Upload Speed Capping ?

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jasatt
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Upload Speed Capping ?

#1 Post by jasatt » 2019-09-12 03:27

Hi there,

Recently I have upgraded my internet connection to fibre; the upload speed went from 1Mbps to 20Mbps. The strange thing is that I have noticed no upload speed difference; the speed starts around 2.5MB/s (the 20Mbps) and then very quickly drops down to around 125/250KB/s (the 1Mbps). The files I am uploading (and testing) are single 720p and 1080p .mp4 files ranging from 250mb to 1GB size. The 'Enable speed limits' setting in Filezilla is disabled. I have also contacted my webhosting customer support to check if there is an upload capping from their side but the reply was no. A speed test from the ISP website and speedtest.net shows that I am receiving the correct download and upload speed I am paying. Could this be a limitation from the ftp protocol or the software ? Anyone experienced such a problem ? Any help is greatly appreciated.

Thanks
Jason
Last edited by jasatt on 2019-09-12 16:41, edited 1 time in total.

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botg
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Re: Upload Speed Capping ?

#2 Post by botg » 2019-09-12 08:32

If you ping your server, what's the reported latency?

jasatt
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Re: Upload Speed Capping ?

#3 Post by jasatt » 2019-09-12 14:50

botg thanks for your reply. This is the result of the pinging....

Pinging 50.116.92.83 with 32 bytes of data:
Reply from 50.116.92.83: bytes=32 time=210ms TTL=48
Reply from 50.116.92.83: bytes=32 time=179ms TTL=48
Reply from 50.116.92.83: bytes=32 time=175ms TTL=48
Reply from 50.116.92.83: bytes=32 time=190ms TTL=48

Ping statistics for 50.116.92.83:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 175ms, Maximum = 210ms, Average = 188ms

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botg
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Re: Upload Speed Capping ?

#4 Post by botg » 2019-09-13 07:15

That's high, transatlantic by chance?

There are two possible reasons for this:
  1. The server advertises a too small receive window, smaller than the bandwidth-delay product. If you could transfer 2MiB/s, at a latency of 0.2s, the BDP is about 410 KiB. It's the amount of data that would be in-flight. Server administrator would need to increase the receive window if it's smaller than the BDP.
  2. There is packet loss, which results in TCP's congestion control/avoidance algorithm to limit transfer speeds to prevent congestive collapse. In case of non-congestive packet loss however, loss recovery takes too much time. It's up to the research community to standardize a new algorithm and for operating system vendors to implement this algorithm.
I don't have specific instructions, but you could use Wireshark to analyze if there's packet loss and what the server's advertised receive window maxes out at during a transfer.

jasatt
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Re: Upload Speed Capping ?

#5 Post by jasatt » 2019-10-01 14:57

Hi botg,

Thanks for your reply. Sorry for my late reply. I was abroad. As you hinted, It is transatlantic; I'm in Malta-EU and the server is in the US. I have noticed that this does not happen when uploading a video in YouTube; the speed is noticeably faster. Maybe because YouTube has multiple servers around the world and it will upload the file to the nearest server after detecting the ip address the upload is coming from. Any idea?

Thanks
Jason

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