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[kitz]

Without doubt some routers perform better on some lines than on others. Its not specifically 'BT modems' but more to do with the chipset.  For example the 2Wire 2700HGs seem work really well on long lines but are rubbish for short lines.  They do dont annex_m so I'd lose 1.6 Mbps from my upstream and I should have been easily able to sync at 24Mbps, but I could never get more than about 17/18Mbps on the downstream.  Thats a massive drop.  The Infineon chipsets didnt do too well on my line either again couldnt get more than 18Mbps, yet put a broadcom based chipset on and I could get considerably higher speeds.   The sometimes hated ST585v6 and TG582n though worked fantastic and at one time gave me a rock steady 24Mb down 2.6 up, and just slightly better than the Netgear DG series.

So sometimes its a case of suck it and see.  On the whole BCM based chipsets do seem the most favoured across the board.  Its also said to help if you match your router chipset with the DSLAM chipset, which is possibly why BCM do quite well for a lot of people.

-----

That said however, its not the main issue here.  The OP was lumbered with 2Mbps speeds for months using the BT modem and its only buy purchasing his own router that hes been able to see his stats to prove that something is wrong with the line and its capable of acheiving more.   

Whatever happened to band the line happened whilst using the BTor modem, but its still not right now and something is wrong with the upstream too, It looks like there may be a fault on the line but without using something like routerstats to monitor the SNRm its difficult to say. 


Brian may have missed my suggestion to try a Quiet Line test to see if he can hear any noise on the line.  Its a shame that routerstats isnt monitoring because Id also like to see what happens to the SNRm when the phone line is in use. 

[boe323]

Oh I see, oh well.

[NewtronStar]

You will probably see better results if you use bt's modem, im sure(my theory) that the dlm looks for something in the modem, see's its not Bt openreach and gives you pooh speed, I spent a fortune on a draytek router

looking at some TalkTalk members they are having better download experience when using the HH4 that could be because its using more modern tech than what the ISP is providing at the time the customer signs up "HG533" to there designated ISP and nothing to do with BT/Openreach firmware inside router/modem.

[kitz]

^ Back to chipsets again?

Despite what some may say or think, the Talktalk HG533 has MediaTek (Trendchip) TC3086.

The HH4 has a Lantiq ARX368.  Dunno what lantiq are like but seeing the AR immediately made me think of TI.. and sure enough google tells me Lantiq took over what used to be Texas Instruments - infamous for their AR7 chipsets.*


*Lot of history behind AR chipsets - used to be considered better than BCM and rock steady on problematic lines. Used in routers like the DG834G until Zen found a problem with the firmware. 

[NewtronStar]

Lantiq took over what used to be Texas Instruments -

please stop reminding us of how old we are, I use to potter about in the Maplins shop in early 80's with my eyes set on the TI-99 computer but could only afford a spectrum 

[kitz]

 

[Brian Coat]

Thanks for all your inputs.

Here is an update

1. As others have surmised, I got same rates from both modems before, maybe because the IP profile was clamped.

2. I asked Zyxel how they plan accommodate rumoured forthcoming changes to tone scheme on Infinity - they tell me they plan a firmware update for December.

3. BT did more tests over the phone then send an engr.

"I'm a phone engr not an Internet guy but I'll have a go" he said. Fairy nuff.

He reset ip profile and his kit showed 3 potential faults. One on a pole checked out NFF, one is is our roof space (on BT's side) he could not reach it, one in road underground, he could not reach it.

They are intermittent.

Will need a repeat engr visit.

(I had previouslydone a quiet line test - as advised - for long periods and heard nothing but I expect the engrs kit is far more sophisticated than a phone please my middle aged ears!).

Meanwhile d/s rate is now 12 MBPS yay! - 6x what it was but its dropping out and is bound to 'learn down', I think.

I'm OK With a slightly lower speed as long as it does not learn back to 2MBPS whilst they trace these tricky intermittent faults.

Idea: until the fault is fixed, if I fit Zyxel modem and clamp the d/s rate to say 4MBPS using a QoS clamp, will the resultant stability stop the IP profile learning down too far at night?

Thoughts??

Thanks.

[kitz]

>> they tell me they plan a firmware update for December.

Thanks for that info.

>> "I'm a phone engr not an Internet guy but I'll have a go

Glad that hes reset your IPporfile.  Not so good that he wasnt able to rectify the fault the same say.  Hopefully he has arranged for someone to come who can access the required areas.

>> Idea: until the fault is fixed, if I fit Zyxel modem and clamp the d/s rate to say 4MBPS using a QoS clamp,

Not sure if QoS would do the trick.  Im not familiar with your router, but it would be the sync speed you would need to reduce.  QoS normally only affects the throughput, so youd still have the sync overhead.

The way to cut down on your sync and lessen the chance of the DLM kicking in too hard would be to lower the sync by increasing the SNR Margin.  BTor set the SNRm to 6dB by default and dont seem to bother with SNRm changes (unlike the BTw DLM).  Some routers have the ability to change the target SNRm and this works on BTw based DLMs.

I dont know if the BTor DLM would respond to a target SNRm tweak to say 9 or 12 dB.   Some have tried lowering it to 3dB which doesnt work and the DLM has over-ridden it.  However Ive not know anyone attempt to increase it.. so you'd be the guinea pig if you did try it.   Increasing the target SNRm (if it works on BTor) is the best way to artificially lower the sync for stability until another engineer gets around to fixing things properly.

[Brian Coat]

Next update.

THANKS for all the advice.

Another BT engr came today and "found something".

I'm still getting 12 MBPS d/s and IP Profile is 12.61 MBPS  about 30 hours

I'm interested in the idea of using an upward tweak of the SNR margin but I do not know how to do this from the Zyxel, anyone know?

Otherwise, I need to get another OR Modem and put unlocked firmware on I guess.

Looking on the forum, you guys seem to have been busy getting into the workings of that Huwei box - I am impressed!

[kitz]

Im not at all familiar with this router Im afraid.   A very quick google didnt come up with a CLI reference manual.  Nor the chipset... its not to say the info isnt out there.

What I did find though was this.   I havent had time to read through it all but a quick scan showed me it supposedly has a console port (page 20), yet I dont see any evidence of this from the photos on their site.

I notice from there that console mode supposedly has a debug mode... and there's a shell which can be accessed using the #sh command.  hmmmm  Now that reminds me a wee bit of the netgear cli.  You may well have a BCM 63x8 chipset in there.   

I didnt see any instructions for telnet in the manual but it would be interesting to see if you can telnet into it.

[Brian Coat]

Thanks - really useful

I'd downloaded that but did not have the knowledge to infer what you did.

Zyxel seem helpful so I'll email them to ask "CLI reference? , chipset ?"

I did find out what Telnet is and logged in

I typed HELP and got a list of commands so that looks hopeful?

Theres No command Adslctl like on the net gear CLI  link you gave me but I did see xdslctl and asdl - either of those sound familiar?


I'm a mechanical engineer so this is going to take me some time ...

I also downlOaded a stats (lite) program which I plan to run next time the Zyxel is connected to the DSL line

[kitz]

I wouldnt bother too much about the chipset, thats just nosiness, to give us an indication of what they are capable of.
A CLI reference manual may be useful though if you can get one.

I did see xdslctl and asdl

Excellent   It looks like its possibly a BCM6368.   
If this is true, it makes me rather interested in that router especially as it includes 4xGbE.  Price is just a little bit high atm though for me

I also downlOaded a stats (lite) program

I think you may be able to do better than that..  DSLstats IMHO is far superior for logging BCM routers.


Im going to pass you over to eric because hes our resident expert when it comes to the different BCM routers and has probably tried most of them. So he will have more experience than me with that particular chipset and if it can be SNRm tweaked.  Any input from other kitizens with similar chipsets is also welcomed.

[roseway]

Im going to pass you over to eric because hes our resident expert when it comes to the different BCM routers and has probably tried most of them. So he will have more experience than me with that particular chipset and if it can be SNRm tweaked.  Any input from other kitizens with similar chipsets is also welcomed.

All the information I've gleaned about routers which have Broadcom chipsets is in this table: http://wiki.kitz.co.uk/index.php/BCM_routers

As far as I know, all of the BCM 6*** chipsets can be tweaked for SNRM, but some router manufacturers have denied access to the full CLI, so you would need to experiment. Some information on how to use the Broadcom CLI is here: http://wiki.kitz.co.uk/index.php/Broadcom_CLI

[Brian Coat]

Roseway:This is so helpful. Thank you.

I opened a telnet session and typed xdslctl <cr> and I got a buch of commands, including ...

xdslctl configure [--snr <snrQ4>]

Is this likely to be the SNR tweak command?

If so it looks like it is accessible.

I think I'll connect the Zyxel today and download the Kitz-suggested line stats program today so I can record what it happening over time, during a phone call etc.

I then need to decide whether to *wait* for a week or so before I do anything. As you know I was thinking of *increasing* the target SNR margin.

If I increase the target SNR margin *now*, I have a [loose, ill informed!] idea it might insure me against the DLM getting over excited if there is intermittent line noise out here in the sticks. I'm still not certain BT has found all the intermittent line faults. I don't want the IP to 'learn' profile down to 2MBPS again - I just cant take many more calls to Bombay, if that happens. 

Case for waiting: After the learn period the IP profile will be more stable? If I mess with target SNR during learn period it could confuse the learn algorithm and mess things up? So far, the IP profile is not falling (after 2 days) so I could get lucky and get a stable 10MBPS+ IP profile, in a week's time.

I could do my 'experiment' at the end of the 'learn' period, provided nothing happens in the meantime to drive the IP profile down and/or band it.

As Kitz says, I'd be a guinea pig if I do this SNR margin increase thing but if anyone has info which suggests 'Lemming' would be more apposite, please do shout up!!!!

Thanks again for the various bits of advice given on here - I would not have got this far without it. 

[roseway]

opened a telnet session and typed xdslctl <cr> and I got a buch of commands, including ...

xdslctl configure [--snr <snrQ4>]

Is this likely to be the SNR tweak command?

Yes, that's it. The command will be something like (for example):

xdslctl configure --snr 50

which would reduce your target SNRM by about 3 dB. But Kitz' advice to do some monitoring first is good advice. DSLstats should work OK with this router - on the login page just enter the same login details as you've used for a manual telnet login.