Upgrade to 21CN

Hi, our line has been upgraded to 21CN today, and with us being a bit thick we thought it would improve our service, is there a new training period? Our attenuation has gone from 33 to 45db and our noise margin has increased from 10 to 12. The download noise margin is 3db

Our sync rate has dropped to 6296Kb but our upload speed has increased from 448 to 1099Kb

our line is about 2.5km long

Regards

Lisa J

Edited by lisaj (Mon 25-Jul-11 19:47:52)

Although you are now upgraded to 21CN have you requested an upgrade to ADSL2+ because by default most ISP's that move you to 21CN keep you on the ADSL 8Mb product (with uncapped upstream).

Because the OP is reporting a downstream SNR of 3dB, this suggests that it is indeed a 21CN connection, on ADSL2 (20CN connections don't go that low, 6dB at most). The drop in downstream sync, however, might be due to line length, and the fact it is opting to go with an ADSL2+ connection. For longer lines, it is better to try and set the router NOT to attempt ADSL2+ and instead opt for ADSL2 (without the +) only.

Also, yes, a switch from 20CN to 21CN will cause another retraining of the line (as it is connecting to a completely new/independent system).

We had to order the upgrade from AAISP rather than wait for the multiple upgrades to be done, I think the hubby paid £13 for it to be done, so hopefully they will have changed there systems

Lisa J

A change of 3dB is normal in attenuation if going from ADSL mode to ADSL2+. Some routers do get the maths a little wrong and display odd numbers sometimes.

What was the sync before?

If running in ADSL2+ mode this is more sensitive to the presence of the ring wire, multiple extensions etc

If you had anything other than the full 8128Kbps sync with the old 33dB attenuation, then you had an underlying issue of one sort or another, which increases the chance of odd behaviour from ADSl2+.

Some people do find running the hardware in ADSL2 mode can produce better results, but with the WBC training mode, too much fiddling can slow you down as it increases the target margins.

Hi,

thanks for the reply, our original sync was 7200 giving us a bras of 6000, got home this evening and there had been a few loses of sync and the router was showing 5200 sync, but I think earlier BT had reduced the bras profile to 5500.

I have rebooted the router and our sync is now 7124 attenuation is 46 noise margin is 12 and our up sync is 1091 attenuation 20 and noise margin is now 6

Included a link to pic of our AAISP stats

http://imageshack.us/photo/my-images/189/adslstats.png

Regards

Lisa

Edited by lisaj (Tue 26-Jul-11 21:24:34)

7124Kbps, attenuation 46dB and a 12dB margin is actually pretty good.

The modem will only be resyncing if there is a noise spike, or you turn off/on so its a case of monitoring the figures to understand it, and see if there is a pattern.

If your line was stable and the target margin could be reduced you would sync faster, but something is making things unstable. It may be you had just ADSL before, in which case try forcing the modem to ADSL2 mode which can be more stable on some lines.

In reply to a post by MrSaffron:

7124Kbps, attenuation 46dB and a 12dB margin is actually pretty good.

The modem will only be resyncing if there is a noise spike, or you turn off/on so its a case of monitoring the figures to understand it, and see if there is a pattern.

If your line was stable and the target margin could be reduced you would sync faster, but something is making things unstable. It may be you had just ADSL before, in which case try forcing the modem to ADSL2 mode which can be more stable on some lines.

Hi, thanks for the response, the line has always been fairly stable usually around 6mb down, not sure how we would force the modem to ADSL2 mode, its a Belkin 8233 router

Lisa