Force a ATM re sync on VDSL chipset

[adventurer]

I have a ADSL line which always tends to drop line sync and re sync back at a lower line rate.

My solution has always been shut the ATM interface and un shut. This will force it to re sync back at the usual line rate. This method has worked fine on Alcatel chipsets such as 877

Now that I have upgraded to a 887VA with a Broadcom chipset, this method of shut/un shut no longer works. The ATM interface does not drop line sync when in shutdown. I haven't found any solution other than reload the whole router.

If anyone knows how to force ATM re sync on a Broadcom chipset, please let me know. It will save me a lot of time.

[Leo Laohoo]

If the line is bad, how come the ISP doesn't want to fix it?

[adventurer]

Lots of things too hard to fix in this country.

Service agreement doesn't state how many dropouts a day is acceptable. As long as there's a dial tone present on the line, ISP won't do much about it.

[Leo Laohoo]

Post the complete output to the command "sh dsl interface".

[adventurer]

"sh dsl interface" is for the older Alcatel chipset

For Broadcom chipset, the equivalent is this,

sh controllers vdsl 0
Controller VDSL 0 is UP

Daemon Status:           Up

                        XTU-R (DS)              XTU-C (US)
Chip Vendor ID:         'BDCM'                   'BDCM'
Chip Vendor Specific:   0x0000                   0x939F
Chip Vendor Country:    0xB500                   0xB500
Modem Vendor ID:        'CSCO'                   '    '
Modem Vendor Specific:  0x4602                   0x0000
Modem Vendor Country:   0xB500                   0x0000
Serial Number Near:   
Serial Number Far:
Modem Version Near:    15.4(3)M6
Modem Version Far:     0x939f

Modem Status:            TC Sync (Showtime!)

DSL Config Mode:         AUTO
Trained Mode:   G.992.5 (ADSL2+) Annex A
TC Mode:                 ATM
Selftest Result:         0x00
DELT configuration:      disabled
DELT state:              not running

Full inits:             2
Failed full inits:      2
Short inits:            2
Failed short inits:     0

Firmware        Source          File Name
--------        ------          ----------
VDSL            user config     flash:VA_A_39h_B_38h3_24h_j.bin

Modem FW  Version:      140305_1531-4.02L.03.A2pv6C039h.d24h
Modem PHY Version:      A2pv6C039h.d24h
Trellis:                 ON                       ON
SRA:                     disabled                disabled
 SRA count:              0                       0
Bit swap:                enabled                 enabled
 Bit swap count:         89                      1
Line Attenuation:        60.5 dB                 40.2 dB
Signal Attenuation:      57.6 dB                 40.0 dB
Noise Margin:            12.4 dB                  9.3 dB
Attainable Rate:        4048 kbits/s             740 kbits/s
Actual Power:            18.2 dBm                12.4 dBm
Total FECC:             203862                   711
Total ES:               2926                     0
Total SES:              22                       0
Total LOSS:             1                        0
Total UAS:              124                      124
Total LPRS:             0                        0
Total LOFS:             9                        0
Total LOLS:             0                        0


                  DS Channel1     DS Channel0   US Channel1       US Channel0
Speed (kbps):             0             3105             0               740
SRA Previous Speed:       0                0             0                 0
Previous Speed:           0             3791             0               740
Total Cells:              0        155267358             0          37006822
User Cells:               0         10327701             0           2546511
Reed-Solomon EC:          0             2856             0               507
CRC Errors:               0             7191             0                 0
Header Errors:            0              156             0                 0
Interleave (ms):       0.00             9.79          0.00              9.56
Actual INP:            0.00             0.93          0.00              1.12

Training Log :  Stopped
Training Log Filename : flash:vdsllog.bin

[Leo Laohoo]

Noise Margin:            12.4 dB                  9.3 dB

This alone would be be justifiable to get the ISP to investigate. 

[Georg Pauwen]

Hello,

on a side note, there is a hidden command on the 800 router that lets you influence the noise margin. Values are from -3 to +3

service internal
int atm 0
dsl noise-margin x

The higher the noise margin, the slower the speed, and the higher the attenuation. Setting this to a high value may stabilize your line, at the cost of some speed.

Once you change the value, reload the router, and ignore the warning/error message.

[adventurer]

887VA does not have that command. That's for the non VA models, with Alcatel chipset.

Anyway, to bring this back to the topic, I still hope someone will have a easy way to force a 887VA Broadcom chipset to drop sync and re-learn without having to reload the router.

[adventurer]

Nothing the ISP will do. Or worse they might increase the margin and give me a slower sync speed.