.

 

Community Veteran
Posts: 470
Thanks: 34
Fixes: 2
Registered: 26-09-2015

Re: Drop in responsiveness when uploading

This is a problem with the 2704N router. When the upload direction is maxed out, which is quite easy to do on ADSL, the router queues up the backlog of packets for a stupidly long time instead of implementing a sensible tail drop algorithm. The so-called "buffer bloat". The problem is that this backlog now delays every upstream packet, including those that acknowledge data transfer in the download direction, thus causing your downloads to slow down as well as making everything else unresponsive. I would make VoIP completely useless.
The quick solution is a better router. A more sophisticated solution is a better router, and some configuration to prioritise data on upload allowing important stuff like voice to jump the queue altogether.