Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Author Topic: Could someone comment on 0 (db) SNR and stable connection - Vigor 130  (Read 1004 times)

m48t02

  • Just arrived
  • *
  • Posts: 11

Hi,

Long time lurker but first post. I was hoping if someone could explain some of the statistics I am seeing on my FTTC VDSL line with a new Vigor 130 I have just purchased?

Firstly, I have had the line for 4+ years now and been running the BT ECI B-Focus and a Netgear D7000 (v1) for a number of years without any issues. I am a reasonable distance from the cabinet and have (according to the D7000) been getting sync rates of  64000-65000 Kbps which have always been stable. I assume the same rate with the ECI, the DSLAM's are Huawei BDCM. Speedtest sites would agree with this.

So I am reorganising my network, with a Linux router and didn't want to use the Netgear any longer to avoid double-NAT, but the ECI doesn't give me line stats, so I thought I would go the Vigor 130 route.....

So, as Draytek state default settings should work in UK I replaced the ECI with 130. Immediately observed training issues, and the line stability went out the window. Left it overnight and observed several flaps. Faulty 130 ?

So after some googling I tried altering SNR, but could seem to get the line stable, reverted back to the ECI and all stable again. Eventually I saw a post regarding disabling the 130 vectoring.....

vdsl optn g.vector off
vdsl reboot


Line went stable..... at a higher than normal sync rate.

I have established that vectoring is on in the cab from Draytek guide: https://www.draytek.co.uk/support/guides/kb-dsl-ginp

------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) --------
                  Near End        Far End    Note
 ...
 ReTxEnable   :      0               1
...


The line has been stable since, however the 130 is reporting an SNR of 0 (db) on both sides - I thought this would cause some stability issues, but it continues to be stable. An SNR below 6db should be causing issues I believed, so was hoping you guys could shed some light on what is going on with my line, I have included the various reports from the 130 below:


VDSL2 Information      (VDSL2 Firmware Version:   576D17_A/B/C )
  Profile       State   UP Speed        Down Speed      SNR Upstream    SNR Downstream
  17A   SHOWTIME        16201 (Kbps)    67141 (Kbps)    0 (dB)          0 (dB)

> sys ver
Router Model: Vigor130    Version: 3.8.4_BT English
Profile version: 3.0.0    Status: 1 (0x495137dc)
Router IP: 192.168.2.1    Netmask: 255.255.255.252
Firmware Build Date/Time: Sep 13 2018 13:40:44
Router Name:
Revision: 76500 V376
Current VDSL2 Firmware Version: 05-07-06-0D-01-07
ADSL Firmware Version: 05-07-02-08-00-01 Annex A
VDSL2 Firmware Version: 05-07-06-0D-01-07

> vdsl status
  ---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
   Running Mode            :      17A       State                : SHOWTIME
   DS Actual Rate          : 67141000 bps   US Actual Rate       : 16201000 bps
   DS Attainable Rate      : 61573532 bps   US Attainable Rate   : 16201000 bps
   DS Path Mode            :        Fast    US Path Mode         :        Fast
   DS Interleave Depth     :        1       US Interleave Depth  :        1
   NE Current Attenuation  :       16 dB    Cur SNR Margin       :        0  dB
   DS actual PSD           :     6. 7 dB    US actual PSD        :    15. 6  dB
   NE CRC Count            :    16470       FE CRC Count         :     7857
   NE ES Count             :     3370       FE  ES Count         :     2710
   Xdsl Reset Times        :        0       Xdsl Link  Times     :        1
   ITU Version[0]          : fe004452       ITU Version[1]       : 41590000
   VDSL Firmware Version   : 05-07-06-0D-01-07   [with Vectoring support]
   Power Management Mode   : DSL_G997_PMS_L0
   Test Mode               : DISABLE
  -------------------------------- ATU-C Info ---------------------------------
   Far Current Attenuation :       18 dB    Far SNR Margin       :        5  dB
   CO ITU Version[0]       : b5004244       CO ITU Version[1]    : 434db12d
   DSLAM CHIPSET VENDOR    : < BDCM >

> vdsl status more
  ---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
                  Near End        Far End    Note
 Trellis      :      1               1
 Bitswap      :      1               1
 ReTxEnable   :      0               1
 VirtualNoise :      0               0
 20BitSupport :      0               0
 LatencyPath  :      0               0
 LOS          :      0               0
 LOF          :      0               0
 LPR          :      0               0
 LOM          :      0               0
SosSuccess   :      0               0
 NCD          :      0               0
 LCD          :      0               0
 FECS         :      0            1201699 (seconds)
 ES           :   3373            2710 (seconds)
 SES          :    230             184 (seconds)
 LOSS         :      0               3 (seconds)
 UAS          :     40            27240 (seconds)
 HECError     :      0               0
 CRC          :   16491            7857
 RsCorrection :      0               0
 INP          :      0             195 (symbols)
 InterleaveDelay :      0              21 (1/100 ms)
 NFEC         :    254              32
 RFEC         :     14              16
 LSYMB        :   4312              16
 INTLVBLOCK   :    127              32
 AELEM        :      0            ----

> vdsl snr
  delta: SNR margin delta. The SNR margin delta should range from -50 to 50.
  delta=1 means 0.1dB.
  Current VDSL SNR Margin is 0 dB.
  Current VDSL SNR Margin delta setting is 0.



Many thanks

« Last Edit: February 23, 2019, 10:56:06 PM by m48t02 »
Logged

j0hn

  • Kitizen
  • ****
  • Posts: 2617
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #1 on: February 23, 2019, 04:52:03 PM »

Resyncing the line should see the SNR return to normal.

Looks like the line is on a 3dB (maybe 4dB) target SNRM.

It should be syncing around 61.5Mb but you may have synced while a crosstalker was online.
Logged
Plusnet FTTC 80/20 -  ECI now Huawei cab
retx low @ 3dB target SNRM
Zyxel VMG1312-B10A bridged with 1508 MTU + Asus RT-AC68U running Asuswrt-Merlin

m48t02

  • Just arrived
  • *
  • Posts: 11
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #2 on: February 23, 2019, 05:08:59 PM »

Hi j0hn,

Many thanks for the feedback.

Resyncing the line should see the SNR return to normal.

Following the disabling of vectoring, which was late night, I did resync (and reboot) several times to ensure the fix wasn't a fluke. All these saw a higher sync rate than I was used to.

Quote
Looks like the line is on a 3dB (maybe 4dB) target SNRM.

It should be syncing around 61.5Mb but you may have synced while a crosstalker was online.

So is disabling the vectoring likely to have a long term issue, assuming the crosstalk is reasonable and growing?

I did see a couple of posts implying the Draytek vectoring implementation was buggy, but couldn't find a source.
I don't believe I have been down as far as 61.5Mb on the older modems.

So as far as long term stability is concerned, I guess it's a suck it and see....
Logged

ejs

  • Kitizen
  • ****
  • Posts: 1995
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #3 on: February 23, 2019, 05:31:04 PM »

You've said that you've switched off vectoring, said vectoring was enabled on your cab, but then given stats about retransmission (G.INP), not vectoring. I can't read the Draytek article without a login.

If your cab actually has vectoring it would be better to get it working rather than switch it off. Most cabs don't even have vectoring, but then I wouldn't expect switching vectoring off in your modem to do anything if there were no vectoring anyway.

You don't want to be resyncing too many times per day either, or you'll make the DLM lower your speed.
Logged

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 27475
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #4 on: February 23, 2019, 05:54:16 PM »

I have established that vectoring is on in the cab from Draytek guide: https://www.draytek.co.uk/support/guides/kb-dsl-ginp

------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) --------
                  Near End        Far End    Note
 ...
 ReTxEnable   :      0               1
...


The above does not show that the DSLAM has vectoring enabled.  :no:

All it shows is the status of ReTx at the two end-points of the VDSL2 (ITU-T G.993.2) circuit.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

m48t02

  • Just arrived
  • *
  • Posts: 11
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #5 on: February 23, 2019, 05:59:26 PM »

The above does not show that the DSLAM has vectoring enabled.  :no:

All it shows is the status of ReTx at the two end-points of the VDSL2 (ITU-T G.993.2) circuit.

Apologies guys, you are quite correct, the Draytek article covers Vectoring and G.INP / G.998.4 - I was looking at the wrong part.

Ok, so that now makes a little more sense.
Logged

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 27475
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #6 on: February 23, 2019, 06:06:54 PM »

Apologies guys, you are quite correct, the Draytek article covers Vectoring and G.INP / G.998.4 - I was looking at the wrong part.

Ok, so that now makes a little more sense.

So you have turned off G.Inp (ITU-T G.998.4) for the VDSL2 circuit. I am very surprised that turning it off has had a beneficial effect.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

m48t02

  • Just arrived
  • *
  • Posts: 11
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #7 on: February 23, 2019, 10:52:45 PM »

So you have turned off G.Inp (ITU-T G.998.4) for the VDSL2 circuit. I am very surprised that turning it off has had a beneficial effect.

Well, I turned off whatever Draytek disable with the command:

vdsl optn g.vector off

It has certainly worked thus far.....

Edit: According to this page: https://www.increasebroadbandspeed.co.uk/g.inp

BT have implemented G.INP on the downlink only, which appears to agree with what my stats are showing, I believe.
« Last Edit: February 24, 2019, 09:44:16 AM by m48t02 »
Logged

j0hn

  • Kitizen
  • ****
  • Posts: 2617
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #8 on: February 24, 2019, 10:22:33 AM »

You're correct in that G.INP is on the downstream only by default.
Upstream G.INP is used when needed, if supported.

Disabling Vectoring shouldn't make the line perform better.
Vectoring isn't widely used by OpenReach and is active on a relatively small number of cabinets.
If it isn't active on your cabinet then disabling it should have no effect at all.
If it is active on your cabinet then disabling it should have a negative impact not a positive 1.

Which firmware version are you using?
Logged
Plusnet FTTC 80/20 -  ECI now Huawei cab
retx low @ 3dB target SNRM
Zyxel VMG1312-B10A bridged with 1508 MTU + Asus RT-AC68U running Asuswrt-Merlin

m48t02

  • Just arrived
  • *
  • Posts: 11
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #9 on: February 24, 2019, 10:31:28 AM »

Disabling Vectoring shouldn't make the line perform better.

So this does imply that it could be an issue with Draytek Vectoring algorithm as reported on a few sites.

Which firmware version are you using?

Router Model: Vigor130    Version: 3.8.4_BT English
Firmware Build Date/Time: Sep 13 2018 13:40:44


This was the default firmware, but it does appear to be the latest from the Draytek site.

They do have an 'alternate' firmware, but the 'BT' version appears to be recommended when connected to Huawei cabs, due to the Infineon/Lantiq chipset in the Vigor.

Many thanks for all your help guys.
« Last Edit: February 24, 2019, 11:54:44 AM by m48t02 »
Logged

m48t02

  • Just arrived
  • *
  • Posts: 11
Re: Could someone comment on 0 (db) SNR and stable connection - Vigor 130
« Reply #10 on: February 24, 2019, 07:43:39 PM »

I had a resync today, and SNR and attenuation all look fine now albeit at a lower sync rate.

As I couldn't find documentation on the Draytek site, and there is not a means to configure via the web interface, I'll put it here for future reference as this allows me to monitor via syslog moving forward on the Vigor 130's fairly limited IP stack. A DNAT is setup on 192.168.2.2 WAN interface to send the NTP and SYSLOG packets to the correct place.

sys time server 192.168.2.2
sys time zone 24    <- GMT
sys time inquire

sys syslog -a 1 -s 1 -r 1 -e 1 -w 0 -v 0 -c 0 -f 0 -i 192.168.2.2 -d 514

Feb 24 18:52:30 192.168.2.1 Vigor: [Telnet]Login success from IP 192.168.2.2
Feb 24 18:52:33 192.168.2.1 Vigor: ADSL_Status:[Mode=17A States=SHOWTIME UpSpeed=16298000 DownSpeed=66070000 SNR=3 Atten=16 ]
Feb 24 18:53:01 192.168.2.1 Vigor: ADSL_Status:[Mode=17A States=SHOWTIME UpSpeed=16298000 DownSpeed=66070000 SNR=3 Atten=16 ]
Feb 24 18:53:29 192.168.2.1 Vigor: ADSL_Status:[Mode=17A States=SHOWTIME UpSpeed=16298000 DownSpeed=66070000 SNR=3 Atten=16 ]


It doesn't (unsurprisingly) have an SMNP agent, but I intend to poll stats from the router wan PPPoE interface, when I get a chance,
Logged