ATM ADSL Trouble shooting!

neil grant · ‎01-11-2011

Hi Guys / Gals.

Thought I would start another tread as you all have been very very useful

Im having issues with a site basically the atm interface drops periodically and the ISP has confirmed the link as working fine (supposedly at 6Mb but clients at site are not seeing this even when router is up) I would like your advise to see if I am troubleshooting the issue correctly:

show int atm 0

ATM0 is up, line protocol is up

Hardware is MPC ATMSAR (with Alcatel ADSL Module)

MTU 4470 bytes, sub MTU 4470, BW 446 Kbit/sec, DLY 820 usec, <--------------------BW is this the actual bandwidth available to the router?

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5 AAL2, PVC mode

10 maximum active VCs, 1024 VCs per VP, 1 current VCCs

VC Auto Creation Disabled.

VC idle disconnect time: 300 seconds

Last input never, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: Per VC Queueing

5 minute input rate 1000 bits/sec, 3 packets/sec

5 minute output rate 1000 bits/sec, 2 packets/sec

7154 packets input, 628130 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

6764 packets output, 640759 bytes, 0 underruns

2 output errors, 0 collisions, 0 interface resets

0 unknown protocol drops

0 output buffer failures, 0 output buffers swapped out

show dsl interface atm 0

ATM0

Alcatel 20190 chipset information

ATU-R (DS) ATU-C (US)

Modem Status: Showtime (DMTDSL_SHOWTIME)

DSL Mode: ITU G.992.5 (ADSL2+) Annex A

ITU STD NUM: 0x03 0x3

Chip Vendor ID: 'STMI' 'TSTC'

Chip Vendor Specific: 0x0000 0x0510

Chip Vendor Country: 0x0F 0xB5

Modem Vendor ID: 'CSCO' 'TSTC'

Modem Vendor Specific: 0x0000 0x5100

Modem Vendor Country: 0xB5 0xB5

Serial Number Near: FCZ143293KG

Serial Number Far: 0000000000Chip ID: C196P (1)

DFE BOM: DFE3.0 Annex A (1)

Capacity Used: 57% 100%

Noise Margin: 11.5 dB 21.0 dB

Output Power: 20.0 dBm 12.0 dBm

Attenuation: 25.0 dB 11.0 dB

FEC ES Errors: 277 34161

ES Errors: 227 20763

SES Errors: 215 15853

LOSES Errors: 31 1018946

UES Errors: 0 1018667

Defect Status: None None

Last Fail Code: None

Watchdog Counter: 0x1C

Watchdog Resets: 0

Selftest Result: 0x00

Subfunction: 0x00

Interrupts: 4443 (0 spurious)

PHY Access Err: 0

Activations: 31

LED Status: ON

LED On Time: 100

LED Off Time: 100

Init FW: init_AMR-3.0.014_no_bist.bin

Operation FW: AMR-3.0.014.bin

FW Source: embedded

FW Version: 3.0.14

DS Channel1 DS Channel0 US Channel1 US Channel0

Speed (kbps): 0 6656 0 446 <----------------------------- Speed Is this the what the router should be running at?

Cells: 0 644 0 648061

Reed-Solomon EC: 0 3 0 228039

CRC Errors: 0 0 0 666995

Header Errors: 0 0 0 36077

Total BER: 0E-0 0E-0

Leakage Average BER: 0E-0 0E-0

Interleave Delay: 0 16 0 38

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 2 4 5 6 7 7 8 8 8

010: 8 9 9 9 9 9 9 9 8 8 8 7 6 5 3 0

020: 0 2 2 3 5 5 6 7 7 8 8 8 8 9 8 9

030: 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

040: 9 9 9 9 9 9 8 9 9 9 9 9 9 9 8 8

050: 9 9 9 9 9 9 9 8 9 9 9 9 9 9 9 9

060: 8 8 9 9 9 9 9 8 8 7 8 8 8 8 8 8

070: 8 7 7 8 8 8 8 8 2 8 8 8 8 8 8 8

080: 8 8 8 7 8 8 8 8 8 8 7 5 2 7 7 8

090: 8 8 8 8 8 8 8 8 8 8 8 8 8 7 8 7

0A0: 6 4 7 8 8 7 6 8 8 8 8 8 8 8 7 7

0B0: 8 8 8 8 8 8 8 8 8 8 8 8 7 8 8 8

0C0: 7 8 8 8 8 8 8 8 7 7 7 7 7 7 7 7

0D0: 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7

0E0: 7 7 7 5 7 7 7 7 7 7 7 6 5 7 7 7

0F0: 7 7 7 6 2 5 5 4 0 0 0 5 5 3 5 6

100: 7 7 7 7 6 4 2 5 6 6 4 0 4 5 5 2

110: 4 5 6 6 5 5 5 4 2 0 0 2 4 5 5 4

120: 2 4 5 5 5 5 5 5 3 2 4 5 5 5 5 5

130: 5 5 5 5 5 5 5 5 5 5 2 2 5 5 5 5

140: 5 4 2 0 2 4 5 4 5 5 4 2 2 3 4 2

150: 2 0 0 0 0 2 3 4 4 4 4 4 2 0 0 3

160: 4 2 3 4 3 2 0 2 3 4 4 4 4 4 2 2

170: 4 4 4 4 4 3 2 0 0 2 3 2 2 2 2 2

180: 0 0 2 2 2 3 3 2 2 0 2 2 3 3 3 3

190: 3 2 2 2 2 2 2 2 2 2 0 0 2 2 2 2

1A0: 2 2 2 0 2 2 2 2 2 2 2 2 2 2 2 2

1B0: 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

1C0: 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

1D0: 2 2 2 2 2 2 2 0 2 2 2 2 2 2 2 2

1E0: 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

1F0: 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0

DSL: Training log buffer capability is not enabled

----------

The interface seems to drop randomly for no specific reason I could be telneted to the device while pinging from another location, or just pinging.

provider has tested the line & confirmed as working.

Is the attenuation, noise margin acceptable? the configuration template is used on other sites without issue,

Any guidance on this matter would be very helpful.

show run in atm 0

Building configuration...

Current configuration : 132 bytes

!

interface ATM0

no ip address

no atm ilmi-keepalive

pvc 0/38

encapsulation aal5mux ppp dialer

dialer pool-member 1

!

end

show run int d1

Building configuration...

Current configuration : 306 bytes

!

interface Dialer1

ip unnumbered Loopback0

encapsulation ppp

dialer pool 1

dialer-group 1

no cdp enable

ppp authentication chap callin

ppp chap hostname xxxxx

ppp chap password 0 xxxx

ppp multilink

ppp multilink interleave

ppp multilink fragment delay 20

end

What is the correct method for viewing available bandwidth?

Cheers Neil

Regards Neil http://uk.linkedin.com/pub/neil-grant/20/5b0/267

mavespig · ‎01-11-2011

Hi Neil,

The speed on a DSL link is forced by the DSLAM and you can see it in show dsl interface:

DS Channel1 DS Channel0 US Channel1 US Channel0

Speed (kbps): 0 6656 0 446

So in this case you have a download speed of 6.6 Mbps and 446 kbps in upload.

The upload speed is inherited by the interface, so you will see this value under show interface atm.

Regarding noise margin and attenuation, you can use these values as reference:

Noise margin: the higher the better.

8-13 average, 14-22 good, 23-28 excellent. Under 8 dB the interface will loose synchronization, or it will not train up at all.

Attenuation: the lower the better.

20-30 excellent, 30-40 very good, 40-60 average.

In your case, you have an excellent attenuation value, but a lot of noise on the line, although it's within limits.

I also see a lot of CRC errors:

Reed-Solomon EC: 0 3 0 228039

CRC Errors: 0 0 0 666995

Are these errors incrementing?

I'd suggest to verify the output of show dsl interface on normal situation and when the line flaps.

Perhaps you may check with the ISP how the line react when you reduce the speed. With a lower speed the line will be less sensible to noise, hence more stable.

Try also to change the phone cable between router and wall plug, and verify if there may be any interference from electrical appliances close to the cable.

Hope this helps

Marco

neil grant · ‎01-11-2011

Hello Marco,

Cheers for the response, im not whether or not the counters are incrementing, Does anyone know the command to reset the counters to Zero, if i do this on 2 sites then compare the 2. Splitter and cable will be replaced shortly.

I will also compare the versions of code.

Best Regards Neil

Regards Neil http://uk.linkedin.com/pub/neil-grant/20/5b0/267

paolo bevilacqua · ‎01-11-2011

You should start updating ADSL firmware.

The access to it is different based if you have a support contract or not.