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Standard User tboorman
(fountain of knowledge) Fri 22-May-20 10:14:43
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Broadband fault or bandwidth saturation


[link to this post]
 
My broadband connection was reinstated on Monday after my line was ceased in error by Plusnet. Since then, I have noticed that when I am uploading a file, I get high round trip times on a ping test to 1.1.1.1, and also some packet loss. Is this just bandwidth saturation, or could this be being caused by a fault?

Ping test to 1.1.1.1 during an upload:

Ping statistics for 1.1.1.1:
Packets: Sent = 31, Received = 29, Lost = 2 (6% loss),
Approximate round trip times in milli-seconds:
Minimum = 64ms, Maximum = 1233ms, Average = 717ms

Ping test to my router during an upload:

Ping statistics for 192.168.1.1:
Packets: Sent = 39, Received = 39, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 443ms, Average = 60ms

Thanks,

Tim
Standard User AndrewNi
(regular) Fri 22-May-20 11:47:34
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
I used to get the same thing when I had 448Kbps upload speed. Any device that saturated the upstream caused all other devices to effectively lose their connection because sending requests or acknowledgements became too slow.

Having said that, my pings were up into the 5000ms+ range when that happened, whereas your maximum is (a still not great) 1233ms.

Did you change the router or any settings between the cease and reinstatement? In particular relating to Quality of Service.

It would also be worth comparing the current connection speed with what you had before, especially to see if your upload speed has dropped.
Standard User tboorman
(fountain of knowledge) Fri 22-May-20 11:53:42
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Re: Broadband fault or bandwidth saturation


[re: AndrewNi] [link to this post]
 
Thanks for your reply Andrew. The router is the same one that I was using before, and the only setting that has changed is my username, as Plusnet had to create a new account. My upload speed is about the same as what it was previously. My download speed has dropped, as my target SNR margin is now 6 dB rather than 3 dB.


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Administrator MrSaffron
(staff) Fri 22-May-20 12:41:08
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
If saturating the upload direction why would you not expect ping times to be elevated?

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User tboorman
(fountain of knowledge) Fri 22-May-20 14:16:26
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Re: Broadband fault or bandwidth saturation


[re: MrSaffron] [link to this post]
 
Thanks for your reply Andrew. The ping times are a lot more elevated when I am uploading a file than when I am downloading one, and I also only get any packet loss when uploading a file.

Edited by tboorman (Fri 22-May-20 14:17:16)

Administrator MrSaffron
(staff) Fri 22-May-20 14:38:31
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
Not that odd to see the two directions behaving differently, the asymmetry of the speeds is part of the reason for this.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User jchamier
(eat-sleep-adslguide) Fri 22-May-20 14:38:51
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
In reply to a post by tboorman:
Thanks for your reply Andrew. The ping times are a lot more elevated when I am uploading a file than when I am downloading one, and I also only get any packet loss when uploading a file.

When you're uploading, by default you use all the capacity. So there is nothing left for the ping to get out from your connection, it ends up in a queue (which slows it down) until a gap.

If you are measuring packet loss using the BQM, pings coming in are not replied to for ages, as the sending capacity is full with your upload.

This is how TCP/IP works - if you want pings to work whilst uploading, you need to use QoS techniques to limit uploading to 95% of your upload bandwidth.

20 years of broadband connectivity since 1999 trial - Live BQM
Standard User tboorman
(fountain of knowledge) Fri 22-May-20 14:55:26
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Re: Broadband fault or bandwidth saturation


[re: jchamier] [link to this post]
 
The reason that I carried out the ping test was because my work VPN disconnected while I was uploading a file on a different PC, and the audio during a Microsoft Teams meeting also dropped out while uploading a file. Would you expect this behaviour?
Standard User jchamier
(eat-sleep-adslguide) Fri 22-May-20 16:30:39
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
In normal networking the answer is yes, you can disrupt other users of a network by filling up the connection in one direction. So a large upload that takes many minutes can stop other applications from working. MS Teams and other applications need to talk to the server regularly, and if they don't get a reply they assume the connection has failed.

It is as if you are on the M25 and all 4 lanes going clockwise past Heathrow are full, and the hard shoulder is full of a breakdown. The police car at the back cannot get through.

What speeds do you get when nobody else is usnig the connection? up and down.

20 years of broadband connectivity since 1999 trial - Live BQM

Edited by jchamier (Fri 22-May-20 16:31:04)

Standard User tboorman
(fountain of knowledge) Fri 22-May-20 17:17:44
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Re: Broadband fault or bandwidth saturation


[re: jchamier] [link to this post]
 
From the data provided by my SamKnows box, 51.3 Mbps down, and 18.3 Mbps up.
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