Investigating sudden rise of carrier drop outs with 877 DSL router

[Zenith888]

Can anyone suggest what should be done to investigate why in the last 2 weeks there is an increase in dropped carrier from 1-2 a day to 20+ a day?

Will enabling training log buffer provide any useful information?

Should I attempt to use dsl noise-margin command?

Here is sh dsl int atm0:

Thank you!

ATM0
Alcatel 20190 chipset information
                  ATU-R (DS)               ATU-C (US)
Modem Status:      Showtime (DMTDSL_SHOWTIME)
DSL Mode:      ITU G.992.1 (G.DMT) Annex A
ITU STD NUM:       0x03                     0x1 
Vendor ID:         'STMI'                   'ALCB'
Vendor Specific:   0x0000                   0x0000
Vendor Country:    0x0F                     0x0F
Chip ID:           C196 (0)
DFE BOM:           DFE3.0 Annex A (1)
Capacity Used:      47%                     79%
Noise Margin:      27.0 dB                  13.0 dB
Output Power:      19.0 dBm                 12.0 dBm
Attenuation:       22.0 dB                  11.0 dB
Defect Status:     None                     None                        
Last Fail Code:    None
Watchdog Counter:  0x62
Watchdog Resets:   0
Selftest Result:   0x00
Subfunction:       0x00 
Interrupts:        429616 (0 spurious)
PHY Access Err:    0
Activations:       118
LED Status:        ON
LED On Time:       100
LED Off Time:      100
Init FW:           init_3.0.010_nobist.bin
Operation FW:      AMR-3.0.010.bin
FW Source:         external
FW Version:        3.0.10

                   Interleave             Fast     Interleave             Fast
Speed (kbps):               0             5056              0              800
Cells:                      0         17229326              0          8141395
Reed-Solomon EC:            0                0              0                0
CRC Errors:                 0              246              3               14
Header Errors:              0              247              1                7
Total BER:                  0E-0           1374E-8
Leakage Average BER:        0E-0           1038E-8
                          ATU-R (DS)     ATU-C (US)
Bitswap:            enabled               enabled
Bitswap success:          0                     0
Bitswap failure:          0                     0

LOM Monitoring : Disabled


DMT Bits Per Bin
000: 0 0 0 0 0 0 0 8 8 9 A A B B B B
010: B B B A A A A A A 9 9 9 8 7 0 0
020: 0 0 0 0 0 0 6 7 7 7 7 7 8 8 8 8
030: 8 8 8 8 8 8 8 8 7 8 8 8 8 8 8 8
040: 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8
050: 8 8 8 8 7 8 7 8 8 8 8 7 7 7 7 7
060: 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7
070: 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7
080: 7 7 7 7 2 7 6 7 7 6 7 7 7 7 7 6
090: 7 7 6 6 6 7 6 7 7 6 6 6 7 7 6 6
0A0: 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6
0B0: 6 6 6 6 6 6 6 6 6 6 5 6 6 6 6 6
0C0: 6 6 6 6 6 6 6 5 5 5 6 5 5 5 5 6
0D0: 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
0E0: 5 5 5 5 5 5 5 5 5 5 4 5 5 5 5 4
0F0: 5 5 4 4 4 5 4 4 4 4 4 4 4 4 4 4

DSL: Training log buffer capability is not enabled

[paolo bevilacqua]

Maybe your loop got worst due to environmental factors.

The only thing you can try, is update ADSL firmware

[KBCISCO]

Are the lines adsl2+ as I have experienced compatibility issue with these lines and 877 routers. Try upgrading the dsl firmware on the router. I have also found that a workout is to manually set the dsl operating mode rather than having it set to auto

[Zenith888]

Where can I get an updated firmware with the version higher than 3.0.10?

Thank you!

[paolo bevilacqua]

Try ftp://ftp.cisco.com/pub/access/800

For newest versions, you need a support contract.

[Zenith888]

I am a little confused. According to the ftp link you've posted, I am already on the highest version 3.0.10 applicable to 877 router.

Are you saying that to just learn what other versions are availalbe, I need to pay Cisco $$$?

That would be extremely unethical IMO - to release buggy firmware with the device, than charge users money for fixing issues.

Please clarify your previous post.

[paolo bevilacqua]

Read the readme files to know what is what.

Regarding Cisco's software release policy - do not pick on me - I'm not responsibile.

[Zenith888]

If there are two firmware versions in the flash:

adsl_alc_20190.1.bin

adsl_alc_20190.2.bin

which of them would be loaded?

[paolo bevilacqua · Accepted solution]

None, as neither is the correct alternative filename.

[Zenith888]

Got it! Need to remove ".1." or ".2." respectively. I've misread the update instructions and renamed 4.0.15 to a "2". last time, so it was running on 3.0.10

Now I am on the right FW and there is a difference: before it would drop carrier and re-train for a minute or so, now it immediately retrains so no connections are dropped. Is that expected behaviour or do I still have to look for further updates past 4.0.15?

It drops carrier when noise margin goes from 26-28 to 25, 15, 13, 8, -1, -2.5 within a few seconds.

[paolo bevilacqua · Accepted solution]

Most likely you have a degraded loop that needs repair or replacement.

[Zenith888]

Pardon my ignorance - networking is not really my cup of tea and I am just an 'advanced user'.

"degraded loop" - does that mean that Bell's line from their switch to my office is unstable?

There is only 3' of cable from the demarcation box into the office and another 3'  of RJ11 cable soldered to that cable, so nothing appears degraded inside the building.

[paolo bevilacqua · Accepted solution]

Yes, it means that. The damage can be anywhere and not be visibile. Try asking to be moved to a different pair.

[Zenith888]

Appreciate your help! Sorry if I sounded snappy initially, I did not mean that towards you - just was upset after loosing connection so often.

The 4.0.15 FW really changed the things - when looking at the router the PPP light now stays on and carrier detect light goes off only briefly when carrier is dropped. I can live with that for a while until Bell looked at the line.

Thank you!

[paolo bevilacqua]

No problem, thank you for the nice rating and good luck!