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Standard User madnutter56
(newbie) Mon 26-Nov-12 17:19:38
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Is this normal?


[link to this post]
 
Just posting this graph from my HG612 here for any opinions on whether this is a normal/expected level of crosstalk as a result of my neighbour having 80/20 FTTC installed this morning.

Graph Here

They have a 71.38Mbps IP Profile. We (currently) sync at the full 80/20, so 77.43Mbps profile. As you can see this won't be continuing due to our DS SNRM being ~ 4.5db, down from 8db this morning. I'm not too fussed just wondering if this is normal?

The increased crosstalk is causing some packet loss by the looks of my BQM.

I'm tempted to resync and take the hit on sync speed so the DLM doesn't step in and add interleaving.

Modem stats are: here and here.

Any thoughts?

Alex smile
Standard User Ixel
(member) Mon 26-Nov-12 18:36:13
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Re: Is this normal?


[re: madnutter56] [link to this post]
 
It looks a little odd in my view. Your line is closer than mine, lower line attenuation figures than my line, so I'm surprised your downstream speed is less than mine. Makes me wonder if there's a possibility of a line fault that's not clearly showing.

In my case, I had a lower speed a short while ago. I reported a fault to BT for another reason (one morning my whole internet was just getting bad throughput and ping, resolved itself in afternoon). Engineer arrived one morning (not planned) and still said there's a fault he needs to fix when I was sure it was resolved. Anyway, long story short he found a 'battery contact' fault of around 50v, he cleared most of it up and my attainable speed went up.

Here's my pbParams stats for comparison:
Text
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# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 2Max:    Upstream rate = 28485 Kbps, Downstream rate = 93168 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 59999 Kbps 
Discovery Phase (Initial) Band PlanUS: (0,95) (880,1195) (1984,2771)
DS: (32,859) (1216,1959) (2792,4083)Medley Phase (Final) Band Plan
US: (0,95) (880,1195) (1984,2771)DS: (32,859) (1216,1959) (2792,4083)
       VDSL Port Details       Upstream        DownstreamAttainable Net Data Rate:      28485 kbps         93168 kbps
Actual Aggregate Tx Power:        6.8 dBm          12.5 dBm============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3  Line Attenuation(dB):  0.7     20.7    30.6     N/A    11.3    26.5    40.8
Signal Attenuation(dB):  0.7     20.6    30.5     N/A    11.3    26.5    40.8        SNR Margin(dB):  12.6    12.4    11.9     N/A    14.9    15.3    14.8
         TX Power(dBm): -4.1    -23.1    6.4      N/A    8.9     7.7     6.4


That comes from the current_stats output by the graphing scripts.
Standard User MHC
(sensei) Mon 26-Nov-12 20:23:30
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Re: Is this normal?


[re: madnutter56] [link to this post]
 
4.5 dB at this time of day will increase again tomorrow morning.

With an 8dB margin and full sync you have some in hand so you may/maynot see a slight drop.

Cross talk from a neighbour will cause increased noise especially if they share a drop wire or the final cable with you.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit


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Standard User madnutter56
(newbie) Mon 26-Nov-12 20:39:34
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Re: Is this normal?


[re: Ixel] [link to this post]
 
In reply to a post by Ixel:
It looks a little odd in my view. Your line is closer than mine, lower line attenuation figures than my line, so I'm surprised your downstream speed is less than mine. Makes me wonder if there's a possibility of a line fault that's not clearly showing.


Hmm, do you have any idea how many FTTC lines there are on your cab? I know there are at least 10 on our road (almost half the street), so I'd imagine there's quite a bit of crosstalk already dragging it down.

There may well be some kind of fault here but the problem is getting anyone to care about it, given that I'm still syncing at 79999 or ~75000 if/when I reboot.

Alex smile
Standard User madnutter56
(newbie) Mon 26-Nov-12 20:42:18
Print Post

Re: Is this normal?


[re: MHC] [link to this post]
 
I don't think I explained it too well, basically up until this morning, I had an 8db margin with full 79,999 sync.

I still have 79,999 sync but the margin is down at 4.5db because of the increased crosstalk from the neighbours install, I was wondering if this is excessive?

Strangely our DS SNRM only seems to drop by 0.1 or 0.2db at night so that isn't affecting it much if at all.

Given that they are our neighbour, I'd take a guess they are on the same (underground) DP and thus the same cable back to the cab as us?

Edited by madnutter56 (Mon 26-Nov-12 20:43:01)

Standard User MHC
(sensei) Mon 26-Nov-12 21:17:57
Print Post

Re: Is this normal?


[re: madnutter56] [link to this post]
 
So just a small day night change.

It is high but not excessive. The feed from the cabinet to the pole could be a 10 pair, 25 or 100 ... and if your pair is close to another that is carrying VDSL signals then there will be a lot of cross talk. If you are on the opposite side of the bundle then it may be you would see no change. Predicting the effects of cross talk is a very difficult art and never perfect.

There are lots of reasons as to why the effect is so high and they would all be guesses and could send you on a wild goose chase ... For example and it is just an example so don't go looking! Your neighbour could have a phone cable that is a perfect antenna for a radio station ... so it picks up the transmission and that affects his signal ... because it is injected into his wiring, you will get a cross talk effect from that and it will hit your sync too.

Do a modem reset - just one and see where it comes back. Gut feel says you will only be just under full sync and not as low as your neighbour.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User WWWombat
(experienced) Mon 26-Nov-12 21:21:32
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Re: Is this normal?


[re: madnutter56] [link to this post]
 
I might not go to say that your case is "normal", it is certainly the kind of effect that could be expected. Your neighbour's line is one of the ones most likely to cause crosstalk with yours, but not guaranteed. The lines need to be running close together within the outer sheath; the closer they are, the more crosstalk... and it isn't just the drop line that matters, it is the whole of the distribution cable on the way back.

It could just as easily have been someone in the next street.

Your error rate looks perfectly fine - the modem stats show increased FEC counts (so the errors are getting corrected) and zero in the CRC counts. The small blobs on the BQM aren't enough to worry about.

It does, however seem likely that you'll still lose some of your speed if you resync

Before you do, can you post the output from the "xdslcmd info --stats" command? It'd be good to see the setup of your interleaving & FEC configuration.
Standard User RobertoS
(sensei) Mon 26-Nov-12 21:24:57
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Re: Is this normal?


[re: WWWombat] [link to this post]
 
In reply to a post by WWWombat:
Before you do, can you post the output from the "xdslcmd info --stats" command? It'd be good to see the setup of your interleaving & FEC configuration.
xdslcmd info --pbParams can be very useful as well. It shows what is in use out of what was "discovered".

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet Extra Fibre (FTTC). Sync ~ 53.5/15.2Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User madnutter56
(newbie) Mon 26-Nov-12 21:34:22
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
OK so here's the data requested from the modem:

Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
2627
2829
3031
3233
3435
3637
3839
4041
4243
4445
4647
4849
5051
5253
5455
5657
5859
6061
6263
6465
6667
6869
7071
7273
7475
7677
7879
8081
8283
8485
8687
8889
9091
9293
9495
9697
9899
100101
102103
104105
106107
# xdslcmd info --stats
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 1Max:    Upstream rate = 27099 Kbps, Downstream rate = 74428 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps 
Link Power State:       L0Mode:                   VDSL2 Annex B
VDSL2 Profile:          Profile 17aTPS-TC:                 PTM Mode
Trellis:                U:ON /D:ONLine Status:            No Defect
Training Status:        Showtime                Down            Up
SNR (dB):        4.5             12.2Attn(dB):        0.0             0.0
Pwr(dBm):        13.9            6.0                        VDSL2 framing
                        Path 0B:              239             237
M:              1               1T:              23              45
R:              0               16S:              0.0955          0.3782
L:              20107           5373D:              1               1
I:              240             127N:              240             254
                        Counters                        Path 0
OHF:            28926201                3357163OHFErr:         3805            63
RS:             0               3396968RSCorr:         0               264
RSUnCorr:       0               0 
                        Path 0HEC:            4283            0
OCD:            0               0LCD:            0               0
Total Cells:    3060538644              0Data Cells:     29094453                0
Drop Cells:     0Bit Errors:     0               0
 ES:             5072            113
SES:            13              4UAS:            59              59
AS:             47835 
                        Path 0INP:            0.00            0.00
PER:            1.64            4.25delay:          0.00            0.00
OR:             116.56          60.17 
Bitswap:        10247           656 
Total time = 1 days 4 hours 57 min 36 secFEC:            0               0
CRC:            15501           0ES:             5072            113
SES:            13              4UAS:            59              59
LOS:            10              0LOF:            5               0
Latest 15 minutes time = 12 min 36 secFEC:            0               0
CRC:            135             0ES:             123             0
SES:            0               0UAS:            0               0
LOS:            0               0LOF:            0               0
Previous 15 minutes time = 15 min 0 secFEC:            0               0
CRC:            204             0ES:             178             0
SES:            0               0UAS:            0               0
LOS:            0               0LOF:            0               0
Latest 1 day time = 4 hours 57 min 36 secFEC:            0               0
CRC:            2352            0ES:             1711            17
SES:            0               0UAS:            0               0
LOS:            0               0LOF:            0               0
Previous 1 day time = 24 hours 0 secFEC:            0               0
CRC:            8399            0ES:             1406            30
SES:            11              0UAS:            40              40
LOS:            10              0LOF:            5               0
Since Link time = 13 hours 17 min 15 secFEC:            0               264
CRC:            3805            63ES:             2688            36
SES:            0               0UAS:            0               0
LOS:            0               0LOF:            0               0


and
Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
24
xdslcmd: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 1
Max:    Upstream rate = 27115 Kbps, Downstream rate = 74428 KbpsPath:   0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps
 Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)DS: (32,859) (1216,1963) (2792,3959)
Medley Phase (Final) Band PlanUS: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3959)       VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:      27115 kbps         74428 kbpsActual Aggregate Tx Power:        6.0 dBm          13.9 dBm
============================================================================  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB):  2.9     16.9    24.7     N/A    9.7     21.2    31.8 
Signal Attenuation(dB):  2.9     15.8    24.1     N/A    9.7     21.2    31.8 
        SNR Margin(dB):  12.1    12.2    12.2     N/A    4.4     4.5     4.5 
         TX Power(dBm): -9.2    -28.7    6.0      N/A    11.2    8.0     6.9


I will do a resync in the morning and see what happens then smile
Standard User Ixel
(member) Mon 26-Nov-12 22:07:10
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Re: Is this normal?


[re: madnutter56] [link to this post]
 
I'd imagine at least a dozen or more, Openreach have been at the cabinet on a regular basis over the past few months since FTTC was available here. I was first for FTTC in the cabinet and am getting about 12 megabits (downstream) less than I did when I was first activated. Sadly I don't know where the stats are for back then (I think I had them on my SSD which I had to send back ages ago as it just failed suddenly).
Standard User WWWombat
(experienced) Mon 26-Nov-12 22:11:21
Print Post

Re: Is this normal?


[re: madnutter56] [link to this post]
 
Ignore what I said before - I misread some of the graphs - some of the FEC and CRC counts in the graphs come from the modem's GUI, which unfortunately gets them from the wrong fields compared to the "--stats" command.

With the "--stats" output, I can see that downstream, you aren't interleaved or set to have any FEC processing working. That means you *are* seeing CRC errors - and the stats for the 12 minute period, 15 minute period and (near) 5 hour period suggest an average of around 500-800 errors per hour, broadly spread out over time.

(To see it in the graphs, watch the "OHFErr" graph instead of the CRC one.)

That sounds quite high compared with ADSL, where it could easily cause interleaving to be added. My working hypothesis is that VDSL2 can have an error rate 10x higher and continue to work effectively. If that is true, then the DLM threshold might well be around 600 errors per hour. Mighty close... so worth watching each day.

Some observations over timing though...
- You resync'ed at 8:15 - was this manual, or caused by the neighbour's installation?
- The SNRM change happens at 8:45. Is this the time the neighbour's was turned on?
- But the CRC errors started at 8:30. Interesting, but not obvious why.
Standard User Bald_Eagle1
(committed) Tue 27-Nov-12 01:48:46
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
5072 DS Error Seconds in the 13 hours or so connection time also looks very high.

My connection is quite poor due to a long distance from the cabinet, but I usually only see around 110 Error Seconds in a 24 hour period, admittedly with DS Interleaving at a depth of 443, INP at 3.00 & delay at 8.00.

(To see it in the graphs, watch the "OHFErr" graph instead of the CRC one.)

Yes, I can confirm that.
The next version (to be released fairly soon) does not use any of the "duff" stats from the modem's GUI, taking all the data from xdslcmd info --stats instead.

Using the current script version, use the OHFErr graph instead of CRC & use the RSCorr graph instead of FEC.
HEC is still O.K. though.

Edited by Bald_Eagle1 (Tue 27-Nov-12 01:56:13)

Standard User madnutter56
(learned) Tue 27-Nov-12 09:15:36
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
Ok, so I got up this morning to find my line is now a 67Mbit line with interleaving frown I'd imagine that over the next few weeks the DLM will notice the lack of errors now and remove interleaving and leave me with a lower sync speed on fast path?

On the timings:

The guy first arrived at 8:10, but didn't stop, just drove straight back up the road again.
He then came back and parked on next doors driveway as I was leaving the house at 8:20

From here on out I'm relying on what I've been told with regards to timings.

He stayed for maybe 5 minutes (8:25) and then drove off again. At this point I'm assuming he went to the cab to connect the patch cables over to the FTTC cab?

He then came back, don't know what time but I'd imagine it would have been shortly before 8:35?
Don't know what time he left but I'd imagine that he finished the install and turned the modem on at 8:45, right when my attainable rate dropped. The CRC'd then must have started when he connected then in the cab.

Has he knocked something?

Anyway, here is the latest data from the modem:

Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
2627
2829
3031
3233
3435
3637
3839
4041
4243
4445
4647
4849
5051
5253
5455
5657
5859
6061
6263
6465
6667
6869
7071
7273
7475
7677
7879
8081
8283
8485
8687
8889
9091
9293
9495
9697
9899
100101
102103
104105
106107
xdslcmd: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 2
Max:    Upstream rate = 27153 Kbps, Downstream rate = 79516 KbpsPath:   0, Upstream rate = 20000 Kbps, Downstream rate = 67333 Kbps
 Link Power State:       L0
Mode:                   VDSL2 Annex BVDSL2 Profile:          Profile 17a
TPS-TC:                 PTM ModeTrellis:                U:ON /D:ON
Line Status:            No DefectTraining Status:        Showtime
                Down            UpSNR (dB):        6.3             15.0
Attn(dB):        0.0             0.0Pwr(dBm):        13.8            6.0
                        VDSL2 framing                        Path 0
B:              63              237M:              1               1
T:              64              45R:              16              16
S:              0.0302          0.3782L:              21160           5373
D:              1067            1I:              80              127
N:              80              254                        Counters
                        Path 0OHF:            8664341         2968811
OHFErr:         3               13RS:             1663553210              420793
RSCorr:         19940           256RSUnCorr:       5               0
                         Path 0
HEC:            2               0OCD:            0               0
LCD:            0               0Total Cells:    1634389645              0
Data Cells:     1053718         0Drop Cells:     0
Bit Errors:     0               0 
ES:             6641            130SES:            20              4
UAS:            76              76AS:             12630
                         Path 0
INP:            3.00            0.00PER:            1.45            4.25
delay:          8.00            0.00OR:             115.71          60.17
 Bitswap:        1907            60
 Total time = 1 days 16 hours 28 min 39 sec
FEC:            19940           1777CRC:            3               228
ES:             6641            130SES:            20              4
UAS:            76              76LOS:            15              0
LOF:            10              0Latest 15 minutes time = 13 min 39 sec
FEC:            87              1CRC:            0               1
ES:             0               1SES:            0               0
UAS:            0               0LOS:            0               0
LOF:            0               0Previous 15 minutes time = 15 min 0 sec
FEC:            1565            4CRC:            0               1
ES:             0               1SES:            0               0
UAS:            0               0LOS:            0               0
LOF:            0               0Latest 1 day time = 16 hours 28 min 39 sec
FEC:            19940           499CRC:            3               63
ES:             3280            34SES:            7               0
UAS:            17              17LOS:            5               0
LOF:            5               0Previous 1 day time = 24 hours 0 sec
FEC:            0               127CRC:            0               32
ES:             1406            30SES:            11              0
UAS:            40              40LOS:            10              0
LOF:            5               0Since Link time = 3 hours 30 min 29 sec
FEC:            19940           256CRC:            3               13
ES:             1               10SES:            0               0
UAS:            0               0LOS:            0               0
LOF:            0               0#


and..

Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
x
dslcmd info --pbParamsxdslcmd: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 2
Max:    Upstream rate = 27130 Kbps, Downstream rate = 79516 KbpsPath:   0, Upstream rate = 20000 Kbps, Downstream rate = 67333 Kbps
 Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783) DS: (32,859) (1216,1963) (2792,3959) 
Medley Phase (Final) Band PlanUS: (0,95) (868,1207) (1972,2783) 
DS: (32,859) (1216,1963) (2792,3959)        VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:      27130 kbps         79516 kbpsActual Aggregate Tx Power:        6.0 dBm          13.8 dBm
============================================================================  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB):  2.9     16.9    24.7     N/A    9.7     21.2    32.0   Signal Attenuation(dB):  2.9     15.9    24.1     N/A    9.7     21.2    32.0   
        SNR Margin(dB):  14.8    15.0    15.0     N/A    6.3     6.3     6.2             TX Power(dBm): -9.0    -29.0    5.9      N/A    11.2    7.8     7.0


Sorry if the formatting isn't quite right, posting this on an iPad..

Alex smile
Standard User madnutter56
(learned) Tue 27-Nov-12 09:17:41
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
Also just to note, I cannot explain the resync at 8:15. Very strange..
Standard User Ixel
(member) Tue 27-Nov-12 11:29:46
Print Post

Re: Is this normal?


[re: madnutter56] [link to this post]
 
The reduction or complete removal of interleaving, if that happens, will increase your sync speed, not reduce them as you stated in the previous post to the one I'm replying to. I presume that was a typo.

Anyway, one possible way I can think of to determine if their Infinity has caused this loss in attainable speed is if they're willing to switch off/unplug their modem for a few minutes while you check your attainable rate. It does very much sound like their connection has brought your connection speed down though, given your timings.

Your current interleaving to me would indicate you have a moderate level. I don't really go by 'D' as that varies depending on your sync as well as some other parameters. I usually observe the INP and delay, and in my experience I've seen DLM set INP from 2 all the way to 5, not sure I've ever seen it higher than 5. I've never seen DLM use an INP of 1 either, just 0, 2, 3, 4 or 5.

Edited by Ixel (Tue 27-Nov-12 11:33:46)

Standard User Chrysalis
(eat-sleep-adslguide) Tue 27-Nov-12 11:38:01
Print Post

Re: Is this normal?


[re: madnutter56] [link to this post]
 
In reply to a post by madnutter56:
Just posting this graph from my HG612 here for any opinions on whether this is a normal/expected level of crosstalk as a result of my neighbour having 80/20 FTTC installed this morning.

Graph Here

They have a 71.38Mbps IP Profile. We (currently) sync at the full 80/20, so 77.43Mbps profile. As you can see this won't be continuing due to our DS SNRM being ~ 4.5db, down from 8db this morning. I'm not too fussed just wondering if this is normal?

The increased crosstalk is causing some packet loss by the looks of my BQM.

I'm tempted to resync and take the hit on sync speed so the DLM doesn't step in and add interleaving.

Modem stats are: here and here.

Any thoughts?

Alex smile


looks like a DLM cause not your neighbour, your latency bumps on tbb graph meaning interleaving.
Standard User madnutter56
(learned) Tue 27-Nov-12 17:07:10
Print Post

Re: Is this normal?


[re: Ixel] [link to this post]
 
Yup that was a typo, I was thinking in my head that it would come back slightly under 79,999 on fastpath, but that's not what I wrote. Don't like mornings..

I don't really know my neighbours well enough to go round and ask them to switch off their modem for a few minutes, although I'd like to just to see what happens.

Hopefully the DLM will gradually reduce the interleaving depth over the next few days. I'll post an update in a weeks time, or if I get back on fastpath before then, whichever comes first.
Standard User madnutter56
(learned) Tue 27-Nov-12 17:08:38
Print Post

Re: Is this normal?


[re: Chrysalis] [link to this post]
 
In reply to a post by Chrysalis:
looks like a DLM cause not your neighbour, your latency bumps on tbb graph meaning interleaving.


Yes the DLM caused the interleaving but that was as a result of next doors FTTC install causing increased crosstalk and thus errors on our line, hence the addition of interleaving to calm things down smile
Standard User WWWombat
(experienced) Wed 28-Nov-12 02:38:16
Print Post

Re: Is this normal?


[re: Chrysalis] [link to this post]
 
In reply to a post by Chrysalis:
looks like a DLM cause not your neighbour, your latency bumps on tbb graph meaning interleaving.

I think that is because you are now looking at the next day's BQM - not the graph for the day that I was looking at yesterday.

Alex - when you post a link on here, can you make it something that doesn't change? Anyone who finds this thread in a few days, weeks or months won't understand what we're talking about!
Standard User WWWombat
(experienced) Wed 28-Nov-12 03:03:14
Print Post

Re: Is this normal?


[re: Ixel] [link to this post]
 
In reply to a post by Ixel:
Anyway, one possible way I can think of to determine if their Infinity has caused this loss in attainable speed is if they're willing to switch off/unplug their modem for a few minutes while you check your attainable rate. It does very much sound like their connection has brought your connection speed down though, given your timings.

I agree on both fronts... it seems to be the neighbours, and a way to check your co-dependence would be to see how each other's lines perform when one modem is turned off. You can check their stats too if they're willing to let you plug your hacked modem in wink

Your current interleaving to me would indicate you have a moderate level. I don't really go by 'D' as that varies depending on your sync as well as some other parameters. I usually observe the INP and delay, and in my experience I've seen DLM set INP from 2 all the way to 5, not sure I've ever seen it higher than 5. I've never seen DLM use an INP of 1 either, just 0, 2, 3, 4 or 5.

I agree with this - the 'INP' and 'delay' values are the ones set by DLM, and specify the degree of interleaving required.

Here's my understanding of the VDSL2 standard:
- INP can be from 0 to 16 incl
- INP=0 means no protection is required
- delay can be from 0 to 63 incl, or 255
- delay=0 means the delay is unbounded (so can be really high)
- delay=1 means the interleaving depth D should be set to 1 (minimum delay)
- delay=255 means a delay of 1ms
- delay=N otherwise means a delay of Nms

Higher INP values mean more protection is needed. High delays make it easier for the data to be spread out; lower delays make it harder - and so requires that the protection comes from a higher (relative) amount of parity protection. I think high INP and low delay forces a low N with high R.

I personally think the percentage value that comes from (R/N) gives you the best indication of how protected the data is - how much overhead is being consumed.
Standard User WWWombat
(experienced) Wed 28-Nov-12 03:22:32
Print Post

Re: Is this normal?


[re: madnutter56] [link to this post]
 
In reply to a post by madnutter56:
Ok, so I got up this morning to find my line is now a 67Mbit line with interleaving frown I'd imagine that over the next few weeks the DLM will notice the lack of errors now and remove interleaving and leave me with a lower sync speed on fast path?

Yes - that is indeed what you have (with identical INP & delay values to bald_eagle, so it suggests that DLM's first effort believes you need a fair degree of intervention).

As someone else's line on this forum, you've been given protection level of 16 parity bytes out of every block of 80 - so 20% of the line is being used as extra protection.

And it shows. The "Since Link" stats show near 20,000 FEC, 3 CRC and 1 ES in the 3.5 hours since the line was resynced. The parity protection has worked.

Hopefully the DLM will gradually reduce the interleaving depth over the next few days. I'll post an update in a weeks time, or if I get back on fastpath before then, whichever comes first.

Understand the nuances of setting interleaving is (as you can tell) quite a technical sport. I have no idea if you will see improvements, or if they'll happen in less than a month. But keeping us updated will be good wink

But be patient!

On the timings:

The guy first arrived at 8:10, but didn't stop, just drove straight back up the road again.
He then came back and parked on next doors driveway as I was leaving the house at 8:20

From here on out I'm relying on what I've been told with regards to timings.

He stayed for maybe 5 minutes (8:25) and then drove off again. At this point I'm assuming he went to the cab to connect the patch cables over to the FTTC cab?

He then came back, don't know what time but I'd imagine it would have been shortly before 8:35?

Don't know what time he left but I'd imagine that he finished the install and turned the modem on at 8:45, right when my attainable rate dropped. The CRC'd then must have started when he connected then in the cab.

Has he knocked something?


That's a bit more back-and-forth to the cabinet than I've seen in a previous "normal/working" installation. Normally the OR guy would attend the cabinet once only, and would go there first, to patch the line through to the FTTC cab.

So perhaps he did knock something, or took your line down in some way (IIRC the width of the red spike was a little wider than a plain resync; so it may have lasted a while), or perhaps he even took out the whole cabinet!

Perhaps your CRC errors started once the neighbour was patched into FTTC, even if he had no modem locally. And then your "attainable" numbers dropped only after the modem was plugged into the line too.
Standard User WWWombat
(experienced) Wed 28-Nov-12 03:27:47
Print Post

Re: Is this normal?


[re: Bald_Eagle1] [link to this post]
 
In reply to a post by Bald_Eagle1:
My connection is quite poor due to a long distance from the cabinet, but I usually only see around 110 Error Seconds in a 24 hour period, admittedly with DS Interleaving at a depth of 443, INP at 3.00 & delay at 8.00.

Yes, you'd hope that the interleaving/FEC level chosen would be enough to keep CRC and ES down (to a low, but non-zero, level).

What do you get for the corresponding N and R values?

I sure hope these can be graphed in some way! I'll be going back to look at some of my old logs, to see what I can infer from the different interleaving & FEC parameters now...
Standard User Bald_Eagle1
(committed) Wed 28-Nov-12 06:34:12
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
December 2011 - Frequent but intermittent disconnections:-
Max: Upstream rate = 6244 Kbps, Downstream rate = 34640 Kbps
Path: 0, Upstream rate = 6311 Kbps, Downstream rate = 27189 Kbps

Path 0
R: 12 12
N: 44 204
D: 1743 1
INP: 8.50 0.00
delay: 16.00 0.00


May 2012 - DLM reset following line problems being FINALLY & permanently fixed:-
Max: Upstream rate = 4800 Kbps, Downstream rate = 31280 Kbps
Path: 0, Upstream rate = 4815 Kbps, Downstream rate = 30813 Kbps

Path 0
R: 0 12
N: 240 156
D: 1 1
INP: 0.00 0.00
delay: 0.00 0.00



November 2012 (today) - Stable connection since May 2012:-
Max: Upstream rate = 5452 Kbps, Downstream rate = 33088 Kbps
Path: 0, Upstream rate = 5279 Kbps, Downstream rate = 28043 Kbps

Path 0
R: 16 12
N: 80 172
D: 443 1
INP: 3.00 0.00
delay: 8.00 0.00

My D-side is somewhere between 850m & 1000m in length, depending on which of 2 possible routes is actually taken nearer to the cabinets.
I suspect it is the longer of the two.
The old PCP is around 60m closer to me than the fibre cabinet.

TDR tests suggest a length of around 1200m based on the electrical properties of the cabling/joints etc.

Edited by Bald_Eagle1 (Wed 28-Nov-12 06:34:53)

Standard User madnutter56
(learned) Wed 28-Nov-12 09:10:00
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
Yeah sorry about that, the stats graphs will be fine, but luckily I set up a script to cache my BQM every time it is loaded through my site, so I have the original graph:

http://bqm.alexhoulton.co.uk/archive/bqm_2012-11-26_...
Standard User MHC
(sensei) Wed 28-Nov-12 09:20:17
Print Post

Re: Is this normal?


[re: madnutter56] [link to this post]
 
You can choose any day on BQM and link to that directly so why do you need to cache it yourself?


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User madnutter56
(learned) Wed 28-Nov-12 09:20:38
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
In reply to a post by WWWombat:
Understand the nuances of setting interleaving is (as you can tell) quite a technical sport. I have no idea if you will see improvements, or if they'll happen in less than a month. But keeping us updated will be good wink


I had no idea it was so complicated, but yes I'll be sure to keep you updated, either weekly or whenever something changes smile

That's a bit more back-and-forth to the cabinet than I've seen in a previous "normal/working" installation. Normally the OR guy would attend the cabinet once only, and would go there first, to patch the line through to the FTTC cab.


Perhaps he went to the cab, couldn't find the line (maybe thought it was ours but then realised it wasn't when he saw it already connected to the FTTC cab), came to put something on the line to help him find it? Then went back to the cab to connect it?
Standard User madnutter56
(learned) Wed 28-Nov-12 10:31:21
Print Post

Re: Is this normal?


[re: MHC] [link to this post]
 
I just completely forgot frown
Standard User WWWombat
(experienced) Wed 28-Nov-12 13:12:47
Print Post

Re: Is this normal?


[re: MHC] [link to this post]
 
In reply to a post by MHC:
You can choose any day on BQM and link to that directly so why do you need to cache it yourself?

Because the BQM tool loses them. My history has nothing available from before May 2012, rendering any old threads I posted about my line meaningless.

Never rely on someone else's website...
Standard User RobertoS
(sensei) Wed 28-Nov-12 18:20:06
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
In reply to a post by WWWombat:
In reply to a post by MHC:
You can choose any day on BQM and link to that directly so why do you need to cache it yourself?
Because the BQM tool loses them. My history has nothing available from before May 2012, rendering any old threads I posted about my line meaningless.

Never rely on someone else's website...
Change of IP address?

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet Extra Fibre (FTTC). Sync ~ 53.5/15.2Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User madnutter56
(learned) Tue 04-Dec-12 19:09:26
Print Post

Re: Is this normal?


[re: WWWombat] [link to this post]
 
First update, the modem has been in sync for over 7 days now since interleaving was applied. The error stats for the 7 day period are below:

Text
1
23
45
67
8
Since Link time = 7 days 13 hours 30 min 57 sec
FEC:            917540          4980CRC:            68              395
ES:             15              333SES:            0               0
UAS:            0               0LOS:            0               0
LOF:            0               0
Standard User dave2150
(experienced) Wed 05-Dec-12 05:49:37
Print Post

Re: Is this normal?


[re: madnutter56] [link to this post]
 
In reply to a post by madnutter56:
Ok, so I got up this morning to find my line is now a 67Mbit line with interleaving frown I'd imagine that over the next few weeks the DLM will notice the lack of errors now and remove interleaving and leave me with a lower sync speed on fast path?

On the timings:

The guy first arrived at 8:10, but didn't stop, just drove straight back up the road again.
He then came back and parked on next doors driveway as I was leaving the house at 8:20

From here on out I'm relying on what I've been told with regards to timings.

He stayed for maybe 5 minutes (8:25) and then drove off again. At this point I'm assuming he went to the cab to connect the patch cables over to the FTTC cab?

He then came back, don't know what time but I'd imagine it would have been shortly before 8:35?
Don't know what time he left but I'd imagine that he finished the install and turned the modem on at 8:45, right when my attainable rate dropped. The CRC'd then must have started when he connected then in the cab.

Has he knocked something?

Anyway, here is the latest data from the modem:

Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
2627
2829
3031
3233
3435
3637
3839
4041
4243
4445
4647
4849
5051
5253
5455
5657
5859
6061
6263
6465
6667
6869
7071
7273
7475
7677
7879
8081
8283
8485
8687
8889
9091
9293
9495
9697
9899
100101
102103
104105
106107
xdslcmd: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 2
Max:    Upstream rate = 27153 Kbps, Downstream rate = 79516 KbpsPath:   0, Upstream rate = 20000 Kbps, Downstream rate = 67333 Kbps
 Link Power State:       L0
Mode:                   VDSL2 Annex BVDSL2 Profile:          Profile 17a
TPS-TC:                 PTM ModeTrellis:                U:ON /D:ON
Line Status:            No DefectTraining Status:        Showtime
                Down            UpSNR (dB):        6.3             15.0
Attn(dB):        0.0             0.0Pwr(dBm):        13.8            6.0
                        VDSL2 framing                        Path 0
B:              63              237M:              1               1
T:              64              45R:              16              16
S:              0.0302          0.3782L:              21160           5373
D:              1067            1I:              80              127
N:              80              254                        Counters
                        Path 0OHF:            8664341         2968811
OHFErr:         3               13RS:             1663553210              420793
RSCorr:         19940           256RSUnCorr:       5               0
                         Path 0
HEC:            2               0OCD:            0               0
LCD:            0               0Total Cells:    1634389645              0
Data Cells:     1053718         0Drop Cells:     0
Bit Errors:     0               0 
ES:             6641            130SES:            20              4
UAS:            76              76AS:             12630
                         Path 0
INP:            3.00            0.00PER:            1.45            4.25
delay:          8.00            0.00OR:             115.71          60.17
 Bitswap:        1907            60
 Total time = 1 days 16 hours 28 min 39 sec
FEC:            19940           1777CRC:            3               228
ES:             6641            130SES:            20              4
UAS:            76              76LOS:            15              0
LOF:            10              0Latest 15 minutes time = 13 min 39 sec
FEC:            87              1CRC:            0               1
ES:             0               1SES:            0               0
UAS:            0               0LOS:            0               0
LOF:            0               0Previous 15 minutes time = 15 min 0 sec
FEC:            1565            4CRC:            0               1
ES:             0               1SES:            0               0
UAS:            0               0LOS:            0               0
LOF:            0               0Latest 1 day time = 16 hours 28 min 39 sec
FEC:            19940           499CRC:            3               63
ES:             3280            34SES:            7               0
UAS:            17              17LOS:            5               0
LOF:            5               0Previous 1 day time = 24 hours 0 sec
FEC:            0               127CRC:            0               32
ES:             1406            30SES:            11              0
UAS:            40              40LOS:            10              0
LOF:            5               0Since Link time = 3 hours 30 min 29 sec
FEC:            19940           256CRC:            3               13
ES:             1               10SES:            0               0
UAS:            0               0LOS:            0               0
LOF:            0               0#


and..

Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
x
dslcmd info --pbParamsxdslcmd: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 2
Max:    Upstream rate = 27130 Kbps, Downstream rate = 79516 KbpsPath:   0, Upstream rate = 20000 Kbps, Downstream rate = 67333 Kbps
 Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783) DS: (32,859) (1216,1963) (2792,3959) 
Medley Phase (Final) Band PlanUS: (0,95) (868,1207) (1972,2783) 
DS: (32,859) (1216,1963) (2792,3959)        VDSL Port Details       Upstream        Downstream
Attainable Net Data Rate:      27130 kbps         79516 kbpsActual Aggregate Tx Power:        6.0 dBm          13.8 dBm
============================================================================  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
  Line Attenuation(dB):  2.9     16.9    24.7     N/A    9.7     21.2    32.0   Signal Attenuation(dB):  2.9     15.9    24.1     N/A    9.7     21.2    32.0   
        SNR Margin(dB):  14.8    15.0    15.0     N/A    6.3     6.3     6.2             TX Power(dBm): -9.0    -29.0    5.9      N/A    11.2    7.8     7.0


Sorry if the formatting isn't quite right, posting this on an iPad..

Alex smile


67mbit, you are still very lucky to have such a fast connection, do you not realize this?

There is nothing you can do with 70, or 75mbit that you cannot do with 67.

Yes, crosstalk will slow you line down overtime, as more and more get connected. It's a fact of life, there is nothing you can do about it.

Is it really worth all this effort, for a few measly mbit, when you already have 67?

My Broadband Speed Test
60db Attenuation
Standard User madnutter56
(learned) Wed 05-Dec-12 09:15:49
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Re: Is this normal?


[re: dave2150] [link to this post]
 
In reply to a post by dave2150:
67mbit, you are still very lucky to have such a fast connection, do you not realize this?

There is nothing you can do with 70, or 75mbit that you cannot do with 67.

Yes, crosstalk will slow you line down overtime, as more and more get connected. It's a fact of life, there is nothing you can do about it.

Is it really worth all this effort, for a few measly mbit, when you already have 67?


First off, I'm not complaining here in any way. Of course I realise I'm very lucky to have FTTC.

I get that crosstalk will slow everyone down over time, I'm not trying to do anything about it.

Also, the aim of this thread is in no way to get 'a few measly mbit', it's more an example of what can happen for future reference for others.
Standard User WWWombat
(experienced) Wed 05-Dec-12 21:27:06
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Re: Is this normal?


[re: madnutter56] [link to this post]
 
In reply to a post by madnutter56:
First update, the modem has been in sync for over 7 days now since interleaving was applied. The error stats for the 7 day period are below:

That looks like the FEC rate has continued at a similar level for the week, so it looks to be a continuous thing for you.

I've been reading more about DLM, and have come to the conclusion that on FTTC lines, DLM will be set to try to eradicate hard (CRC) errors even more than before. This seems to be because SFBB can decently support "proper" HD video services - by which I mean transmission of BBC1 for the family's evening viewing on TV, rather than 3 minutes of YouTube on the PC.

The quality requirements on this seem to be set at 1 error every hour (SD) or 1 error every 4 hours (HD).

So don't expect the speed to recover any time soon wink
Standard User WWWombat
(experienced) Wed 05-Dec-12 21:34:40
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Re: Is this normal?


[re: madnutter56] [link to this post]
 
I agree with that sentiment.

How do we know this is crosstalk until we discuss it? How do we know it isn't the first sign of a fault?

How do we know whether someone in the future is suffering crosstalk or a faulty line, unless we've seen the behaviour of both before, and discussed it?

How do we know whether a line is behaving at its best, unless we learn to read the statistics, and are able to understand what they mean?

How can we help people with their expectations in the future unless we can explain what is happening *now* rationally?

For me, it is all a part of the process of learning, and helping...
Standard User WWWombat
(experienced) Wed 05-Dec-12 21:39:53
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Re: Is this normal?


[re: Bald_Eagle1] [link to this post]
 
In reply to a post by Bald_Eagle1:
December 2011 - Frequent but intermittent disconnections:-
Max: Upstream rate = 6244 Kbps, Downstream rate = 34640 Kbps
Path: 0, Upstream rate = 6311 Kbps, Downstream rate = 27189 Kbps

Path 0
R: 12 12
N: 44 204
D: 1743 1
INP: 8.50 0.00
delay: 16.00 0.00


May 2012 - DLM reset following line problems being FINALLY & permanently fixed:-
Max: Upstream rate = 4800 Kbps, Downstream rate = 31280 Kbps
Path: 0, Upstream rate = 4815 Kbps, Downstream rate = 30813 Kbps

Path 0
R: 0 12
N: 240 156
D: 1 1
INP: 0.00 0.00
delay: 0.00 0.00



November 2012 (today) - Stable connection since May 2012:-
Max: Upstream rate = 5452 Kbps, Downstream rate = 33088 Kbps
Path: 0, Upstream rate = 5279 Kbps, Downstream rate = 28043 Kbps

Path 0
R: 16 12
N: 80 172
D: 443 1
INP: 3.00 0.00
delay: 8.00 0.00

My D-side is somewhere between 850m & 1000m in length, depending on which of 2 possible routes is actually taken nearer to the cabinets.
I suspect it is the longer of the two.
The old PCP is around 60m closer to me than the fibre cabinet.

TDR tests suggest a length of around 1200m based on the electrical properties of the cabling/joints etc.



Ooops - missed those.

So around 27% parity overhead when things were unstable (and very high INP and delay values), but 20% parity overhead when stable (and a more "normal" INP and delay values).

I wonder if there are some thresholds we can use here, to help distinguish fault from crosstalk?
Administrator MrSaffron
(staff) Wed 05-Dec-12 21:44:17
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Re: Is this normal?


[re: WWWombat] [link to this post]
 
Any ISP worth its salt should be able to offer BBC iPlayer HD live streams on any broadband connection faster than 5 Meg, and with ease on ones that run at 8 Meg or more.

To say iPlayer HD needs a connection of 25 Mbps or faster suggests an ISP has a contention issue, rather than the technology of the last mile or two.

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User WWWombat
(experienced) Thu 06-Dec-12 00:11:14
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Re: Is this normal?


[re: MrSaffron] [link to this post]
 
It's nothing to do with the speed (except, of course, it appears to be...) and everything to do with quality.

Nothing to do with speed:
My argument was related to people wanting to watch IPTV on their main TV in the evening, with the expectation of HIGH quality.

The first requirement for that is that people need sufficient speed, and a lack of buffering. As you say, any ISP worth its salt should be able to deliver.

The next requirement is, essentially, that *all* those packets get to your TV without fail. Certainly without incurring the kind of packet loss that we can live with in a TCP/IP world on the "plain" internet.

The Broadband Forum requirements for this can be seen in their TR-126 document: "Triple-Play Services Quality of Experience (QoE) Requirements".

However, the important bits I took from a summary within NICC's document on the state of DSM/DLM in the UK Access Network. Their they show that acceptable packet loss rates for SD (in MPEG-4) are around 1E-6 (1 in a million), and for HD around 1E-7 (1 in 10 million). Less than 25 CRC faults per day.

That's a pretty decent loss rate, right? The minimum visible in the BQM is probably 1% (1E-2, 1 in a hundred). And that loss has to be shared through the ISP network, BTw's backhaul, the fibre access network *and* the copper line.

How does this relate to FTTC?
It doesn't exactly - it really relates to the timing of when people start demanding decent video via their internet connection, companies start supplying it, and the internet access technology enables it.

It just happens to be that deployment of FTTC is the time that all those concepts come together. Including (and the point of occuring in this thread) the part that DLM plays in this - particularly because it seems to go to quite heavy FEC overheads very readily.

FTTC is an enabler in multiple ways; the speed of FTTC alone is a red herring.
Standard User madnutter56
(learned) Mon 31-Dec-12 10:33:59
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Re: Is this normal?


[re: madnutter56] [link to this post]
 
Just a quick update to this thread, this morning at around 4am DLM turned interleaving off and returned my line to an uncapped profile which is syncing around 74Mbps.

All of the stats links in the first post should still be working.

Alex smile
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