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.

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