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Author Topic: Advice on some mediorce lines  (Read 469 times)

boozy

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Advice on some mediorce lines
« on: November 29, 2018, 03:49:13 PM »

Hi,

I'm looking for some advice, at least enough to sway me to one of my options :).

I installed a second line to create a load balanced pair as the existing line was falling over in heavy rain (and the existing line was still under contract).  The installation of the second line cured weather related problems - well I suspect that it was where the second line was taken from that cured the problem.  The only downtimes during the first month was for the target SNR to be dropped to 3Db.  Some time in early November the line that was disconnected to give me a second pair must have been reconnected, as now I get noise spikes once every 10 days or so.  Not enough to complain about, but it does take out both lines simultaneously - which defeats the purpose of having 2.

The two lines have different profiles (on 3Db target)

original has 57/12 (was 57/17 but 5 vanished one morning) - HG612 (might be better with the VMG8924)
New has 60/8 - VMG8924

EDIT
original has 63/11 - VMG8924
New has 57/9 - HG612

The new line also has double/tripe the CRCs of the original line upstream (the original line got to 3550+ ES per hour upstream on occasions, but is now generally under 20 ES per hour).

Just to make the new line seem even worse it seems to need a margin or 7/8 to manage the noise burst, whereas the original needs 4/5 (that's for the last burst - I had the new line on 9.5 and the original on 3 as an experiment).

The original line is out of contract now and the new line will be out of contract in March

The options I can think of are:

1. Get the cheapest and most cheerful 40/10 I can find for the first line (Higher SNR will likely mean it'll stay up).
2. Bond the two lines (the new one is AAISP) and keep one of the lines with a high margin
3. Add 4G failover to the original line
4. Leave as-is and wait for 5G
5. Beg to be part of the SRA trial

A reliable connection is worth approximately 120+ per month (as that's how much the business expenses reduce by).

The graphs are the result of SNR experiments during the noise (the original line didn't survive the 10:16 spike, but an extra 1Db Margin enabled it to stay up thereafter).

Now that I've written it all down, I'm favouring option 1... but advice welcomed.
« Last Edit: November 29, 2018, 09:20:54 PM by boozy »
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kitz

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Re: Advice on some mediorce lines
« Reply #1 on: December 01, 2018, 11:10:54 AM »

Quote
EDIT
original has 63/11 - VMG8924
New has 57/9 - HG612

The new line also has double/tripe the CRCs of the original line upstream (the original line got to 3550+ ES per hour upstream on occasions, but is now generally under 20 ES per hour).

I take it from your edit that those new figures are after you swapped the modems - if so then the VMG8924 is the better performer on both lines so may be worthwhile keeping your eye open for another.

Quote
The two lines have different profiles (on 3Db target)

The new line certainly appears to be experiencing noise bursts.   Its not clear from your post if it sync at 57Mbps @ 3dB or if thats when you apply 9.5Db Target SNRm...  but I shall assume it's 9.5dB for the rest of my answer.

If you can keep that line stable at 60Mbps using the Zyxel and thats with the 9.5dB target, then that 20Mbps could be a good chunk of useful speed.

I can understand why perhaps you are considering 40/10...   but before you do that... would it be worthwhile seeing if you can find the cause of the noise.     The reason I say that is atm by forcing it to run at 9.5dB then you are 'masking' what is going on.   DLM obviously thinks everything is fine to put you on 3dB target Margin.
What I'm thinking is if you let that line run doing it's own thing, DLM will likely kick in and start reducing speed.  It will also start recording a lot more errors and probably loss of syncs...  at which point you could probably get your ISP and Openreach involved to see if its anything that can be fixed.
As it stands right now your ISP & OR think the line is good so wont do anything.

----

eke..  and after I typed that I noticed that you say it only happens about every 10 days and takes out both lines :(   Tracking something down like that is not going to be easy.  Could it possibly be related to heavy rain again?

I don't think bonding rather than load balancing would make things much better... other than possibly increase your outgoings.
I can now see perhaps why you are considering dropping the 2nd line to 40Mbps so at least you will have one connection that will always stay up.  :-\

Thing is though if you do drop to 40Mbps that that too will mask the fact there is an underlying problem.   Only you can decide if stability is more important than trying to find the cause.   Sorry not much help :(
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j0hn

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Re: Advice on some mediorce lines
« Reply #2 on: December 01, 2018, 02:48:03 PM »

What I'm thinking is if you let that line run doing it's own thing, DLM will likely kick in and start reducing speed.  It will also start recording a lot more errors and probably loss of syncs...  at which point you could probably get your ISP and Openreach involved to see if its anything that can be fixed.
As it stands right now your ISP & OR think the line is good so wont do anything.

I would have agreed if there wasn't such a big gap between the noise bursts.
With this only happening once every 10 days, even if DLM took action the line would be back at 3dB SNRM target again by the time 10 days rolled back round.

It would probably only increase the SNRM target once to 4dB. After 2 days it would lower the SNRM target back to 3dB.
As you say tracking this 1 down could be problematic.

To the OP,
I think I recall the original thread with the theory rain was causing issues on line 1.
Though squirting the line at the assumed trouble spot with a water gun didn't replicate the issue.
(if I'm remembering the wrong thread I apologise).
A 2nd line being fitted making that issue go away would make me think it probably wasn't rain causing it.

Or is it possible that the issue that was affecting line 1 is still present, and is what is being seen on both lines?
I'm on my phone at the moment so unable to read your previous threads right now.

Could you attach images of the ES graphs for during the noise. LEFTERS from the G.INP tab would also help.
Could you also dump the full results of xdslctl info --stats within [code] [/code] tags for both lines.

edit: tag fail. I keep typing [nobb] instead of [/nobbc]
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boozy

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Re: Advice on some mediorce lines
« Reply #3 on: December 01, 2018, 04:48:20 PM »

@both - definitely not heavy rain, it's been torrential on and off for the past week, and the particular pattern on SNRM hasn't been repeated since the new line went in.


The stats for the original line are:

Code: [Select]
xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    1
Last initialization procedure status:   0
Max:    Upstream rate = 10785 Kbps, Downstream rate = 64948 Kbps
Bearer: 0, Upstream rate = 10789 Kbps, Downstream rate = 62153 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State:       L0
Mode:                   VDSL2 Annex B
VDSL2 Profile:          Profile 17a
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        3.8             6.3
Attn(dB):        22.4            0.0
Pwr(dBm):        13.6            6.9

                        VDSL2 framing
                        Bearer 0
MSGc:           -6              26
B:              244             237
M:              1               1
T:              0               48
R:              10              16
S:              0.0000          0.7012
L:              16319           2898
D:              4               1
I:              255             127
N:              255             254
Q:              4               0
V:              3               0
RxQueue:                138             0
TxQueue:                23              0
G.INP Framing:          18              0
G.INP lookback:         23              0
RRC bits:               0               24
                        Bearer 1
MSGc:           154             -6
B:              0               0
M:              2               0
T:              2               0
R:              16              0
S:              6.4000          0.0000
L:              40              0
D:              3               0
I:              32              0
N:              32              0
Q:              0               0
V:              0               0
RxQueue:                0               0
TxQueue:                0               0
G.INP Framing:          0               0
G.INP lookback:         0               0
RRC bits:               0               0

                        Counters
                        Bearer 0
OHF:            0               944143
OHFErr:         211             444
RS:             769641512               350127
RSCorr:         26994766                925
RSUnCorr:       0               0
                        Bearer 1
OHF:            9892482         0
OHFErr:         0               0
RS:             98924202                0
RSCorr:         1452            0
RSUnCorr:       0               0

                        Retransmit Counters
rtx_tx:         104174032               0
rtx_c:          18644748                0
rtx_uc:         504763          0

                        G.INP Counters
LEFTRS:         18201           0
minEFTR:        62153           0
errFreeBits:    3469070450              0

                        Bearer 0
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    1799654393              0
Data Cells:     97499582                0
Drop Cells:     0
Bit Errors:     0               0

                        Bearer 1
HEC:            0               0
OCD:            0               0
LCD:            0               0
Total Cells:    0               0
Data Cells:     0               0
Drop Cells:     0
Bit Errors:     0               0

ES:             664             14490
SES:            267             4
UAS:            325066          324970
AS:             158941

                        Bearer 0
INP:            57.00           0.00
INPRein:        1.00            0.00
delay:          0               0
PER:            0.00            8.44
OR:             0.01            30.30
AgR:            62472.12        10819.53

                        Bearer 1
INP:            4.50            0.00
INPRein:        4.50            0.00
delay:          3               0
PER:            16.06           0.01
OR:             79.68           0.01
AgR:            79.68   0.01

Bitswap:        112414/112415           9092/9101

Total time = 61 days 23 hours 32 min 48 sec
FEC:            641477292               28477
CRC:            18482           16253
ES:             664             14490
SES:            267             4
UAS:            325066          324970
LOS:            8               0
LOF:            52              0
LOM:            4               0
Latest 15 minutes time = 2 min 48 sec
FEC:            12546           0
CRC:            0               2
ES:             0               1
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 15 minutes time = 15 min 0 sec
FEC:            78367           1
CRC:            0               7
ES:             0               3
SES:            0               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Latest 1 day time = 23 hours 32 min 48 sec
FEC:            3947364         475
CRC:            101             252
ES:             17              156
SES:            7               0
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
Previous 1 day time = 24 hours 0 sec
FEC:            25956747                502
CRC:            656             290
ES:             18              201
SES:            14              2
UAS:            1830            1820
LOS:            1               0
LOF:            6               0
LOM:            0               0
Since Link time = 1 days 20 hours 8 min 59 sec
FEC:            26994766                925
CRC:            211             444
ES:             25              262
SES:            11              2
UAS:            0               0
LOS:            0               0
LOF:            0               0
LOM:            0               0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0
 >

New Line (may not be useful as I just plugged it back in):

Code: [Select]
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 6
Last initialization procedure status: 0
Max: Upstream rate = 8833 Kbps, Downstream rate = 56624 Kbps
Bearer: 0, Upstream rate = 8833 Kbps, Downstream rate = 57263 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 3.4 6.2
Attn(dB): 22.8 0.0
Pwr(dBm): 13.5 4.1
VDSL2 framing
Bearer 0
MSGc: -6 26
B: 227 239
M: 1 1
T: 0 40
R: 10 14
S: 0.1266 0.8632
L: 15035 2354
D: 4 1
I: 238 127
N: 238 254
Q: 4 0
V: 0 0
RxQueue: 138 0
TxQueue: 23 0
G.INP Framing: 18 0
G.INP lookback: 23 0
RRC bits: 0 24
Bearer 1
MSGc: 122 -6
B: 0 0
M: 2 0
T: 2 0
R: 16 0
S: 8.0000 0.0000
L: 32 0
D: 1 0
I: 32 0
N: 32 0
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0
Counters
Bearer 0
OHF: 0 19125
OHFErr: 0 3
RS: 5159968 764583
RSCorr: 32082 0
RSUnCorr: 0 0
Bearer 1
OHF: 10272 0
OHFErr: 0 0
RS: 81680 0
RSCorr: 0 0
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 21962292 0
rtx_c: 36094878 0
rtx_uc: 1134348 0

G.INP Counters
LEFTRS: 20982 0
minEFTR: 57253 0
errFreeBits: 3261570553 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 18129955 0
Data Cells: 853 0
Drop Cells: 0
Bit Errors: 0 0

Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0

ES: 593 9595
SES: 1528 99
UAS: 85755 85409
AS: 165

Bearer 0
INP: 57.00 0.00
INPRein: 1.00 0.00
delay: 0 0
PER: 0.00 8.66
OR: 0.01 29.54
AgR: 57388.93 8862.38

Bearer 1
INP: 2.00 0.00
INPRein: 2.00 0.00
delay: 0 0
PER: 16.06 0.01
OR: 63.75 0.01
AgR: 63.75 0.01

Bitswap: 115/115 10/10

Total time = 1 days 23 hours 25 min 28 sec
FEC: 2513153742 40793
CRC: 13062 15623
ES: 593 9595
SES: 1528 99
UAS: 85755 85409
LOS: 9 0
LOF: 113 0
LOM: 59 0
Latest 15 minutes time = 10 min 28 sec
FEC: 32082 0
CRC: 0 3
ES: 0 3
SES: 0 0
UAS: 463 463
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 900 900
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 23 hours 25 min 28 sec
FEC: 175814 103
CRC: 1042 136
ES: 18 124
SES: 18 0
UAS: 74991 74973
LOS: 0 0
LOF: 13 0
LOM: 12 0
Previous 1 day time = 24 hours 0 sec
FEC: 11171337 772
CRC: 786 857
ES: 24 815
SES: 24 0
UAS: 1856 1843
LOS: 0 0
LOF: 13 0
LOM: 10 0
Since Link time = 2 min 45 sec
FEC: 32082 0
CRC: 0 3
ES: 0 3
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
#

And I've attached the Errored Seconds from both at the time of the noise.

Reliability is definately needed as my current client has paid for the second line (I had three losses of connection during a presentation, so for them it was cheaper than it happening again).
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boozy

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Re: Advice on some mediorce lines
« Reply #4 on: December 01, 2018, 10:08:55 PM »

@john - I went back and had a look at old SNRM graphs.  If I split problems into two categories, the first I can tie to rain and has a gradual effect (depending on how heavy the rain is) and the second which was a bit more instantaneous and "violent".  The first isn't apparent anymore, but you could be right and the second one could have always been there.

I've attached the LEFTRS from the original line, too - although DSLStats appears to give rtx_tx if you take a snapshot.

I also think I've answered my own question - I'm being paid to have a working connection...  the only way to do that is give myself enough margin to ride out any noise.  A second line can be there for speed, but it's got to be redundant.  I reckon I could have two lines, with bugger all in the way of support, for less than either of the current lines.

To be fair, I'm getting over 60MB on a line that's 780m from the cabinet which might mean that any noise will have a very bad effect (that's a guess). I also can't see how anyone could find the source of the problem without lottery winning luck.
« Last Edit: December 01, 2018, 10:22:41 PM by boozy »
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boozy

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Re: Advice on some mediorce lines
« Reply #5 on: December 07, 2018, 04:57:24 PM »

Went for a PN 40/10 on one line 16.88 for 12 months and 19.38 for 6 months which seems quite good.  I'll deal with the other in March.
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anything