Download speed degradation

When our village had FTTC enabled in July, I switched from ADSL2+ to BT Infinity 2. At first the speed was not too bad but being 500m from the cab I guess 54/8 is to be expected, but now its down to this:

http://www.thinkbroadband.com/speedtest/results.html...

The upload actually seems to have got slightly better but the download has gotten a lot worse. What could be the cause of this? Increased crosstalk due to more users signing up? It's a bit disappointing as basically I'm getting Infinity 1 speeds at Infinity 2 prices...

Do you have G.INP ?

Seems like crosstalk is the issue, BT should let you downgrade to Infinity 1.

What are the estimates for your line, yo can find these at the BT Wholesale Checker by entering your phone number or full address

Currently (although they were higher when I signed up):


Featured Products
Downstream Line Rate(Mbps)
Upstream Line Rate(Mbps)
Downstream Range(Mbps)
Availability Date
High Low High Low
FTTC Range A (Clean) 51 35 12 7.2 -- Available
FTTC Range B (Impacted) 43.5 25 12 5.5 -- Available
WBC ADSL 2+ Up to 13 -- 7.5 to 17.5 Available
WBC ADSL 2+ Annex M Up to 13 Up to 1 7.5 to 17.5 Available
ADSL Max Up to 8 -- 7 to 8 Available
WBC Fixed Rate 2 -- -- Available
Fixed Rate 2 -- -- Available
Other Offerings
Fibre Multicast -- -- -- Available
Copper Multicast -- -- -- Available

For all ADSL and WBC Fibre to the Cabinet (FTTC or WBC SOGEA) services, the stable line rate will be determined during the first 10 days of service usage.

This line has jumpers in place.

Edited by keith969 (Sun 01-Nov-15 13:06:49)

In reply to a post by BatBoy:

Do you have G.INP ?

How do I find that out? I have a HH5 which does seem to give much useful info...

First, find out if your cabinet is a Huawei or an ECI http://www.kitz.co.uk/adsl/cabinet-lookup.htm
If it's an ECI it currently doesn't offer G.INP.

Then check your modem. There's a label on the bottom.
If it's a HH5 Type A, it doesn't support G.INP. If it's a HH5 Type B, it does.

On Infinity 1 your speedtest result would be 38.7Mbps absolute tops. Upstream probably unchanged.

In reply to a post by keith969:

FTTC Range A (Clean) 51 35 12 7.2 -- Available
FTTC Range B (Impacted) 43.5 25 12 5.5 -- Available

All I can suggest is asking BT to be downgraded to Infinity 1 then

PS. This

In reply to a post by BatBoy:

If it's a HH5 Type A, it doesn't support G.INP

...is unproven and my neighbours BT Hub seems to say opposite...

In reply to a post by mlmclaren:

In reply to a post by BatBoy:

If it's a HH5 Type A, it doesn't support G.INP

...is unproven and my neighbours BT Hub seems to say opposite...

Where does it say it? In its GUI, or telnet output?

Thanks BatBoy,

It looks like a Huawei. Cab 2 in Chinnor. And I have a HH5 type A.

Question is will BT allow me to downgrade as effectively I renewed a contract with them in July...

Would a change of modem/router help? I don't like the HH5, the wifi performance sucks, wondering if its worth shelling out for a Billion 8800axl...

A change from the HH5A would probably solve most if not all your problems, as long as the replacement has a Broadcom chipset (or at least support G.INP) like the Billion.

For a quick fix, you could buy a Huawei HG612 v3B from the Bay Of Fleas, load on the latest hacked firmware and monitor your connection. This can be connected to the phone line and then LAN1 on the modem to the red WAN port on the HH5A instead.

In reply to a post by keith969:

Would a change of modem/router help?

A new modem is unlikely to improve your sync speed by anything noteworthy.

Over 18 months, we've lost 40% of our speed, falling from 44 Mbps when FTTC first arrived, to just 26 Mbps today. No longer much improvement over our old LLU ADSL2+ service. From which we could squeeze up to 20Mbps just by tweaking the target SNR margin. Alas, such a tweak isn't possible with BT's VDSL2 offering.

Since our line is in otherwise 'good order' with very low DSL error rates, that drop in speed is due to crosstalk. Which is a problem across the board, as migrations from ADSL to FTTC gather pace.

Switching to a Broadcom-based device can perhaps see small gains. Maybe an increase of a megabit or two per second. Compared to devices with less-refined DSP chipsets. But nothing - short of full deployment of system-level or maybe even node-level vectoring - can recover much of what we've lost already to crosstalk.

And since full-blown vectoring will likely involve stripping-out and replacing the existing DSLAMs and linecards - definitely the ECI kit and likely Huawei's too - that ain't going to happen any time soon. Until BT pulls its finger out and invests, we're stuck with an ever degrading service.

Edited by deleted (Mon 02-Nov-15 00:51:42)

In reply to a post by BatBoy:

A change from the HH5A would probably solve most if not all your problems, as long as the replacement has a Broadcom chipset (or at least support G.INP) like the Billion.

For a quick fix, you could buy a Huawei HG612 v3B from the Bay Of Fleas, load on the latest hacked firmware and monitor your connection. This can be connected to the phone line and then LAN1 on the modem to the red WAN port on the HH5A instead.

I changed to a HG612 as the modem and the HH5 as the router / WAP. This improved the upload performance from about 8.5 to 10 Mb/s but the download did not change and is now down to 39Mb/s. BT, who I just called, said it was within 'acceptable range', the lower bound being 35Mb/s and they would not change my contract from Infinity 2 to Infinity 1 despite only getting Infinity 1 speeds. Told me to call their tech team instead...

When did you start using the HG612?

In reply to a post by BatBoy:

When did you start using the HG612?

Probably about a week ago.

It can take a couple of weeks for G.INP to be turned on. Is the HG612 unlocked?

In reply to a post by BatBoy:

It can take a couple of weeks for G.INP to be turned on. Is the HG612 unlocked?

yep its unlocked. As far as G.INP, the stats indicate for bearer 1:

G.INP Framing: 18 18
G.INP lookback: 27 7

does this mean G.INP is enabled? The upload speed went up by 10% or so when the HG612 was connected...

Yes G.INP looks to be enabled. More stats will help diagnosis.

In reply to a post by BatBoy:

Yes G.INP looks to be enabled. More stats will help diagnosis.

This was from a few days ago...

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 12683 Kbps, Downstream rate = 51360 Kbps
Bearer: 0, Upstream rate = 12687 Kbps, Downstream rate = 43998 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 8.1 6.1
Attn(dB): 20.4 0.0
Pwr(dBm): 12.4 7.5
VDSL2 framing
Bearer 0
MSGc: -6 -6
B: 89 227
M: 1 1
T: 0 0
R: 8 14
S: 0.0648 0.5716
L: 12108 3387
D: 8 4
I: 98 242
N: 98 242
Q: 8 4
V: 3 0
RxQueue: 135 21
TxQueue: 27 7
G.INP Framing: 18 18
G.INP lookback: 27 7
RRC bits: 24 24
Bearer 1
MSGc: 90 58
B: 0 0
M: 2 2
T: 2 2
R: 16 16
S: 10.6667 16.0000
L: 24 16
D: 1 1
I: 32 32
N: 32 32
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0
Counters
Bearer 0
OHF: 0 0
OHFErr: 0 0
RS: 21352688 2428343
RSCorr: 79 13
RSUnCorr: 0 0
Bearer 1
OHF: 21665 21690
OHFErr: 0 0
RS: 129619 86763
RSCorr: 0 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 227561531 1
rtx_c: 15 4307
rtx_uc: 0 8202

G.INP Counters
LEFTRS: 0 98
minEFTR: 43989 12688
errFreeBits: 233508 86033498

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 29423105 0
Data Cells: 16661 0
Drop Cells: 0
Bit Errors: 0 0

Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0

ES: 0 0
SES: 0 0
UAS: 31 31
AS: 349

Bearer 0
INP: 55.00 45.00
INPRein: 1.00 0.00
delay: 0 0
PER: 0.00 0.00
OR: 0.01 0.01
AgR: 44305.29 12714.56

Bearer 1
INP: 2.50 4.00
INPRein: 2.50 4.00
delay: 0 0
PER: 16.06 16.06
OR: 47.81 31.87
AgR: 47.81 31.87

Bitswap: 106/106 18/18

Total time = 6 min 20 sec
FEC: 79 13
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 31 31
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 6 min 20 sec
FEC: 79 13
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 31 31
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 6 min 20 sec
FEC: 79 13
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 31 31
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 5 min 47 sec
FEC: 79 13
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
#

Isn't this what you want?
Bearer: 0, Upstream rate = 12687 Kbps, Downstream rate = 43998 Kbps

In reply to a post by BatBoy:

Isn't this what you want?
Bearer: 0, Upstream rate = 12687 Kbps, Downstream rate = 43998 Kbps

That wouuld be better than the 10.5up / 39down that the TBB tester gives me. And with a wired connection before anyone asks...

Also, your downstream looks capped by DLM and you have some SNRM available for an increase

SNR (dB): 8.1

DLM caps the speed in response to excessive disconnections.

Understand that the DSL estimates are for line speed, aka sync speed, not throughput measured by testers or by running downloads.

When you talk to support, they will be comparing your sync speed to the acceptable range.

As for the stats...
The DLM settings INP=55, INPRein=1, aren't brilliant, and likely imply that DLM has been seeing too many errors or disconnections. The speed of a few bits below 44Mbps and an SNR >>6dB suggests banding ... which again implies DLM intervention.

Probably the best thing to do with the 612 is to leave it in place, undisturbed. Keeping an eye on the error rate - ES per 24 hours.

Incidentally - if your 612 started out with those same two INP settings on the first day you plugged it in, and with that banding, then I reckon that G.INP was already active on the HH5A. I doubt that DLM would have started out with retransmission settings like that for the first time the 612 was plugged in. In fact DLM (as an overnight process) won't have had chance to change settings

G.INP is turned on upstream and downstream

Blah Blah Blah to you and WWWombat.

In reply to a post by RobertoS:

I haven't time to think about those stats in depth but notice a couple of things.

1) From your suspiciously close to 44000kbps sync and 8.1dB SNRM after 6 minutes uptime I think the line has probably been banded.

2) Not only is G.INP enabled, it is also operating on your upstream. That may be why the upstream interleaving D: line is set to 4 rather than the normal 1.

I believe that now you have the HG612 running that in a few weeks the banding will be removed and your speed increase.

3 Feb.

Edited by RobertoS (Sat 06-Feb-16 16:55:10)

In reply to a post by RobertoS:

Blah Blah Blah to you and WWWombat.

3 Feb.

Different post http://forums.thinkbroadband.com/fibre/t/4457564-gin...

Edited by deleted (Sat 06-Feb-16 17:09:57)

In reply to a post by WWWombat:

As for the stats...
The DLM settings INP=55, INPRein=1, aren't brilliant, and likely imply that DLM has been seeing too many errors or disconnections. The speed of a few bits below 44Mbps and an SNR >>6dB suggests banding ... which again implies DLM intervention.

Could be, I had problems unlocking it last weekend and power cycled it quite a few times. I'll wait and see what happens.

In reply to a post by BatBoy:

Different post http://forums.thinkbroadband.com/fibre/t/4457564-gin...

Yep. You were there. Plus, it can be seen in the quote header .

In reply to a post by RobertoS:

it can be seen in the quote header .

That's where I got it from

You have 23 posts in the thread. I would expect you to have remembered we had seen the stats before and that I had commented about the three points recently raised here.

You're supposed to be the one with the instant recall of every post there has been. I'm just a tyro compared to you.

No, I was busy after Groundhog day - didn't see the stats or your analysis, which was spot on btw.

Well down to 38Mb/s download today so called BT tech support on callback (at least you don't have to wait on the phone for half an hour).

The guy did the usual tests then said he thought it must be a line problem so he would send an OR engineer round. Booked in for Thursday (I couldn't be sure I would be in Tues/Wed) so fingers crossed he will find a line fault...