Fibre 1 upload speed limiting?

[threetreesderek]

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

30

--

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

Available

Premise Environment StatusBridge TapVRINTE FacePlateLast Test Date

N

N

N

12-01-2021

Exchange Product Restrictions StatusFTTP Priority ExchangeWLR WithdrawalSOADSL Restriction

N

N

Y

[imjolly]

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   

[threetreesderek]

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.

[threetreesderek]

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 

[imjolly]

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

[threetreesderek]

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.

[imjolly]

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

[threetreesderek]

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

[threetreesderek]

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. 

[threetreesderek]

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.