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Author Topic: No FECs recorded even though interleaved  (Read 1373 times)

renluop

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No FECs recorded even though interleaved
« on: October 11, 2017, 03:55:00 PM »

A few days ago I noticed that none were showing despite being listed for monitoring; neither is any shown in Telnet.
It's not of great concern, but I do wonder what the cause of the non collection of the stats could be.
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roseway

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Re: No FECs recorded even though interleaved
« Reply #1 on: October 11, 2017, 04:50:11 PM »

I'm afraid I can't read that data. Could you post a copy of the Connection Stats page in the Telnet Data.
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  Eric

j0hn

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Re: No FECs recorded even though interleaved
« Reply #2 on: October 11, 2017, 05:01:44 PM »

INP 0, Depth 1 and R 0 suggests fastpath to me. The high ES also suggests this. Perhaps it's just wrongly reporting channel Interleaved.
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renluop

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Re: No FECs recorded even though interleaved
« Reply #3 on: October 11, 2017, 06:50:59 PM »

Sorry, posting like that was a stupid aberration!
Code: [Select]
xdsl info expand=enabled
Physical Layer Statistics:       

  Modem state:                  up
  Up time (Days hh:mm:ss):      6 days, 7:35:18
  xDSL Standard:                ITU-T G.992.5
  xDSL Annex:                    Annex A
  Channel Mode:                        [color=red]Interleaved[/color]

  Number of reset:              0

  Chipset Vendor info (G.994.1):    Local Remote
    Country code:                  B500  B500
    ID:                            BDCM  IFTN
    Specific:                      0000  71C8

  System Vendor info (showtime): Local Remote
    Country code:                0F00  0000
    ID:                          TMMB  ----
    Specific:                    3C61  0000

  Bearers generic info          DS          US       
    Payload rate [Kbps]: 7075    939   
    Attenuation [dB]:      48.0           25.9           
    Margins [dB]:          5.9            6.4           
    Output power [dBm]:    0.0            12.6           

    Number of bearers:          1
    Bearer 0                    DS          US       
      INP [DMT symbols]:    0.00           0.00           
      [color=red]Delay [ms]:            0.24           0.24           
      Depth []:            1              0.00
      R:                  0          0      [/color]

G.997.1 Statistics (Current):       

  Failures:
    Line failures              Near end
      Loss of signal (LOS):    0       
      Loss of frame (LOF):    0       
      Loss of power (LPR):    0       

  Performance monitoring:
    Line PM:            Near end
      Error second (ES):      4251   

    Channel PM:        Near end Far end
      Bearer 0:
        Code Violation (CV):    8089      1077   
        [color=red]FEC:                    0        0       
[/color]
    ATM data path PM:            Near end Far end
      Bearer 0:
        HEC violation count (HEC):        20125    N/A

G.997.1 Statistics (last 15 minutes):       

  Failures:
    Line failures              Near end
      Loss of signal (LOS):    0       
      Loss of frame (LOF):    0       
      Loss of power (LPR):    0       

  Performance monitoring:
    Line PM:            Near end
      Error second (ES):      1       

    Channel PM:        Near end Far end
      Bearer 0:
        Code Violation (CV):    8089      1077   
        [color=red]FEC:                    0        0       
[/color]
    ATM data path PM:            Near end Far end
      Bearer 0:
        HEC violation count (HEC):        20125    N/A

G.997.1 Statistics (last 24 hours):       

  Failures:
    Line failures              Near end
      Loss of signal (LOS):    0       
      Loss of frame (LOF):    0       
      Loss of power (LPR):    0       

  Performance monitoring:
    Line PM:            Near end
      Error second (ES):      191     

    Channel PM:        Near end Far end
      Bearer 0:
        Code Violation (CV):    8089      1077   
        [color=red]FEC:                    0        0       
[/color]
    ATM data path PM:            Near end Far end
      Bearer 0:
        HEC violation count (HEC):        20125    N/A

{admin}=>
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roseway

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Re: No FECs recorded even though interleaved
« Reply #4 on: October 11, 2017, 07:16:17 PM »

Yes, I agree with j0hn, you're on fastpath. There are lots of HECs and quite a lot of CRCs (code violations) but no FECs. The downstream depth (presumably interleaving depth) is 1, which means no interleaving.
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  Eric

kitz

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Re: No FECs recorded even though interleaved
« Reply #5 on: October 11, 2017, 08:09:07 PM »

As above, but a little bit more info.
DSL has a couple of different bearer channels over which it can send data - Fast Path and Interleaved Path.  If the SP uses INP then they tend to use the interleave channel which allows for easily configurable parameters for error protection.   INP=0 or Interleave=1 indicates that data is being transmitted over the interleaved path, but the data isnt actually being interleaved.

Historically we used to say FAST path or Interleaved Path, but since ADSL2 its actually more correct to use the term error protection or INP which covers both interleave and RS encoding.
Its possible to have a small amount of RS encoding without interleave being applied..  in fact Openreach does this on FTTC upstream by default, which is why we may sometimes see upstream FEC despite interleaving being 'off'.   
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renluop

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Re: No FECs recorded even though interleaved
« Reply #6 on: October 11, 2017, 10:55:29 PM »

Thanks Kitz et al for the explanation. The situation was confusing, because of the minimal supposed depth of the interleaving, lack of sync loss and, finally, that the other not currently used router used to report no interleaving.

BTW is anything else in those connection stats worthy of comment?
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