This topic

Fibre 1 upload speed limiting?

threetreesderek — Thu, 21 Jan 2021 20:08:04 GMT

Good evening,

I'm seeing some strange results on the real-life upload speeds for our broadband line [FYI: this message contains more detail than my previous question about upload / download speeds, thank you for your patience].

The modem is connected at a very stable 6.7Mbit/s (SNRs are high and I am waiting hopefully for DLM to gradually resync the line up to the 39Mb/s or so it should be capable of achieving). We are contracted with BT on Fibre 1 which I understand provides max 55/10 Mb/s speeds which is a little above the capability of this line.

My concern is that real-life upload speeds are significantly below expectations and show some sign of throttling. It is easiest to show using a snapshot (as below, from speedtest.net). The purple trace shows the upload speed which peaks at around 5Mit/s (as expected) and then stabilises at around 1.7.

Exactly the same results are seen when carefully watching the figures on the BT wholesale speed tester, but in that case the final reported speed is the maximum number (today, the maximum reported was around 6Mbit/s, and is included below).

The result has been consistent over the last couple of weeks I've been looking, using a variety of modems, client devices on cables/WiFi, speedtest services, and at different times of day. Today I asked some friends who are connected to the same cabinet to run a test, and their results show a curve up to the max. line speed, so I have a strong feeling this issue is unique to this line or account.

I am struggling to find details of previous contracts and speed estimates but seem to recall that a previous contract had a 2Mb/s speed limit.

Is it possible this limit is still being applied somewhere and is it likely to be be possible to remove? Any advice?

Thank you,

Derek

(all the data below)

Modem stats:

Stats recorded 21 Jan 2021 19:37:26 DSLAM type / SW version: BDCM:0xc190 (193.144) / v0xc190 Modem/router firmware: AnnexA version - A2pv6C038m.d24j DSL mode: VDSL2 Profile 17a Status: Showtime Uptime: 3 days 12 hours 49 min 28 sec Resyncs: 0 (since 18 Jan 2021 07:17:14) Downstream Upstream Line attenuation (dB): 26.2 0.0 Signal attenuation (dB): Not available on VDSL2 Connection speed (kbps): 32399 6758 SNR margin (dB): 8.7 6.7 Power (dBm): 12.1 3.1 Interleave depth: 8 1 INP: 58.00 0 G.INP: Enabled Not enabled Vectoring status: 5 (VECT_UNCONFIGURED) RSCorr/RS (%): 0.0150 1.0499 RSUnCorr/RS (%): 0.0000 0.0000 ES/hour: 0.15 6.52

BTW speed checker:

Results[CLOSE][RESET] Summary of Performance Test Timestamp Thursday 21 January 2021 | 19:51:34 Ping 46 Ms Download 28.09 Mbps Upload 6.08 Mbps Advance Test Download Test Download speed achieved during the test was 28.09 Mbps For your connection, the acceptable range of speeds is 20 - 30.01 Mbps IP Profile for your line is 30.01 Mbps 28.09 Mbps 30.01 Mbps Upload Test Upload speed achieved during the test was 6.08 Mbps IP Profile for your line is 10 Mbps 6.08 Mbps 10 Mbps

Openreach availability checker

Exchange DIDMARTON is served by Cabinet E2

Featured Products Downstream Line Rate(Mbps) Upstream Line Rate (Mbps) Downstream HandbackThreshold(Mbps) WBC FTTC Availability Date WBC SOGEA Availability Date Left in JumperHigh Low High Low VDSL Range A (Clean)
VDSL Range B (Impacted)

40	25	7.9	6	20	Available	Available	--
39.1	21.4	7.8	5.7	17.7	Available	Available	--

Featured Products Downstream Line Rate(Mbps) Upstream Line Rate (Mbps) Downstream Range (Mbps) Availability Date FTTP Install ProcessFTTP on Demand

330

Available

ADSL Products Downstream Line Rate (Mbps) Upstream Line Rate (Mbps) Downstream Range(Mbps) ADSL Availability Date WBC SOADSL Availability Date Left in JumperWBC ADSL 2+WBC ADSL2+ Annex MADSL MaxWBC Fixed RateFixed Rate

Up to 2	--	1 to 3.5	Available	Available	--
Up to 2	Up to 0.5	1 to 3.5	Available	Available	--
Up to 1.5	--	1 to 2.5	Available	Available	Yes
0.5	--	--	Available	Available	--
0.5	--	--	Available	--	Yes

Observed Speeds VDSLMax Observed Downstream SpeedMax Observed Upstream SpeedObserved Date

32.39

6.64

2021-01-17

Other Offerings Availability DateVDSL MulticastADSL Multicast

Available

Premise Environment StatusBridge TapVRINTE FacePlateLast Test Date

12-01-2021

Exchange Product Restrictions StatusFTTP Priority ExchangeWLR WithdrawalSOADSL Restriction

Re: Fibre 1 upload speed limiting?

imjolly — Thu, 21 Jan 2021 22:13:36 GMT

your stats look ok and with 32/6.6mb are within your expected speed range when looking at the results from dslchecker. The btspeedtester results show download/upload speed as expect for conenction speed

speedtest.net looks like it was done using wireless not Ethernet

Re: Fibre 1 upload speed limiting?

threetreesderek — Fri, 22 Jan 2021 07:14:26 GMT

Hi imjolly, thanks for your comments. I'm happy you agree the actual line stats look good. Hopefully they should improve over time as it stays stable.

For completeness I performed the same test this morning over a hardwired connection - the result is the same. An initial peak (numbers read 5-6Mbit/s but soon tailing off to a 2Mb continuous, slightly better than last night.

The result is the same when using the BT wholesale speed tester at https://speedtest.btwholesale.com/, only it doesn't produce a graph so it is harder to capture a meaningful screenshot. Also the same using speedtest.net but selecting different servers.

I see on this forum some FTTP users have had similar issues but couldn't find any references to FTTC (as this line is).

Thanks for your advice so far, I'm really hoping there is some kind of profiling active on the line to cause this.

Re: Fibre 1 upload speed

threetreesderek — Fri, 22 Jan 2021 21:23:00 GMT

Well there is at least one more thing to rule out.

I directly connected a PC to the modem today over PPPoE to rule out any issues in our home network set-up. Same issue; speeds start around 5Mb/s and then drop to 2 over the first second of the test or so.

Modem connection stats have remained steady throughout (actually really strong today as it has been bright and dry).

Every other test result I see (on this or other cabinets, but all at around the same downstream sync speeds) shows a completely steady upload speed within 20% or so of the initial peak, which is obviously making me think there is some kind of challenge I need to solve here!

Any thoughts - is it likely this kind of behaviour is a fundamental part of this particular line / cabinet connection, and if so am I stuck?

(I am in day 5 since my last DSL retrain / fiddling with wiring so sort of hopeful that as DLM starts to increase line download speeds the situation may resolve, though I can't really understand why that would be)

Thanks so much for any insights, I'm looking for inspiration

Re: Fibre 1 upload speed

imjolly — Fri, 22 Jan 2021 21:49:42 GMT

If you did a reser 5 days ago then have you had more drops in connection as uptime only 3 days

have you or are you having problems with your connection dropping or doing manual resets trying to improve speed or maybe both? Although stats looks ok and within expected speed range it looks line problems resulting in a banded profile hence why speed never changes and noise margin higher than normal 6db

Re: Fibre 1 upload speed

threetreesderek — Fri, 22 Jan 2021 22:15:53 GMT

As far as I'm aware the modem has not resynced without me telling it to. I'm trying to stay firmly hands off until the banding is resolved, I'm hoping to see some improvement towards end of next week.

The connection has been super stable since last resync was done (in hope that the banding had been removed) , but I realised that we would need to wait a bit longer.

The only issues have been about managing the upstream bandwidth, hence this current focus, but the connection itself seems to have stayed solid. I will look tomorrow to see if the upstream error seconds correlate to periods of high usage, that might explain why it appears to pull back.

Re: Fibre 1 upload speed

imjolly — Fri, 22 Jan 2021 22:37:23 GMT

It can take weeks of stable connection before the DLM will start to release the banding just have to wait especially as you are well within your expected speed range

Re: Fibre 1 upload speed

threetreesderek — Sat, 23 Jan 2021 05:29:26 GMT

Thanks for that,

It sounds like from experience you are suggesting we wait for the easing of DLM banding to kick in before further looking at the upload rate problem.

I have to admit I thought they were separate cases.

Are there any metrics we can use to find out when (all being well with the line) that may take place, or what banding rules have been enacted? I am certain the DLM banding on download is the result of wiring problems at my end which are now fixed. Upload rate though has been stable throughout and I don't think I'm expecting DLM to make a big change there.

Thank you for all your support, I really do appreciate the guidance.

Derek

Re: Fibre 1 upload speed

threetreesderek — Tue, 26 Jan 2021 07:52:52 GMT

Good morning,

Doing a bit more searching around I have come across this quote which seems to come from an Openreach guide.

Note : The upstream throughput is also constrained on the DSLAM to the upstream rate requested in the order, i.e. 2 Mbit/s, 10 Mbit/s or 20 Mbit/s, so even if the VDSL2 upstream line speed is higher, the upstream throughput is constrained to the level ordered for the product.

The guide can be found here: SIN 498 v7. 7 APR 2020

The statement ties in exactly with the symptoms I'm seeing on the upload part of my line; has anyone had luck asking BT to confirm that the line is correctly provisioned according to the order? (in this case we are paying for 40/10 but I suspect constrained to 2Mb as per the note above).

Could I ask, is checking this something the moderators could help with?

It looks like this limit is independent of the DLM process.

Re: Fibre 1 upload speed

threetreesderek — Thu, 28 Jan 2021 06:49:17 GMT

Sorry to bump this; I do appreciate all the support so far and feel I am close to narrowing down the upload issue here.

Can I ask, is there a route through this forum to check which rate was actually ordered by BT and provisioned by Openreach?

Meanwhile we are on the 10th day of continuous connection with no restrains here, SNRs remaining above 9 on the download side and stable at 6 on upload, so I am hopeful DLM will relax soon.

Re: Fibre 1 upload speed

pippincp — Thu, 28 Jan 2021 08:35:03 GMT

You don't need any route, you already have that answer in your first post. 10Mbps.

Re: Fibre 1 upload speed

threetreesderek — Thu, 28 Jan 2021 12:32:35 GMT

Thanks Pippin, I do appreciate the help trying to get to the bottom of this issue.

Can you offer any comment why I am seeing a 2Mbit/s limit on sustained uploads (over say half a second in duration)? It is so consistent on this line, and does not match the profile I see on other lines to the same cabinet.

The modem itself is clocking in at far above that and as a burst rate I do see the capability for 5-6 Mbit, but I never see this in any kind of sustained test even when my PC is hardwired to the modem directly, ignoring any home router etc. The limit is clearly visible on speed test results.

Re: Fibre 1 upload speed

pippincp — Thu, 28 Jan 2021 12:46:50 GMT

Try this speedtest. https://labs2.thinkbroadband.com/speedtest/

Re: Fibre 1 upload speed

threetreesderek — Thu, 28 Jan 2021 13:10:40 GMT

Thanks for that, I will try that when I get home back onto that line. Much appreciated.

Re: Fibre 1 upload speed

threetreesderek — Thu, 28 Jan 2021 19:46:30 GMT

Hi @pippincp , thanks for the link.

Here is the result (hardwired to the router and the only device connected). I confirm that this evening I get similar results from speedtest.net and other checkers, though to be fair they report a high speed at the very start of the test before dropping to a stable 2 Mbit.

https://www.thinkbroadband.com/speedtest/1611860779828270755

Modem is connected at 6758 up / 32399 down, DSL uptime 10 days 12 hours with no retrains. Previously tested with an NL8800 and HH5b, similar results. This one is an HG612.

Results the same from Firefox and Chrome.

I also ran the special test for cabinets with congestion. Here are the results:

Re: Fibre 1 upload speed

threetreesderek — Sat, 30 Jan 2021 05:20:35 GMT

To round this off with some more data, here is the same speed test result when connected direct to the modem:
PC <-- cable / PPPoE --> modem <-- cable VDSL2 --> cabinet

There is clearly something not right:

IP profile (from https://speedtest.btwholesale.com/) indicates 10 Mb / sec
Expected upstream (https://www.broadbandchecker.btwholesale.com/) indicates 5.7 - 7.9 Mb / sec
Modem upstream sync at 6758 kbps (stable now for 12 days) which is consistent with the above
Real performance is capped at 2Mb / sec (https://www.thinkbroadband.com/speedtest/1611981962555634855)

Without trying to make assumptions about what might be going wrong in the BT / Openreach systems, the real question is what can I do about it? Is there any advice?

Re: Fibre 1 upload speed

threetreesderek — Mon, 01 Feb 2021 07:10:14 GMT

Good morning folks, still trying to diagnose this 2Mbit/sec upload issue and managed to capture the burst / stable upload speeds on the checker recommended by @pippincp . This profile is consistent with nearly every other checker (apart from BTW official which only records the peak value).

Modem is currently syncing in at 6681 on the upstream side which is my focus for now, so I would expect throughput at around 5Mbit / sec which is what it sees at the peak before it is limited. (on the upload plot you can clearly see this - a very high peak at the start and then a stable level for the rest of the test)

Knowing that

This line used to be at a 2Mbit / sec profile
Openreach are able to cap lines at 2Mbit / sec without it being seen on sync speed
This line is being capped to 2Mbit / sec upload

Is there any likelihood that

The IP profile is correctly set but that there is an equipment fault in the cabinet which is causing the limit
There is another limit in the Openreach system which does not appear under the IP profile associated with the line (I'm not sure how the caps in SIN498 are applied, but up until now had assumed they would be reported in the IP profile)
A previous BT limiting system has a memory of an old profile for this line, but this has not been disabled (I'm not sure what that would be, but I'm sure this line has not been unlimited for ever)

I may be barking up the wrong tree but I'm almost certain we have a stuck profile of some kind somewhere.

(Don't worry about the download results here - this particular laptop happens to be on 2.4Ghz wifi so the result is not valid - no such problem for these upload speeds though, and the result is consistent across a range of devices and wired / wireless connections)

Re: Fibre 1 upload speed

threetreesderek — Thu, 18 Mar 2021 20:04:14 GMT

Hi forum, just closing out this topic for any future readers as it seems have been resolved today thanks to the excellent support from the community mods (especially @NeilO and I guess@StuartH ) in response to this other post

It seems there was a configuration error somewhere between Openreach and BT wholesale which meant that even though the cabinet profile had been set to 10Mbps upload, it was being limited elsewhere to 2Mbps. No Openreach engineer or BT customer support staff could find it. In the end (over the course of 3 weeks) the problem was escalated to BT's line team who located the issue during a weekly joint call with Openreach. There would have been no chance without support from the mods.

@pippincp and @imjolly thank you for your support on this forum post also - perhaps one to store away for future that there was a real problem here which would have benefitted from a moderator referral, though I appreciate it sounds like a bit of a strange one.

Re: Fibre 1 upload speed

pippincp — Thu, 18 Mar 2021 21:53:06 GMT

Glad to see you are sorted. It was an unusual one.