Noise Margin on new 21CN Connection

My line has recently been switched to 21CN equipment in my Market 1 exchange but I have yet to make make the jump to ADSL2+ and am wondering whether this would in fact be a good move.

Before the connection was switched, the downstream noise margin was a fairly steady 10dB with a router connection speed of 8128 kbit/s.

Since the switch the noise margin has risen to 15dB, although the connection speed is still almost the same (8064 kbit/s).

Router is a Thomson 546v6

Any advice would be gratefully received.

Some stats:-

Modemstate : Up
xDSL Type : ADSL
xDSL Standard : ITU-T G.992.1
xDSL Annex : Annex A
Channel Mode : Interleaved
Uptime (days hh:mm:ss) : 0 days, 2:26:20

Number of resets : 1

Total Available Bandwidth Cells/s kbit/s
Downstream : 19018 8064
Upstream : 2339 992

Intrinsic/Actual and Maximum Bandwidth % kbit/s
Downstream : 74 10848
Upstream : 86 1144

Bearer Generic Info Downstream Upstream
Margin (dB) : 15.0 11.0
Attenuation (dB) : 22.0 10.5
OutputPower (dBm) : 19.5 12.5

With the 22dB attenuation and 15dB SNR on ADSL Max you are getting full speed.

Moving to ADSL2+ will give a significant improvement in your downstream speeds - possibly 15 Mbps or probably even more along with an improvement in upstream too.

The DSLAM will eventually drop that down to 3.0db if the line is stable.

Mine is running on 3.0db and its far far longer than your line.

ISP may have the user on an like ADSL type profile, so may need the ISP to actually regard to an up to 16/20/24 speed option

Should run nice and fast though

Yes - still on ADSL (up to 8) profile but going for the regrade option.

So am I right in thinking that once the ADSL2+ regrade takes place the MSAN & Router will try to negotiate the highest stable speed possible and so the noise margin will reduce as this happens?

What threw me was the increased noise margin on the 21CN equipment - but I guess if the full 8064kbp/s is being achieved then there is no need for the margin to be any tighter.

Thanks for your help

The increased noise margin is taking up the slack cuz you're still on 8 Meg ADSL Max on a line capable of much more.

On ADSL2+ you should get 18 Meg @ 6 dB NM or even 19-20 Meg @ 3 dB NM which DLM on WBC will attempt if it is sufficiently stable.

In reply to a post by wolvesmad:

The DSLAM will eventually drop that down to 3.0db if the line is stable.

Mine is running on 3.0db and its far far longer than your line.

No it will not. If he remain on an 8Mbps product then it will stay at around that figure unless the total output power is also reducced which is unlikely.

If the OP moves to ADSL2+ the SNR will drop to probably 6dB to start.

So why did mine gradually go down from 12db to 3db AFTER I migrated to 21CN?

Absolutely no idea ... but if the OP remains on an 8Mb product there is no reason for his SNR to change significantly.

Cuz you were migrated to ADSL2+ WBC.

It is not sufficient for your exchange to be 21CN'ed but for your particular line to be moved to WBC from IPStream.