Attainable rate

I'm curious how attainable rate is calculated by router. I've noticed in general attainable rate value is much higher than actual rate immediately after synchronization establishing. It seems attainable rate is not only depended on synchronization rate which occured when it would be 6 dB SNR margin. What also attainable rate is depended on?

Edited by konrado5 (Sat 09-Nov-13 20:28:34)

It is a calculation based on what the modem thinks if could do if no limits were imposed by the exchange based hardware

http://www.coolwebhome.co.uk/calc does a vaguely similar calculation based on your current router stats

Thank you for reply.

In reply to a post by MrSaffron:

It is a calculation based on what the modem thinks if could do if no limits were imposed by the exchange based hardware

I know it. I'm interested with details of "no limits"? I know it's for example target SNR margin. What else is regarded with attainable rate calculation in router?

http://www.coolwebhome.co.uk/calc does a vaguely similar calculation based on your current router stats

I have completely other result with this calculator.

If you can post the figures then we can see if there is something odd or just post the sharing link from the calculator

Some routers display an attainable rate that is based on a 0dB noise margin, some may also look at the unused bits per pin - they are unused because to meet the target noise margin DSLAM has set.

In reply to a post by MrSaffron:

http://www.coolwebhome.co.uk/calc does a vaguely similar calculation based on your current router stats

Don't think it does! It estmates speeds at various NMs but never at 0dB.

In reply to a post by MrSaffron:

Some routers display an attainable rate that is based on a 0dB noise margin, some may also look at the unused bits per pin - they are unused because to meet the target noise margin DSLAM has set.

Isn't that one & the same?

Possibly - doing the maths on just the margin figure is different to doing it on a per bin basis.

So while the two methods are usually similar they can be instances where they diverge. Seeing the stats in each case helps as then can see if connection speeds are nice round figures e.g. banding/fixed speed/DLM type ones.