Meaning of "Attainable Rate"?

Hi,

My router stats look as follows (sorry about the formatting):

adsl status
--------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
Running Mode : ADSL2+(G.992.5) State : SHOWTIME
DS Actual Rate : 6648972 bps US Actual Rate : 1063878 bps
DS Attainable Rate : 7876000 bps US Attainable Rate : 1064000 bps
DS Path Mode : Fast US Path Mode : Fast
DS Interleave Depth : 1 US Interleave Depth : 1
NE Current Attenuation : 42 dB Cur SNR Margin : 8 dB
DS actual PSD : 19. 0 dB US actual PSD : 12. 8 dB
ADSL Firmware Version : 232201_A
-------------------------------- ATU-C Info ---------------------------------
Far Current Attenuation : 18 dB Far SNR Margin : 9 dB
CO ITU Version[0] : 00004946 CO ITU Version[1] : 0000544e
DSLAM CHIPSET VENDOR : < IFTN >

Can anyone help with explaining what the "DS Attainable Rate" and "US Attainable Rate" are governed by? Obviously they're DownStream and UpStream but how are they determined?

Thanks,

Tom

As I understand it 'attainable rate' means the rate the modem could connect at if it were allowed. A bit like saying the attainable speed of my Honda Jazz is 105mph. In practice road conditions and most especially the Police prevent me reaching that. The only thing I find a bit puzzling in your case is why your actual rate is so far below the attainable when both are below 80Mb/s. It probably relates to the BT profiling and/or DLM. For some reason the modem isn't being allowed to reach its full potential.

Doesn't look abnormal though - just a little sub optimal. Perhaps your line is a bit noisy.

The noise margin also affects it. I don't know what the Attainable rate calculation assumes for that. It's also quite common on ADSLx, and I find even more so on VDSL2, for the actual to be higher than the "maximum".

In reply to a post by Andrue:

The only thing I find a bit puzzling in your case is why your actual rate is so far below the attainable when both are below 80Mb/s

OP''s on ADSL2+ not VADS!. He's syncing at < 8 Meg.

With an 8dB margin you are getting the actual. The attainable will be what is possible is you used a lower target noise margin generally. Of course if noise is such that the line becomes unstable, there is little point in pushing the extra sync

42dB attenuation on ADSL2+ you are a little slow, but not massively so.

In reply to a post by XRaySpeX:

In reply to a post by Andrue:

The only thing I find a bit puzzling in your case is why your actual rate is so far below the attainable when both are below 80Mb/s

OP''s on ADSL2+ not VADS!. He's syncing at < 8 Meg.

Oops, yeah I wasn't in the forum I thought I was.

There's a lot of that about

Thanks Everyone.

Very useful - I has wondered if it had referred to an ISP or Network-set limit (banding) but it sounds like it's a Draytek set guess based on what the sync could be if the noise was lower.

Cheers

Tom

In reply to a post by Anonymous:

what the sync could be if the noise was lower.

If the noise were lower it would go like the clappers

No, it's if the target Noise Margin were lower.

In reply to a post by XRaySpeX:

In reply to a post by Anonymous:

what the sync could be if the noise was lower.

If the noise were lower it would go like the clappers

No, it's if the target Noise Margin were lower.

theoretically yes, but how many lines would sync with the target noise margin set at 0db ? never mind hold a sync with a 0 db margin for any period of time
But the theoretical attainable rate also increases or decreases according to what the margin is showing , mine at now is saying 194.500 kbps attainable, it fluctuates all the time, i think the highest Ive seen is around the 21000kbps mark and that was last summer

Edited by tommy45 (Thu 02-Aug-12 21:31:28)