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Author Topic: What now?  (Read 5133 times)

ColinS

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What now?
« on: June 09, 2013, 04:23:59 PM »

I'm trying hard not to compete with Bald_Eagle_1 for the longest-running VDSL saga, honest.  ;) :D

First the good news. :) In case you were still wondering, on Thursday 05/06 at ~05:30, DLM finally relented after 52days, and set my profile back to 80/20. :dance:

=~=~=~=~=~=~=~=~=~=~=~= log 2013.06.05 05:37:10 =~=~=~=~=~=~=~=~=~=~=~=
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   2

Max:   Upstream rate = 33166 Kbps, Downstream rate = 92028 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps

Link Power State:   L0
Mode:         VDSL2 Annex B
VDSL2 Profile:      Profile 17a
TPS-TC:         PTM Mode
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    0.0       15.2
Attn(dB):    0.0       0.0
Pwr(dBm):    12.4       2.3
         VDSL2 framing
         Path 0
B:      239      237
M:      1      1
T:      23      45
R:      0      16
S:      0.0955      0.3782
L:      20107      5373
D:      1      1
I:      240      127
N:      240      254
         Path 0
INP:      0.00      0.00
PER:      1.64      4.25
delay:      0.00      0.00
OR:      116.56      60.17

Of course, on that very day (to be known as day 1) BTOR UG cable teams started working on the same D-side cable from the PCP that supplies my DP and others. :o

They worked on it for 2 days, tone-tracing pairs, rodding a new cable length and rejointing it.  All the while completely oblivious to the concept of always-on DLM-monitored broadband. :angel:  Wasn't even my DP!

Fortunately on the second day I was able to power down the modem while they were working in an attempt to avoid the worst impacts.  Nevertheless their work resulted in several large transient surges of CRC errors on both days, although the line remained in sync. :o 

On day 3, after they had finished,  I was amused to find that DLM regarded their work as serious REIN, imposing an interleaving depth of 1541, and an INP of 3 (8ms delay). :lol:

For comparison, the worst interleaving depth ever experienced in many years over the entire 2-3km D- & E-side on ADSL2+ was only 128!

=~=~=~=~=~=~=~=~=~=~=~= log 2013.06.08 11:26:11 =~=~=~=~=~=~=~=~=~=~=~=
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   2

Max:   Upstream rate = 33974 Kbps, Downstream rate = 92152 Kbps
Bearer:   0, Upstream rate = 20000 Kbps, Downstream rate = 78750 Kbps

Link Power State:   L0
Mode:         VDSL2 Annex B
VDSL2 Profile:      Profile 17a
TPS-TC:         PTM Mode
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime

      Down      Up
SNR (dB):    6.3       15.1
Attn(dB):    0.0       0.0
Pwr(dBm):    12.4       2.9
         VDSL2 framing
         Bearer 0
MSGc:      14      26
B:      51      237
M:      1      1
T:      64      45
R:      12      16
S:      0.0210      0.3782
L:      24362      5373
D:      1541      1
I:      64      127
N:      64      254
         Bearer 0
INP:      3.00      0.00
INPRein:      0      0
delay:      8      0
PER:      1.34      4.25
OR:      118.95      60.17

It seems only to have replaced modest CRC levels beforehand of say ~<1/sec on fastpath with something like ~7,500 FEC errors a second.  All recovered of course, but it does seem like a massive overhead to me. ???

On a technical note R/N*100 gives the %overhead given over to error-correction, in this case 18.75%.
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Chrysalis

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Re: What now?
« Reply #1 on: June 09, 2013, 05:10:16 PM »

funny stuff, I wish BT did work on my D side, as I think its a complete mess.
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ColinS

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Re: What now?
« Reply #2 on: June 10, 2013, 11:07:42 AM »

and it gets worse ...

=~=~=~=~=~=~=~=~=~=~=~= log 2013.06.10 05:25:09 =~=~=~=~=~=~=~=~=~=~=~= DLM resync
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   2

Max:   Upstream rate = 33007 Kbps, Downstream rate = 91592 Kbps
Bearer:   0, Upstream rate = 20000 Kbps, Downstream rate = 72817 Kbps

Link Power State:   L0
Mode:         VDSL2 Annex B
VDSL2 Profile:      Profile 17a
TPS-TC:         PTM Mode
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    6.2       15.2
Attn(dB):    0.0       0.0
Pwr(dBm):    12.4       2.5
         VDSL2 framing
         Bearer 0
MSGc:      14      26
B:      47      237
M:      1      1
T:      64      45
R:      16      16
S:      0.0210      0.3782
L:      24407      5373
D:      1553      1
I:      64      127
N:      64      254
         Bearer 0
INP:      4.00      0.00
INPRein:      0      0
delay:      8      0
PER:      1.34      4.25
OR:      119.17      60.17

Error-recovery overhead R/N*100 is now 25%

FEC recovered errors in the last 30mins was 24,829,174 or 13,794/sec  :o
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Bald_Eagle1

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Re: What now?
« Reply #3 on: June 10, 2013, 01:10:13 PM »

and it gets worse ...


Oh dear  :(



Quote

Max:   Upstream rate = 33007 Kbps, Downstream rate = 91592 Kbps
Bearer:   0, Upstream rate = 20000 Kbps, Downstream rate = 72817 Kbps



I see from those details (Bearer: rather than Path:) that you are currently using the HG622 modem.

I wonder.....................
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ColinS

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Re: What now?
« Reply #4 on: June 10, 2013, 03:20:55 PM »

Oh dear  :(
I wonder.....................

Wonder no longer BE!  ;) 612 (original BLOB) back in use from 14:08, earlier DLM-initiated sync on the 622 at 05:25.

Trying to work up the strength to go through Plusnet's BB fault reporting, although they have been very helpful.

Or I could just wait and see, since apart from FEC counts which have gone through the roof, ES are Zero!

xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   0
Max:   Upstream rate = 32675 Kbps, Downstream rate = 94240 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 73322 Kbps

Link Power State:   L0
Mode:         VDSL2 Annex B
VDSL2 Profile:      Profile 17a
TPS-TC:         PTM Mode
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    6.8       15.1
Attn(dB):    0.0       0.0
Pwr(dBm):    12.4       2.6
         VDSL2 framing
         Path 0
B:      47      237
M:      1      1
T:      64      45
R:      16      16
S:      0.0208      0.3782
L:      24576      5373
D:      1553      1
I:      64      127
N:      64      254
         Counters
         Path 0
OHF:      3142966      989468
OHFErr:      0      5
RS:      804598848      1565821
RSCorr:      15107      13
RSUnCorr:   0      0

         Path 0
HEC:      0      0
OCD:      0      0
LCD:      0      0
Total Cells:   592940708      0
Data Cells:   93556      0
Drop Cells:   0
Bit Errors:   0      0

ES:      0      5
SES:      0      0
UAS:      18      18
AS:      4209

         Path 0
INP:      4.00      0.00
PER:      1.33      4.25
delay:      8.00      0.00
OR:      120.00      60.17

Bitswap:   700      8

Total time = 1 hours 10 min 27 sec
FEC:      15107      13
CRC:      0      5
ES:      0      5
SES:      0      0
UAS:      18      18
LOS:      0      0
LOF:      0      0
Latest 15 minutes time = 10 min 27 sec
FEC:      4144      1
CRC:      0      1
ES:      0      1
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
Previous 15 minutes time = 15 min 0 sec
FEC:      3768      7
CRC:      0      1
ES:      0      1
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
Latest 1 day time = 1 hours 10 min 27 sec
FEC:      15107      13
CRC:      0      5
ES:      0      5
SES:      0      0
UAS:      18      18
LOS:      0      0
LOF:      0      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
Since Link time = 1 hours 10 min 9 sec
FEC:      15107      13
CRC:      0      5
ES:      0      5
SES:      0      0
UAS:      0      0
LOS:      0      0
LOF:      0      0
#
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asbokid

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Re: What now?
« Reply #5 on: June 11, 2013, 03:47:40 PM »

Sorry to hear you've got another line fault, ColinS.  Hope it resolves asap. 

The CRC counter isn't incrementing. Indicating that the error rate is within the correction capabilities of the Reed-Solomon algorithm.   Could it be ingressed RF noise, generated somewhere along your line?

Did you notice the time span between the rise in errors (and the magnitude of the rise) and the DLM re-profiling?

cheers, a
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ColinS

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Re: What now?
« Reply #6 on: June 11, 2013, 04:12:37 PM »

Sorry to hear you've got another line fault, ColinS.  Hope it resolves asap.

Thanks.  I think it's just BTOR helpfully providing me with extra data with which to model their DLM.  ;) ;D :lol:

Quote
The CRC counter isn't incrementing. Indicating that the error rate is within the correction capabilities of the Reed-Solomon algorithm.   Could it be ingressed RF noise, generated somewhere along your line?

If you mean somwhere between the two UG joint-boxes that BTOR have been messing around in for days now, quite possibly!  If you mean have I attached a half-wave dipole to my master-socket as an experiment in introducing Gaussian noise, then no! :D

Quote
Did you notice the time span between the rise in errors (and the magnitude of the rise) and the DLM re-profiling?
Yes, initially from the point @ ~05:30 on 05/06 when the profile was reset to 80/20 fastpath, it seems like it was the 3-day 'poor' line counter before it switched on interleaving and INP.  But then it tweaked both of those again 6hrs later, and then adjusted the interleaving depth a little more overnight the next morning, until it had completely squished all unrecoverable error out of the line (or BTOR had finally gone home at last  :D)
BE's graphs below shows error rates over a 7 day period from before the point that the profile was finally reset (after 52 days) to 80/20 on fastpath, through the BTOR work, and the imposition of interleaving and INP, right up to today.  Prior to 05/06, they were virtually zero.  Then during 05-07/06 BTOR caused several large transient CRC error rates, before interleaving was switched on on 08/06.  Since then there were large sustained bursts of recovered FEC errors between 08-10/06, particularly on 09/06 when they appear to have reached 10^7/min, before settling back to a more modest 425/min!

However, one silver lining is that it may have given us some more clues to DLM in that:
1) with a large number of forced resyncs, but very few errors, DLM saw they line as unstable and responded with a banded max rate profile, but still on fastpath. It may take a long time before it thinks it's stable again!
2) with no forced resyncs,but a large (if transient) level of errors, DLM saw the line as noisy and responded with interleaving and INP switched on in the profile.  It remains to be seen how long it will be before it no longer thinks it's noisy.

What do you think?  :hmm: :shrug2:
« Last Edit: June 11, 2013, 04:15:20 PM by ColinS »
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waltergmw

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Re: What now?
« Reply #7 on: June 12, 2013, 10:05:35 AM »

@ Colin,

That's the first time I've seen the embarrassment hidden with an opaque sheet !

Surely that's not still lead sheathed and paper insulated cables though?

Kind regards,
Walter
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ColinS

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Re: What now?
« Reply #8 on: June 12, 2013, 11:41:42 AM »

That's the first time I've seen the embarrassment hidden with an opaque sheet !

Surely that's not still lead sheathed and paper insulated cables though?

I'm afraid so!!!!!!  (You may already be aware of an earlier part of this story :-\) We have our our own real-live personal telecomms museum around here!  :lol:

Last week they were out tone-tracing, cable-rodding a new section, and rejointing - yes the paper-sleeved ones - between this joint box, which is the main distribution one on this cable from PCP 9 (i.e. the start of the DP splices) about 120m away, and is adjacent to DP 1825, and DP 81.

 Some of the properties are fed from that DP with wall-mounted feeds.  The rest continues UG to the poles and serves DP 1824 (mine), then DP 81 (must have been the original pole-DP around here), and then DP 1823, and so on.  The new section they were rejointing was from that joint box to a similar one between DP 1824 and DP 81, and yes both ends were paper-sleeved.

In fact, it's been like BTOR-central around here for the last week. :D Working UG on the 5-6th as described above; then OH Pole-testing on the 10th; then UG back again into that joint box on the 11th (which is when that photo is from).

I was thinking of offering a year's supply of tea-and-biscuits if they would go away!

And you think you've got problems!!!!!  :lol:

Actually, if there is a serious point to any of this it's that unfortunately UG repairs have to be done, but there doesn't seem to be any part of the process that takes account of the impact of that essential work on the services (be they voice/xDSL) of collaterally affected customers.  With more-and-more people (at least in cities, anyway, I appreciate) with so-called 'always-on' connections, this could and does, if my experience is anything to go by, have a serious impact on user's services for a considerable time thereafter.  :(

You might think that with TR069 they could shut everyone's modems off remotely while they worked, or at least suspend/reset DLM be it in the cabinet or the exchange.  Perhaps BS will give a personal view?
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ColinS

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Re: What now?
« Reply #9 on: June 12, 2013, 02:16:03 PM »

and today's good news, for a change!  ;D
=~=~=~=~=~=~=~=~=~=~=~= log 2013.06.12 06:05:12 =~=~=~=~=~=~=~=~=~=~=~= HG612
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason:   2

Max:   Upstream rate = 32671 Kbps, Downstream rate = 95788 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 80000 Kbps

Link Power State:   L0
Mode:         VDSL2 Annex B
VDSL2 Profile:      Profile 17a
TPS-TC:         PTM Mode
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):    6.3       15.1
Attn(dB):    0.0       0.0
Pwr(dBm):    12.4       2.3
         VDSL2 framing
         Path 0
B:      54      237
M:      1      1
T:      64      45
R:      14      16
S:      0.0219      0.3782
L:      25239      5373
D:      1438      1
I:      69      127
N:      69      254

INP:      3.00      0.00
PER:      1.04      4.25
delay:      8.00      0.00
OR:      160.02      60.17

Watch this space  :-X

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asbokid

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Re: What now?
« Reply #10 on: June 15, 2013, 02:52:04 PM »

and it gets worse ...

Code: [Select]
=~=~=~=~=~=~=~=~=~=~=~= log 2013.06.10 05:25:09 =~=~=~=~=~=~=~=~=~=~=~= DLM resync
xdslcmd info --stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2

Max: Upstream rate = 33007 Kbps, Downstream rate = 91592 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 72817 Kbps

Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.2 15.2
Attn(dB): 0.0 0.0
Pwr(dBm): 12.4 2.5
VDSL2 framing
Bearer 0
MSGc: 14 26
B: 47 237
M: 1 1
T: 64 45
R: 16 16
S: 0.0210 0.3782
L: 24407 5373
D: 1553 1
I: 64 127
N: 64 254
Bearer 0
INP:         4.00 0.00
INPRein: 0 0
delay: 8 0
PER: 1.34 4.25
OR: 119.17 60.17

Error-recovery overhead R/N*100 is now 25%

It could be worse!  This is the worst case scenario (sfaics) that can be engineered between an ECI modem and a Huawei DSLAM:

The highest minimum INP level that the MA5616 DSLAM will accept is 16 protected DMT symbols in both downstream and upstream:

Code: [Select]
MA5616(config)#vdsl channel-profile modify 995
  Start modifying profile 995. New setting will take effect automatically after the modification succeeds
  Press 'Q' to quit the current configuration and new configuration will be neglected
>  Data path mode 1-ATM, 2-PTM, 3-Both (1~3) [2]:
>  Will you set the minimum impulse noise protection? (y/n) [n]:y
>    Minimum impulse noise protection downstream:
>    1-noProtection    2-halfSymbol      3-singleSymbol     4-twoSymbols
>    5-threeSymbols    6-fourSymbols     7-fiveSymbols      8-sixSymbols
>    9-sevenSymbols    10-eightSymbols   11-nineSymbols     12-tenSymbols
>    13-elevenSymbols  14-twelveSymbols  15-thirteenSymbols 16-fourteenSymbols
>    17-fifteenSymbols 18-sixteenSymbols
>    Please select (1~18) [18]:
>    Minimum impulse noise protection upstream:
>    1-noProtection    2-halfSymbol      3-singleSymbol     4-twoSymbols
>    5-threeSymbols    6-fourSymbols     7-fiveSymbols      8-sixSymbols
>    9-sevenSymbols    10-eightSymbols   11-nineSymbols     12-tenSymbols
>    13-elevenSymbols  14-twelveSymbols  15-thirteenSymbols 16-fourteenSymbols
>    17-fifteenSymbols 18-sixteenSymbols
>    Please select (1~18) [10]:18
>  Will you set interleaving delay parameters? (y/n) [n]:
>  Will you set parameters for rate? (y/n) [n]:
>  Will you set rate thresholds? (y/n) [n]:
>  Will you set PHY-R function? (y/n) [n]:
>  Will you set erasure decoding? (y/n) [n]:
>  Will you set SOS bit rate? (y/n) [n]:
>  Will you set the G.998.4 retransmission function? (y/n) [n]:
>  Will you set channel initialization policy selection? (y/n) [n]:
  Modify profile 995 successfully, and new setting is taking effect now

The effect of the FEC overhead from that level of INP, as measured at the ECI /r CPE is catastrophic.

Even with a juicy max attainable rate of 138/60 Mbps, the FEC overheads result in the ACTual Net Data Rate being slashed to just 16/8 Mbps:

Code: [Select]
root@OpenWrt:/# /etc/init.d/dsl_control status
CPE Chipset:            Lantiq-VRx:5.4.8.6.1.6
CO Chipset:             BDCM:v10.07.26
Line State:             UP [0x801: showtime_tc_sync]
Attain Data Rate:       138810 Kbps / 59952 Kbps
Actual Data Rate:       16316 Kbps / 8348 Kbps
Interleave Delay:       32.0 ms / 32.25 ms
Impulse Noise Prot:     16.0 sym / 16.0 sym
Line Attenuation:       0.4 dB / 0.0 dB
Signal Attenuation:     0.2 dB / 0.0 dB
Noise Margin:           33.5 dB / 32.6 dB
Transmit Power:         6.3 dBm / -11.3 dBm
Line Uptime:            26s
FEC Errors:             0 / 0
CRC Errors:             0 / 0
ES:                     0 / 0
SES:                    0 / 0
UAS:                    33 / 33

With the above settings, the VDSL2 framing parameters look like the following:

Code: [Select]
root@OpenWrt:/# dsl_cpe_pipe.sh g997fpsg 0 0
nReturn=0 nChannel=0 nDirection=0 nNFEC=32 nRFEC=16 nLSYMB=4211 nINTLVDEPTH=1053 nINTLVBLOCK=32 nLPATH=0

root@OpenWrt:/# dsl_cpe_pipe.sh g997fpsg 0 1
nReturn=0 nChannel=0 nDirection=1 nNFEC=32 nRFEC=16 nLSYMB=8204 nINTLVDEPTH=2051 nINTLVBLOCK=32 nLPATH=0

That's an R/N*100 ratio of 50% !

Luckily, the highest minimum INP levels that Openreach uses are: 8 DMT symbols downstream and 4 DMT symbols upstream.

And with the same zero loop, those minimum INP levels cause the ACTual Net Data Rates to be slashed from the Profile 17a maximum (100/60Mbps) to the figures below (36/19 Mbps).

Code: [Select]
root@OpenWrt:/# /etc/init.d/dsl_control status
CPE Chipset:            Lantiq-VRx:5.4.8.6.1.6
CO Chipset:             BDCM:v10.07.26
Line State:             UP [0x801: showtime_tc_sync]
Attain Data Rate:       140513 Kbps / 60405 Kbps
Actual Data Rate:       36680 Kbps / 18988 Kbps
Interleave Delay:       17.0 ms / 8.25 ms
Impulse Noise Prot:     8.1 sym / 4.0 sym
Line Attenuation:       0.5 dB / 0.0 dB
Signal Attenuation:     0.3 dB / 0.0 dB
Noise Margin:           29.6 dB / 29.7 dB
Transmit Power:         12.0 dBm / -4.2 dBm
Line Uptime:            27s
FEC Errors:             0 / 0
CRC Errors:             0 / 0
ES:                     0 / 0
SES:                    0 / 0
UAS:                    70 / 70

With framing parameters that are:

Code: [Select]
root@OpenWrt:/# dsl_cpe_pipe.sh g997fpsg 0 0
nReturn=0 nChannel=0 nDirection=0 nNFEC=41 nRFEC=16 nLSYMB=7835 nINTLVDEPTH=490 nINTLVBLOCK=41 nLPATH=0

root@OpenWrt:/# dsl_cpe_pipe.sh g997fpsg 0 1
nReturn=0 nChannel=0 nDirection=1 nNFEC=40 nRFEC=16 nLSYMB=15360 nINTLVDEPTH=1961 nINTLVBLOCK=40 nLPATH=0

In this case, the R/N ratio is "just" 16/40 = 40%

Still pretty awful :-(

cheers, a
« Last Edit: June 15, 2013, 03:49:05 PM by asbokid »
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ColinS

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Re: What now?
« Reply #11 on: June 15, 2013, 08:08:48 PM »

 :graduate:
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