Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[dgilbert2]

I have moved my post from another thread and hope someone could advise please.

Before moving from BT to Plusnet on 1st December 2017 I was on a steady and reliable 3dB profile, happy days 

With the profile reset due to ISP migration I lost the 3dB profile (along with G.Inp) and about 15Mbps download speed. Now, I am unable to get back again to 3dB or get G.Inp re-activated.

Could someone look at my MDWS stats (username dgilbert2) and suggest why this might be please? I am already on Fast Path since 3rd Feb, triggered by changing to a HG612. Since then I had a few days with my upload going back to interleave, but this was removed again on the 10th February.

In my case, I don't think "capping" would make much difference to try and re-activate G.Inp? Any thoughts please?

(My HG612 is running the latest B030SP08 firmware)

[skyeci]

whilst I can't comment on the g.inp much your latency chart looks very odd.  As you moved ISP I guess this could take some time  to re-apply?

[dgilbert2]

Hi, yes my latency chart is a waste of time to be honest as I'm pinging a PI3 which is not reliable or fast enough  I should delete it really.

[dgilbert2]

Still no signs of G.Inp coming back after 12 weeks now 

[burakkucat]

I've taken a quick look and see that your circuit is accumulating a significant number of ES per hour on the downstream.

The tried and tested method is to apply a cap to get those ES per hour down to around almost zero. But then I am not that much of an expert in the art of fooling the DLM process . . .

Edited to add: Nonsense alert. The above doesn't make sense to me, now that I've read it back, sometime later.

[re0]

I've taken a quick look and see that your circuit is accumulating a significant number of ES per hour on the downstream.

The tried and tested method is to apply a cap to get those ES per hour down to around almost zero. But then I am not that much of an expert in the art of fooling the DLM process . . .

That would only increase the likelihood of him getting a lower SNR? Because G.INP is considered a "corrective"? Unless you mean he caps his sync speed using inbuilt modem parameter settings to attain 3db then remove the cap to allow for G.INP to potentially set after when/if the tresholds are exceeded?

While nothing in regards to G.INP is mentioned in the opening post, it is mentioned in the subject so I suppose he wants G.INP to be reactivated on his line so he can reach the goal of 3db.

[burakkucat]

Unless you mean . . .

Not a lot; just like nothing. (See my subsequent edit to my previous post, above.    )

[dgilbert2]

Thank you for the replies. I am a bit confused though now to be honest.

Yes, my goal is to get back to a 3dB profile with the benefits of the higher downstream speeds. I understand that this will need G.Inp to be activated first?

If so, my understanding from reading other threads is that the steps to try and "force" G.Inp to be activated are;

1) Set a cap on the line (through a local telnet command to the HG612), eg 40Mbps down, 10Mbps up.
2) Wait for Interleave to be removed, ie return to Fast Path
3) Remove cap
4) Fingers crossed the resultant error increase will now activate G.Inp again.

BUT, in my case I am already on Fast Path since 3rd February and the lines performance seems quite happy without any "corrections", so I'm not sure if capping would do anything?

[re0]

@burakkucat - We all make mistakes, but none more than me.

@dgilbert2 - No, G.INP does not have to be enabled first to attain 3 dB. However, looking at the current state of your line and errors then you are probably not going to attain it in its current state without G.INP.

Now, I do not actually know the prerequisites for G.INP are. I know that on my line (on the Standard profile, as opposed to Speed which you are on), in reference to Mean Time Between Errors (MTBE) and Mean Time Between Retrains (MTBR), it was pretty much always in the Amber/Green for Downstream MTBE, Green for Upstream MTBE, and MTBR was mostly in the Green here (except when my router decided it wanted to reboot itself 3 times in a short space of time). So, in short, it should have not made any "corrective" changes but G.INP was enabled anyway. Though I had noticed somewhat outstanding spikes of CRC on the downstream, which may have indicated that G.INP would benefit my line.

You can read more about the DLM and thresholds here http://www.kitz.co.uk/adsl/DLM.htm.

From reading other threads you are getting a general idea, but each line is unique and needs different parameters in order to attain what the DLM thinks is the best it can do.

As your stats show Amber for the Speed profile for the Downstream MTBE so you will not see any corrective measures, nor will you see any improvements (it should remain the same if the error rates remain consistent). You are just narrowly missing Green for Downstream MTBE (yours is 296, you would need ≥300), so maybe if you capped it about at least 5 Mbps lower then the MTBE should be equal to or greater than 300 to make the positive changes to get you a 3 dB profile. You could then remove the cap and hope that G.INP is applied.

I must advise you that doing the above may not work, and you may potentially end up with interleaving and high levels of delay if the line experiences high error rates after removing the cap if you attain 3 dB. Furthermore, the DLM may even set you back to 6 dB.

Please take note that the information I have provided may have some minor discrepancies so I actively encourage people to make corrections to my information as they see fit.

Edited to reflect a later reply by another user correcting my information. See http://forum.kitz.co.uk/index.php/topic,21066.msg366045.html#msg366045

[dgilbert2]

Thank you @re0 your information is really helpful.

I will give your capping suggestion a try and see what happens over the next few days.

[dgilbert2]

I have now applied a cap 10Mbps lower on the downstream "too be sure" and 5Mbps on the up and will see what happens.

How will I know if anything changes, as the cap will hide a lowering of the default 6dB profile when looking at the down SNRM. Will I see a resync and then the "attainable" go up?

[re0]

I should add that if you get the 3 dB profile after artificially capping your line, even if you remove the cap your Downstream MTBE may not even be low enough to get the DLM to do corrective measures since a MTBE of <30 would be needed to get your Downstream to fall into the Red. So that if you get 3 dB the DLM decides it is stable so you can keep it, or even then apply G.INP to stabilise if you are getting large, single (but spaced out) bursts of errors.

I should have mentioned that I do not know how to circumvent the DLM. I am just going on based on what I have seen before and thresholds for the DLM.

----------------------------------
I was originally writing a reply and when I came back I noticed you posted a new reply.

There is no real need to cap the upstream as the parameters are adjusted independently by the DLM (so if ONLY your upstream had excessive errors exceeding the threshold, the DLM would only do corrective measures on the upstream and not the downstream).

I actually should probably leave this for someone else to answer who has done capping on the modem before, since the capping can survive a disconnection (but not a reboot). I would have imagined a rise in the attainable would have been expected, but I cannot answer for sure.

Edited to reflect a later reply by another user correcting my information. See http://forum.kitz.co.uk/index.php/topic,21066.msg366045.html#msg366045

[j0hn]

@dgilbert2 - No, G.INP does not have to be enabled first to attain 3 dB. However, looking at the current state of your line and errors then you are probably not going to attain it in its current state without G.INP.

It absolutely does.
DLM will not lower the target snrm to 5dB until the line has retransmission (G.INP) applied 1st.
All lines run with a 6dB target snrm by default.
Within a couple days of retransmission being applied if the line is stable enough DLM will try 5dB.
A couple of days later if the line is still stable it will drop to 4dB.
A couple days later it will drop to 3dB.

I've never seen a line with a lower target snrm without retransmission.
We see plenty lines sitting at 3dB without retransmission, but the target snrm is still 6dB. They will have synced at 6dB and then dropped down.
There's dozens of reasons that can cause a lines snrm to drop below the target like that.

DLM always drops the target snrm in 1dB increments. It will never jump from 6dB to 3dB.

[dgilbert2]

@j0hn thank you for your input.

I think I'm back on the page where I started in that capping will not do much in my case as I'm already on Fast Path. I will leave things for a few days now that I have applied a cap and see if anything does happen. With such low errors though now and already being on Fast Path, DLM has no need to change anything at the minute?

My only thought is that after removing the cap in a few days, is if the sync speed will be higher than before and start to introduce enough errors for the interleaving / G.Inp / 3dB journey to start.

IF ONLY, when migrating ISP's my line was not reset, as I would then have still have had the 3dB / G.Inp profile!

P.S. An interesting observation since capping is that it has introduced a few FEC's which I don't understand 

[re0]

@j0hn - I stand corrected and have therefore altered my existing posts to reflect this, and in order to prevent misinforming any further viewers of this topic.

@dgilbert2 - You have had an increase in FECs (Forward Error Correction) and a decrease in CRCs (Cyclic Redundancy Check) as more errors experienced on the line have been corrected.