Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: v0x on September 24, 2021, 12:44:55 PM
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Hello all, my fibre keeps repeatedly getting stuck at 62 even though it can (and has) achieved higher speeds. When I report as a fault the DLM gets reset which puts the speed at 79 but at some point the speed will drop back to 62 again and never appears to target and speeds between 63-78
Line State: Showtime with TC-Layer sync
Line Mode: G.993.2 (VDSL2, Profile 17a)
Line Uptime: 1d 12h 59m 15s
Annex: B
Data Rate: 62.675 Mb/s / 19.999 Mb/s
Max. Attainable Data Rate (ATTNDR): 91.812 Mb/s / 24.913 Mb/s
Latency: 7.00 ms / 6.00 ms
Line Attenuation (LATN): 12.1 dB / 10.6 dB
Signal Attenuation (SATN): 12.1 dB / 10.5 dB
Noise Margin (SNR): 9.0 dB / 6.4 dB
Aggregate Transmit Power (ACTATP): 0.0 dB / -0.1 dB
Forward Error Correction Seconds (FECS): 146 / 77865
Errored seconds (ES): 0 / 2887
Severely Errored Seconds (SES): 0 / 111
Loss of Signal Seconds (LOSS): 0 / 2082
Unavailable Seconds (UAS): 83 / 83
Header Error Code Errors (HEC): 0 / 0
Non Pre-emptive CRC errors (CRC_P): 0 / 0
Pre-emptive CRC errors (CRCP_P): 0 / 0
ATU-C System Vendor ID: Infineon 178.6
Power Management Mode: L0 - Synchronized
If I connect my old Sky router it will connect at 79 too, but the two Talktalk routers I used to have both had the same problem as my current BT Home Hub 5A (openwrt), is this a stuck profile or something else?
Thanks
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I suspect this is a result of contention with other users, this happens frequently.
Regards Stuart
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There is no contention at the DSL layer.
You have a line fault that needs to be fixed before you will see any improvement. A DLM reset is pointless unless the underlying fault that is causing DLM to intervene is fixed.
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Hello all, my fibre keeps repeatedly getting stuck at 62 even though it can (and has) achieved higher speeds. When I report as a fault the DLM gets reset which puts the speed at 79 but at some point the speed will drop back to 62 again and never appears to target and speeds between 63-78
If I connect my old Sky router it will connect at 79 too, but the two Talktalk routers I used to have both had the same problem as my current BT Home Hub 5A (openwrt), is this a stuck profile or something else?
Thanks
which lantiq dsl driver are you using on your BT Home Hub 5A?
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Firmware for my Home Hub 5A is 5.8.1.8.1.6
I forgot to mention when the speed lowers, the transmit power shoots up to around 2db; also I found the line coming in is made of aluminium/tin/or something because it's silver.
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That's strange, as at least from what you posted there isn't a lot of errors so not sure why it would keep pulling the stats down. Though aluminium lines are never a good thing.
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Data Rate: 62.675 Mb/s / 19.999 Mb/s
Max. Attainable Data Rate (ATTNDR): 91.812 Mb/s / 24.913 Mb/s
Latency: 7.00 ms / 6.00 ms
Noise Margin (SNR): 9.0 dB / 6.4 dB
Something has caught my attention. I'm wondering... assuming your line supports G.INP if, perhaps, the modem in question doesn't support G.INP and is falling back to a 'compatibility state'... that being traditional interleaving (INP/delay). I say this because I assume that your latency values are 'delay' values, typically seen on traditional interleaving, although odd values I must admit but that could be down to the modem. This is speculation though as I don't know what your other modem reports, and I could be wrong about the 'latency' values. Even so it's odd that it won't go higher than 62Mbit~ downstream given the spare noise margin. Assuming you go back to the other modem, am I right in understanding that it resyncs at full speed without a DLM reset?
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Firmware for my Home Hub 5A is 5.8.1.8.1.6
I forgot to mention when the speed lowers, the transmit power shoots up to around 2db; also I found the line coming in is made of aluminium/tin/or something because it's silver.
Your firmware doesn't support vectoring according to xdarklight https://xdarklight.github.io/lantiq-xdsl-firmware-info/
Please may you try a lantiq firmware with vectoring support
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Something has caught my attention. I'm wondering... assuming your line supports G.INP if, perhaps, the modem in question doesn't support G.INP and is falling back to a 'compatibility state'... that being traditional interleaving (INP/delay). I say this because I assume that your latency values are 'delay' values, typically seen on traditional interleaving, although odd values I must admit but that could be down to the modem. This is speculation though as I don't know what your other modem reports, and I could be wrong about the 'latency' values. Even so it's odd that it won't go higher than 62Mbit~ downstream given the spare noise margin. Assuming you go back to the other modem, am I right in understanding that it resyncs at full speed without a DLM reset?
The Sky router (ER110) will sync at the same speed but normally (overnight) it will then sync back at 79, just tried the Annex B vectoring firmware and the max attainable rate has dropped
Line State: Showtime with TC-Layer sync
Line Mode: G.993.2 (VDSL2, Profile 17a)
Line Uptime: 0h 0m 43s
Annex: B
Data Rate: 62.675 Mb/s / 20.000 Mb/s
Max. Attainable Data Rate (ATTNDR): 62.910 Mb/s / 25.317 Mb/s
Latency: 7.00 ms / 6.00 ms
Line Attenuation (LATN): 12.3 dB / 10.7 dB
Signal Attenuation (SATN): 12.3 dB / 10.6 dB
Noise Margin (SNR): 9.2 dB / 6.6 dB
Aggregate Transmit Power (ACTATP): 0.6 dB / 0.6 dB
Forward Error Correction Seconds (FECS): 184 / 77917
Errored seconds (ES): 0 / 2887
Severely Errored Seconds (SES): 0 / 111
Loss of Signal Seconds (LOSS): 0 / 2088
Unavailable Seconds (UAS): 127 / 127
Header Error Code Errors (HEC): 0 / 0
Non Pre-emptive CRC errors (CRC_P): 1 / 0
Pre-emptive CRC errors (CRCP_P): 0 / 0
ATU-C System Vendor ID: Infineon 178.6
Power Management Mode: L0 - Synchronized
I assume the right firmware is VDSL over ISDN Annex B firmware, which is confusing as I thought ISDN was dead
Here is the router stats from the Sky router, which I just plugged in and is syncing at the same speed, no idea why there's DS1, 2 and 3
(https://i.imgur.com/fwzcfVf.jpg)
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I assume the right firmware is VDSL over ISDN Annex B firmware, which is confusing as I thought ISDN was dead
UK uses POTS not ISDN.
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DS1 2 3 are the download bands of the VDSL2 spectrum
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UK uses POTS not ISDN.
Guess this could be the reason since all the firmware I've got all says VDSL over ISDN (including the original firmware), I'll see if I can get different firmware for VDSL over POTS instead, thanks.
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UK uses POTS not ISDN.
Er no, vdsl in the UK is annex b which is correctly termed as vdsl over ISDN, but Openreach uses an Annex B bandplan (tone set) from the VDSL2 spec (G.993.2) over Annex A physical infrastructure. So for the UK, the modem hardware/firmware needs to be Annex A, but it will sync using Annex B.
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Guess this could be the reason since all the firmware I've got all says VDSL over ISDN (including the original firmware), I'll see if I can get different firmware for VDSL over POTS instead, thanks.
Anytime ;) I think that may make a difference.
Er no, vdsl in the UK is annex b which is correctly termed as vdsl over ISDN, but Openreach uses an Annex B bandplan (tone set) from the VDSL2 spec (G.993.2) over Annex A physical infrastructure. So for the UK, the modem hardware/firmware needs to be Annex A, but it will sync using Annex B.
There seems to be some confusion about what is meant by Annex A/B. 'Annex' in this context is a Euro word meaning 'Appendix'. It refers to an appendix to an official document. There are two relevant documents being mixed up here, one describing the hardware for a DSL service and one describing the band plan configuration. A modem described as Annex A means that its hardware supports xDSL over POTS (the UK system) and Annex B means that its hardware supports xDSL over ISDN (the German system) Some modems may support both, but most don't. An Annex B modem is no use in the UK.
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Guess this could be the reason since all the firmware I've got all says VDSL over ISDN (including the original firmware), I'll see if I can get different firmware for VDSL over POTS instead, thanks.
When I looked at the unofficial Lantiq firmware site (https://xdarklight.github.io/lantiq-xdsl-firmware-info/), there is no mention of VDSL over POTS on ANY firmware.
VDSL over POTS seems to be included in the VDSL over ISDN firmware. This makes sense as the only difference is likely to be the band plan.
There's nothing wrong with the OpenWRT Lantiq firmware, its rock-solid stable for me and syncs higher than any other device I've tried.
The only possible exception is as mentioned above, it doesn't include vectoring support, but swapping out the firmware is very easy.
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Anytime ;) I think that may make a difference.
Thank you, according to the openwrt forum, annex a and b only apply to ADSL.
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No worries :thumbs:
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So I changed the firmware which has vectoring support the only thing that has changed is the max attainable data rate.
Data Rate: 62.675 Mb/s / 19.999 Mb/s
Max. Attainable Data Rate (ATTNDR): 71.647 Mb/s / 24.946 Mb/s
Previously it was
Data Rate: 62.675 Mb/s / 19.999 Mb/s
Max. Attainable Data Rate (ATTNDR): 91.812 Mb/s / 24.913 Mb/s
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I'm not sure how we got on the topic of vectoring to be honest, isn't your cabinet ECI so no vectoring support anyway?
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The line definitely looks capped/banded by the DLM
No amount of firmware or modem swapping will increase the sync speed
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Sadly there's a fair amount of speculation and/or guesswork because we don't know some of the actual characteristics of their connection. Particularly the brand of DSLAM and then some other considerations such as the status of G.INP on a modem which syncs at full speed.
EDIT: Actually, if this is to be believed, I think we can conclude that they are at least on an ECI DSLAM. ATU-C if I'm not mistaken is the far end (e.g. the DSLAM)?
ATU-C System Vendor ID: Infineon 178.6
That at least eliminates that, if so.
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Multiple syncs at exactly 62.675 Mb/s with a 9db+ SNRM sounds like a banded line.
Asking the ISP to run an RTT test will show the DLM line profile and confirm any banding.
A GEA test will show the line profile 13 days ago.
There may be an underlying line fault causing the line to be banded.
It could have been user initiated/self inflicted.
I've banded my own line in the past from swapping modems, upgrading firmware/constantly rebooting the modem.
Swapping between Broadcom and Lantiq chipset modems can even see the banding level change between each modem.
An example previously on the forum saw the Broadcom sync at 14,999, and Draytek (Lantiq) would sync at 11,399, with each modem always syncing at those figures when swapped. Both are banding figures used by OpenReach at the time.
The example I just mentioned. (https://forum.kitz.co.uk/index.php/topic,21060.msg365727.html#msg365727)
OpenReach have since increased the number of banding levels that they use considerably (was done around 2019 I think).
I've no idea if 62.7 is a banded figure, I can't keep up.
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EDIT: Actually, if this is to be believed, I think we can conclude that they are at least on an ECI DSLAM. ATU-C if I'm not mistaken is the far end (e.g. the DSLAM)?
ATU-C System Vendor ID: Infineon 178.6
That at least eliminates that, if so.
Yes, xTU-C is the far end; the DSLAM in this case. And yes, a line-card with an Infineon chipset == an ECI Hi-FOCuS MiniShelf M41.
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Thanks for the replies, it is indeed a ECI cabinet but I've left the firmware on Annex A (as it was previously)
One thing I didn't mention is that I have an MK4 filter fitted could that cause issues? I've ordered a converter as I've not got a landline phone and I'm going to try plugging the dsl direct to the master socket and see what happens.
Is it me or is this figure just extremely low?
Aggregate Transmit Power (ACTATP): -0.4 dB / -0.2 dB
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One thing I didn't mention is that I have an MK4 filter fitted could that cause issues?
The Mk4 SSFP (which fits the NTE5C) is electronically equivalent to the Mk3 SSFP (which fits the NTE5/A & /B). So the answer to your question is "no".
I've ordered a converter as I've not got a landline phone and I'm going to try plugging the dsl direct to the master socket and see what happens.
Ah, as there isn't a telephone connected then the SSFP really isn't necessary.
Is it me or is this figure just extremely low?
Aggregate Transmit Power (ACTATP): -0.4 dB / -0.2 dB
With what are you comparing those two values?
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From what I can gather the Aggregate Transmit Power has zero bearing on anything, I've seen reports of really high and negative values both syncing at high speeds.
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Earlier quote stated - "Thank you, according to the openwrt forum, annex a and b only apply to ADSL."
Whilst true, the use of Annex A or B within the OpenWRT definition does affect which version of the
line driver is used. Look at the following thread, page 5,
https://forum.kitz.co.uk/index.php?topic=25544.60
You'll notice I tested using both Annex A and B and the result was a different line driver.
By default, for Lantiq devices, OpenWRT ships 5.8.1.8.1.6 but there is also 5.7.9.9.0.6.
Rather that ship two full drivers, there is a patch file for 5.7.9.9.0.6 and that only gets applied if you
select Annex B in the line definition details.
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You'll notice I tested using both Annex A and B and the result was a different line driver.
By default, for Lantiq devices, OpenWRT ships 5.8.1.8.1.6 but there is also 5.7.9.9.0.6.
Rather that ship two full drivers, there is a patch file for 5.7.9.9.0.6 and that only gets applied if you
select Annex B in the line definition details.
Yup, I've used both and did not notice any functional difference.
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I ended up replacing the jelly crimps and cable from the crimps to master socket. Jelly crimps were full of dust and only one had jelly in it.
Hopefully this will hold up, on another note why does TalkTalk use an SNR of 9 but other providers use 6?
(https://i.imgur.com/dAhbqod.jpg)
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Providers don't set the SNRM target. OpenReach control it via their DLM (Dynamic Line Management).
The upstream is always say to a 6dB target.
The downstream is 6dB, but on Huawei cabinets it can be lowered to 5, 4 or 3dB.
The SNRM target is never above 6dB on both downstream and upstream.
What your stats show is the current SNRM at that moment in time, not the target set.
Your current downstream SNRM is on target at 6dB.
Your upstream is above the target as the line isn't syncing as high as it could.
It is capped at 20Mb by OpenReach as that's the max they offer on VDSL2/FTTC. If it wasn't capped you could get around 29Mb.
The result of your upstream syncing under what it's capable of is the current SNRM is above the 6dB target. So you have "spare" SNRM.
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Providers don't set the SNRM target. OpenReach control it via their DLM (Dynamic Line Management).
The upstream is always say to a 6dB target.
The downstream is 6dB, but on Huawei cabinets it can be lowered to 5, 4 or 3dB.
The SNRM target is never above 6dB on both downstream and upstream.
What your stats show is the current SNRM at that moment in time, not the target set.
Your current downstream SNRM is on target at 6dB.
Your upstream is above the target as the line isn't syncing as high as it could.
It is capped at 20Mb by OpenReach as that's the max they offer on VDSL2/FTTC. If it wasn't capped you could get around 29Mb.
The result of your upstream syncing under what it's capable of is the current SNRM is above the 6dB target. So you have "spare" SNRM.
I forgot to mention, I was talking about the downstream SNR which goes to 9 and the speed drops but if at 6 the speed goes back to normal. Hopefully it will stay as it is for now but the information I was looking at was here https://www.increasebroadbandspeed.co.uk/SNR-tweak which says 9 is TalkTalks default.
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. . . the information I was looking at was here https://www.increasebroadbandspeed.co.uk/SNR-tweak which says 9 is TalkTalks default.
That is outdated and wrong information. ::)