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Erroneous PN IP profile update

RPMozley
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Registered: ‎04-11-2011

Erroneous PN IP profile update

Something very odd has happened. Upon checking our line speed today I find this:
Quote
Estimated line speed:
There's no speed estimate currently held on your account.
Current line speed:
3.8 Mb

It should be 7.2 Mb and has been for many days. But here comes the strange part, there has been no loss of sync or re-sync for over 100+ days and no PPP drop for over 23 days.
Where the heck does this 3.8 Mb value crop up from? Seems totally spurious but it's not the first time our line has gotten a completely inaccurate value for the PN IP profile. Something is not right and it should really be looked into. Rubbish data from BT possibly? Huh
That's RPM to you!!
20 REPLIES
Community Veteran
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Registered: ‎29-06-2010

Re: Erroneous PN IP profile update

What's your IP Profile from the BT Performance tester - Further diagnostics?
RPMozley
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Re: Erroneous PN IP profile update

Hi Brian (Jaggies)
Can't run that BT test on my iPod Touch but it should be 88.2% of my current 117 days sync of 8196 Kbps. Download speeds haven't changed yet as there's not been any PPP drop - connect, if there was I'd be stuck on a slow speed.
I'm just waiting for someone from the DCT to check things out and try to get to the bottom of this as it may be a sign of a wider problem affecting more customers.
That's RPM to you!!
Plusnet Staff
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Registered: ‎26-11-2011

Re: Erroneous PN IP profile update

Hi RPMozley ,
I've just taken a look, the profile is right in what it did, your sync rate did drop, interestingly, it doesn't always have to drop sync to change the sync value - it's very rare that it does this.
I've attached a screen grab which should give you some insight as to when this happened. I can't really advise why it happened, it just looks as though your connection suffered a poor sync event without the need to resync.
Chris Pettitt
Cloud Environments Engineer
Superuser
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Re: Erroneous PN IP profile update

Chris,
How much confidence can one place in these figures?
Across all of the lines, only one figure changes.  What particularly caught my eye was the up time - it never changes from 18 hours - number of retrains is zero.  Is it feasible that a synch rate change could occur without a retrain?
We've seen diagnostics mislead before...!
Kevin
Plusnet Staff
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Re: Erroneous PN IP profile update

These figures are taken directly from Openreach who feed them from their DLM Data.
There is mopre information on the left hand side which includes Line Quality, bRAS Speeds and more, so those updates which show the same sync rate are showing updates for another reason, it's not strictly just for resyncs.
I've seen many lines that have had the sync rate change without the need of a retrain.
Chris Pettitt
Cloud Environments Engineer
RPMozley
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Re: Erroneous PN IP profile update

A change of sync value without a re-sync, that's a new one on me. Is there any info from the TG582n that could show that this occurred (apart from actually looking at the sync rate when this strange event happened)?
[Edit] Just to add the PN profile still hasn't updated to the correct value as of yet today.
That's RPM to you!!
Plusnet Staff
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Re: Erroneous PN IP profile update

It's something that I noticed when working on the Faults Team, it changed the way we looked at faults as we couldn't solely rely on the RADIUS Graphs we have available to us entirely as it doesn't register each and every drop. It's important we look at this information as it gives us valuable information on how often your sync rate is changing as well as your historic line data.
The Speed Profile doesn't update within our core hours at the moment, as your sync rate update wasn't until this morning, the script hasn't run yet - I've changed your profile manually though.
Chris Pettitt
Cloud Environments Engineer
RPMozley
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Re: Erroneous PN IP profile update

Thanks for the manual intervention Chris.  Smiley
Well I'm sure most of us on the forums know that the RADUS logs only show PPP link connectivity and do not always show quick re-syncs where PPP timeout hasn't been reached. I've seen personally quick re-sync events without a new PPP session in the past, mostly on my old NetGear modem (which is now relegated to being a backup router).
What I've not seen, though, is a change of sync value without a re-sync event. I would have thought that occurrence was impossible as it would require a renegotiation of speed with the exchange. On-the-fly sync speed changes, is there a facility for this to happen?
That's RPM to you!!
Plusnet Staff
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Registered: ‎26-11-2011

Re: Erroneous PN IP profile update

I know it's strange isn't it, I thought exactly as you just have.
I'll see if I can get some clarification on it as I've been meaning to, but it hasn't been high on my list Smiley
Chris Pettitt
Cloud Environments Engineer
Superuser
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Registered: ‎22-08-2007

Re: Erroneous PN IP profile update

Chris,
Thank you for sharing the "new" knowledge.  It supports what I believe I saw many months ago when we were working on the pub line issue - a loss / re-establishment of DSL without dropping PPP.
It this knowledge now widely known / understood by the front-line agents?
Kevin
Plusnet Staff
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Re: Erroneous PN IP profile update

It certainly is - anything new like that goes straight to the Faults Team(s).
I'm prepping some new FTTC DLM stuff at the moment to share with the teams and eventually on here Smiley
Chris Pettitt
Cloud Environments Engineer
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Registered: ‎10-06-2010

Re: Erroneous PN IP profile update

One possible explanation for the lower sync speed is that the ADSL was in a low power state at the time the sync rate data was collected.
Described in section 3.2.5 of http://www.sinet.bt.com/sinet/SINs/pdf/472v2p6.pdf
Of course, it would be pretty stupid to mess about lowering the profile based on a low power sync rate.
Superuser
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Re: Erroneous PN IP profile update

ejs,
Interesting document - thank you.

Off topic: I read within interest in section 3.2 "Openreach provide a copper line with an NTE box" - does that mean that if the d-side has aluminium within its length, by definition it is not copper and therefore not within the published specification?  Cheesy
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Re: Erroneous PN IP profile update

Well it also says at the beginning "This document does not form a part of any contract with BT customers or suppliers." and "Due to technological limitations, a very small percentage of customer interfaces may not comply with some of the individual characteristics, which may be defined in this document." The technological limitations probably being the inability to turn aluminium into copper without spending money.