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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.
Standard User jchamier
(eat-sleep-adslguide) Fri 22-May-20 18:22:09
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
What size was the upload, how long did it take? I’d like to test here, and see what happens on my setup. I have Virgin Media cable, 200 down / 20 up.

Really random guess is it is something to do with the free Plusnet router.

20 years of broadband connectivity since 1999 trial - Live BQM
Standard User ggremlin
(experienced) Fri 22-May-20 19:13:55
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Re: Broadband fault or bandwidth saturation


[re: jchamier] [link to this post]
 
very simple test,
run a ping in the background, then run a tbb speedtest
my fttc 45mbit line results, you can see idle, single download, multiple stream, upload, then idle again
PS C:\WINDOWS\system32> ping bbc.co.uk -4 -n 100

Pinging bbc.co.uk [151.101.192.81] with 32 bytes of data:
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=45ms TTL=57
Reply from 151.101.192.81: bytes=32 time=47ms TTL=57
Reply from 151.101.192.81: bytes=32 time=46ms TTL=57
Reply from 151.101.192.81: bytes=32 time=44ms TTL=57
Reply from 151.101.192.81: bytes=32 time=46ms TTL=57
Reply from 151.101.192.81: bytes=32 time=45ms TTL=57
Reply from 151.101.192.81: bytes=32 time=47ms TTL=57
Reply from 151.101.192.81: bytes=32 time=47ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=74ms TTL=57
Reply from 151.101.192.81: bytes=32 time=77ms TTL=57
Reply from 151.101.192.81: bytes=32 time=90ms TTL=57
Reply from 151.101.192.81: bytes=32 time=90ms TTL=57
Reply from 151.101.192.81: bytes=32 time=89ms TTL=57
Reply from 151.101.192.81: bytes=32 time=91ms TTL=57
Reply from 151.101.192.81: bytes=32 time=89ms TTL=57
Reply from 151.101.192.81: bytes=32 time=86ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=115ms TTL=57
Reply from 151.101.192.81: bytes=32 time=240ms TTL=57
Reply from 151.101.192.81: bytes=32 time=196ms TTL=57
Reply from 151.101.192.81: bytes=32 time=235ms TTL=57
Reply from 151.101.192.81: bytes=32 time=180ms TTL=57
Reply from 151.101.192.81: bytes=32 time=225ms TTL=57
Reply from 151.101.192.81: bytes=32 time=265ms TTL=57
Reply from 151.101.192.81: bytes=32 time=213ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57
Reply from 151.101.192.81: bytes=32 time=5ms TTL=57


edit speed test result
https://www.thinkbroadband.com/speedtest/15901705011...

Edited by ggremlin (Fri 22-May-20 19:19:25)

Standard User jchamier
(eat-sleep-adslguide) Fri 22-May-20 19:44:40
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Re: Broadband fault or bandwidth saturation


[re: ggremlin] [link to this post]
 
I did your test, the highest my latency went to was 133ms for a couple of packets. My normal latency is 12ms, and there were 5 or so pings of 85ms.

However that's all happening on the same machine - so the sharing is handled by Windows (in my case).

I need a test where I upload something massive, and then try a video call on another machine, to see if the router handles sharing in a better way than the OP's.

20 years of broadband connectivity since 1999 trial - Live BQM
Standard User tboorman
(fountain of knowledge) Fri 22-May-20 22:32:06
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Re: Broadband fault or bandwidth saturation


[re: jchamier] [link to this post]
 
I used the 1 GB test file that I downloaded from this site. I did not let the upload complete. Incidentally, I am not using the Plusnet supplied router, but a TP-Link one.
Standard User jchamier
(eat-sleep-adslguide) Sat 23-May-20 11:05:20
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
In reply to a post by tboorman:
I used the 1 GB test file that I downloaded from this site. I did not let the upload complete. Incidentally, I am not using the Plusnet supplied router, but a TP-Link one.

Where did you upload to? I need somewhere that can saturate my upload speed, and then I can try and run a video call on another machine to see if it breaks up.

All routers should do the same in theory, unless there is a bug in their firmware.

20 years of broadband connectivity since 1999 trial - Live BQM
Standard User tboorman
(fountain of knowledge) Sat 23-May-20 11:57:16
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Re: Broadband fault or bandwidth saturation


[re: jchamier] [link to this post]
 
I uploaded to https://www.azurespeed.com/Azure/UploadLargeFile.
Standard User jchamier
(eat-sleep-adslguide) Sat 23-May-20 12:37:06
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
Useful, thank you!

Ok, I have combined two of the 1GB files into a 2GB file, and set an upload going to the Azure test (using UK South region). My desktop is wired ethernet to my Asus router, and it started with a 20 Mbps upload speed, visible on Win10 task manager.

I then made a Facetime call from my iPad (on WiFi) to my iPhone (on 4G), which worked fine. I also tried a constant ping to Google's DNS, 8.8.8.8 and no loss in packets, and responses of 17ms.

The upload is still going, but has slowed down, my task manager showing only 1 Mbps in use, so I've switched Azure region to the US. My ping times are now 30 to 50ms. And its stopped uploading at 7% again.

So I've cleared some space from a VPS I have, and uploading there using WinSCP. This is saturating my uplink, hoping to see something on the BQM shortly.

The upload speed has now slowed to 19 Mbps, as my mate has called me on Facetime!

So no problems here .

20 years of broadband connectivity since 1999 trial - Live BQM

Edited by jchamier (Sat 23-May-20 13:11:48)

Standard User jchamier
(eat-sleep-adslguide) Sat 23-May-20 13:44:58
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Re: Broadband fault or bandwidth saturation


[re: jchamier] [link to this post]
 
BQM shows a small peak, and no packet loss.

20 years of broadband connectivity since 1999 trial - Live BQM
Standard User kevindb
(regular) Sat 23-May-20 14:44:58
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Re: Broadband fault or bandwidth saturation


[re: tboorman] [link to this post]
 
Sounds like classic bufferbloat to me. Limiting egress rate to slightly below line rate using whatever QoS or shaper options are available in your router would likely help.

Is this behaviour common, yes. Should it be like this, no. 'Latency under load' is an important metric for interactive response/latency sensitive traffic.
Standard User tboorman
(fountain of knowledge) Sat 23-May-20 22:49:06
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Re: Broadband fault or bandwidth saturation


[re: jchamier] [link to this post]
 
Thanks for testing this out. It looks like my issue was down to the TP-Link router - I have changed it for an AVM FRITZ!Box, and the ping times are a lot better during an upload, although I am still seeing some packet loss:

Ping statistics for 1.1.1.1:
Packets: Sent = 91, Received = 84, Lost = 7 (7% loss),
Approximate round trip times in milli-seconds:
Minimum = 14ms, Maximum = 188ms, Average = 35ms
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