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[GaryW]

Looks like the Draytek 2760 has been superseded by the 2762.  Does anyone have any experience of the 2762?  Specifically, does it use the same/newer/worse/better Lantiq chipset versus the 2760?  Also, does it still support the "adsl snr [delta]" tweak?

[ejs]

No experience of it, but it's a newer Intel/Lantiq chipset.

[Ixel]

The manual doesn't mention such a command exists from what I can see, same for the 2862.

[GaryW]

In the spirit of "if in doubt, order it with a decent returns policy" my 2762 arrived today.  I haven't had a chance to switch yet (that'll have to wait until tomorrow morning) but I did have a play with the GUI and console, and can confirm that it does indeed still support the "adsl snr [delta]" command.  Also seems to have some decent looking diagnostics in the GUI (e.g. tone graph) which might go some way to making up for the lack of dslstats 

[atkinsong]

The tone graph is also a feature of the 2760.

[Ixel]

In the spirit of "if in doubt, order it with a decent returns policy" my 2762 arrived today.  I haven't had a chance to switch yet (that'll have to wait until tomorrow morning) but I did have a play with the GUI and console, and can confirm that it does indeed still support the "adsl snr [delta]" command.  Also seems to have some decent looking diagnostics in the GUI (e.g. tone graph) which might go some way to making up for the lack of dslstats 

Does it also contain vdsl snr [delta]?

I'm also currently developing a program for my DrayTek and LEDE which records and graphs stats from those devices, such as bitswaps.

A preview of my work in progress so far from my DrayTek: http://754.dsl.diagnostics.fr89.uk

Not done a tone graph, Hlog or QLN though. I tried requesting bitloading for my own program but the request seems to lag the router each time so I may avoid that. Hlog and QLN don't seem to work with 'vdsl' when I try them.

[GaryW]

I'll be posting in detail over the next couple of days, but spoiler alert: on my long line, Broadcom is way better.  Even with adsl snrm -50, and therefore running at 1db SNRM and (crazily) high FEC (and ES) errors, I can't hit the banded limit of 14999 that my Broadcom modems bump up against easily...   Bitloading and attenuation comparisons are very interesting, details to follow!

[Ixel]

I'll be posting in detail over the next couple of days, but spoiler alert: on my long line, Broadcom is way better.  Even with adsl snrm -50, and therefore running at 1db SNRM and (crazily) high FEC (and ES) errors, I can't hit the banded limit of 14999 that my Broadcom modems bump up against easily...   Bitloading and attenuation comparisons are very interesting, details to follow!

Interesting. Well I've got one coming tomorrow, I hope it has a 'vdsl snr [delta]' command or I'll probably have to send it back if it doesn't perform any better than what I've currently got. It will be ideally replacing the LEDE and rack mounted in my cabinet (above the current DrayTek I'm using on my other line), it will also serve as a backup should for some reason the Firebrick fail.

I think this may be a case of Broadcom not applying reed solomon on fastpath (assuming you're on fastpath?), where Lantiq/Infineon/Intel does (R: 16). This can create some overhead on some lines, depending on the quality of the line I guess. I notice no discernable difference between using Broadcom or Lantiq on my 'good quality' line (fairly low errors, at least when there's no storms potentially on the way/nearby or when it's not quite hot weather like at the moment). Broadcom does seem to produce more errors on the good quality line however, and a fractionally higher latency (1-2 milliseconds more). Currently the line with my 2860 has had 377 ES in the last 24 hours while my other line has had 922 ES in the last 24 hours.

Some modem chipsets work better on certain lines than they do on other lines. It's a matter of finding what works best for yours.

[Ixel]

To anyone wondering, the DrayTek Vigor 2862 does still include the 'vdsl snr [delta]' command in addition to the adsl variant. I received mine today, it has replaced the LEDE. Still some storm activity nearby. Interestingly the upstream speed test is about two megabits faster since replacing the LEDE and the sync rate isn't that much different for the upstream, so I can only assume the LEDE was being a bit of a bottleneck.

[GaryW]

The adsl vs vdsl is a bit of a red herring - if you use the adsl command it affects vdsl as well

I'm definitely not on fastpath for downstream, in fact the Draytek was user a lower interleaving depth than the broadcom based modems.  This chart shows the difference in bitloading, and bear in mind that:

• The broadcom modem (a Billion 8900AX) was hitting the 15000 banding at a little over 7db SNRM
• The Draytek was only getting 14400ish with 1db SNRM (and CRAZY FEC rates!) - at the default 6db it could only sync at 10700ish so the bit loading would be even worse, and at 3dB it could sync at 13000

Why the difference?  The broadcom modems report my line attentuation as 28db whereas the Draytek (and other Lantiq-based modems) report it as 33db...  The only thing that stops the Draytek sync being even worse is that it seems to be allowed to use all of the tones from 33 upwards on the downstream, whereas the DSLAM (ECI) only allows the broadcom modems to use tones from 67 upwards, and you can load a lot of bits in those low-numbered tones.

[Ixel]

Hmm, interesting. Well it still depends on the line somewhat as to what chipset performs best. It's also possible that DrayTek on traditional interleaving performs worse than Broadcom in terms of attainable rate. It's interesting how the line attenuation values differ a fair bit, I can't say I noticed the same when comparing Broadcom to Lantiq/Infineon/Intel on my line.