Reasonable Single Threaded Performance BT Fibre 900

Hi,

I've recently had BT Full Fibre 900 installed.

Narrowed down the issue I'm seeing to single threaded peformance when downloading files.

When testing single threaded downloads using speedtest files from OVH (FR, 10Gbit, UK, 1-2Gbit), Leaseweb (NL), Hetzner (DE, 1Gbit, 1Gbit+), NFORCE (NL), and AWS S3 (UK, IE), I'm seeing around 20MB/s.

When testing the exact same speedtest files at the exact same hosts and DC's, using 8 threads, I saturate the line.

When using web based speedtests (such as thinkbroadband and speedtest.net) that offer the option of using a single thread, then using multiple threads, I see the same speeds repeated, slow single thread, fast multithread.

Testing from my Hetzner server (1Gbit up/down, DE, using FTPS), and brand new OVH server (10Gbit down/1-2Gbit up, UK, using HTTP), I see the same performance.
Previously with Virgin Media, I was able to saturate the 600Mbit line doing the same test over FTPS on the Hetzner server.

I've reached the end of the line with BT, they've issued me a deadlock letter, refuse to deal with the issue, and were completely useless beforehand.

Can anyone with BT Fibre 900 check their single threaded performance for me, and does anyone know what is commonly reached?

OVH
Leaseweb
Hetzner
NFORCE

Edited by kst (Thu 26-Aug-21 10:35:19)

In reply to a post by kst:

When using web based speedtests (such as thinkbroadband and speedtest.net) that offer the option of using a single thread, then using multiple threads, I see the same speeds repeated, slow single thread, fast multithread.

What sustained and burst single thread perf are you seeing?

I only have a BT 300Mbps service.

Running multithread it will give 320-330 Mbps. Going to single thread it drops very slightly and tends to be 310-320 so, not really noticable.

BT Full Fibre 900 here, lowest single threaded seen was 610Mbits/s, highest 790Mbits/s. Similar results on both IPv4 and IPv6. Multithreaded is normally close to 900.

What does your TBB speed test graph look like? That can give clues on what the issue might be.

It is probably congestion somewhere. I moved to FTTP 900 down via Openreach and on single thread tests got around 300Mbit/sec on Thinkbroadband, and multi-threaded around 800 and this was consistent for around 7 months. On speedtest.net I could pick some sites that easily achieved > 700M on single threaded tests, so it was what ever route it took to Thinkbroadband that was busy.

Then suddenly some extra capacity was added somewhere and Thinkbroadband is now > 600M on single threaded and > 900 on multi-thread tests, this is similar speeds to many tests I've seen for FTTP 900, so that busy link must have been upgraded.

When you say 20MB/sec do you mean Mega bytes, so 160Mbit/sec which if yes isn't unusable and many things we do on the Internet ends up using multiple threads to get at the data anyway.

There are other things which will be better and arguably more important than raw speed with being on FTTP rather than Virgin such as jitter, latency and packet loss, have you set up a BQM here and compared the two services? You might also have IPv6 now that Virgin don't do, this may or may not be important to you of course.

I'd put money on your speed issues resolving themselves in the coming months, there will be someone somewhere that knows a certain link is busy and plans will be in place to upgrade it. You might change to another ISP and find speeds the same if the busy link is close to you and you are just passing over the same route.

Edited by E300 (Thu 26-Aug-21 13:15:36)

What sustained and burst single thread perf are you seeing?

Single-thread, graphed:
ovh_1gbit_speedtest_file_singlethreaded_graphed.png
oshi.at/yfMjgN

leaseweb_1gbit_speedtest_file_singlethreaded_graphed.png
oshi.at/ziPhgT

hetzner_1gbit_speedtest_file_singlethreaded_graphed.png
oshi.at/zBggAc

Single-threaded tests, Firefox:

hetzner_1gb_speedtest_file_singlethreaded.png
oshi.at/hjgQQJ

leaseweb_1gb_speedtest_file_singlethreaded.png
oshi.at/sxjuUh

nforce_1gb_speedtest_file_singlethreaded.png
oshi.at/iniNMH

nvidia_graphics_card_drivers_singlethreaded.png
oshi.at/eKKVFu

ovh_1gb_speedtest_file_singlethreaded.png
oshi.at/EgFXjW

ovh_private_server_1gb_speedtest_file_singlethreaded.png
oshi.at/AXAdtZ

speedtest_net_singlethreaded.png
oshi.at/gRPRzs

windows_iso_download_singlethreaded.png
oshi.at/mPGFTW

windows_iso_download_singlethreaded_2.png
oshi.at/ESqVRD

Multi-threaded tests, 8 threads, graphed:

hetzner_private_server_1gb_speedtest_file_multithreaded.png
oshi.at/uDoqRn

leaseweb_speedtest_file_multithreaded.png
oshi.at/HJeQur

nforce_speedtest_file_multithreaded.png
oshi.at/eaaXcU

nvidia_graphics_card_drivers_multithreaded.png
oshi.at/GYuRNJ

ovh_private_server_1gb_speedtest_file_multithreaded.png
oshi.at/mwpGFM

ovh_speedtest_file_multithreaded.png
oshi.at/eKKVJB

speedtest_net_multithreaded.png
oshi.at/jHCLdf

windows_iso_download_multithreaded.png
oshi.at/xNujGj

windows_iso_download_multithreaded_2.png
oshi.at/jqkLMP

Edited by kst (Thu 26-Aug-21 22:15:59)

I only have a BT 300Mbps service.

Running multithread it will give 320-330 Mbps. Going to single thread it drops very slightly and tends to be 310-320 so, not really noticable

Single-threaded downloads are peaking higher than that, but sustained below.

What does your TBB speed test graph look like? That can give clues on what the issue might be.

Late last night:
thinkbroadband_singlethreaded_and_multithreaded.png
oshi.at/voYpZP

Right now, 22/08 22:19
thinkbroadband_singlethreaded_and_multithreaded_2608_2219.png
oshi.at/yyeiNx

Edited by kst (Thu 26-Aug-21 22:21:52)

Something wrong there. Are you testing directly wired up to the ONT (bypass any BT routers etc)

I can hit between 700-800 Mbps on single thread on Openreach FTTP using TTB. Through all my network.

Ping times seem on the high side too. I'd expect around half that (although not if your hitting a server in London from Scotland say)

Then suddenly some extra capacity was added somewhere and Thinkbroadband is now > 600M on single threaded and > 900 on multi-thread tests, this is similar speeds to many tests I've seen for FTTP 900, so that busy link must have been upgraded.

Realistically I'm seeing much slower single-threaded performance than the other couple people that responded.

When you say 20MB/sec do you mean Mega bytes, so 160Mbit/sec which if yes isn't unusable and many things we do on the Internet ends up using multiple threads to get at the data anyway.

Big B luckily, or unluckily in this case as BT are useless.

have you set up a BQM here and compared the two services?

I have not, and don't have the VM service anymore.

You might also have IPv6 now that Virgin don't do, this may or may not be important to you of course.

I do indeed!

I'd put money on your speed issues resolving themselves in the coming months, there will be someone somewhere that knows a certain link is busy and plans will be in place to upgrade it. You might change to another ISP and find speeds the same if the busy link is close to you and you are just passing over the same route.

I'm hoping so.

My complaint with BT reached deadlock within hours.
I've submitted a complaint through the ombusdman shortly ago.

Thanks for the response