ADSL WIC interface troubleshooting

Unanswered Question
Oct 3rd, 2008

Hi all,

my experience with ADSL WIC cards are limited and i was wondering whether there are any useful commands which can show PPP connection logs?

I need to confirm that the ADSL links are reliable.

Thanks all!

I have this problem too.
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Giuseppe Larosa Fri, 10/03/2008 - 01:55

Hello Mario,

I would start from OSI layer1

sh dsl interface

sh atm pvc x/y

in my case x/y= 8/35 with Acaltel chipset you can find out using

sh atm pvc

if both are fine the ADSL line is working well

examples:

RT-TGR-BRESCIA#sh atm pvc 8/35

Description: N/A

ATM0.1: VCD: 1, VPI: 8, VCI: 35

UBR, PeakRate: 640 (1510 cps)

AAL5-LLC/SNAP, etype:0x0, Flags: 0xC20, VCmode: 0x0, Encapsize: 12

OAM frequency: 0 second(s), OAM retry frequency: 1 second(s)

OAM up retry count: 3, OAM down retry count: 5

OAM END CC Activate retry count: 3, OAM END CC Deactivate retry count: 3

OAM END CC retry frequency: 30 second(s),

OAM SEGMENT CC Activate retry count: 3, OAM SEGMENT CC Deactivate retry count: 3

OAM SEGMENT CC retry frequency: 30 second(s),

OAM Loopback status: OAM Disabled

OAM VC Status: Not Managed

ILMI VC status: Not Managed

InARP frequency: 15 minutes(s)

InPkts: 1323884, OutPkts: 1213584, InBytes: 493599478, OutBytes: 289523102

InPRoc: 157735, OutPRoc: 152462

InFast: 1166149, OutFast: 1061122, InAS: 0, OutAS: 0

InPktDrops: 0, OutPktDrops: 0/0/0 (holdq/outputq/total)

CrcErrors: 0, SarTimeOuts: 0, OverSizedSDUs: 0, LengthViolation: 0, CPIErrors: 0

Out CLP=1 Pkts: 0

OAM cells received: 91857

F5 InEndloop: 91857, F5 InSegloop: 0,

F5 InEndcc: 0, F5 InSegcc: 0, F5 InAIS: 0, F5 InRDI: 0

F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0

OAM cells sent: 91857

F5 OutEndloop: 91857, F5 OutSegloop: 0,

F5 OutEndcc: 0, F5 OutSegcc: 0, F5 OutRDI: 0

F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0

OAM cell drops: 0

Status: UP

RT-TGR-BRESCIA#sh dsl int

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

Capacity Used: 26% 64%

Noise Margin: 30.0 dB 21.0 dB

Output Power: 15.0 dBm 12.0 dBm

Attenuation: 20.0 dB 11.0 dB

Defect Status: None None

Last Fail Code: None

Watchdog Counter: 0x17

Watchdog Resets: 0

Selftest Result: 0x00

Subfunction: 0x00

Interrupts: 7658 (0 spurious)

PHY Access Err: 0

Activations: 1

LED Status: ON

LED On Time: 100

LED Off Time: 100

Init FW: embedded

Operation FW: embedded

FW Version: 2.542

Interleave Fast Interleave Fast

Speed (kbps): 2464 0 640 0

Cells: 11320912 0 2070118174 0

Reed-Solomon EC: 2 0 2 0

CRC Errors: 0 0 5 0

Header Errors: 0 0 0 0

LOM Monitoring : Disabled

Hope to help

Giuseppe

marioderosa2008 Fri, 10/03/2008 - 02:15

Thanks Giuseppe! Thats very helpful.

Does the router store any kind of PPP connection logs / attempts?

Giuseppe Larosa Fri, 10/03/2008 - 04:00

Hello Mario,

a starting point to get info could the

sh users

that should list also current PPP session

then depending on the type of ADSL service you have other commands can be available like

sh pppoe session

if using PPPoE

Hope to help

Giuseppe

marioderosa2008 Tue, 10/14/2008 - 02:25

Hi Giuseppe,

I have been comparing my output results to yours.

Now baring in mind that i am in the UK and all four lines a DSL MAX lines, i notice a couple of differences.

Firstly,

on all 4 ATM interfaces, the Capacity used is 99% & 58% there abouts.

Your figures seem to be half of that nearly... What does this capacity used mean?

Secondly,

on your print out, you seem to have no CRC errors where as mine on a couple of the interfaces are in the thousands.

The same goes for the Reed-solomon EC figures. Yours a near enough 0, where as mine are a lot higher.

Any advice on my findings will be appreciated. I am going to try and find out where i can find what the recommended noise margins should be for DSL MAX lines.

Thanks again!

marioderosa2008 Tue, 10/14/2008 - 02:32

I have also found out another useful output... can you see anything out of the ordinary from the following output...?

Virtual-Access5, bundle name is th-lns-entanet-1

Endpoint discriminator is th-lns-entanet-1

Bundle up for 2w3d, total bandwidth 1792, load 8/255

Receive buffer limit 48768 bytes, frag timeout 1000 ms

Dialer interface is Dialer0

0/0 fragments/bytes in reassembly list

7688 lost fragments, 12465261 reordered

4925/1818468 discarded fragments/bytes, 432 lost received

0xB122F4 received sequence, 0xE4DC8A sent sequence

Member links: 4 (max not set, min not set)

Vi2, since 2w3d

PPPoATM link, ATM PVC 0/38 on ATM0/0/0

Packets in ATM PVC Holdq: 0, Particles in ATM PVC Tx Ring: 0

Vi3, since 2w0d

PPPoATM link, ATM PVC 0/38 on ATM0/1/0

Packets in ATM PVC Holdq: 0, Particles in ATM PVC Tx Ring: 0

Vi4, since 2d20h

PPPoATM link, ATM PVC 0/38 on ATM0/2/0

Packets in ATM PVC Holdq: 0, Particles in ATM PVC Tx Ring: 0

Vi6, since 2d01h

PPPoATM link, ATM PVC 0/38 on ATM0/3/0

Packets in ATM PVC Holdq: 0, Particles in ATM PVC Tx Ring: 0

No inactive multilink interfaces

I notice that there are lost fragments, however i am not sure whether these numbers mean anything or whether that amount of lost fragments is usual for ADSL.

Giuseppe Larosa Tue, 10/14/2008 - 09:09

Hello Mario,

1) Capacity

In my case is Capacity Used: 26% 64%.

I think this capacity means how DMT tones are used: DMT uses multiple subcarriers tones where each of these can use a different modulation and they are characterized by different bits for tone.

Depending on the upstream and downstream rates that can be configured different bits per tone distributions are used.

In your case your lines are used with higher bit rates so you get higher capacity figures in both directions

2) errors

A line using higher bit rates is more exposed to errors because it requires an higher SNR (signal to noise ratio).

Line quality actually changes line by line so you can have two lines working well and two with some errors over them.

Reed-solomon is a line code that can correct some errors if only one bit error is in a bit block.

So a correlation between RS errors and CRC errors on interfaces is to be expected.

Another possible source of errors could be the form of PPP multilink you are using over the four ATM/ADSL links: the lost ppp fragments can be frames discarded by CRC errors and carrying a fragment of the original IP packet (or the whole IP packet depending on packet size) on the two lines with less then perfect performance that are a result of multiple bit errors in the same bit block that appear as RS EC figures.

The question is if the error rate is low and it is not a problem or you need to do some corrective actions.

For doing this you can compare the total number of input packets to the number of input errors if the ratio is > 1000 you can be fine even with some error figures

Hope to help

Giuseppe

marioderosa2008 Wed, 10/15/2008 - 01:27

Hi Giuseppe,

do you mean comparing the total number of input packets & errors of each individual ATM interface?

Also, in the last print out that i posted, it advises a total bandwidth of 1792.

Is that made up of total bandwidth accross all 4 ATM interfaces?

marioderosa2008 Wed, 10/15/2008 - 02:25

Hi Giuseppe, just to make it easier, Here is the output of show dsl int for atm0/3/0

ATM0/3/0

Alcatel 20166/20174 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: 0x01 0x1

Vendor ID: 'ALCB' 'TSTC'

Vendor Specific: 0x0000 0x0400

Vendor Country: 0x00 0xB5

Capacity Used: 99% 58%

Noise Margin: 6.0 dB 22.0 dB

Output Power: 20.0 dBm 11.5 dBm

Attenuation: 44.0 dB 25.5 dB

Defect Status: None None

Last Fail Code: None

Selftest Result: 0x00

Subfunction: 0x17

Interrupts: 6118 (1 spurious)

PHY Access Err: 0

Activations: 5

LED Status: ON

LED On Time: 100

LED Off Time: 100

Init FW: embedded

Operation FW: embedded

SW Version: 13.101

FW Version: 0xC166

Interleave Fast Interleave Fast

Speed (kbps): 4064 0 448 0

Cells: 18142552 0 277520684 0

Reed-Solomon EC: 736 0 9 2

CRC Errors: 7731 0 5 3

Header Errors: 6451 0 4 5

Bit Errors: 0 0

BER Valid sec: 0 0

BER Invalid sec: 0 0

LOM Monitoring : Disabled

DMT Bits Per Bin

00: 0 0 0 0 0 0 0 2 2 5 5 7 7 7 8 8

10: 8 8 8 8 8 8 8 7 8 7 7 6 5 5 0 0

20: 0 0 0 0 0 0 2 2 4 4 5 5 6 6 6 6

30: 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

40: 0 6 6 6 6 6 6 6 6 6 6 5 5 5 5 5

50: 5 5 5 6 6 6 6 6 6 6 6 6 2 6 6 6

60: 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7

70: 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 9

80: 9 9 9 A 9 A A B B A A A 9 8 9 9

90: 9 8 8 8 8 8 7 8 8 8 7 7 7 7 7 7

A0: 7 6 7 7 7 7 7 5 5 6 7 6 6 6 6 6

B0: 4 5 6 6 6 6 6 6 5 5 5 5 5 5 5 5

C0: 5 5 5 5 5 5 5 5 5 5 4 4 5 6 6 6

D0: 6 6 5 3 4 5 6 6 6 6 6 6 6 6 6 5

E0: 6 6 6 5 5 4 4 5 6 5 5 5 5 3 2 2

F0: 4 2 3 3 2 0 0 0 0 0 0 0 0 0 0 0

DSL: Training log buffer capability is not enabled

I can see from here that this line is syncing at 4mbps down.

The SNR margin is only 6dB and the attenuation is a wopping 44dB. So it looks to me that this line is pretty long and there is not a lot of margin for sync loss.

Giuseppe Larosa Wed, 10/15/2008 - 02:33

Hello Mario,

I agree it would be wise to go slower to get a better noise margin.

the error rate is 0.82 10exp-3

So you can be fine also as now

Hope to help

Giuseppe

marioderosa2008 Thu, 10/16/2008 - 06:09

Hi Giuseppe,

have you any ideas on how i improve my SNR?

And do you think the Capacity readings on the interface i showed you in the previous post is a bad reading? Do you know if that will affect performance in any way?

I'll see if i can research this myself too.

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