FTTC stability profile/banding

[#1]

Hi,

I have a new FTTC activation that has been running just over a week, on a ~1km line from the cabinet. Could I please confirm which BTWholesale stability profile my line is provisioned on? I ask, as the line is already banded at 22.4Mbit (confirmed in router web interface as it shows the profile speeds) despite hardly any resyncs. I also noticed this message during the provisioning process:

Selected product: WBC FTTC Annex A 10Mbit/s, Stable

If the line is provisioned on 'stable' (which I understand to be the 'middle' profile of standard/stable/super-stable in BTW terms) could this please be modified to 'standard', as the DLM behaviour of stable on this line is too conservative, and when sync is around 22Meg, a few megabits makes a big difference indeed.

Just to be clear, I'm in the master socket with no extensions at all, and a mk4 filtered faceplate with a short cable to the router. Voice service is clear. It's just a very long line back to the cabinet.

Cheers,

Jon

[#2]

Hi Jon,

I've placed an order to drop the provisioned stability profile down to Standard which should start to take effect from tomorrow. With time (normally 7 to 14 days) you should hopefully see an improvement in your speed. 

Let us know how it goes.

[#3]

Thanks again for your help, I'll let you know how it goes.

Jon

[#4]

No problem at all Jon, sounds like a plan

[#5]

Hi,

It's now been 3 weeks since the profile change and the line still appears to be banded. The line has been in sync now for almost 17 days (after I swapped the router over for one that I know to run better on this long line), with very low error rates.

Since Link time = 16 days 20 hours 21 min 9 sec
FEC: 2238905 17697
CRC: 24 178
ES: 11 183

Would it be worth a DLM reset, to try and unstick the banding?

Cheers,

Jon

[#6]

Hi Jon, I've had another look into this for you and while your line's banded at "Downstream: 0.128M-22.4M with Retransmission (High). Upstream: 0.128M-10M with no error protection" your router's only in sync at around 15mbps. As the banding isn't restricting your speed, we wouldn't be able to arrange for the banding to be removed. 

Having said that...  we appear to have now got the ability to submit a DLM reset for FTTC like we can for ADSL.

I've put it through now and it should take up to half an hour to complete. I can't guarantee this will work though but I'm definitely intrigued and hopeful that it will do. Can you let me know how it goes? 

Cheers

[#7]

Thanks. The Zyxel router seems to react strangely to the banding, and sync much lower. The downstream noise margin is a giveaway (irrelevant bits trimmed):

ZySH> xdslctl info --stats

Bearer: 0, Upstream rate = 3405 Kbps, Downstream rate = 15809 Kbps

                 Down Up

SNR (dB): 11.3 6.5

It's been like this since sync-time, and if the banding wasn't restricting the sync, the noise margin would be around the target of 6dB. I'm not sure why the Zyxel is reacting to the banding by syncing at such a low rate, but other routers hit the top of the band.

In any case, lets see how the reset goes. I'll let you know.

[#8]

Thanks for getting back to me Jon.

Ah that's odd. From what I can see your line's still banded but let's leave this until tomorrow and retest things then.

Can you let me know how your speed looks tomorrow? I'm happy to add this to the unbanding/caution counter reset tracker based on what you've said if the DLM reset I've put through doesn't do anything. 

[#9]

Sounds good. Thanks again for your help.

Jon

[#10]

No problem Jon

[#11]

Hi,

No change since yesterday. Can this please be added to the unbanding/caution counter reset tracker as you said yesterday?

ZySH> xdslctl info --stats

Bearer: 0, Upstream rate = 3405 Kbps, Downstream rate = 15809 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps

Down Up
SNR (dB): 10.8 6.4
Attn(dB): 26.5 0.0

Since Link time = 17 days 22 hours 35 min 29 sec
FEC: 2309993 18745
CRC: 24 191
ES: 11 195
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
HostInitRetr: 0
FailedRetr: 0

[#12 · Accepted solution]

Ah that's disappointing. Sure, I've arranged that now and your line should be reset within 3 working days.

Let us know how it goes.

[#13]

Thanks again, I'll let you know. Have a good weekend.

Jon

[#14]

No problem Jon. Cheers, you have a good weekend too

[#15]

Hi Gandalf,

Looks like the reset went through yesterday around 3pm. The speed increased to around 23Mbit using the same modem (which shows the banding was limiting the speed, even though it was considerably lower than the band. Now with an old HG612 I'm getting the following:

Max: Upstream rate = 3498 Kbps, Downstream rate = 27392 Kbps
Bearer: 0, Upstream rate = 3498 Kbps, Downstream rate = 27473 Kbps

Down Up
SNR (dB): 6.4 6.0

And it's running nice and clean:

Since Link time = 18 hours 15 min 13 sec
FEC: 3083071 877
CRC: 3 12
ES: 2 10
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0

As you can see, this has made a significant improvement. I'll keep the Lantiq-based routers off this line, as they seem to drive DLM crazy.

Thanks again,

Jon