Topic: DLM adding or removing INP protection? (Read 2209 times)

Sheepie · « **on:** November 12, 2016, 11:18:59 AM »

I had really odd latency spikes on my FTTC line after a powercut 2.5 weeks ago (ping_25_oct attached). Until this point it had been sync'ed for a long time at 80000/20000 and GINP applied of depth 16 and INP 48 in downstream only.

I decided to replace the router yesterday, leaving at least 30 mins between switching off old router and powering up new router. Now the latency looks to have been resolved (ping_11_nov attached) but the DLM is still doing something and I can't work out which way it is going.

Yesterday it was syncing up at 66000/15000 (capped by me) and GINP applied of depth 8 and INP 55 downstream AND GINP applied of depth 4 and INP 44 upstream.

This morning it did a resync and the upstream GINP is depth 2 and INP 53 and only 60000/15000.

So the questions are:
1. does Interleave depth change from 4 to 2, and INP of 44 to 53 indicate the DLM is applying more protection or less??
2. why has max attainable rate gone from 89000/30000 to 74000/28000

MDSW user = Sheepie

kitz · « **Reply #1 on:** November 12, 2016, 01:54:14 PM »

When it comes to G.INP, its easier to see the params if you post them from your line stats.
I dont have G.INP so show you exactly, but they will look similar to this, only also with Bearer 1 as well

Code: [Select]

adsl info --stats


                        VDSL2 framing
                        Bearer 0
MSGc:           18              150
B:              239             236
M:              1               1
T:              23              5
R:              0               16
S:              0.0974          0.3771
L:              19704           5410
D:              1               1
I:              240             255
N:              240             255

                        Counters
                        Bearer 0
OHF:            132644487               943793
OHFErr:         5945            32
RS:             0               3921389
RSCorr:         0               434
RSUnCorr:       0               0

Quote

So the questions are:
1. does Interleave depth change from 4 to 2, and INP of 44 to 53 indicate the DLM is applying more protection or less??
2. why has max attainable rate gone from 89000/30000 to 74000/28000

1. Interleave and INP/g.inp are 2 separate params which can work independently... hence asking for full stats to see if more info is available.
2. When interleaving is applied, it messes up the max attainable figure. ie it increases it by an unrealistic amount. So if interleave has gone down, then it will decrease the max attainable closer to the true figure.
I think its something to do with the way the modem calculates max attainable figure, but they dont appear to make the correct adjustment for RS overheads.

Sheepie · « **Reply #2 on:** November 12, 2016, 02:46:54 PM »

Thanks for the reply. I really wished I could do more self troubleshooting but that will only send the DLM into a strop. I have read that leaving the modem off for more than 30 mins will avoid DLM recording it as a loss of signal, is that true?

Here are my current stats:

$ adsl info --stats
adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 28150 Kbps, Downstream rate = 74617 Kbps
Bearer: 0, Upstream rate = 13999 Kbps, Downstream rate = 60000 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode(0x0)
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 9.5 15.4
Attn(dB): 12.7 0.0
Pwr(dBm): 12.6 4.2

VDSL2 framing
Bearer 0
MSGc: -6 -6
B: 122 130
M: 1 1
T: 0 0
R: 8 16
S: 0.0647 0.2960
L: 16186 3973
D: 8 2
I: 131 147
N: 131 147
Q: 8 2
V: 7 0
RxQueue: 135 115
TxQueue: 27 23
G.INP Framing: 18 18
G.INP lookback: 27 23
RRC bits: 24 24
Bearer 1
MSGc: 122 58
B: 0 0
M: 2 2
T: 2 2
R: 16 16
S: 8.0000 16.0000
L: 32 16
D: 1 1
I: 32 32
N: 32 32
Q: 0 0
V: 0 0
RxQueue: 0 0
TxQueue: 0 0
G.INP Framing: 0 0
G.INP lookback: 0 0
RRC bits: 0 0

Counters
Bearer 0
OHF: 0 0
OHFErr: 0 0
RS: 1494333128 1748960
RSCorr: 3184 89
RSUnCorr: 0 0
Bearer 1
OHF: 1511782 469251
OHFErr: 0 0
RS: 12094257 1776343
RSCorr: 0 1
RSUnCorr: 0 0

Retransmit Counters
rtx_tx: 306277 7
rtx_c: 333 803
rtx_uc: 0 40384

G.INP Counters
LEFTRS: 1 19
minEFTR: 59993 13997
errFreeBits: 22218898 327580551

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 2801867715 0
Data Cells: 20045338 0
Drop Cells: 0
Bit Errors: 0 0

Bearer 1
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 0 0
Data Cells: 0 0
Drop Cells: 0
Bit Errors: 0 0

ES: 0 0
SES: 0 0
UAS: 0 0
AS: 24287

Bearer 0
INP: 55.00 53.00
INPRein: 1.00 1.00
delay: 0 0
PER: 0.00 0.00
OR: 0.01 0.01
AgR: 60553.63 14107.15

Bearer 1
INP: 2.00 4.00
INPRein: 2.00 4.00
delay: 0 0
PER: 16.06 16.06
OR: 63.75 31.87
AgR: 63.75 31.87

Bitswap: 1369/1374 0/0

Total time = 6 hours 44 min 47 sec
FEC: 3184 89
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
Latest 15 minutes time = 14 min 47 sec
FEC: 15 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
Previous 15 minutes time = 15 min 0 sec
FEC: 3 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: N/A
Latest 1 day time = 6 hours 44 min 47 sec
FEC: 3184 89
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
Since Link time = 6 hours 44 min 45 sec
FEC: 3184 89
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Retr: 0
NTR: mipsCntAtNtr=0 ncoCntAtNtr=0

ejs · « **Reply #3 on:** November 12, 2016, 04:31:44 PM »

It's actually quite simple. A higher INP value = more protection, that's what INP stands for, Impulse Noise Protection.
Interleaving+FEC is one way of providing INP. G.998.4 (G.INP) is another way of providing INP. A higher INP value indicates more protection, regardless of which method is being used to provide that INP value.

I think the interleaving depths seen with G.998.4 active (on Huawei cabinets) are not particularly significant.

NewtronStar · « **Reply #4 on:** November 13, 2016, 12:08:17 AM »

Have always wondered about the relationship with interleaving Depth and INP level with G.INP shorter or quiet lines seem to have less INP values and higher interleaving depths of 8 to 16 the longer or noisy lines have a larger INP value and lower interleaving depth.

If I look back into G.INP Tech it has three types of errors to correct REIN PEIN & SHINE Rein can be dealt with by using FEC the other two must be used by INP (Impluse Noise Protection) system on G.INP by using the re-transmission techniques to recover the lost packets during PEIN OR SHINE events

http://www.kitz.co.uk/adsl/rein.htm

ejs · « **Reply #5 on:** November 13, 2016, 01:31:26 PM »

Minimum INP values for SHINE and REIN will be specified in the line profile, the term PEIN doesn't appear in the G.998.4 (G.INP) document. The INP_min_rein parameter only exists with G.INP.

I haven't checked vast numbers of stats, so I don't know if this is always done, but it looks like interleaving depth D = Q (number of RS codewords per DTU), so that the interleaving covers one DTU.

FEC can also be applied to enhance the net data rate, if the coding gain from the FEC outweighs the bandwidth used to carry the FEC data.

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Author Topic: DLM adding or removing INP protection? (Read 2209 times)

Sheepie

DLM adding or removing INP protection?

kitz

Re: DLM adding or removing INP protection?

Sheepie

Re: DLM adding or removing INP protection?

ejs

Re: DLM adding or removing INP protection?

NewtronStar

Re: DLM adding or removing INP protection?

ejs

Re: DLM adding or removing INP protection?