SNRM & Error levels :: Fibre Broadband

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deleted
(deleted) Sun 11-Dec-11 14:33:20

Re: SNRM & Error levels

[re: deleted] [link to this post]

Hmm, interesting point. Here's my output for contrast and compare;

GUI

Text

DSL up time     2088000   (24 days 04:00:00)
 Attainable rate (kbit/s)    26420     6169
SNR margin (dB)               5.3     15.1Line attenuation (dB)           0        0
Output power (dBmV)          12.4     -1.9 
Line rate (kbit/s)          27399     1999CRC errors                      0        0
FEC errors                  51550        9HEC errors                  98169        0

xdslcmd info --show

Text

# xdslcmd info --show
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 0Max:    Upstream rate = 6183 Kbps, Downstream rate = 26420 Kbps
Path:   0, Upstream rate = 1999 Kbps, Downstream rate = 27399 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):        5.3             15.1Attn(dB):        0.0             0.0
Pwr(dBm):        12.5           -1.9                        VDSL2 framing
                        Path 0B:              239             31
M:              1               2T:              64              36
R:              0               16S:              0.2787          0.9922
L:              6889            645D:              1               1
I:              240             80N:              240             80
                        Counters                        Path 0
OHF:            466307980               537260OHFErr:         51542           9
RS:             0               1158332RSCorr:         0               37
RSUnCorr:       0               0 
                        Path 0HEC:            98158           0
OCD:            0               0LCD:            0               0
Total Cells:    2489088163              0Data Cells:     1013536711              0
Drop Cells:     0Bit Errors:     0               0
 ES:             21050           9
SES:            138             0UAS:            17              17
AS:             2087571 
                        Path 0INP:            0.00            0.00
PER:            4.45            13.39delay:          0.00            0.00
OR:             50.23           57.33 
Bitswap:        393769          19555

xdslcmd info --stats

Text

# xdslcmd info --stats
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 0Max:    Upstream rate = 6183 Kbps, Downstream rate = 26420 Kbps
Path:   0, Upstream rate = 1999 Kbps, Downstream rate = 27399 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):        5.3             15.1Attn(dB):        0.0             0.0
Pwr(dBm):        12.4           -1.9                        VDSL2 framing
                        Path 0B:              239             31
M:              1               2T:              64              36
R:              0               16S:              0.2787          0.9922
L:              6889            645D:              1               1
I:              240             80N:              240             80
                        Counters                        Path 0
OHF:            466308426               537414OHFErr:         51542           9
RS:             0               1166636RSCorr:         0               37
RSUnCorr:       0               0 
                        Path 0HEC:            98158           0
OCD:            0               0LCD:            0               0
Total Cells:    2489193423              0Data Cells:     1013536737              0
Drop Cells:     0Bit Errors:     0               0
 ES:             21050           9
SES:            138             0UAS:            17              17
AS:             2087573 
                        Path 0INP:            0.00            0.00
PER:            4.45            13.39delay:          0.00            0.00
OR:             50.23           57.33 
Bitswap:        393769          19555 
Total time = 1 days 3 hours 53 min 10 secFEC:            0               0
CRC:            51542           0ES:             21050           9
SES:            138             0UAS:            17              17
LOS:            0               0LOF:            0               0
Latest 15 minutes time = 8 min 10 secFEC:            0               0
CRC:            6               0ES:             6               0
SES:            0               0UAS:            0               0
LOS:            0               0LOF:            0               0
Previous 15 minutes time = 15 min 0 secFEC:            0               0
CRC:            17              0ES:             16              0
SES:            0               0UAS:            0               0
LOS:            0               0LOF:            0               0
Latest 1 day time = 3 hours 53 min 10 secFEC:            0               0
CRC:            933             0ES:             171             0
SES:            4               0UAS:            0               0
LOS:            0               0LOF:            0               0
Previous 1 day time = 24 hours 0 secFEC:            0               0
CRC:            5930            0ES:             1171            0
SES:            28              0UAS:            0               0
LOS:            0               0LOF:            0               0
Since Link time = 24 days 3 hours 52 min 53 secFEC:            0               37
CRC:            51542           9ES:             21050           9
SES:            138             0UAS:            0               0
LOS:            0               0LOF:            0               0

So that means

CRC = 51542
FEC = 0 (interleaving off?)
HEC = 98158

deleted
(deleted) Sun 11-Dec-11 15:09:02

Re: SNRM & Error levels

[re: deleted] [link to this post]

Hi WWWombat & mikecrawford80,

In reply to a post by WWWombat:
In case anyone is still listening to the real thread, rather than arguing over the meaning of SNR, I've come across something of a hitch...

That is that the HG612 is not reporting error data consistently!

As far as I can make out, the GUI reports CRC, FEC and HEC by taking values from the "xdslcmd info --show" command, extracting the data as follows:

I have very recently been corresponding with asbokid regarding these "discrepancies"

From my own findings, it would appear that the GUI uses the data from the URL
http://192.168.1.1/html/status/xdslStatus.asp

Exactly how it gets there is a little bit of a mystery at this time - possibly via a bit of "secret" Broadcom PHP coding, not revealed in Huawei's recent publication of their "open source licence" code.

This detail in turn (via Javascript) posts it to this URL
http://192.168.1.1/html/status/xdslStatus.gz.html

which is one of the frames displayed in the GUI at the normal user URL of
http://192.168.1.1/html/content.asp

So which numbers should we believe?

That's a really good question, to which there is currently no confirmed answer.

asbo believes there may be a number of bugs in the Broadcom software, the observations above being just some of them.

So to examine the scripts in xdslStatus.asp it appears you would need to get into the Huawei's root file system.
I think you will need Linux here to be able to unsquash the Huawei's root file system on your PC.

I only use Windows, so I don't have access to the required tools.

I too experienced a whole bunch of errors from around 18:30 yesterday, accumulating to over 1.5 Million CRC errors by the early hours of this morning.
I had only been connected for around 47 hours.

At that point, my connection gave up the ghost & re-synced "on the fly".
This "on the fly" event will NOT be seen in my ISP's logs & the dynamically allocated IP address was retained.

The end result for me is that my ever increasing error count has slowed down (a bit), but my SNRM levels have increased & my DS Sync rate has decreased.

Paul.

Edited by deleted (Sun 11-Dec-11 15:19:08)

deleted
(deleted) Sun 11-Dec-11 15:09:35

Re: SNRM & Error levels

[re: deleted] [link to this post]

Yes. Seems much more likely that, after 24 days, for you to have zero FEC (because no interleaving) than zero CRC.

Your RS counts seem to be zero, which also goes to confirm that there is no FEC process going on.

deleted
(deleted) Sun 11-Dec-11 15:15:33

Re: SNRM & Error levels

[re: deleted] [link to this post]

I agree - that little ASP scriptlet is probably to blame for the GUI errors.

Are you still using that in your scripts, or have you swapped to getting data from the xdslcmd output?

deleted
(deleted) Sun 11-Dec-11 15:25:03

Re: SNRM & Error levels

[re: deleted] [link to this post]

Hi WWWombat,

In reply to a post by WWWombat:
I agree - that little ASP scriptlet is probably to blame for the GUI errors.

Are you still using that in your scripts, or have you swapped to getting data from the xdslcmd output?

Yes, I'm still using it, but only because it is what is also reported in the GUI (for some sort of consistency), & because we don't yet know for sure which data to use.

Paul.

Edit:
Latest 4 day statswas the FEC or HEC errors, so maybe it is the data as reported in the GUI that is correct after all?

FWIW these are my latest 4 days stats graphs:-

Latest 4 day stats

Edited by deleted (Sun 11-Dec-11 16:13:32)

RobertoS
(sensei) Sun 11-Dec-11 17:25:06

Re: SNRM & Error levels

[re: deleted] [link to this post]

In reply to a post by WWWombat:
Yes. Seems much more likely that, after 24 days, for you to have zero FEC (because no interleaving) than zero CRC.

Your RS counts seem to be zero, which also goes to confirm that there is no FEC process going on.

IIRC the interleaving depths are shown on the "D:" line, with 1 meaning Fast Path. (1 means each cell is split across 1 packet - ie not interleaved).

701 in an earlier example is a strange number though.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - IDNet Home Starter Fibre. Live BQM.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.

deleted
(deleted) Sun 11-Dec-11 18:19:34

Re: SNRM & Error levels

[re: deleted] [link to this post]

Hi guys,

In reply to a post by Bald_Eagle1:
I think you will need Linux here to be able to unsquash the Huawei's root file system on your PC. I only use Windows, so I don't have access to the required tools.

There is a Win32 build [1] of the squashfs-tools developed by Phillip Lougher [2].

The Win32 tools were compiled by Nikolay Pelov. Pelov included the unofficial LZMA patch used by Broadcom to build the root file system in the 6368 firmware.

The unsquashfs tool for win32 appears to work fine.

However, the corresponding mksquashfs tool will not work. It seems that Broadcom changed the mksquashfs tool in the toolchain used to build the squashfs file system in the Huawei. [3]

To date, the Corporation has not released the modifications it made to Lougher's GPL'ed source code for squashfs-tools.

At least it's possible to unsquash and examine the Huawei's root file system in Windows, even if it can't be modified and rebuilt without using Linux.

The embedded web server in the Huawei looks like Jef Poskanzer's mini-http [4].

The mini-httpd web server has been patched to use a packed web image, and to support server-side scripting. The source code for those modules does not seem available.

cheers, a

[1] http://www.slax.org/forum.php?action=view&parentID=2...
[2] http://squashfs.sourceforge.net/
[3] http://code.google.com/p/firmware-mod-kit/issues/det...
[4] http://acme.com/software/mini_httpd/

Edited by deleted (Sun 11-Dec-11 19:10:54)

XRaySpeX
(eat-sleep-adslguide) Sun 11-Dec-11 18:22:15

Re: SNRM & Error levels - EDITED

[re: deleted] [link to this post]

In reply to a post by WWWombat:
As far as I can make out, the GUI reports CRC, FEC and HEC by taking values from the "xdslcmd info --show" command, extracting the data as follows:

- CRC comes from the "RSUnCorr" field
- FEC comes from the "OHFErr" field (I have no idea what this is. Some kind of framing error?)
- HEC comes from the "HEC" field

The GUI is confusing the CRC and FEC type errors. They should be obtained as follows:

CRC from the "OHFErr" field; often called "SFErr" with many routers
FEC from the "RSCorr" field and is 0 when on Fast Path (D=1)
HEC from the "HEC" field

Always believe the xdslcmd results.

BTW: The total time since the last reboot, to which all the counts relate, is given by the AS field.

EDIT: You're right! FEC should be the "RSCorr" field. I was forgetting as mine's on Fast Path.

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC

Edited by XRaySpeX (Mon 12-Dec-11 05:36:30)

deleted
(deleted) Sun 11-Dec-11 18:32:54

Re: SNRM & Error levels

[re: XRaySpeX] [link to this post]

I guess RS means Reed-Solomon, the algorithm used in Forward Error Correction.

Most routers seem to use RSCorr for the FEC count (the count of packets with errors which were successfully corrected with the Reed-Solomon algorithm) and RSUnCorr for the CRC count (the packet was too severely damaged to correct and so fails the CRC).

deleted
(deleted) Sun 11-Dec-11 20:26:07

Re: SNRM & Error levels

[re: XRaySpeX] [link to this post]

As an aside, I thought HEC errors were errors detected within the header at an ATM level, while CRC errors were detected from the blocks within the ATM payload. Given there is no ATM here, I'm obviously wrong. Can anyone say what it is?

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