Tech answers needed to ADSL2
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page
- Plusnet Community
- :
- Forum
- :
- Help with my Plusnet services
- :
- Broadband
- :
- Re: Tech answers needed to ADSL2
Tech answers needed to ADSL2
25-12-2012 7:06 PM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Yesterday my line changed over from 20cn to 21cn, and the 2700hgv duly re synced showing the attempted try at adsl2+ (G.DMT2 Annex A+) , then settled on adsl2 ( G.DMT2 Annex A).
Before the changeover my stats were 2848kb at 5db snr at 60.3db attenuation.
After the changeover my stats were 3131kb at 3.9db snr at 57.4db attenuation.
But several hours after the router itself did a hard reset (reboot), and adsl2 speeds reduced.
Why did the router do a re boot, and not a re train ?
Also the adsl2 specs show that minimum bitloading of 1 (compared to adsl1 of 2), my adsl2 shows minimum bitloading of 2 ?
Thanks,
Paul.
Re: Tech answers needed to ADSL2
25-12-2012 7:24 PM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Most lines need about 6Db to operate without too many errors.
Your line accumulated too many errors, so BT increased the margin, your speed reduced.
How do you know your router did a hard reset?
I think it did a soft reset; i.e. a disconnect and reconnect.
BTW ADSL1 uses 256 possible slots 4Kbits wide, ADSL2+ uses 512 slots.
See http://www.kitz.co.uk/adsl/
"In The Beginning Was The Word, And The Word Was Aardvark."
Re: Tech answers needed to ADSL2
25-12-2012 9:32 PM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Where the figure 6db snrm allows extra headroom for fluctuations without losing sync.
At the time of the hard reset i was next to the router and saw it happen, this was not due to excessive errors, far from it !
The second part to my question regarding minimum bitloading has nothing to do with frequency bandwidth allocation, but the adsl2 (and +) spec says 1 bit minimum bitloading, i am getting 2 as in adsl1 spec.
Paul.,
Re: Tech answers needed to ADSL2
25-12-2012 9:44 PM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Re: Tech answers needed to ADSL2
26-12-2012 2:04 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
When the router does a re sync the power stays solid, but the inernet and sync go through the flash/solid phase.
As i was next to the router when this happened, i followed the sequence of events.
The router did a hard reset, the psu is not faulty as i am running a dc converter block from a 12v floated battery.
The errors were minimal rightup to the hard reset, i regularly keep a look at the bitloading.
Btw Anotherone, during the 10 day training period is the fault threshold rate set referenced from the lowest sync rate or the final sync rate ?
Regarding noise levels after dark, i am very aware to the increase in noise, but bitloading is always a min of 2, the 2700hgv router can and does automatically re allocates unused tones without re sync between night/day.
Paul.
Re: Tech answers needed to ADSL2
26-12-2012 6:24 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Other than that, I can only guess Paul. Have you ever seen minimum bit loading of 1 on the (a) 2700hgv?
Re: Tech answers needed to ADSL2
26-12-2012 7:13 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Re: Tech answers needed to ADSL2
26-12-2012 9:02 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Quote Why did the router do a re boot, and not a re train ?
I'm afraid there's really no way to determine that. The reboot will have cleared any history.
If it helps, in my experience of 2700s ( in the office and at home ) I've only ever seen reboots happen for 2 reasons:- after a firmware upgrade and for power supply issues.
I very much doubt it's a f/w upgrade since I'm pretty sure that BT have stopped that since they don't use the 2700 anymore, and you seem to have eliminated the PSU as the cause.
I suggest just putting it down to one of those things... if it happens again then it might be the 2700 developing a h/w fault.
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
Re: Tech answers needed to ADSL2
26-12-2012 9:53 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Eventually solved the problem after removing Enhanced Services as described here
http://bt2700hgv.tripod.com/163.htm
Re: Tech answers needed to ADSL2
26-12-2012 2:28 PM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Interesting ejs regarding trellis coding, i will have to look in to that, looks a bit complicated !
I am using the sbc 4.25.19 firmware, i am pretty sure this is not getting any udate .
I do have several other spare 2700 routers with v5 and v6 firmwares, but i am resisting swapping them for obvious reasons during the training period, and also i do not believe it is faulty !
Such is life,
Paul.
Re: Tech answers needed to ADSL2
26-12-2012 3:28 PM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
You might be better trying a v5. Tbh I've only ever used v5 or v6 pi n 21cn connections
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
Re: Tech answers needed to ADSL2
26-12-2012 11:50 PM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Edit: If you use the Disconnect method during daylight, I wouldn't have thought swapping would have been a problem. At the end of the day if the wotsit hit the fan you could always have a line reset.
Re: Tech answers needed to ADSL2
27-12-2012 12:10 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Quote from: MisterW Wasn't v4 a very early version of the Adsl2 modem code ?
You might be better trying a v5. Tbh I've only ever used v5 or v6 pi n 21cn connections
I was always lead to believe that v4 firmware was not adsl2+ compatable, but my router shoiws an attempt upon a re sync, then defaults to adsl2, which on my line length i expected it to anyway even if i had a brand new model .
The router has now re synced higher, and unexpectedly routerstats shows interleaving off !
Did not expect that on this line, i checked the routers stats and fec's are 0 so looks to be true.
As the dlm sets the MSR as the lowest sync during the 10 day training period, i think i will leave any router testing till after that period, don't want to tempt fate !
Interestingly my upload sync rate changed before and after the re train, was 444kb, now 431kb, strange as it has 15.8db snrm ?
Seems a bit odd compared to adslmax where the upload stayed at 448kb all the time, except when the phone rings, and a few times dropped to 128kb, but download stayed unaffected.
Anotherone, just spotted your response as i was just about to reply above, As adsl2+ is very unlikely to work on my line attenuation, i did not think that would matter, adsl2 should be ok on v4.
Btw, do you know exactly what the the test it does at the exchange to determine if adsl2+ is used or kicked out ?
Does it look for tone usage above a certain frequency as a trigger point to accept or not use that mode ?
Paul.
Re: Tech answers needed to ADSL2
27-12-2012 12:39 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
Re: Tech answers needed to ADSL2
27-12-2012 1:50 AM
- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Report to Moderator
My line struggles to see 144 let alone 255 !
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page
- Plusnet Community
- :
- Forum
- :
- Help with my Plusnet services
- :
- Broadband
- :
- Re: Tech answers needed to ADSL2