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Author Topic: Stats - UAS without connection drop  (Read 233 times)

tubaman

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Stats - UAS without connection drop
« on: May 04, 2021, 07:27:51 AM »

Yesterday the stats from my VMG8924-B10A were as below, with 11 Unavailable Seconds (UAS) in the last 24 hours but no drop in service. I've never seen this before and didn't know it was even possible as the only time I've seen UAS before is after a resync. I don't have any more detailed stats so don't know if the UAS were consecutive or not.
Purely out of academic interest does anyone know how this can happen?
 :)

Code: [Select]
====================================================================================
    VDSL Training Status:   Showtime
                    Mode:   VDSL2 Annex B
            VDSL Profile:   Profile 17a
                G.Vector:   Disable
            Traffic Type:   PTM Mode
             Link Uptime:   28 days: 9 hours: 8 minutes
====================================================================================
       VDSL Port Details       Upstream         Downstream
               Line Rate:      7.295 Mbps       42.732 Mbps
    Actual Net Data Rate:      7.269 Mbps       42.733 Mbps
          Trellis Coding:         ON                ON
              SNR Margin:        5.9 dB            3.3 dB
            Actual Delay:          0 ms              0 ms
          Transmit Power:        6.5 dBm          12.0 dBm
           Receive Power:      -15.4 dBm         -23.1 dBm
              Actual INP:        0.0 symbols      52.0 symbols
       Total Attenuation:        0.0 dB          26.5 dB
Attainable Net Data Rate:      7.269 Mbps       43.630 Mbps
====================================================================================
  VDSL Band Status        U0      U1      U2      U3      U4      D1      D2      D3
  Line Attenuation(dB): 11.5 50.7   N/A   N/A   N/A 21.3 60.3 90.3
Signal Attenuation(dB): 11.5 50.1   N/A   N/A   N/A 33.1 60.0   N/A
        SNR Margin(dB): 5.8 6.0   N/A   N/A   N/A 3.4 3.3   N/A
         TX Power(dBm): -4.0 6.1   N/A   N/A   N/A 9.9 7.9   N/A
====================================================================================

            VDSL Counters

           Downstream        Upstream
Since Link time = 8 min 11 sec
FEC: 1898764381 0
CRC: 1976 930
ES: 406 805
SES: 66 0
UAS: 11 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 1 min 37 sec
FEC: 72505 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 546742 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 22 hours 1 min 37 sec
FEC: 60140104 0
CRC: 167 34
ES: 50 34
SES: 4 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 24 hours 0 sec
FEC: 163302877 0
CRC: 339 23
ES: 63 23
SES: 12 0
UAS: 11 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Total time = 1 days 22 hours 1 min 37 sec
FEC: 2197130226 0
CRC: 3313 1144
ES: 610 995
SES: 109 0
UAS: 88 56
LOS: 1 0
LOF: 7 0
LOM: 0 0
====================================================================================
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BT FTTC 80/20 Huawei Cab - Zyxel VMG8924-B10A

licquorice

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Re: Stats - UAS without connection drop
« Reply #1 on: May 04, 2021, 10:40:19 AM »

10 CSES (consecutive SES) will result in UAS
See G.826 https://www.itu.int/rec/T-REC-G.826-200212-I/en
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tubaman

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Re: Stats - UAS without connection drop
« Reply #2 on: May 04, 2021, 11:28:03 AM »

10 CSES (consecutive SES) will result in UAS
See G.826 https://www.itu.int/rec/T-REC-G.826-200212-I/en

Thanks - assume I had 11 consecutive SES that created the 11 UAS then?
 :)

Curiously I can get to your link on my work's PC but not my home one. I wonder if it doesn't like IPV6?  ???
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BT FTTC 80/20 Huawei Cab - Zyxel VMG8924-B10A

kitz

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Re: Stats - UAS without connection drop
« Reply #3 on: May 04, 2021, 12:04:16 PM »

There's some explanations on this page which may help

https://kitz.co.uk/adsl/linestats_errors.htm

Work backwards starting from UAS to LOS etc
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tubaman

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Re: Stats - UAS without connection drop
« Reply #4 on: May 04, 2021, 12:44:59 PM »

There's some explanations on this page which may help

https://kitz.co.uk/adsl/linestats_errors.htm

Work backwards starting from UAS to LOS etc

Thanks kitz - all makes some sense now. It was just something that I've never seen happen before.
 :)
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BT FTTC 80/20 Huawei Cab - Zyxel VMG8924-B10A

Weaver

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Re: Stats - UAS without connection drop
« Reply #5 on: May 05, 2021, 06:12:27 AM »

For some reason I can’t see what your interleave setting is - must me just being really stupid. Need more interleave depth to stop bad burst errors producing such a severe error burst?
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tubaman

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Re: Stats - UAS without connection drop
« Reply #6 on: May 05, 2021, 07:42:05 AM »

For some reason I can’t see what your interleave setting is - must me just being really stupid. Need more interleave depth to stop bad burst errors producing such a severe error burst?

It's on G.INP on the downstream so I don't believe it is interleaved. Sometimes it'll run for months with barely any SES at all so hopefully it was a one off event.
 :)
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BT FTTC 80/20 Huawei Cab - Zyxel VMG8924-B10A

Weaver

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Re: Stats - UAS without connection drop
« Reply #7 on: May 05, 2021, 08:14:25 AM »

Understood. If it was a one-off, then who cares.
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CarlT

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Re: Stats - UAS without connection drop
« Reply #8 on: May 05, 2021, 08:30:40 AM »

Broadband, constant noise can't really be mitigated by anything other than either not using the frequencies in question or dropping their bit loading down to a point where they can cope with the lower worst case SNR.

Which is what banding does.
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