again it depends.

under 10 crc errors a week I have not seen a single line achieve that so I would say more like the following.

sub 30db attenuation line on adsl1.

crc a week

0-200 excellent
200-1000 ok
1000+ needs looking at

45+ db adsl1

0-1000 excellent
1000-10000 good
10000-100000 ok but may cause problems
100000+ needs looking at

the best of lines on adsl2+ are likely to get significantly more errors than they do on adsl1, all these figures are far from set in stone as so many variables and different routers handle crc errors better.

In reply to:

---

There is no fixed figures, you get a feel for these in combination with all the other data for a line.

---

Agreed.

My CRC error rate of around 63,000 is good for an uptime of nearly 34 days!


Uptime: 34 days, 6:44:55
Modulation: G.992.1 Annex A
Bandwidth (Up/Down) [kbps/kbps]: 448 / 3,520
Data Transferred (Sent/Received) [MB/GB]: 834.66 / 12.21
Output Power (Up/Down) [dBm]: 11.5 / 18.0
Line Attenuation (Up/Down) [dB]: 31.5 / 55.0
SN Margin (Up/Down) [dB]: 18.0 / 8.5
Vendor ID (Local/Remote): TMMB / 
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 20,341 / 0
FEC Errors (Up/Down): 5,288 / 7,031,983
CRC Errors (Up/Down): 3,188 / 63,768
HEC Errors (Up/Down): 2,218 / 56,264


p.s. the FEC error rate is quite low as well.

In reply to:

---

My CRC error rate of around 63,000 is good for an uptime of nearly 34 days

---

That's a CRC count. The rate per day is that divided by 34.

Swapping words that mean different things isn't a good idea . You and I both know what you mean, but does everybody?

Does the OP even, seeing as in another thread he clearly didn't know the difference between SNR and SNRM?

"There is no fixed figures, you get a feel for these in combination with all the other data for a line. "

I know what you mean but the DLM doesn't have feelings so it must work to some sort of algorithm. Is it really so secret that BT won't release it or is your target SNR based on some sort of random pot luck generator.

John.

They won't release it, and I wasn't realy referring to the DLM, but CRC and error counts in general

fwiw I'm on adsl2 synching at 24574/1402 with an attenuation of 18db and snr of 4.9db and usually get around 40 crc errors per hour.

I agree with that completely - if the distance is far, or there is noise on the line, I would expect that there to be a much higher CRC error rate and that to me would be a natural correlation.

If we assume that the line was within 1.8 km with a good SNR, and with a good modem, then we could work out some sort of baseline. And then I can work out what the other factors are (eg if Attenuation is X then that is likely to increase the CRC errors by y)

If it gets a higher CRC error then those other factors could be relevant. (does that make sense?)

Do you think sampling it over an hour would be better? That is certainly something that I have traditionally done I have seen some routers do thousands within 3 mins, so my feel for it is that it can generally sit quite low all things being equal, and it can spike up dramatically once the fault condition is on the line. And then LCP typically has a paddy so drops the line.

I have heard that a modem is relevant and that certainly sounds correct to me, and I may try to work out what brands of modems have this as an issue and I have seen some firmwares just appear to suck.

But it often as a combination of say firmware, interleaving, DSL2+, distance, noise, CPE etc, but I think it would be possible to work out some sort of baseline and then compare modem types against that to see if it is over or above and then I could work out the "Less stable" modems.

You could try to factor in the Errored Seconds and Severely Errored Seconds to try to cater for the bursty nature of noise. A problem is I'm not sure if those numbers have a consistent meaning as reported by the various routers.

In reply to:

---

My CRC error rate of around 63,000 is good for an uptime of nearly 34 days

-------------------------------------------------------------------------------------------------------

That's a CRC count. The rate per day is that divided by 34.

Swapping words that mean different things isn't a good idea . You and I both know what you mean, but does everybody?

---

Sorry I didn't know that (above)

No problem

Sorry if I came across a bit stroppy. Just that after a lifetime in IT inaccurate descriptions are anathema, as very few correct diagnoses come from incorrect information.