Router vs. Telco DSL Quality Stats
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Posted by on April 2, 2008, 2:30 pm
Please log in for more thread options We have been having an on-going battle with several local telcos over DSL line quality. For some reason their testers always show a much higher line quality than does the routers. For example, I have taken the exact same DSL POTS cable, and plugged it into a Cisco 827, 837, and 877 router and got essentially the same line quality stats. When the local telco test the line (usually using a SunSet MTT test set), they consistently see a good quality line, where the routers see a marginal line -- one that keeps dropping. (And this is not just a single line at a single location -- we have the same problem at multiple locations, and at some locations, on multiple lines at that location.) For example, here is what the router reports: ATU-R (DS) ATU-C (US) Capacity Used: 98% 53% Noise Margin: 5.0 dB 12.0 dB Output Power: 17.0 dBm 8.0 dBm Attenuation: 64.0 dB 31.5 dB Interleave Fast Interleave Fast Speed (kbps): 1216 0 256 0 and the test set reports: Capacity: 47% / 40% SNR: 8.5dB / 15dB Attenuation: 40dB / 28dB kbps: 1472 / 256 (noise profile) Why such a substantial disagreement between telco test sets and Cisco routers? Especially when there is no difference between the wiring to the device, up to and including the cable plugged into the device. This is getting to be a real pain. We have flaky connections and numerous drops, yet the telco says everything is fantastic. It just doesn't make sense. TIA for any insights into this problem. Jon K. | ||||||||||||||||||||||
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Posted by LouB on April 2, 2008, 4:34 pm
Please log in for more thread options The telcos are lying to save money. Escalate the complaint. | ||||||||||||||||||||||
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Posted by Merv on April 3, 2008, 4:12 am
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you should check that you have the latest DSL firmware loaded see Cisco doc "IOS Software Release-to-DSL Firmware Version Mapping on Cisco Access Routers" http://www.cisco.com/en/US/prod/collateral/routers/ps221/prod_bulletin0900aecd801d5c4c.html | ||||||||||||||||||||||
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Posted by on April 3, 2008, 9:39 am
Please log in for more thread options > you should check that you have the latest DSL firmware loaded
> > see Cisco doc "IOS Software Release-to-DSL Firmware Version Mapping on > Cisco Access Routers" > > http://www.cisco.com/en/US/prod/collateral/routers/ps221/prod_bulleti... There are free ftp downloads of firmware for the 8[57]7. ftp://ftp.cisco.com/pub/access/800 I have found them to be useful in a number of cases but since the IOS bundled firmware went to 3.x I have not bothered. Certainly with the 857 and 877 I have seen numerous issues that firmware changes have resolved. This has been in the UK. | ||||||||||||||||||||||
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Posted by on April 3, 2008, 11:13 am
Please log in for more thread options Thanks to all. I will try some firmware upgrades this weekend.
I guess that leaves me with the question of how the firmware can effect apparent line quality? It seems that line quality should be independent of the chipset/firmware used. Can someone please explain this? Again, THANKS! Jon Kibler | ||||||||||||||||||||||
>
> We have been having an on-going battle with several local telcos over
> DSL line quality. For some reason their testers always show a much
> higher line quality than does the routers.
>
> For example, I have taken the exact same DSL POTS cable, and plugged
> it into a Cisco 827, 837, and 877 router and got essentially the same
> line quality stats. When the local telco test the line (usually using
> a SunSet MTT test set), they consistently see a good quality line,
> where the routers see a marginal line -- one that keeps dropping. (And
> this is not just a single line at a single location -- we have the
> same problem at multiple locations, and at some locations, on multiple
> lines at that location.)
>
> For example, here is what the router reports:
> ATU-R (DS) ATU-C (US)
> Capacity Used: 98% 53%
> Noise Margin: 5.0 dB 12.0 dB
> Output Power: 17.0 dBm 8.0 dBm
> Attenuation: 64.0 dB 31.5 dB
> Interleave Fast
> Interleave Fast
> Speed (kbps): 1216 0
> 256 0
>
> and the test set reports:
>
> Capacity: 47% / 40%
> SNR: 8.5dB / 15dB
> Attenuation: 40dB / 28dB
> kbps: 1472 / 256 (noise profile)
>
> Why such a substantial disagreement between telco test sets and Cisco
> routers? Especially when there is no difference between the wiring to
> the device, up to and including the cable plugged into the device.
>
> This is getting to be a real pain. We have flaky connections and
> numerous drops, yet the telco says everything is fantastic. It just
> doesn't make sense.
>
> TIA for any insights into this problem.
>
> Jon K.