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Author Topic: DSL stats interpretation question  (Read 2292 times)

Weaver

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  • Retd s/w dev; A&A; 4x7km ADSL2 lines; Firebrick
DSL stats interpretation question
« on: December 12, 2020, 12:31:26 AM »

Here are the stats for my line #2 just now.

Q: If you look down to the framing parameters, B, M and R downstream, am I right in thinking this means 4 * 34 = 136 bytes of data downstream and only 10 bytes of Reed-Solomon error correction ?

Q: And for upstream it’s 62 bytes of payload data with 14 bytes of error correction info added?

The upstream SNRM is really low, because it fluctuates up and down in an irregular square wave pattern and I resynched on the high part of the duty cycle setting the then current SNRM to the 6dB upstream target.

It seems a very small amount of error correction downstream. Q: If am interpreting this correctly does this mean that downstream reliability is only supported by the power of PhyR L2 ReTx ? But successfully, because the number of uncorrected CRC errors according to Johnson’s graphs is very low (good).

Q: One final question: where it says "ReXmtUnCorr:   8   0" what time period do these figures cover ? ie it is the number of uncorrected errors in what period?



xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:   8000
Last initialization procedure status:   0
Max:   Upstream rate = 463 Kbps, Downstream rate = 3240 Kbps
Bearer:   0, Upstream rate = 579 Kbps, Downstream rate = 3001 Kbps

Link Power State:   L0
Mode:         ADSL2 Annex A
TPS-TC:         ATM Mode(0x0)
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    2.9       3.8
Attn(dB):    64.0       40.6
Pwr(dBm):    18.1       12.4

         ADSL2 framing
         Bearer 0
MSGc:      52      13
B:      34      62
M:      4      1
T:      3      1
R:      10      14
S:      1.4688      3.4222
L:      817      180
D:      2      8

         Counters
         Bearer 0
SF:      4783994      604788
SFErr:      4      154
RS:      208103740      3965445
RSCorr:      4068      43357
RSUnCorr:   8      0

ReXmt:      1718      0
ReXmtCorr:   1647      0
ReXmtUnCorr:   8      0

         Bearer 0
HEC:      7      241
OCD:      0      0
LCD:      0      0
Total Cells:   544472312      105176100
Data Cells:   7041858      4563851
Drop Cells:   0
Bit Errors:   491      21709

ES:      1726      462
SES:      352      2
UAS:      198005      197664
AS:      76939

         Bearer 0
INP:      26.00      2.00
INPRein:   0.00      0.00
delay:      8      7
PER:      15.97      16.25
OR:      29.04      9.35
AgR:      3016.56   586.79

Bitswap:   21367/21367      471/471

Total time = 37 days 1 hours 2 min 36 sec
FEC:      702973      359376
CRC:      5101      675
ES:      1726      462
SES:      352      2
UAS:      198005      197664
LOS:      55      0
LOF:      95      0
LOM:      52      0
Latest 15 minutes time = 2 min 36 sec
FEC:      13      103
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:      83      619
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 = 1 hours 2 min 36 sec
FEC:      394      2442
CRC:      0      0
ES:      0      0
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
Previous 1 day time = 24 hours 0 sec
FEC:      4875      42009
CRC:      4      155
ES:       3      82
SES:      0      0
UAS:      54      54
LOS:      0      0
LOF:      0      0
LOM:      0      0
Since Link time = 21 hours 22 min 19 sec
FEC:      4068      43357
CRC:      4      154
ES:      3      81
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
LOM:      0      0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0


[[Edit: D corrected to read R above.]]
« Last Edit: December 30, 2020, 10:06:44 PM by Weaver »
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ejs

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Re: DSL stats interpretation question
« Reply #1 on: December 21, 2020, 07:07:47 PM »

R gives the number of Reed-Solomon error correction bytes, not D.

Yes the downstream reliability will largely be due to the retransmission. Probably the downstream bandwidth will also be due to the retransmission, because all the error correction facilities will be taken into account when calculating what data rate can be supported.
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Weaver

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Re: DSL stats interpretation question
« Reply #2 on: December 30, 2020, 12:40:53 PM »

@EJS thanks for spotting that - don’t know what I was thinking.
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