Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

High Reed-Solomon EC on 887VA with VDSL

Hi,

I've recently set up a C887VA-W-E-K9 router to connect to Vodafone fibre 80/20.  It's my first time setting up a xDSL circuit from scratch on these routers so I don't know if the config is 100% right - but it is working anyway (much to my delight).

After an initial teething period of unexplained CRC & header errors, and chronically low download speeds (~6Mbps download, 19Mbps upload) the line seems to have "settled".

Despite being told we would likely be only able to get around 50Mbps due to our distance from the cabinet, the router is reporting that attainable speeds in the 80s, and syncing consistently over 73Mbps.

Although no one has complained of any issues in the office that I'm aware of, I am seeing consistently high Reed-Solomon EC values in the statistics for the VDSL controller.  The fact the rest of the numbers there are zero makes me think it shouldn't be this high?

Here is the output from sh controller vdsl 0, taken about 30 minutes after I cleared the counters on it:

Controller VDSL 0 is UP

Daemon Status:         Up

            XTU-R (DS)        XTU-C (US)
Chip Vendor ID:        'BDCM'             'IFTN'
Chip Vendor Specific:   0x0000             0xB203
Chip Vendor Country:    0xB500             0xB500
Modem Vendor ID:    'CSCO'             '    '
Modem Vendor Specific:  0x4602             0x0000
Modem Vendor Country:   0xB500             0x0000
Serial Number Near:    FCZ17****** C887VA-W 15.3(3)M3
Serial Number Far:     55023*****
Modem Version Near:    15.3(3)M3
Modem Version Far:     0xb203

Modem Status:         TC Sync (Showtime!)
DSL Config Mode:     AUTO
Trained Mode:         G.993.2 (VDSL2) Profile 17a
TC Mode:         PTM
Selftest Result:     0x00
DELT configuration:     disabled
DELT state:         not running
Trellis:         ON              ON
SRA:              disabled             disabled
 SRA count:          0             0
Bit swap:          enabled             enabled
 Bit swap count:     0             0
Line Attenuation:      0.0 dB          0.0 dB
Signal Attenuation:      0.0 dB          0.0 dB
Noise Margin:          6.3 dB          9.8 dB
Attainable Rate:    86392 kbits/s         28273 kbits/s
Actual Power:         12.7 dBm          4.5 dBm
Per Band Status:           D1     D2     D3     U0     U1     U2     U3
Line Attenuation(dB):   10.9    25.7    39.9    0.6    20.4    31.5    N/A    
Signal Attenuation(dB): 10.9    25.7    39.9    0.6    20.2    31.4    N/A    
Noise Margin(dB):       6.3    6.3    6.3    10.2    10.0    9.6    N/A    
Total FECC:        107824             69
Total ES:        1             3
Total SES:        0             0
Total LOSS:        0             0
Total UAS:        0             0
Total LPRS:        0             0
Total LOFS:        0             0
Total LOLS:        0             0

Full inits:        1
Failed full inits:    0
Short inits:        0
Failed short inits:    0

Firmware    Source        File Name (version)
--------    ------        -------------------
VDSL        embedded       VDSL_LINUX_DEV_01212008 (1)

Modem FW  Version:    130205_1433-4.02L.03.A2pv6C035j.d23j
Modem PHY Version:    A2pv6C035j.d23j
Vendor Version:        Ap6v35j.23j 68


           DS Channel1      DS Channel0    US Channel1      US Channel0
Speed (kbps):              0           73775             0           20000
SRA Previous Speed:       0               0             0               0
Previous Speed:              0               0             0               0
Reed-Solomon EC:          0          107824             0              69
CRC Errors:              0               1             0               3
Header Errors:              0               0             0               0
Interleave (ms):       0.00            8.00          0.00            0.00
Actual INP:           0.00            3.00          0.00            0.00

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

As you can see - the Reed-Solomon EC count is already at 107,824 and it carries on rising into the millions.  There doesn't seem to be any particular consistently to it.

I've been in contact with our broadband providers who haven't really able to help, and insist that we have to use the BT Openreach modem in front of our router otherwise it's not a supported configuration.  Vodafone are also telling them the same thing when it was escalated.  I've also been told - which I don't believe - that the 887VA can't support 80/20 VDSL, but the CPU utilisation on it barely goes above 15% even with CBAC and IPSEC active, so it seems meaty enough.

Vodafone also gave me a load of settings that don't (I think?) apply to VDSL at all - e.g. VCI, VPI and VC-Mux/VC-based multiplexing?  I can't see any way of setting these on the Dialer0 interface, and the ATM0 interface is administratively down as it's unused.

Can anyone shed any light on this?

Is our "Noise margin" too low?  Could a mismatch of MTU cause this kind of problem? (currently I have no MTU settings explicitly set, and sh int shows it as 1500 - which Vodafone also said we should aim for).

I should point out that speed wise the speed tests I've run have consistently shown download speeds of ~70Mbps, and upload of ~18Mbps, and there hasn't been any desyncs that I've seen - so whatever is causing those Reed-Solomon EC numbers doesn't seem to be adversely affecting the line or the quality of service.

Everyone's tags (5)
1 ACCEPTED SOLUTION

Accepted Solutions
New Member

HiIn response to user889988,

Hi

In response to user889988, it's a very good point suggesting an upgrade to the modem FW as Cisco worked with BT to produce specific code relating to UK exchanges.

The fix is well documented and you can search for;

operating mode auto

service internal

modem ukfeature

firmware filename flash:[name]

 

BUT in this case it's not necessary, 887VA's have been shipping for a while (approx. <12mths), with later firmware embedded.

The clue is in the filename

...35j.d23j

Earlier patched versions were 35d...  and hence are superseded by the above.

 

It could be worth your while checking out the other commands above though (excluding the firmware filename one).

n.b. operating mode auto is the default and doesn't show in the running config,

(sh contr vdsl 0 does contain "DSL Config Mode :   AUTO" though)

and 'modem ukfeature' - you can see in the output of

"show controller vdsl 0 console [number]" after the DSL modem trains;

you see something like:-

Force UKFeatureBit SET

There used to be a link to the doc at the following but I think it is a dead link now;

www.cisco-bt-portal.com/iusr/DSL/Product_Bulletin_DSL.pdf

10 REPLIES
New Member

Here's an update today,

Here's an update today, router has been up 4 1/2 days:

Controller VDSL 0 is UP

Daemon Status:         Up

            XTU-R (DS)        XTU-C (US)
Chip Vendor ID:        'BDCM'             'IFTN'
Chip Vendor Specific:   0x0000             0xB203
Chip Vendor Country:    0xB500             0xB500
Modem Vendor ID:    'CSCO'             '    '
Modem Vendor Specific:  0x4602             0x0000
Modem Vendor Country:   0xB500             0x0000
Serial Number Near:    FCZ17****** C887VA-W 15.3(3)M3
Serial Number Far:     55023*****
Modem Version Near:    15.3(3)M3
Modem Version Far:     0xb203

Modem Status:         TC Sync (Showtime!)
DSL Config Mode:     AUTO
Trained Mode:         G.993.2 (VDSL2) Profile 17a
TC Mode:         PTM
Selftest Result:     0x00
DELT configuration:     disabled
DELT state:         not running
Trellis:         ON              ON
SRA:              disabled             disabled
 SRA count:          0             0
Bit swap:          enabled             enabled
 Bit swap count:     0             0
Line Attenuation:      0.0 dB          0.0 dB
Signal Attenuation:      0.0 dB          0.0 dB
Noise Margin:          6.2 dB         12.2 dB
Attainable Rate:    86732 kbits/s         28822 kbits/s
Actual Power:         12.6 dBm          6.9 dBm
Per Band Status:           D1     D2     D3     U0     U1     U2     U3
Line Attenuation(dB):   10.9    25.8    40.1    0.6    20.5    31.6    N/A    
Signal Attenuation(dB): 10.9    25.8    40.1    0.6    20.3    31.5    N/A    
Noise Margin(dB):       6.2    6.2    6.2    11.7    12.6    12.1    N/A    
Total FECC:        14382829             1009
Total ES:        52             21
Total SES:        0             0
Total LOSS:        0             0
Total UAS:        0             0
Total LPRS:        0             0
Total LOFS:        0             0
Total LOLS:        0             0

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

Firmware    Source        File Name (version)
--------    ------        -------------------
VDSL        embedded       VDSL_LINUX_DEV_01212008 (1)

Modem FW  Version:    130205_1433-4.02L.03.A2pv6C035j.d23j
Modem PHY Version:    A2pv6C035j.d23j
Vendor Version:        Ap6v35j.23j 68


           DS Channel1      DS Channel0    US Channel1      US Channel0
Speed (kbps):              0           74425             0           20000
SRA Previous Speed:       0           73775             0           20000
Previous Speed:              0           73775             0           20000
Reed-Solomon EC:          0        14382829             0            1009
CRC Errors:              0             183             0              21
Header Errors:              0              79             0               0
Interleave (ms):       0.00            8.00          0.00            0.00
Actual INP:           0.00            3.00          0.00            0.00

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


As you can see - there's been 14,382,829 Reed-Solomon EC errors, so something clearly not right?

New Member

 I have exactly the same

 

I have exactly the same issue as you Daz... have to got the bottom of this one yet?

 

Thanks

 

 

 

New Member

I'm afraid not.  As things

I'm afraid not.  As things stand our line is behaving very strangely.  At present there are no Reed-Solomon EC errors being reported, instead they've been replaced by thousands of CRC & Header errors - also for reasons unexplained.

Our providers have tried to be helpful, but Vodafone have been next to useless.  The only supported configuration is with the white Openreach box in front of the router.  The fact that I would cease to see ANY information like this if that was the configuration doesn't seem to matter (or register) to them.  I could put the white box in front, still have thousands of errors happening but the difference is that I would be then oblivious to them.  That's not a solution in my book.

So yeah, I haven't progressed this any further.  The only reason I haven't been shouting thus far is that in spite of these errors the line appears to be functioning - I haven't had any complaints about dropped connections, and speed tests are uniformly fast.

I've hit a brick wall with it really.

New Member

 I get where you're coming

 

I get where you're coming from with regard to monitoring when the modem/driver is installed in front...

I have asked the provider to try and hard code the SNR their end as high as possible (15db) to hopefully stop these forwarding errors. This will obviously bring the profile down and decrease the bandwidth but stability is the key here

 

Total FECC:             20950                    0

Reed-Solomon EC:          0            21203             0                 0

 

I will keep you updated if I find a solution Daz

 

 

Regards

 

 

New Member

Thanks, would appreciate that

Thanks, would appreciate that.

Our SNR is low here too, and line attenuation is pretty high.  Despite that we consistently sync at over 70Mb down.  In fact, like you, being able to sync lower would probably result in a more stable line.

New Member

Hi, I'm on BT infinity 80/20

Hi,

 

I'm on BT infinity 80/20 but distance to the cab means i can only get around 40/10 (long story but due to some discount if I reduce my profile it will cost more) 

I have also noted the high Reed-Solomon error rate, I can not work out why. Got a solid line so perhaps I should not complain :-

Router# show controllers vdSL 0
Controller VDSL 0 is UP

Daemon Status:           NA 

                        XTU-R (DS)              XTU-C (US)
Chip Vendor ID:         'BDCM'                   'BDCM'
Chip Vendor Specific:   0x0000                   0xA41B
Chip Vendor Country:    0xB500                   0xB500
Modem Vendor ID:        'CSCO'                   'BDCM'
Modem Vendor Specific:  0x4602                   0xA41B
Modem Vendor Country:   0xB500                   0xB500
Serial Number Near:    GMK173902PP 867VAE- 15.3(3)M   
Serial Number Far:     
Modem Version Near:    15.3(3)M
Modem Version Far:     0xA41B

Modem Status:            TC Sync (Showtime!) 
DSL Config Mode:         AUTO 
Trained Mode:            G.993.2 (VDSL2) Profile 17a
TC Mode:                 PTM 
Selftest Result:         0x00 
DELT configuration:      disabled 
DELT state:              not running 
Trellis:                 ON                       ON
SRA:                     disabled                        disabled
 SRA count:              0                       0
Bit swap:                enabled                         enabled
 Bit swap count:         139693                  0
Line Attenuation:         0.0 dB                  0.0 dB
Signal Attenuation:       0.0 dB                  0.0 dB
Noise Margin:             6.1 dB                  6.4 dB
Attainable Rate:        41988 kbits/s            7562 kbits/s
Actual Power:            11.4 dBm                 3.8 dBm
Per Band Status:        D1      D2      D3      U0      U1      U2      U3
Line Attenuation(dB):   16.6    43.7    68.5    7.0     35.5    54.3    N/A
Signal Attenuation(dB): 16.6    43.7    68.5    7.0     34.5    51.0    N/A
Noise Margin(dB):       6.1     6.1     6.1     6.2     6.4     6.4     N/A
Total FECC:             67929076                         298
Total ES:               2242                     78
Total SES:              16                       0
Total LOSS:             0                        0
Total UAS:              31                       31
Total LPRS:             0                        0
Total LOFS:             0                        0
Total LOLS:             0                        0

Full inits:             1
Failed full inits:      0
Short inits:            0
Failed short inits:     0

Firmware        Source          File Name (version)
--------        ------          -------------------
VDSL            embedded        N/A (0)

Modem FW  Version:      23j
Modem PHY Version:      A2pv6C035j.d23j
Vendor Version:         Ap6v35j.23j 68


                  DS Channel1     DS Channel0   US Channel1       US Channel0
Speed (kbps):             0            36358             0              7506
SRA Previous Speed:       0                0             0                 0
Previous Speed:           0                0             0                 0
Reed-Solomon EC:          0         67929076             0               298
CRC Errors:               0            12842             0                83
Header Errors:            0            80574             0                 0
Interleave (ms):       0.00             8.00          0.00              0.00
Actual INP:            0.00             3.00          0.00              0.00

 

New Member

Hey,You probably fixed this

Hey,

You probably fixed this by now but I notice that you're using the embedded DSL firmware that comes with IOS. According to the output from your sh controller vdsl 0

Firmware    Source        File Name (version)
--------    ------        -------------------
VDSL        embedded       VDSL_LINUX_DEV_01212008 (1)

Modem FW  Version:    130205_1433-4.02L.03.A2pv6C035j.d23j
Modem PHY Version:    A2pv6C035j.d23j
Vendor Version:        Ap6v35j.23j 68

You can actually source firmware updates from the Cisco downloads page and set it up to use the new firmware bin file instead.

If anybody else is having this issue that's what I'd try first as the embedded firmware is known to have some issues according to my research.

New Member

HiIn response to user889988,

Hi

In response to user889988, it's a very good point suggesting an upgrade to the modem FW as Cisco worked with BT to produce specific code relating to UK exchanges.

The fix is well documented and you can search for;

operating mode auto

service internal

modem ukfeature

firmware filename flash:[name]

 

BUT in this case it's not necessary, 887VA's have been shipping for a while (approx. <12mths), with later firmware embedded.

The clue is in the filename

...35j.d23j

Earlier patched versions were 35d...  and hence are superseded by the above.

 

It could be worth your while checking out the other commands above though (excluding the firmware filename one).

n.b. operating mode auto is the default and doesn't show in the running config,

(sh contr vdsl 0 does contain "DSL Config Mode :   AUTO" though)

and 'modem ukfeature' - you can see in the output of

"show controller vdsl 0 console [number]" after the DSL modem trains;

you see something like:-

Force UKFeatureBit SET

There used to be a link to the doc at the following but I think it is a dead link now;

www.cisco-bt-portal.com/iusr/DSL/Product_Bulletin_DSL.pdf

New Member

Currently running the

Currently running the following firmware...

Modem FW  Version:    130205_1433-4.02L.03.A2pv6C035j.d23j

 

"modem ukfeature" was in my config, and after adding it can confirm that "Force UKFeatureBit SET" is present in the "show controller vdsl 0 console [number]" output.  I didn't check beforehand unfortunately.

Will keep an eye on the line and see if it helps.  Thanks!

New Member

I'm not from the UK but

I'm not from the UK but another thing to mention is if they enabled the G.Vector standard on the DSLAM (aka ITU-T G.993.5) then the modem firmware needs to be 38h or above to support it.

IMHO, I would just grab the latest firmware they have out since it will have all the latest features and optimizations plus a host of bug fixes picked up along the way. If it turns out to be worse just downgrade.

1654
Views
5
Helpful
10
Replies
CreatePlease login to create content