*** I have responded to the initial comments but have run out of steam and the will to live to continue any further ****** I have pulled out the Stats from the numerous files and graphs to condense the problem down ***
*** Hope it makes sense *** Beware interpreting the downstream "max attainable" when FEC and interleaving have been turned on: most modems appear to over-estimate the attainable speed at this time.
[My comments re: Max Attainable are based on real measurments from the Modem.
The period Sep24 --> Feb14 had no Interleaving.My line was good. The earlier Interleaving was a DLM Event through too much playing with the modem. Feb14 onwards was issues with my line. Please read onward.]
At the end of February, you were getting speeds of around 63Mbps, with attainables of around 77Mbps, with FEC and interleaving on. Under such circumstances, my rule of thumb would predict a real speed of 70Mbps (half way between the two) if FEC/interleaving were turned off again.
[Beware using a 'window' that is not able to encompass the scope of the issue. Very easy to do.
I am on the 'inside' and it is very difficult for me !!!
This is one of the difficulties at the momemt.
Getting Plusnet/BTW/OR to understand the correct issue & associated 'window' to view the issue correctly.
Mid Feb was when the first indication of problems with the line became obvious.
All stats are via Zyxel VMG8324-B10A Modem running Firmware that supports G.INP. Consistently gives 5M higher DS Sync.
Exceptions are on Engineer visits (in Green) (Sync drops by 5M approx using HG612 as supplied).
Feb 14 03:54 Max Attainable went from 72116/28971 --> 77670/26838 [UP]
Feb 14 03:56 Actual Sync went from 79987/19999 --> 62637/19999 [DOWN] Stayed at this sync until .....
Feb 19 04:00 Actual Sync went from 62637/19999 --> 63159/19999 [UP] until ......
Mar 01 05:00 Actual Sync went from 63159/19999 --> 65122/19999 [UP] until ......
Mar 04 05:59 Actual Sync went from 65122/19999 --> 57679/19999 [DOWN]
***<Remember this Sync>*** until 1st Engineer call out (Fixed HR fault) .......
Mar 10 16:28 Actual Sync went from 57679/19999 --> 70306/19999 [UP] ***<Advised line at JF4 (10M approx) from house tested at 79xxx>***Told to wait to see if DLM recovered the sync speed and that a DLM reset would be asked for, if it does not recover log another call with Plusnet
The line did NOT recover, the Sync reduced to 66999/19999 and stayed there until 2nd Engineer + DCoE 'fixed' the problem.
During this period G.INP was enabled on the line, it did not change anything regarding sync speed.
<<- Quick weekly run to Present day via 2nd Engineer callout ->>Mar 14 05:27 Actual Sync 62562/19999 Max Attain 77542/26342 [DOWN]
Mar 21 04:50 Actual Sync 66999/20000 Max Attain 77101/27022 [UP] (66999/20000 started on Mar 17 continues to Apr 02 ... 2nd Engineer call out)
Mar 28 00:30 Actual sync 66999/20000 Max Attain 77178/26805 [NO Change]
Apr 02 06:00 Actual Sync 66999/20000 Max Attain 72660/26653 [No Change] Before Engineer has touched line or attempted any fix
Apr 02 13:38 Actual Sync 61489/19999 Max Attain 73208/26211 [DOWN] Engineer has, while at cab, request a L&S and this is the result.
Lower DS sync + High Interleave, INP on, Delay on, G.INP OffConvinced Engineer this is not good enough as it is worse than before he touched the line.
Goes to cab again. 10-15 min wait and mobile call is received.
Advised fault at DSLAM, port tests OK but randomly drops speed of sync to 51M.
The original port I had been moved to would not sync at 80M when set but tested at 71M. So moved twice.
After Easter Holidays during which NO activity at cab.
DCoE test port with Woosh test. Declare all is Good and no mention of DSLAM fault.
Close call pass back to Plusnet.
I receive SMS stating all fixed.
Engineers notes from Plusnet Call Log are as follows:========================================================================================================
2015-04-02 15:40:36 : 02/04/2015 15:40:32-
Notes - DCOE DONE LIFT AND SHIFT BUT PORT STILL DROPPING AND SLOWING DOWN TOLD TO SEND BACK INCOMPLETE FOR DIAGNOSTIC TEST
DCOE: The woosh test is a pass no fault found, an engineer has today done a lift and shift and
the line is now in full sync at speeds of 61.5 down and 20 up which are slightly exceeding
the predicted 54.5 down and 15.7 up.
The line may needsome time to settle but i am passing it back to the cp as OK RWT by DT.
========================================================================================================
The predicted DS sync is 55808, very close to 57679
***<Remember this Sync>*** Just a little under what you 'already have', so you look to have 'gained' something.
Of course this is 'in the range expected' for your line, so No 'Line Fault' there.
The Woosh Test was a remote test which conveniently cleared all the faults including the DSLAM fault.
Somehow I am not convinced and the decimation of my Line Performance is NOT reasonable by any measure.
Reality is something else.
Until Feb 14 I had a good 79987/19999 line with no interleaving, delay, INP. [G.INP was working, when enabled, as Zyxel supports G.INP.]
After a HR fault which probably initiated around this time judging by the line degradation, 2 Engineer call outs & DCoE.
I now have a crappy line that by all measures of BTW/OR is perfectly good and 'in spec' only its now giving :
(Bear in mind that I am syncing 5M approx higher than the supplied HG612 so real sync is 64xxx lower than I started with on the morning of the callout)
Right now, with FEC and interleaving turned off, it is achieving and estimating 69Mbps, and it is hard to disagree.
[Totally disagree, See above. The INP & Interleave has just gone off (06/04/15 05:05) with no change in Max Attainable or Sync speed.]Update:
Posted on Plusnet Forum with Supporting Docs/Graphs.
See http://community.plus.net/forum/index.php/topic,138251.msg1217788.html#msg1217788