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Author Topic: A strange Resync  (Read 4116 times)

WWWombat

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A strange Resync
« on: February 27, 2015, 01:16:58 AM »

My HG612 just (about an hour ago) went through a resync (reason: 1) trigger by some outside event.

It was out for a while longer than you'd expect - the modem is now reporting a UAS value of 423, when it was a plain 23 beforehand - so an outage of just over 6 mins. The red spike on the TBB BQM looks wider than usual. So not just a resync. Not a power outage at the house; no idea for the cab, but it is only 100m away.

All line stats figures available on MDWS, and show a slight weird result.

The end result is that downstream SNRM is the same; upstream SNRM dropped by about 1.5dB (visible in both the summary and in each of the 3 bands); upstream power dropped by about 0.3dB (in summary), but with varied amounts per U# band (mostly in U2, where most of the bitloading is concentrated). Sync speeds are the same, at the 80/20 cap.

However, the weird thing is that the downstream attainable has jumped by 8Mbps (from 98 to 106Mbps), and the downstream attainable has jumped by 1Mbps.

Yet there has been no increase in SNRM that would account for it, no change in DLM, and no change in the VDSL2 bearer configuration data. Trellis is on in both cases.

There is no hint of G.INP in the stats output. And, because of no increase in SNRM, I'd guess at no sign of vectoring.
There seems to be no change in any of the software or blob versions, so it doesn't look like a re-flash.

QLN is showing around 5dB less noise, but considerably more jitter - so the red line looks thicker.

I'm stumped. Can anyone explain anything about the increase in attainable speeds?
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Bald_Eagle1

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Re: A strange Resync
« Reply #1 on: February 27, 2015, 03:50:37 PM »

I wonder, have your Discovery phase band plans changed at all?

These are mine:-

Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3970)


But I have seen some other users, also on Huawei DSLAMS with these band plans:-

Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)



Here's a recent example from carlmagic, the only user with stats that confirm that G.INP has been enabled that I am aware of:-

Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3959)


equipcmd swversion display
software version: V100R001C01B030SP08
xdsl firmware version: A2pv6C038m.d24j
cpu version: BCM6368
cfe version: 1.0.37-102.6
display version success


xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Last initialization procedure status:   0
Max:   Upstream rate = 38277 Kbps, Downstream rate = 102812 Kbps
Bearer:   0, Upstream rate = 20000 Kbps, Downstream rate = 79999 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):    12.1       17.9
Attn(dB):    12.3       0.0
Pwr(dBm):    13.5       1.9
         VDSL2 framing
         Bearer 0
MSGc:      -6      -6
B:      130      97
M:      1      1
T:      0      0
R:      8      8
S:      0.0518      0.1554
L:      21468      5457
D:      16      8
I:      139      106
N:      139      106
Q:      16      8
V:      14      2
RxQueue:      60      39
TxQueue:      20      13
G.INP Framing:      18      18
G.INP lookback:      20      13
RRC bits:      24      24

« Last Edit: February 27, 2015, 03:58:16 PM by Bald_Eagle1 »
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burakkucat

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Re: A strange Resync
« Reply #2 on: February 27, 2015, 05:01:31 PM »

I wonder if the information contained in Black Sheep's recent posting may be relevant?  :-\
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NewtronStar

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Re: A strange Resync
« Reply #3 on: February 27, 2015, 11:44:09 PM »

The retrain reason 1 and 6 was a very common retrain reason on my VDSL2 circuit there was no changes that i could see the only thing that sticks out were the DS Sync speed had changed and on my circuit the Pwr(dBm): in the upload aways tends to change after a resync.

Though it's been a while since i've seen a retrain reason 6 (2 months) and have not had any retrain reason 1's since the DLM was reset.
« Last Edit: February 27, 2015, 11:48:47 PM by NewtronStar »
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kitz

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Re: A strange Resync
« Reply #4 on: February 28, 2015, 12:44:31 AM »

Ive not looked at your MDWS graphs, but most obvious area for increase in max attainable without increase in SNRm would make me think of something to do with bit loading of the various tones available.   I note BE has already mentioned to look at the tones available for use.   Also check your bit loading to see if you can see a different pattern, perhaps a new PCB plan has been applied, perhaps either your line/the cabs distance has been re-classified. 

Re the QLN jitter, I'd recheck that at next resync. Ive seen it occur several times before when DLSAM may have been down for some reason, that when all lines come up at the same time then the QLN can look unusual.
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WWWombat

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Re: A strange Resync
« Reply #5 on: February 28, 2015, 01:30:11 AM »

I wonder, have your Discovery phase band plans changed at all?

Nope - the tones in the band plans have stayed the same, with the top matching yours at 3970. In fact, they all match yours.

It's a Huawei cabinet. I'm never sure if the '--vendor' option tells us about the modem or the cab, but here is the output:
# xdslcmd info --vendor
    xdslcmd: ADSL driver and PHY status
    Status: Showtime
    Retrain Reason: 1
    Last initialization procedure status:   0
    Max:    Upstream rate = 34491 Kbps, Downstream rate = 105820 Kbps
    Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 79987 Kbps
   
    ChipSet Vendor Id:      BDCM:0xa44f
    ChipSet VersionNumber:  0xa44f
    ChipSet SerialNumber:


The "equipcmd" results are identical to the ones you posted for carlmagic. However, all the framing information is as before; no indication of the G.INP parameters or the extra bearer.

I can't tell if my cabinet has enabled G.INP, but it certainly doesn't appear to be running on my line.

I wonder if the information contained in Black Sheep's recent posting may be relevant?  :-\

It certainly could be, but I have no way to check other than inducing a huge error rate on the line. I'm not sure I want to experiment quite that badly ;)

the only thing that sticks out were the DS Sync speed had changed and on my circuit the Pwr(dBm): in the upload aways tends to change after a resync.

I don't think I've ever really seen the power change over resyncs before, by anything other than the 0.1dB variation that seems to happen over time anyway. The change in upstream was noticeable here - and I'm close enough for the cab to want to apply UPBO to me.

Also check your bit loading to see if you can see a different pattern, perhaps a new PCB plan has been applied, perhaps either your line/the cabs distance has been re-classified. 
Good thinking ... but no change there either. The CAL for the cab doesn't appear to have changed, and the shape of the PSD mask appears identical.

The shape of the bit-loading looks totally the same. Individual bits in the top layer look slightly different, due to natural variation & bitswapping. A 'diff' seems to show that no tone ever varies by more than 1 bit.

Quote
Re the QLN jitter, I'd recheck that at next resync. Ive seen it occur several times before when DLSAM may have been down for some reason, that when all lines come up at the same time then the QLN can look unusual.

I'll be watching for it. I might force it down over the weekend, to see what happens.
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burakkucat

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Re: A strange Resync
« Reply #6 on: February 28, 2015, 01:51:49 AM »

It's a Huawei cabinet. I'm never sure if the '--vendor' option tells us about the modem or the cab, but here is the output:
# xdslcmd info --vendor
    xdslcmd: ADSL driver and PHY status
    Status: Showtime
    Retrain Reason: 1
    Last initialization procedure status:   0
    Max:    Upstream rate = 34491 Kbps, Downstream rate = 105820 Kbps
    Bearer: 0, Upstream rate = 19999 Kbps, Downstream rate = 79987 Kbps
   
    ChipSet Vendor Id:      BDCM:0xa44f
    ChipSet VersionNumber:  0xa44f
    ChipSet SerialNumber:

It is the MSAN/DSLAM chipset that is reported.

I use a Huawei HG622 (Broadcom chipset) with a TalkTalk LLU'd ADSL2+ service. The TT MSAN has an Infineon chipset, which can be seen reported on the "ChipSet Vendor Id" line --

# xdslcmd info --vendor
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   8000
Max:   Upstream rate = 1068 Kbps, Downstream rate = 6160 Kbps
Channel:   INTR, Upstream rate = 1020 Kbps, Downstream rate = 5699 Kbps

ChipSet Vendor Id:      IFTN:0x71c6
ChipSet VersionNumber:  0x71c6
ChipSet SerialNumber:   
#
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kitz

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Re: A strange Resync
« Reply #7 on: February 28, 2015, 02:32:13 AM »

Quote
Good thinking ... but no change there either. The CAL for the cab doesn't appear to have changed, and the shape of the PSD mask appears identical.

The shape of the bit-loading looks totally the same. Individual bits in the top layer look slightly different, due to natural variation & bitswapping. A 'diff' seems to show that no tone ever varies by more than 1 bit.

Oh well worth a shot.   I agree that 1 bit changes are perfectly normal and you'd be looking for something more obvious.. most likely in U0, U1 or D1.
When it comes to the line, I seem to recall reading somewhere that for the line it was based on the loop loss measured at a specific frequency.  BT defines the CAL values for the Dslam based on the equivalent 'e' side length.  If you know otherwise, Im happy to be corrected.

I'm stumped to think of any other reason, other than it being anything to do with the recent MSE bRAS changes.  AFAIK the majority of that work was carried out during last Oct/Nov, but there is still a little bit of residual work being carried out..   Mine was done last Oct and my cab is now re-routed to a neighbouring exchange rather than via my own.  My stats changed during that episode as I suspect Im now 'bundled' with more or different lines than previously.  Its hard to tell because they screwed up my line during the process, and I also picked up a new (bad) disturber in the same period.  :/

Quote
I'm never sure if the '--vendor' option tells us about the modem or the cab,

Another confirmation its the dslam.  Im on an ECI cab, using a BCM based modem/router.

Code: [Select]
> adsl info --vendor
adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    1
Last initialization procedure status:   0
Max:    Upstream rate = 30948 Kbps, Downstream rate = 83630 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 79987 Kbps

ChipSet Vendor Id:      IFTN:0xb204
ChipSet VersionNumber:  0xb204
ChipSet SerialNumber:   5502152235

btw retrain reason 1 isnt always DLM as my last resync was a manual one by me powering down.  (Not relevant to this topic, but I just happened to spot it during that cmd and recall you talking about this recently with someone else).



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