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Author Topic: Changed from 40/10 to 80/20  (Read 1388 times)

mw2870

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Changed from 40/10 to 80/20
« on: July 02, 2019, 09:57:54 PM »

I have been with Vodafone approx 12 months (of an 18 month contract) and recently switched from their router to an Archer VR2800 (as posted previously), this reduced my latency and gave me better WiFi performance around the house.

I wondered if my line was capable of more, I was on their 40/10 service and syncing at 40000/9997.
I know that back in May 2019 when I was with BT I was synced at 55Mbs on their Infinity 1 product, but this was long before I discovered this site and became slightly more enlightened so I don't have any detailed stats. I do have some screenshots from the Hub back then:



In a moment of madness I decided to upgrade with Vodafone to their 80/20 service rather than waiting for the remaining 6 months of my contract to run out and move to someone else. Some of the cabs near me have been enabled for G.FAST but mine hasn't and I wasn't sure if it would be any time soon. The upgrade was done with the promise that if I was not 100% happy in the first 30 days I could go back to my old service and wait out the contract.

I checked BT Wholesale and was quietly optimistic:


Vodafone even emailed me the following:
Min download speed (in Mbps)   62.72
Max download speed (in Mbps)   76
Min upload speed (in Mbps)   19
Max upload speed (in Mbps)   20
Minimum guaranteed speed (in Mbps)   56.37

So the activation was booked for the 28th June, and shortly after 6am in the morning, my connection dropped and reconnected.
Stats before switch:
http://dslstats.wilson-serve.co.uk/history2.php?date=2019-06-28&fileName=2019-06-28%2FStats-2019-06-28-04.18.45.txt
Stats after switch:
http://dslstats.wilson-serve.co.uk/history2.php?date=2019-06-28&fileName=2019-06-28%2FStats-2019-06-28-06.19.45.txt

G.INP had gone (which I was expecting) and the interleave depth was up to 671.
I was under the impression that I would go on an open profile and hence sync speed should be as high as it could be.
I was expecting errors in the first couple of days as DLM did it thing and stabilised the line.
I gave it 72 hours to see if anything changed but the connection stayed synced.

So I got on the phone to Vodafone as they promise to give you a partial monthly refund while you are not meeting your Minimum guaranteed speed.
I was informed that they would only look at this 14 days after service activation to give the line time to settle.

I believe that they are talking about DLM, but from reading the site I was under the impression that in the initial days sync speed would not go Up only Down as DLM did its thing.
Have I misunderstood?

They are due to call me back on the 10th July, and say they will investigate further if the speed has not increased. I am hoping I can use this as an excuse to break my contact now and go to someone like A&A - who presumably would make a much better job of getting the line improved.

Am I missing anything obvious?

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burakkucat

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Re: Changed from 40/10 to 80/20
« Reply #1 on: July 02, 2019, 10:47:15 PM »

Assuming that G.Inp is re-applied and the circuit remains stable, the DLM will incrementally reduce the target SNRM in 1 dB steps . . . down to a minimum of 3 dB.

With the step-wise reduction in the target SNRM there will be a corresponding step-wise rise in the synchronisation speed.
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mw2870

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Re: Changed from 40/10 to 80/20
« Reply #2 on: July 02, 2019, 11:25:08 PM »

Assuming that G.Inp is re-applied and the circuit remains stable, the DLM will incrementally reduce the target SNRM in 1 dB steps . . . down to a minimum of 3 dB.

Thanks for the response!
The Downstream is clean, but U/S has about 12 ES per hour (this is the same as it was before the upgrade)
I believe that Vodafone use Standard rather than Speed, so that error count would put me in the Amber cat?
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burakkucat

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Re: Changed from 40/10 to 80/20
« Reply #3 on: July 02, 2019, 11:55:38 PM »

. . . U/S has about 12 ES per hour (this is the same as it was before the upgrade)
I believe that Vodafone use Standard rather than Speed, so that error count would put me in the Amber cat?

Hmm . . . So ~12 ES per hr is ~288 ES per day. I can't remember the figures per category but I'm sure that someone who can will be along soon.
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mw2870

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Re: Changed from 40/10 to 80/20
« Reply #4 on: July 03, 2019, 12:00:00 AM »

I used: https://kitz.co.uk/adsl/DLM_calculator.php and https://kitz.co.uk/adsl/DLM.htm

Code: [Select]
Previous 1 day time = 24 hours 0 sec
FEC:            14362           780027
CRC:            560             497
ES:             10              342
SES:            10              2
UAS:            36              26
LOS:            1               0
LOF:            1               0
LOM:            0               0
Retr:           1
FailedRetr:     0
FailedFastRetr: 0

Result = Amber I believe
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j0hn

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Re: Changed from 40/10 to 80/20
« Reply #5 on: July 03, 2019, 01:23:45 AM »

The default DLM profile is now Low Interleaving not fastpath.

G.INP is usually applied within a few days, sometimes it's a few weeks.

I don't think G.INP will be enough to get your line up to the minimum 56.37Mb.
If the DLM lowers the target SNRM to 3dB then it would but that's not a certainty.

My advice is wait for G.INP and the 14 days and if the line is still below the minimum then push Vodafone for a resolution.
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Zyxel VMG1312-B10A bridged with 1508 MTU + Asus RT-AC68U running Asuswrt-Merlin

tubaman

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Re: Changed from 40/10 to 80/20
« Reply #6 on: July 03, 2019, 08:34:02 AM »

Agree with @J0hn - it looks like you might just make the minimum with G.INP and 3dB.
What is a little odd is that your BT Homehub was syncing at 55Mbps with a 7.2dB noise margin (can't tell if G.INP was active), and that was only back in May.
I'm not sure why your VR2800 is struggling to match that now?
 :)
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BT FTTC 80/20 Huawei Cab - Zyxel VMG8924-B10A

ktz392837

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Re: Changed from 40/10 to 80/20
« Reply #7 on: July 03, 2019, 08:52:58 AM »

I used: https://kitz.co.uk/adsl/DLM_calculator.php and https://kitz.co.uk/adsl/DLM.htm

Code: [Select]
Previous 1 day time = 24 hours
ES:             10              342

Result = Amber I believe

Possibly needs Kitz to reply to this one but I thought the boundaries for ES / day are ES=2880 / 1440 / 720  and Resyncs=20 / 10 / 5 so not sure why the calculator is saying it is amber?  Assuming 342 in a day with no resyncs it is Green whatever the profile?
« Last Edit: July 03, 2019, 09:00:12 AM by ktz392837 »
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j0hn

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Re: Changed from 40/10 to 80/20
« Reply #8 on: July 03, 2019, 09:06:10 AM »

Quote
Assuming 342 in a day with no resyncs it is Green whatever the profile?

Not how it works.

It triggers red if it exceeds the threshold.
It's only green if it's very low.
Everything inbetween is Amber.
Amber means take no action.

Those error rates on kitz site aren't very relevant with G.INP.
The ES figures aren't used at all with G.INP.

Upstream G.INP for example is triggered way below the DLM thresholds listed.
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Plusnet FTTC 80/20 -  ECI now Huawei cab
retx low @ 3dB target SNRM
Zyxel VMG1312-B10A bridged with 1508 MTU + Asus RT-AC68U running Asuswrt-Merlin

mw2870

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Re: Changed from 40/10 to 80/20
« Reply #9 on: July 03, 2019, 09:57:26 AM »

Thanks all for the replies!

The plot thickens today....just drove home from the garage and there is an OR engineer in the DSLAM Cab.
Didn't get a close look at what they were doing..... arrived back home and realised that I lost sync around 9:30.
As no fault has been raised against my line I doubt it is specifically to do with me.
Unless OR are in the habit of monitoring new connections/upgrades to see if they don't meet the guaranteed sync?

What is a little odd is that your BT Homehub was syncing at 55Mbps with a 7.2dB noise margin (can't tell if G.INP was active), and that was only back in May.
I'm not sure why your VR2800 is struggling to match that now?

I was wondering this as well, shame I don't have detailed stats from back then, but this was before I discovered the world of dslstats!!
The only thing I could think of was that there has been a big uptake in VDSL from my neighbours since then?
« Last Edit: July 03, 2019, 10:00:54 AM by mw2870 »
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tubaman

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Re: Changed from 40/10 to 80/20
« Reply #10 on: July 03, 2019, 10:09:11 AM »

An interesting experiment might be to put your Homehub back on the line if you still have it and see what speed it syncs at now.
It won't give you an internet connection on Vodafone but it should still sync and allow you to check the stats.
 :)
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mw2870

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Re: Changed from 40/10 to 80/20
« Reply #11 on: July 03, 2019, 10:11:37 AM »

An interesting experiment might be to put your Homehub back on the line if you still have it and see what speed it syncs at now.
It won't give you an internet connection on Vodafone but it should still sync and allow you to check the stats.
 :)
Interesting idea! I shall check the graveyard of routers and modems in the loft, but I think I was a good citizen and returned it to BT.
I hope they get recycled/used for parts..... all these routers being sent out whenever someone switches services can't be good for the environment.
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mw2870

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Re: Changed from 40/10 to 80/20
« Reply #12 on: July 03, 2019, 10:23:16 AM »

Back up! SNR has dropped to 3.
Sync is at 51668.
G.INP is still off.

Still a touch off min guarantee of 56.4....
Wonder if this will creep up once G.INP is enabled?

Code: [Select]
DSLAM type / SW version: BDCM:0xb12d (177.45) / v0xb12d
Modem/router firmware:  AnnexA version - A2pvbH042j2.d26m
DSL mode:                VDSL2 Profile 17a
Status:                  Showtime
Uptime:                  0 hour 24 min 13 sec
Resyncs:                2 (since 02 Jul 2019 21:09:38)

Downstream Upstream
Line attenuation (dB):  13.9 0.0
Signal attenuation (dB): Not monitored
Connection speed (kbps): 51668 19881
SNR margin (dB):        3.6 3.0
Power (dBm):            14.0 6.7
Interleave depth:        769 1
INP:                    3.00 0
G.INP:                  Not enabled Not enabled
Vectoring status:        5 (VECT_UNCONFIGURED)

RSCorr/RS (%):          0.0002 0.0017
RSUnCorr/RS (%):        0.0000 0.0000
ES/hour:                2.18 11.5
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j0hn

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Re: Changed from 40/10 to 80/20
« Reply #13 on: July 03, 2019, 10:58:14 AM »

The SNR dropping you 3dB isn't DLM related.
The target SNRM is still 6dB. It's the actual/current SNRM that is 3dB right now.

You will have synced at 6dB before the neighbours (the whole DSLAM was offline).
As there's less crosstalk you synced higher.

When others on the DSLAM came back online a minute later the crosstalk they caused made your SNRM drop to 3dB.

DLM will only lower the target SNRM on lines with G.INP and it only changes the SNRM target in 1dB increments, so 5dB would be tried first.

If you post the output of xdslctl info --stats you should see the attainable rate is similar to what it was before (it might be the xdslcmd on your modem).
It would increase the attainable rate if the target SNRM was reduced.


If you resynced now then the line would return to the lower rate.
This temporary increase in sync speed (that's very common when a DSLAM reboots) will make it appear to Vodafone the line is performing better than it actually is.

As before I advise waiting for G.INP.
You could resync the line to return the SNRM to 6dB or you could leave as is and take the benefit from it.

The current SNRM being a fair bit below the target can sometimes increase ES quite a bit.
I can't tell what the current ES are like from the above output (I always recommend posting the output of the "info --stats" command as it shows much more detail).

edit: forgetting you have live stats online
« Last Edit: July 03, 2019, 11:04:12 AM by j0hn »
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Plusnet FTTC 80/20 -  ECI now Huawei cab
retx low @ 3dB target SNRM
Zyxel VMG1312-B10A bridged with 1508 MTU + Asus RT-AC68U running Asuswrt-Merlin

mw2870

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Re: Changed from 40/10 to 80/20
« Reply #14 on: July 03, 2019, 04:21:31 PM »

Thanks for the excellent explanations J0hn, you are a knowledgeable chap!

You will have synced at 6dB before the neighbours (the whole DSLAM was offline).
As there's less crosstalk you synced higher.
When others on the DSLAM came back online a minute later the crosstalk they caused made your SNRM drop to 3dB.

I guess this is what this graph shows, everyone else syncing, crosstalk increasing and SNR dropping:

Those pesky neighbours!

If you post the output of xdslctl info --stats you should see the attainable rate is similar to what it was before (it might be the xdslcmd on your modem).
It would increase the attainable rate if the target SNRM was reduced.

Interesting, the current Maxs are higher than they were before the DSLAM reset.
Is this value only calculated at the point of sync, or is it updated continuously?

Before DSLAM reset:
Code: [Select]
Max:    Upstream rate = 15524 Kbps, Downstream rate = 52989 Kbps
Bearer: 0, Upstream rate = 15524 Kbps, Downstream rate = 44894 Kbps

Now:
Code: [Select]
Max:    Upstream rate = 17175 Kbps, Downstream rate = 53950 Kbps
Bearer: 0, Upstream rate = 19881 Kbps, Downstream rate = 51668 Kbps

If you resynced now then the line would return to the lower rate.
This temporary increase in sync speed (that's very common when a DSLAM reboots) will make it appear to Vodafone the line is performing better than it actually is.
You could resync the line to return the SNRM to 6dB or you could leave as is and take the benefit from it.

Hmmm, good point, I might do a re-sync before they call me back and claim some miracle!
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