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[RS1986]

Hi all,

I'm new here on the Forum, I stumbled on this site as I'm trying to correct poor line speed and CRC errors with some help from the advanced tech staff at my new ISP Origin Broadband.

Thanks to the reading I have done on this site and what I could search through the forums I have gleaned enough information to identify the fault on my setup which is essentially the router, I have disabled all advanced DSL settings which causes a very high rate of CRC errors and Downstream fluctuations but I'm still having CRC errors which I've basically read is down to the ASUS equipment.

As it stands now I have had the DLM Disabled on my line and am looking to buy a standalone modem to provide a more stable ADSL2PLUS connection and use my old BT HomeHub 5 for Wireless networking as the ASUS doesn't provide a 5GHz band on WiFi.

Based on the following information could anyone advise which modem would be best suited to pair with my line?

DSL Modulation   ITU G.992.5(ADSL2PLUS)
ANNEX Mode   ANNEX A
DSL Exchange(DSLAM)   Globespan

TCM(Trellis Coded Modulation) [DOWN] 1 [UP] 1
SNR Margin   [DOWN] 6.0 dB [UP] 8.5 dB
Line Attenuation [DOWN] 49.1 dB [UP] 30.0 dB
Path Mode [DOWN] Interleaved [UP] FastPath
Interleave Depth   [DOWN] 32 [UP] 1
Data Rate   [DOWN] 4034 kbps [UP] 876 kbps
MAX Rate   [DOWN] 4544 kbps [UP] 956 kbps
POWER   [DOWN] 19.3 dbm [UP] 12.2 dbm

Also as I understand it, please correct me if I'm wrong, Globespan means that there is an NEC chipset on the exchange?

Many thanks for the Education KITZ!

[burakkucat]

Welcome to the Kitz forum. 

Looking at the information you have provided it is similar to that of my own circuit. I find that a device which uses a Broadcom chip set will perform best and so use a ZyXEL VMG1312-B10D (a modem/router), configured for G.992.3 (a.k.a. ADSL2) rather than for G.992.5 (ADSL2+).

Code: [Select]

$ xdslctl info --show
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 8000
Last initialization procedure status: 0
Max: Upstream rate = 984 Kbps, Downstream rate = 6088 Kbps
Bearer: 0, Upstream rate = 987 Kbps, Downstream rate = 5571 Kbps

Link Power State: L0
Mode: ADSL2 Annex A
TPS-TC: ATM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.3 6.0
Attn(dB): 45.5 28.7
Pwr(dBm): 0.0 12.7

ADSL2 framing
Bearer 0
MSGc: 59 12
B: 174 30
M: 1 4
T: 1 4
R: 12 10
S: 0.9993 3.9851
L: 1497 269
D: 64 8

Counters
Bearer 0
SF: 650006 588757
SFErr: 21 0
RS: 42250315 1997980
RSCorr: 15113 111
RSUnCorr: 229 0

Bearer 0
HEC: 124 0
OCD: 0 0
LCD: 0 0
Total Cells: 138708989 24510725
Data Cells: 8355848 553753
Drop Cells: 0
Bit Errors: 7019 0

ES: 15 0
SES: 0 0
UAS: 46 46
AS: 10553

Bearer 0
INP: 2.00 1.00
INPRein: 0.00 0.00
delay: 16 8
PER: 16.23 17.93
OR: 32.02 8.02
AgR: 5581.93 991.82

Bitswap: 183/183 21/21
$

$ xdslctl profile --show

Modulations:
G.Dmt Disabled
G.lite Disabled
T1.413 Disabled
ADSL2 Enabled
AnnexL Disabled
ADSL2+ Disabled
AnnexM Disabled
VDSL2 Disabled
Phone line pair:
Inner pair
Capability:
bitswap On
sra On
trellis On
sesdrop Off
CoMinMgn Off
24k On
phyReXmt(Us/Ds) On/On
Ginp(Us/Ds) On/On
TpsTc AvPvAa
monitorTone: On
dynamicD: On
dynamicF: Off
SOS: On
Training Margin(Q4 in dB): -1(DEFAULT)
$

$ xdslctl info --vendor
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 8000
Last initialization procedure status: 0
Max: Upstream rate = 984 Kbps, Downstream rate = 6088 Kbps
Bearer: 0, Upstream rate = 987 Kbps, Downstream rate = 5571 Kbps

ChipSet Vendor Id: IFTN:0x71c8
ChipSet VersionNumber: 0x71c8
ChipSet SerialNumber:
$

No two circuits will behave exactly the same. Hence it is a trial and error process as to which modem/router would be the best choice.

[RS1986]

Thanks for your input burakkucat! I had been looking at ZyXEL, so I will check out the model you have suggested 

[burakkucat]

I will point you to a different thread and suggest that you take a look through the devices listed in the very first post.

[RS1986]

Fantastic mate, once again thanks a lot!

I had looked at that thread but got a bit confused with the VDSL bit so to make sure I thought I'd ask just so I know i'm on the right path.

Enjoy your evening

[RS1986]

Hello again!

I wasn't able to get hold of a ZyXEL locally but I did manage to get a Billion BiPAC 8800NL R2 which was on the list provided by burakkucat

I haven't had any troubles setting up and have tried a few different SNR settings, achieving the best speeds and stability with ADSL2 modulation

SNR 6(Default)...[DOWN]3469...[UP]748
SNR 5...............[DOWN]3665...[UP]748
SNR 4...............[DOWN]3810...[UP]748
SNR 3...............[DOWN]3750...[UP]759
SNR 2...............[DOWN]4187...[UP]738
SNR 1...............[DOWN]4314...[UP]745

Here's where I'm a bit stumped, running BER tests for 360 seconds return no errors on all those SNR settings they all seem stable with no connection drops over 5 hour test periods, but I am getting errors.

On the current 6dB setting:

xDSL Statistics

Super Frame Errors........[DOWN]151.......[UP]6
RS Correctable Errors.....[DOWN]2011.....[UP]15
RS Uncorrectable Errors..[DOWN]1210.....[UP]0
HEC Errors....................[DOWN]863......[UP]3
Bit Errors......................[DOWN]69089...[UP]0

WAN Service Statistics show 0 Errors

I know that some of these errors will occur due to the line but which of these Errors should I most keep an eye on? or should I simply not worry and settle for an SNR setting that simply doesn't disconnect?

On ADSL2 modulation I can drop it to 1 and it holds both DSL link and Internet connection, ADSL2+ will establish a DSL link but won't establish an Internet connection below 3.

[burakkucat]

Interesting results.

Let's deal with the modulation first. Due to the length of your circuit, you will find that none of the sub-carriers greater than 255 will be in use. Hence the choice of G.992.3 (a.k.a. ADSL2) would be best. But why not G.992.1 (a.k.a. ADSL1 or G.Dmt)? Although G.992.1 and G.992.3 use the same number of sub-carriers, 256 (numbered 0 - 255), G.993.2 uses them more efficiently.

Now the question as to adjusting the target SNRM to gain an increase in synchronisation speed. Ideally you would constantly monitor your circuit's performance for a number of days. Such monitoring will allow you to see if there is any appreciable drop in SNRM during the hours of darkness. If such a cyclical pattern is observed, it would be sensible to adjust the target SNRM so that the minimum of the diurnal cycle is not too low. But what is "too low"? Without having monitored the circuit, it is difficult to say. I would suggest that you aim to keep the minimum above 2 dB.

The errors you should be watching are ES, SES and CRC. (RS Correctable Errors can be ignored . . . essentially they are CRCs that never occurred.)

[RS1986]

Thanks burakkucat, I had tried ADSL1 and G.Dmt but the line refuses to sync on those modulations.

4dB seems to be the sweet spot so I will adjust after letting 6 run for 24 hours and checking those errors you listed, though I can't seem to find the CRC count anywhere.

Will have to check the Billion documentation!

Thanks again pal, enjoy your evening!

EDIT: Just found out how to use Telnet, it's true you do learn something new every day

Telnet tells me

Code: [Select]

Total time = 10 hours 19 min 22 sec
FEC:            2554            23
CRC:            172             8
ES:             94              7
SES:            0               0
UAS:            17              17
LOS:            0               0
LOF:            0               0
LOM:            0               0
Retr:           0

[burakkucat]

Code: [Select]

Total time = 10 hours 19 min 22 sec
FEC:            2554            23
CRC:            172             8
ES:             94              7
SES:            0               0
UAS:            17              17
LOS:            0               0
LOF:            0               0
LOM:            0               0
Retr:           0

FECs (forward error correction) are "CRCs that never occurred". (They prove that the error detection and correction mechanism is working!)
CRCs (cyclic redundancy check) -- the less the better.
ES (errored seconds) and SES (severely errored seconds).
UAS (unavailable seconds).
LOS (loss of signal)
LOF (loss of framing)
LOM (loss of margin)
Retr (retransmissions)

Here is a reference page.

You might like to consider using roseway's DSLstats utility to monitor your circuit.

[RS1986]

Thanks burakkucat, I had a disconnection in the night (11.29 p.m.) on ADSL2 set at 6dB when it resynced it was down at 3.2 I noticed a high amount of CRC Errors.

I've set up DSLstats as suggested and will leave it running as I'm trying ADSL2+ again at the moment with the 6dB SNR set, Line synced at 3410 Down and 856 Up.

Regarding my service, the guys in the tech department had sent out an OpenReach engineer to make sure everything was fine which apparently it is, if I can't keep a solid connection and the error rate brings my sync speed down like it appears to be continuing to do then my only option is to hard reset my router to bring the sync speed back up as DLM is disabled on my line?

The tech support bloke I last spoke to said "Why don't you just get Fibre?" to which my reply was "Why pay through the teeth for a Porsche when all I need is a basic runaround for my needs?" He then tried selling me Fibre to the merits of better streaming speeds for Music and On-Demand

I'm not a fan of compression so I informed the fella politely I have an extensive Vinyl/CD and DVD/Bluray collection for all my entertainment needs, I just want to download PC Updates and Patches for certain games I like to play which are not multiplayer!

Only 8 months left on my 12 month contract, certainly won't be dealing with another company that doesn't declare they're using Talk Talk networks

[burakkucat]

I've set up DSLstats as suggested and will leave it running as I'm trying ADSL2+ again at the moment with the 6dB SNR set, Line synced at 3410 Down and 856 Up.

Once you have a "picture" of how the circuit is behaving, it's optimisation should then be somewhat easier.

[RS1986]

What sort of sample size are we talking burakkucat?

I have the graph settings at Sample every 600 seconds, Time per page 12 hours

Does it take a snapshot when a new page starts?

[burakkucat]

The ability to take snapshots, and the frequency thereof, is a configuration setting.

When I use the utility, I sample once every 60 seconds, set the (visual) plot width to one hour and also save a snapshot once every hour.

[RS1986]

Okay, so forgive my stupidity

I've set the sample to 60 seconds, Time per page to 1 hour, on the Snapshot configuration under Autosave Graphs I have checked SNR Margin, CRC Errors, FEC Errors, SES, ES per hour and Connection Speed

These should all Snapshot automatically every hour whilst monitoring am I correct?

[burakkucat]

Yes, that looks correct.