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Community Member

Testing reliability of DSL line from CPE to the DSLAM

Hi there,

We are using a Cisco 837 with IOS 12.2(11)YV and have a DSL service from our ISP (2048 kbits/sec donwstream & 256 kbits/sec upstream).

After a couple of weeks of monitoring the bandwidth using SNMP, the highest speed we have recorded downstream is 940 kb/sec. The upstream speed has been fine at 251 kbits/sec.

I am hoping that the problem lies at the DSLAM. I wish to find out if there are tests we can run from the IOS to test the reliability of the DSL line to the DSLAM.

Also, apart from conention ratios and the quality of the PSTN line used for the DSL connection, what other factors can affect our downstream speed?

Thank you,

Jahan Bybordi

Cisco Employee

Re: Testing reliability of DSL line from CPE to the DSLAM

We need to take a look on "show dsl interface atm0" to see the actual down/up stream rates on which the dsl line is trained with dslam. Here is the url explaining the meaning of all the fields.

Now SNR value and the distance from local telco (telco loop) is most inportant to get higher speed.

Community Member

Re: Testing reliability of DSL line from CPE to the DSLAM

Thank you for that, in respect of the SNR value what are expected values?

Would the SNR be the Noise Margin figure below? Would you be able to tell if any of these values are of concern?


Modem Status: Showtime (DMTDSL_SHOWTIME)

DSL Mode: ITU G.992.1 (G.DMT)

ITU STD NUM: 0x01 0x01

Vendor ID: 'ALCB' 'ALCB'

Vendor Specific: 0x0000 0x0000

Vendor Country: 0x00 0x0F

Capacity Used: 25% 35%

Noise Margin: 31.5 dB 25.0 dB

Output Power: 20.0 dBm 12.0 dBm

Attenuation: 32.0 dB 20.0 dB

Defect Status: None None

Last Fail Code: None

Selftest Result: 0x00

Subfunction: 0x15

Interrupts: 643 (1 spurious)

Activations: 1

Init FW: embedded

Operartion FW: embedded

SW Version: 3.919

FW Version: 0x1A04

Thank you and regards


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