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Standard User dave2150
(experienced) Wed 05-Dec-12 05:49:37
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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


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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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