BT Home Hub 5A (bthomehubv5a) VDSL Vectoring connection problems

suppenkasper0815 · August 20, 2019, 10:52pm

Hi,

I need help. I tried severel diffrent Lantiq-Firmware on 2 diffrent devices. Unfortunately I can't get more data rate than 70 Mbit/s with all Bt5 devices. With my old EasyBox 904 I got 95 Mbit/s for downstream and also 33 Mbit/s upstream insted of 22 Mbit/s now.
Here are several results of diffrent used Firmware-Versions:

used Firmware: vectoring-vdsl.bin

root@OpenWrt:~# /etc/init.d/dsl_control status
ATU-C Vendor ID:                          Broadcom 192.85
ATU-C System Vendor ID:                   Broadcom
Chipset:                                  Lantiq-VRX200
Firmware Version:                         5.7.5.6.1.7
API Version:                              4.17.18.6
XTSE Capabilities:                        0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2
Annex:                                    B
Line Mode:                                G.993.5 (VDSL2 with down- and upstream vectoring)
Profile:                                  17a
Line State:                               UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS):  Near: 0 / Far: 1
Errored seconds (ES):                     Near: 0 / Far: 6996
Severely Errored Seconds (SES):           Near: 0 / Far: 19
Loss of Signal Seconds (LOSS):            Near: 0 / Far: 10
Unavailable Seconds (UAS):                Near: 14804826 / Far: 14804826
Header Error Code Errors (HEC):           Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P):        Near: 0 / Far: 0
Pre-emtive CRC errors (CRCP_P):           Near: 0 / Far: 0
Power Management Mode:                    L0 - Synchronized
Latency [Interleave Delay]:               0.18 ms [Fast]   0.0 ms [Fast]
Data Rate:                                Down: 69.990 Mb/s / Up: 22.997 Mb/s
Line Attenuation (LATN):                  Down: 18.6 dB / Up: 21.1 dB
Signal Attenuation (SATN):                Down: 18.6 dB / Up: 21.1 dB
Noise Margin (SNR):                       Down: 10.2 dB / Up: 12.8 dB
Aggregate Transmit Power (ACTATP):        Down: 9.3 dB / Up: 13.8 dB
Max. Attainable Data Rate (ATTNDR):       Down: 94.244 Mb/s / Up: 29.068 Mb/s
Line Uptime Seconds:                      175
Line Uptime:                              2m 55s
root@OpenWrt:~#

used Firmware: dsl_vr9_firmware_xdsl-05.08.01.05.00.07_05.08.00.09.00.01.bin

root@OpenWrt:~# /etc/init.d/dsl_control status
ATU-C Vendor ID:                          Broadcom 192.85
ATU-C System Vendor ID:                   Broadcom
Chipset:                                  Lantiq-VRX200
Firmware Version:                         5.8.1.5.0.7
API Version:                              4.17.18.6
XTSE Capabilities:                        0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2
Annex:                                    B
Line Mode:                                G.993.5 (VDSL2 with down- and upstream vectoring)
Profile:                                  17a
Line State:                               UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS):  Near: 0 / Far: 0
Errored seconds (ES):                     Near: 0 / Far: 6997
Severely Errored Seconds (SES):           Near: 0 / Far: 19
Loss of Signal Seconds (LOSS):            Near: 0 / Far: 10
Unavailable Seconds (UAS):                Near: 14804925 / Far: 14804925
Header Error Code Errors (HEC):           Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P):        Near: 0 / Far: 0
Pre-emtive CRC errors (CRCP_P):           Near: 0 / Far: 0
Power Management Mode:                    L0 - Synchronized
Latency [Interleave Delay]:               0.18 ms [Fast]   0.0 ms [Fast]
Data Rate:                                Down: 69.990 Mb/s / Up: 22.997 Mb/s
Line Attenuation (LATN):                  Down: 18.6 dB / Up: 21.1 dB
Signal Attenuation (SATN):                Down: 18.6 dB / Up: 21.2 dB
Noise Margin (SNR):                       Down: 12.1 dB / Up: 12.4 dB
Aggregate Transmit Power (ACTATP):        Down: 9.3 dB / Up: 13.9 dB
Max. Attainable Data Rate (ATTNDR):       Down: 91.031 Mb/s / Up: 28.584 Mb/s
Line Uptime Seconds:                      25
Line Uptime:                              25s
root@OpenWrt:~#

used Firmware: vr9-B-dsl.bin (AVM-Firmware extraction)

root@OpenWrt:~# /etc/init.d/dsl_control status
ATU-C Vendor ID:                          Broadcom 192.85
ATU-C System Vendor ID:                   Broadcom
Chipset:                                  Lantiq-VRX200
Firmware Version:                         5.9.0.12.1.7
API Version:                              4.17.18.6
XTSE Capabilities:                        0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2
Annex:                                    B
Line Mode:                                G.993.5 (VDSL2 with down- and upstream vectoring)
Profile:                                  17a
Line State:                               UP [0x801: showtime_tc_sync]
Forward Error Correction Seconds (FECS):  Near: 0 / Far: 0
Errored seconds (ES):                     Near: 0 / Far: 6997
Severely Errored Seconds (SES):           Near: 0 / Far: 19
Loss of Signal Seconds (LOSS):            Near: 0 / Far: 10
Unavailable Seconds (UAS):                Near: 14805017 / Far: 14805017
Header Error Code Errors (HEC):           Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P):        Near: 0 / Far: 0
Pre-emtive CRC errors (CRCP_P):           Near: 0 / Far: 0
Power Management Mode:                    L0 - Synchronized
Latency [Interleave Delay]:               0.18 ms [Fast]   0.0 ms [Fast]
Data Rate:                                Down: 69.987 Mb/s / Up: 22.997 Mb/s
Line Attenuation (LATN):                  Down: 19.2 dB / Up: 21.1 dB
Signal Attenuation (SATN):                Down: 19.2 dB / Up: 20.9 dB
Noise Margin (SNR):                       Down: 13.4 dB / Up: 12.8 dB
Aggregate Transmit Power (ACTATP):        Down: 9.4 dB / Up: 13.9 dB
Max. Attainable Data Rate (ATTNDR):       Down: 70.215 Mb/s / Up: 28.957 Mb/s
Line Uptime Seconds:                      178
Line Uptime:                              2m 58s
root@OpenWrt:~#

It seems the AVM-Firmware is even worse than all other versions. - I also tried to play with SNR offset. It seems that the problem is, my connection would also work with 6 dB down SNR and 10 dB up, but it doesn't make any diffrence if I set it on -3 dB or +3db or something else.

moeller0 · August 21, 2019, 6:35am

IMHO is this on a German VDSL2 line operated by Deutsche Telekom? To me this looks like their DLM/DSM system intervened and reduced your max sync to improve stability. That system seems to be based on Assia's DSLEpresse product and is known to affect lines in Germany, a telltale sign of DLM interventions is that the dslam restricts the maxim permitted sync Reyes to multiples of 1000 kbps, and that typically results in actual sync rates a few kbps below full 1000s like in your case. This system seems triggered by an undisclosed number of factors that seem to include CRC errors uncorrected retransmits and resyncs loss of sync events, if whatever caused DLM to activate crises to be a problem DLM will slowly increase the sync rate limits again. Before I get completely into the weeds, I will stop here unless you want to know more....

moeller0 · August 21, 2019, 7:47am

This shows, theoretically ~94/29 should be possible, but either SNR requirements, or more likely IMHO DLM fixing your link's maximal permitted sync profile reduce this down to ~70/23.

Note that different modems/different firmwares perform slightly different so 94/29 is close enough to 95/33 to chalk up the differences to hardware/firmware-blob differences (also sync varies and with more vectoring lines active in a bundle ATTNDR goes down ).

suppenkasper0815 · August 21, 2019, 6:13pm

Thanks for your long answer.

Yes, it's a VDSL Vectoring line of Deutsche Telekom with bitstream to Vodafone. As I say with Easybox 904 with Vodafone Fw it syncs near the 100/40. Unfortunately all BT5 hubs I tried don't... This is idenpendent of the firmware. Same line with FritzBox 7580 gets 85/30 by speedtest.net results and with BT5 Hub its only 55/22.

Here are newest results

OpenWrt SNAPSHOT, r10574-273b803623
 -----------------------------------------------------
root@BT_Hub_5A:~# /etc/init.d/dsl_control status
ATU-C Vendor ID:                          Broadcom 192.85
ATU-C System Vendor ID:                   Broadcom
Chipset:                                  Lantiq-VRX200
Firmware Version:                         5.8.1.5.0.7
API Version:                              4.17.18.6
XTSE Capabilities:                        0x0, 0x0, 0x0, 0x
, 0x0, 0x0, 0x0, 0x2
Annex:                                    B
Line Mode:                                G.993.5 (VDSL2 wi
h down- and upstream vectoring)
Profile:                                  17a
Line State:                               UP [0x801: showti
e_tc_sync]
Forward Error Correction Seconds (FECS):  Near: 0 / Far: 28
72
Errored seconds (ES):                     Near: 3 / Far: 69
8
Severely Errored Seconds (SES):           Near: 2 / Far: 19
Loss of Signal Seconds (LOSS):            Near: 0 / Far: 10
Unavailable Seconds (UAS):                Near: 159 / Far:
59
Header Error Code Errors (HEC):           Near: 0 / Far: 0
Non Pre-emtive CRC errors (CRC_P):        Near: 0 / Far: 0
Pre-emtive CRC errors (CRCP_P):           Near: 0 / Far: 0
Power Management Mode:                    L0 - Synchronized
Latency [Interleave Delay]:               0.18 ms [Fast]
.0 ms [Fast]
Data Rate:                                Down: 69.990 Mb/s
/ Up: 22.997 Mb/s
Line Attenuation (LATN):                  Down: 18.6 dB / U
: 21.3 dB
Signal Attenuation (SATN):                Down: 18.6 dB / U
: 21.3 dB
Noise Margin (SNR):                       Down: 12.1 dB / U
: 12.4 dB
Aggregate Transmit Power (ACTATP):        Down: 9.3 dB / Up
 13.8 dB
Max. Attainable Data Rate (ATTNDR):       Down: 105.399 Mb/
 / Up: 28.656 Mb/s
Line Uptime Seconds:                      10282
Line Uptime:                              2h 51m 22s
root@BT_Hub_5A:~#

The problem seems really the wrong Snr sync of bt.

The 7580 syncs with 8dB/10dB SNR, the BT5 Hub with 12 dB/13 dB.

Any ideas how to solve the problem and why it's newer reaching more than 70 Mbit /s for downstream?

moeller0 · August 21, 2019, 7:12pm

So have you tried that after any of the measurement you posted here, or are the easybox measurements from before that? In the second case please try the easybox again. Same about the FB7580, is the 85/30 sync from now or from earlier?

suppenkasper0815 · August 28, 2019, 9:40pm

I have another line, same house, same cuper line length to first MSAN of Deutsche Telekom.

I tested the same device on both lines. It has nearly same ATTNDR on both lines around 100 Mbit/s and Telekom line syncs with 99 Mbit/s data rate, but only with maximum 69900 kbit/s on Vodafone line (bitstream of Deutsche Telekom)... In the beginning both were syncing with data rates around 100.

If you compare SNR it makes sense that it both could sync with same data rate around 100,but it seems they are forcing to reduce the data rate at Vodafone line...

So any ideas how to proceed or what I can do?

Obviously it's no driver issue anymore...
Vodafone line (bitstream of Telekom)

Telekom line with same device

moeller0 · August 29, 2019, 7:35am

I still am not sure of the sequence of your tests, but the sequence is essential to falsify my DLM hypothesis.
Once DLM engages on a line/link it will reduce the maximum Sync rate a DSLAM/MSAN allows (typically to integer multiples of 1000 Kbps, or 500Kbps for low rates, your observed sync of 69.990/26.997 smells like DLM programmed the DSLAM to a max of 70/27).
DLM can also do a few other things to help stabilizing a line like changing the INP values, but these are much less clear than the effects on the Syncrates.
Anyway, if you connect a BT5H and see ~70/27 and then connect something else like the EasyBox 904 and immediately get something > 70/27 then we can rule out DLM, otherwise this really looks like DLM got triggered on this line and tries to help stabilize your link. Note that DLM is a line-by-line thing, that is not yet monitoring all lines, so having one line with DLM actively interfering and another without DLM is quite probable ATM, as the second line might either not be monitored at all or might simply stay above the thresholds DLM needs to trigger.
In my own experience, the BTHH5A is a bit fickle on vectoring lines* and produces enough code violations to trigger DLM (from ~110/39 down to 100/27 on my link, but I still loose sync every few days)

*) I note that BT does not use vectoring so these devices where never intended to work well with vectoring, and BT will not produce/test vectoring-capable firmware blobs for these either.

suppenkasper0815 · August 29, 2019, 9:00am

Hi, thanks for your support.

The Modem of BT5Hub is made for Vectoring you can check data sheets and it should work very well on Vectoring lines and they are very similar to the chipsets of FritzBox 74xx series. They work all very well with that lantiq chipsets.

As I wrote, Max DATA sync is 70/27. Gross or ATTDNR is often 102/31 or something.

If I put the BT5Hub on Telekom line it has Datarate 95/31 and works like a charm. So BT5 can work well. I USE THE DSL driver 5.8.x

So maybe you should replace your firmware for DSL part.

moeller0 · August 29, 2019, 9:09am

I know this, but there are/were evenissues with FB7490s on less than ideal Telekom vectoring lines (that were partly remedied by AVM supplying new firmware blobs for the modem), and BT does not supply nor test vectoring capable firmware blobs for the HH5A.
Also due to Telekom using (almost) exclusively Broadcom Chips in the DSLAM-Linecards, Lantiq-modems are often reported as being slightly problematic, whether that is justified is a different question though

ATTDNR really is just an estimate the modem makes, this number should not be taken too seriously IMHO.
The DATA sync is 70/27 is what makes me believe your issue is DLM.

My hypothesis DLM is not active on that line, and hence your sync is limited by what modem and line card can negotiate.

Well, leave it on the Telekom link for a few weeks and monitor sync and errors. DLM, if enabled for a line at all, is reported to take a few days/weeks to respond to increased errors/re-syncs. So to be sure the HH5a works well and robust on the Telekom link give it some time

Well, which driver is that, care to share the source and the firmware blob? I am always happy to improve stability.

I am happy to do so, but the one from a Zyxel I am using right now is the most stable of the one's I tested so far (various recent FB7490 modem blobs).

suppenkasper0815 · September 10, 2019, 12:59am

By the way, does anyone know if BT5 will also work on Annex J lines? The data sheet says it should and if we use the AVM firmware driver I think it should. - Unfortunately at my Annex Ich line at home it does not, but I'm not sure if I use the Zyxel or AVM Firmware atm...

So would love if also some others could give it a try

mpa · September 10, 2019, 12:36pm

ADSL with Annex J in Germany does not work:
https://openwrt.ebilan.co.uk/viewtopic.php?f=7&t=275#p2089

suppenkasper0815 · September 10, 2019, 8:12pm

Hi, thanks for the reply. - But there is also the information the modem doesn't work on Annex B and I can confirm it works on Annex B at least with VDSL and also Vectoring lines.

I'm asking because Easybox 904 needs work on Annex J (at least with original Openwrt Barrier Braker of Vodafone) and I think also under Openwrt it does work Hopefully the article will be updated soon

moeller0 · September 10, 2019, 9:14pm

Annex B for VDSL is not related to Annex B for the ADSLs (for VDSL Annex B basically has all the Bansplans for Europe, for ADSL Annex B is the special case that does not touch the frequency band used by ISDN).