Interpreting line stats

Since having Infinity 2 installed I've 'lost' around 10mbit of sync speed.
I know I'm lucky to get 70mbit+ but as I'm <25m from the cab I'm wondering what the issue could be.
I've got the following graphs from RS-UX and appreciate any pointers.

http://farm9.staticflickr.com/8524/8535335580_b2363c...

http://farm9.staticflickr.com/8243/8534227405_7b84e4...

http://farm9.staticflickr.com/8508/8536518186_342c37...

http://farm9.staticflickr.com/8381/8536518234_520685...

Did you know that first graph is scrollable horizontally? Also, it's more recognisable if you untick Expanded View.

What about Bitswaps per min?

Thanks. I did assume that after looking at the 2nd graph so I'll uncheck that option next time.
I saw the option for bitswaps which I'll enable and try again.

Cross talk as the cable bundles get fully populated

http://www.thinkbroadband.com/guide/fibre-broadband.... and scroll down the page a bit and the table there is often accussed of been wrong, but its line length speed estimate takes into account cross talk as well as distance.

I lost about 4Mb/s when interleaving was enabled after an engineer visit.

I've been looking a bit further and the SNR seems to be stable.
My cabinet is <50m away so I'm a bit surprised that my DS SNR is down to 5.7db.

Graphs on Dropbox - http://db.tt/T6xoo39k

Edited by smouty (Tue 19-Mar-13 08:53:57)

"My cabinet" is about 25 yards away, literally just across the road; but the phone wire length is about 125 yards (or possibly longer), going first east from the cabinet and coming across the road (somewhere) to a small Jointing Box, by a near-neighbour's house, before returning west-ward to my front door.

It was a GPO/BT Phones lad who pointed this out to me back about 1990, when sorting out noise interfering with my Dial-Up access to work.

He had already re-made the joints in the very obvious cabinet - but this had not cured the problem.

Looking at the 1967-Installation records he had with him, showed this little Jointing Box, which being at footpath level, was more exposed to rain etc.

Re-making its joints cured the problem.

In reply to a post by smouty:

I've been looking a bit further and the SNR seems to be stable.
My cabinet is <50m away so I'm a bit surprised that my DS SNR is down to 5.7db.

SNRM on FTTC is not treated the same way as on ADSLx. In particular it is not, so far as we know, used to improve stability. It looks as though it is always set at 6dB at sync time.

Stability is achieved through various depths of interleaving if Fast Path proves unreliable, and speed banding if even that doesn't sort things out.

Edited by RobertoS (Tue 19-Mar-13 09:44:25)

In reply to a post by RobertoS:

Stability is achieved through various depths of interleaving if Fast Path proves unreliable, and speed banding if even that doesn't sort things out.

One thing intrigues me. Prior to this month my modem was showing an attainable rate of ~73Mb/s and that's more or less where I connected. Then an SFI engineer visited and I got lumbered with interleaving of 1041 and attainable rate went up to 78Mb/s. After 14 days the interleaving was dropped back down to 1 which as far as I know puts me back where I was before the engineer visited but my attainable rate is now ~71Mb/s.

Is it just a coincidence? I have noticed that my throughput is about where it was back when I connected at ~73Mb/s even though I'm now connected at ~71MB/s so in practical terms I am back where I was before the visit.

My understanding is that 6db is the minimum. If you can hit 80mbit with a higher SNR then you will. I looked for other peoples SNR graphs and this appears to be the case.