Poor single thread on TBB on whole Virgin Media network?

Does everyone on Virgin Media have poor single thread speed results that are not the same as their multi-thread speeds on TBB speed test?

I am particularly interested on those with 200mbps or higher packages as the single-threaded speeds usually lie between 70-120mbps.

I personally can never reach 200mbps single thread speeds at any time of the day on the TBB speed tester (off-peak or peak) and I do not understand why. However what I do find strange is if I download a test file from TBB with 1 connection, it downloads at full speed.

Here is my TBB test:
http://virgin.i.lithium.com/t5/image/serverpage/imag...

Here is my TBB 1GB test on 1 connection:
http://virgin.i.lithium.com/t5/image/serverpage/imag...

Here is a 1GB test file from NL(Netherlands) Leaseweb:
http://virgin.i.lithium.com/t5/image/serverpage/imag...

Here is a UBUNTU ISO on 1 connection:
http://virgin.i.lithium.com/t5/image/serverpage/imag...

Single thread speed test on testmy.net:
http://virgin.i.lithium.com/t5/image/serverpage/imag...

Single thread speed test on DSLReports.com/speedtest:
http://virgin.i.lithium.com/t5/image/serverpage/imag...

So why can I download a test file at full speed single threaded but not achieve the same speed on the TBBx1 test?

Edited by deleted (Wed 24-May-17 16:38:46)

Interesting that so many keep mentioning this and with similar screen shots.

Care to run a test today and post link e.g. http://labs.thinkbroadband.com/speedtest

The testmy.net file is being served from the Virgin Media network so no surprise its working well. Don't know about DSLreports file location.

On the web browser file downloads, which actual browser? Some browsers if you download a file are not actually single thread but use multiple threads to speed things up.

Your speed test on our server was done at a time when that evening things started to go very bad for data going via LINX (https://www.thinkbroadband.com/news/7710-speed-and-latency-problems-repeat-once-again-for-virgin-media-users and then very very bad on 17th).

Virgin Media said this was just a 1% loss in capacity, so if losing 1% can cause those issues then it seems to suggest running the network very close to the point of issues and hence the single thread issues.

http://tbb.st/1495632101496057055 some get the speeds and if that was most other speed testers people would be none the wiser about the slope on multi-thread and single thread performance.

In reply to a post by MrSaffron:

Interesting that so many keep mentioning this and with similar screen shots.

Care to run a test today and post link e.g. http://labs.thinkbroadband.com/speedtest

The testmy.net file is being served from the Virgin Media network so no surprise its working well. Don't know about DSLreports file location.

On the web browser file downloads, which actual browser? Some browsers if you download a file are not actually single thread but use multiple threads to speed things up.

Your speed test on our server was done at a time when that evening things started to go very bad for data going via LINX (https://www.thinkbroadband.com/news/7710-speed-and-latency-problems-repeat-once-again-for-virgin-media-users and then very very bad on 17th).

Virgin Media said this was just a 1% loss in capacity, so if losing 1% can cause those issues then it seems to suggest running the network very close to the point of issues and hence the single thread issues.

http://tbb.st/1495632101496057055 some get the speeds and if that was most other speed testers people would be none the wiser about the slope on multi-thread and single thread performance.

Here is the speedtest as requested:
https://www.thinkbroadband.com/speedtest/14956458068...

As for the browser, I am aware that they are multi-threaded and I do not use the browser to download but an external file download manager called Internet Download Manager (IDM) with connections set to 1 as can be seen in the image where the N. column shows the connections (1,2,3,4,5,6).

In one of the images the file location is in the Netherlands so maybe it isn't LINX as I believe that problem was only at a specific time during the day however I have never seen TBBx1 reach 200mbps at any time of the day.

Are there any Virgin Media speed tests recently on TBB that you can find with TBBx1=HTTPx6 and on 200mbps or higher?

Edited by deleted (Wed 24-May-17 18:21:15)

Okay notice the long slope, so something is not good

As for the LINX issue, while latency is better still seeing a 10ms jump inside the virgin core network, but its not as bad as before, so something is congesting still, but not to the degree of last week.

http://tbb.st/1495643605379635255 is one of the better recent tests today
http://tbb.st/1495645011337834655

casting a wider net
http://tbb.st/1493971965691757355
http://tbb.st/1495102828581851055

And the person running these tests were probably very happy
http://tbb.st/1495348245361947955
http://tbb.st/1494045675132997255

The issues in Virgin Media are not just about the interconnect to LINX there appear to be multiple issues

http://tbb.st/1495634151616639255 FTTP business connection 900 Mbps down on both single and multiple at 3pm this afternoon

Edited by MrSaffron (Wed 24-May-17 19:02:09)

In reply to a post by MrSaffron:

Okay notice the long slope, so something is not good

As for the LINX issue, while latency is better still seeing a 10ms jump inside the virgin core network, but its not as bad as before, so something is congesting still, but not to the degree of last week.

http://tbb.st/1495643605379635255 is one of the better recent tests today
http://tbb.st/1495645011337834655

casting a wider net
http://tbb.st/1493971965691757355
http://tbb.st/1495102828581851055

And the person running these tests were probably very happy
http://tbb.st/1495348245361947955
http://tbb.st/1494045675132997255

The issues in Virgin Media are not just about the interconnect to LINX there appear to be multiple issues

http://tbb.st/1495634151616639255 FTTP business connection 900 Mbps down on both single and multiple at 3pm this afternoon

So it seems that it is possible a very small minority are getting single thread speeds close to their multi-thread. I can't seem to ever reach 200mbps single thread on the tester.

Has there been any Virgin Media customers recently with 300mbps single thread speeds?

What could explain that I can get full speeds on the TBB test files with 1 connection but not on the TBB speed tester? I wonder if Virgin Media are even aware of this and plan on addressing this issue on their network at all?

In reply to a post by MrSaffron:

The testmy.net file is being served from the Virgin Media network so no surprise its working well.

testmy.net isn't served from within Virgin's network, only speedtest.net uses internal servers.

When running testmy.net my router shows it connects to "uk.testmy.net" and a traceroute shows this goes through linx:

1 <1 ms <1 ms <1 ms 192.168.1.1
2 18 ms 18 ms 12 ms 10.250.64.1
3 32 ms 17 ms 15 ms pres-core-2a-xe-710-0.network.virginmedia.net [213.104.74.241]
4 * * * Request timed out.
5 * * * Request timed out.
6 * * * Request timed out.
7 * * * Request timed out.
8 31 ms 30 ms 28 ms brhm-bb-1c-ae0-0.network.virginmedia.net [62.254.42.110]
9 27 ms 36 ms 45 ms tcl5-ic-2-ae0-0.network.virginmedia.net [212.250.15.210]
10 30 ms 29 ms 29 ms linx-224.inx.as13213.net [195.66.226.9]
11 30 ms 49 ms 58 ms 83.170.70.238
12 58 ms 30 ms 30 ms dc5.as13213.net [83.170.70.138]
13 34 ms 27 ms 40 ms uk.testmy.net [109.123.121.170]

Something seems to be dragging down the single thread speed on the TBB test as it constantly shows poor speeds which I can't replicate on testmy.net, dslreports.com or standard HTTP file downloads.

There are some genuine single thread speed problems in parts of Virgin's network, almost exclusively in areas using old Motorola CMTS, but the TBB test seems to be showing poor results even for users who don't actually have any problems with single thread download speeds.

Given the moans about many services not working for many Virgin customers one would hope they are aware of the issues

Seeing SamKnows box testers now reporting problems too

In the past to show to Virgin Media that there are issues with some of their links we have altered routing from our end and suspect if the same experiment took place then the same result would happen

Or put another way that is a different way through line that testmy.net is reached via. The joy of very large networks.

When the same file server is able to produce good speeds for others then what do I do?

There are a lot of factors that can affect single-thread speed more than multi-thread speed. These can be related to the PC/Tablet/Phone doing the test, the method of connection (Wi-Fi 2.4GHz, Wi-Fi 5GHz, Ethernet cable, etc), the devices in the line (switch, router, modem) all before the connection to the ISP is actually involved and then the multitude of devices the ISP will use to route data to/from TBB.

TBB generally just like to claim that the catch-all 'congestion' is the cause without going into any details.

There are also differences in the way cable (DOCSIS) works compared to xDSL. With xDSL you efectively only have one channel for communications even though this is spread over a number of frequency bands whereas cable is more akin to MLPPP with data sent in a number of bonded channels. Cable needs to request permission to transmit on a channel which causes additional latency whereas xDSL doesn't. All of this adds up to very different characteristics for cable and xDSL for speed tests and is why ping/latency graphs also look very different.

But to be honest you really don't need to worry about the single-thread speed unless it drops below what you actually need for a single stream, i.e. about 25Mbps for a UHD video (though most will actually need a lot less than that).

Edited by Daemon66 (Thu 25-May-17 12:17:41)

If cable is so different why market products aimed directly at people like gamers where latency performance is critical and adverts extoling ability to stream video reliably to tablets in the home.

Perhaps we should simply refuse to run BQM for Virgin users and stop running any speed test diagnostics beyond showing an average speed for 32 thread downloads to get around the issues DOCSIS has.

A question though, how does DOCSIS explain the rises in latency we are seeing in the Virgin core network before even reaching the DOCSIS nodes?