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Author Topic: Massive amounts of HEC errors  (Read 1673 times)

ejs

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Re: Massive amounts of HEC errors
« Reply #15 on: March 16, 2017, 03:50:53 PM »

On BTWholesale ADSL2+, the ISP should be able to disable the DLM or set custom thresholds which can be used to disable the DLM.
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Weaver

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Re: Massive amounts of HEC errors
« Reply #16 on: March 17, 2017, 04:13:43 PM »

Guys don't we want HEC_errors / total_cells, not per unit time?

Or does it not matter because cells are sent when the link is idle, is that correct? If that notion is true, are HEC errors even counted in idle cells?
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ejs

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Re: Massive amounts of HEC errors
« Reply #17 on: March 17, 2017, 04:26:49 PM »

I think it does not matter, idle cells are transmitted when there's nothing else to send. Idle ATM cells would be identified by their header, so if the cell header fails the check, you don't really know if it was an idle cell.

In general the DLM doesn't seem to care about the actual number of errors, only the number of errored seconds.
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jon_

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Re: Massive amounts of HEC errors
« Reply #18 on: March 17, 2017, 04:36:30 PM »

From the faster line, which is now SNR tweaked back to around 8dB...

Internet Up Time:   1Day(s) 20:25:32

Code: [Select]
Mode: ADSL_G.dmt.bis
Traffic Type: ATM
Status: Up
Link Power State: L0
 
  Downstream Upstream
Line Coding(Trellis): On On
SNR Margin (0.1 dB): 84 63
Attenuation (0.1 dB): 545 332
Output Power (0.1 dBm): 0 126
Attainable Rate (Kbps): 4,324 928
 
  Path 0 Path 1
  Downstream Upstream Downstream Upstream
Rate (Kbps): 3,449 922 0 0
 
MSGc (# of bytes in overhead channel message): 59 11 0 0
B (# of bytes in Mux Data Frame): 107 122 0 0
M (# of Mux Data Frames in FEC Data Frame): 2 2 0 0
T (Mux Data Frames over sync bytes): 1 1 0 0
R (# of check bytes in FEC Data Frame): 16 8 0 0
S (ratio of FEC over PMD Data Frame length): 1.9850 8.4666 0.0 0.0
L (# of bits in PMD Data Frame): 935 240 0 0
D (interleaver depth): 16 2 0 0
Delay (msec): 8 4 0.0 0.0
INP (DMT symbol): 1.00 0.00 0.0 0.0
 
Super Frames: 9,878,160 8,766,343 0 0
Super Frame Errors: 49,664 527 0 0
RS Words: 321,040,221 2,261,535 0 0
RS Correctable Errors: 1,665,153 1,389 0 0
RS Uncorrectable Errors: 218,213 0 0 0
 
HEC Errors: 89,588 518 0 0
OCD Errors: 11 0 0 0
LCD Errors: 11 0 0 0
Total Cells: 1,296,183,418 346,044,796 0 0
Data Cells: 238,758,184 33,533,844 0 0
Bit Errors: 0 41,334 0 0
 
Total ES: 37,778 355
Total SES: 2 0
Total UAS: 0 0

On the other line, there are a lot less errors (although I've not reset them since the connection last reset so the stats are meaningless), however this jumps out:

D (interleaver depth):   96   2

Not seen interleaving get that high before, theoretical max speed is reporting as 3ish megs, connecting at 2ish, and it's moved itself back to a 6dB SNR margin from 9dB previously...
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Weaver

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Re: Massive amounts of HEC errors
« Reply #19 on: March 17, 2017, 05:46:00 PM »

@ejs - so you and I seem to be in agreement, I did get it right about idle cells. I remember about ATM repeatedly looking at cell headers in order to discover frame boundaries, instead of having the usual start-of-frame + end-of-frame symbols. Clever, in a perverse way.
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jon_

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Re: Massive amounts of HEC errors
« Reply #20 on: March 20, 2017, 11:30:33 AM »

As a slight update to this, both of my connections are now connecting with very high interleaving - 128 for the faster connection, 96 for the slower one, and both reverted to 6dB SNR targets. They both also appear to have been put on banded profiles - 4M attainable rate / 3M actual for the faster line, 3M attainable / 2.2M actual for the slower. Both have INP = 4.

From reading around, does INP=4 mean that the banding won't remove itself if the connection remains stable, and will require a manual reset ISP side?
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tickmike

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Re: Massive amounts of HEC errors
« Reply #21 on: March 21, 2017, 12:06:15 AM »

Mine is .
INP:            8.42 D           0.37 U      it went up to 15 the other week.
It varies with interleaving as I think they are linked.
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Weaver

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Re: Massive amounts of HEC errors
« Reply #22 on: March 21, 2017, 01:20:02 AM »

I'm trying to understand the non-integral interleave factors. Need to look this up again, 8.416667 = 101/12
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