The mysteries of what happens exchange side of one's NTE5 never cease to cause amazement

OK, time to put this thread to bed.

Bad line - engineer called and fixed.

On ADSL2/+ still get errors (but not seen my end). DLM does see errors and kept increasing SNR/lowering 'banded profile' to try to make line stable on every disconnect/reboot et al. DLM still sees more errors and does same again. Ad infinitum...

Got ISP to reset excahnge to just ADSL. Forced my Cisco router sync at 2dB higher. Now d/s SNR hovers around 8.5/~10/5. Stable.

Stats:

Modem Status:	 Showtime (DMTDSL_SHOWTIME)
DSL Mode:	 ITU G.992.1 (G.DMT) Annex A
~
Capacity Used:	 100%				 99%
Noise Margin:	  9.0 dB			 11.0 dB
Output Power:	 19.5 dBm			 12.5 dBm
Attenuation:	 38.0 dB			 21.0 dB
Defect Status:	 None                            None                        
Last Fail Code:	 None
Watchdog Counter: 0xBA
Watchdog Resets: 0
Selftest Result: 0x00
Subfunction:	 0x00 
Interrupts:	 45502 (0 spurious)
PHY Access Err:	 0


 		 Interleave		Fast	Interleave		Fast
Speed (kbps):	          0	        7040	         0	         960
Cells:		          0	     5576576	         0	    40418243
Reed-Solomon EC:          0	           0	         0	           0
CRC Errors:	          0	         500	         3	          14
Header Errors:	          0	         380	         4	           5
Total BER:		  0E-0		 1206E-9
Leakage Average BER:	  0E-0		 2243E-9
			ATU-R (DS)	ATU-C (US)
Bitswap:	       enabled		  enabled
Bitswap success:          0	              0
Bitswap failure:          0	              0

Summary: My line is poor, and cannot handle ADSL2/+ for whatever reason.

Now, why this happened at around Sept/Oct last year I do not know.

Nick

adsl2 is more robust than g.dmt, although adsl2+ most defenitly can be worse on poor lines.

However people often find adsl1 works better and I believe that to be down to equipment been able to deal with adsl1 better whether its the modem, dslam or both in combination.

I know when I tried the netgear dg834 and speedtouch 585v6 both were better on adsl1 than adsl2.
When I was on ukonline and used a bilion router (matched up to chipset on dslam) that worked very well on adsl2 but adsl2+ gave a poor sync speed.

If the line is dodgy I wouldnt even try adsl2+ at all, and if adsl2 is also poor in your experience then just stick with adsl1.

Also certian routers will drop sync much easier than others. I have used routers that will hold onto sync even in the situation of no useable data been transmitted due to very severe errors, but I have also used routers that drop sync whenever I sneezed. You also have to look at your snrm swing, eg. if your snrm drops 6db every night and you sync at 6db in the day then that is not going to hold, as well as snrm movements during any noise bursts you may have.

In reply to a post by Chrysalis:

adsl2 is more robust than g.dmt, although adsl2+ most defenitly can be worse on poor lines.

Yes, but ADSL2 still has that DLM thing going on so that if you do have errors on the line, it tries to make it stable and then you just get lower and a worse profile on every disconnect/resync.

BUT I just had another disconnect - and this time was running polling on the router and caught it! The first time seen in history (where's David Attenborough to narrate this event when you need him?).

The graph:

www.linicks.net/stuff/THE_END.png

To read the graph, polling been running since 14:11. The first down spike (3.5dB) was the disconnect at 262 minutes since 14:11 - I was watching air TV and heard the Cisco router *click* as it reconnected (they do that).

So next, I connected to router, shutdown ATM interface, reset the forced sync +2dB I was trying (obviously doesn't work) to 0 (i.e. default mode), and reloaded; the big spike is the *gasp-of-death*, I think, and the next 3.5 dB spike is reload.

BUT, at least I reconnect now at either slightly slower/faster than before instead of the stupid DLM trying to make my line stable and slower.

I have a fault on the line, that is for sure now. So no more on this.

Thank you everybody for input and feed-back.

Nick

BTW, I have got something out of this - learning the [censored] super http://www.gnuplot.info/ to produce the graphs from my router stats