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Standard User Lethe
(fountain of knowledge) Tue 19-Feb-13 10:51:36
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Sync speed and IP Profile getting lower and lower


[link to this post]
 
This all started around Sept/Oct last year (2012). After being on a rock solid connection for about 4 years, sync'ing anywhere between 5000/6500, my connection sometimes stopped working (but modem was still in sync - sort of like making a phone call where nobody speaks) - so I had no data through-put. The only solution was a reboot/reload.

All the above was with a Cisco 857 dsl/modem. So over Xmas holidays, I found latest firmware for the problem above and also a crafted firmware for special use with BT's kit at the exchange. All worked great for a day or so, but then I started to get disconnects in the evening and early morning - and every time that happened, modem would resync about 2000 LOWER, and IP Profile dropped accordingly (until I ended up sync'ing around 1500). But no matter what I done, I could never get a decent sync back. Checking with the BT speed test, it turned out that after every disconnect my sync rate got 'capped', so no matter what I done, I was stuck on a low connection speed.

My ISP, Enta have been very good, and we tried everything (reset this, reset that etc.). Same problem.

So clutching at straws I bought a TP-Link adsl modem/router, got eveything reset and off we go.

Yesterday, I was connected at 5420, with decent noise margins, IP Profile of 4500. Hunky Dory! smile

Then last night, I got a disconnect, now can only resync at 3000. BT speedtest thing reports my line is now only capable of 4Mb, and my profile is now 2500.

I can be sure that it will disconnect again tonight some time, and my sync will drop to around 2000, profile will drop to 1500, and max line speed will drop too.

So, why do BT cap the sync speed? How can the 10 day training period work it they cap what my line can do?

Here are my latest stats:

Line Status:Connected
DSL Modulation Type:ADSL_G.dmt.bis
Annex Type:Annex A/I/J/L/M
 	              UpstreamDownstream
Current Rate (Kbps)	1128 	3070
Max Rate (Kbps)      	1128	 9424
SNR Margin (dB)	         5.9	17.4
Line Attenuation (dB)	22.4 	39
Errors (Pkts)	           0	  0


Two things to note: I connect using ADSL2, as 2+ is not worth it on my line length (about 3km). I have checked all wiring, filters etc.

Any help appreciated why this all started happening, and why now BT seem to 'cap' connection speeds which to me seems to do away with the way the profile thing works.

Nick

Edited by Lethe (Tue 19-Feb-13 10:57:36)

Administrator MrSaffron
(staff) Tue 19-Feb-13 11:30:31
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Re: Sync speed and IP Profile getting lower and lower


[re: Lethe] [link to this post]
 
The dlm systems react to drops in line. Fix those and things will improve time.

39 db should benefit a bit from adsl2+ suggesting dlm is reacting to a noise issue.

It may be upstream causing the line drops.

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User XRaySpeX
(eat-sleep-adslguide) Tue 19-Feb-13 11:31:33
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Re: Sync speed and IP Profile getting lower and lower


[re: Lethe] [link to this post]
 
It is holding your Down NM too high.
SNR Margin (dB) 5.9 17.4


1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC

Edited by XRaySpeX (Tue 19-Feb-13 12:24:35)


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Standard User Lethe
(fountain of knowledge) Tue 19-Feb-13 11:38:25
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Re: Sync speed and IP Profile getting lower and lower


[re: XRaySpeX] [link to this post]
 
In reply to a post by XRaySpeX:
In reply to a post by Lethe:
I connect using ADSL2, as 2+ is not worth it on my line length (about 3km).
You might have chosen ADSL2 but it has degraded you to ADSL(1):
DSL Modulation Type:ADSL_G.dmt.bis
It is holding your Down NM too high.
SNR Margin (dB) 5.9 17.4


I thought that, but my upstream speed is consistant with ADSL2 (ADSL is around 890?).

I will switch back to ADSL2+ as MrSaffon suggests and post stats bacxk here.

Thanks for your help.

Nick
Standard User Lethe
(fountain of knowledge) Tue 19-Feb-13 11:44:24
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Re: Sync speed and IP Profile getting lower and lower


[re: MrSaffron] [link to this post]
 
Thanks for you help! I have switched back to ADSL2+, here are new stats (also note no increase in sync!):

Line Status:Connected
DSL Modulation Type:ADSL_2plus
Annex Type:Annex A/I/J/L/M
 	             Upstream	Downstream
Current Rate (Kbps)	1117	3071
Max Rate (Kbps)     	1116	10968
SNR Margin (dB)    	5.9	6.1
Line Attenuation (dB)	22.3	42
Errors (Pkts)    	0	0


So, do you think it could be a line fault? Something that happened around last Sept/Oct?

Nick
Standard User XRaySpeX
(eat-sleep-adslguide) Tue 19-Feb-13 11:46:29
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Re: Sync speed and IP Profile getting lower and lower


[re: Lethe] [link to this post]
 
In reply to a post by Lethe:
I thought that, but my upstream speed is consistent with ADSL2 (ADSL is around 890?).
I understand that G.DMT has the same maxima as ADSL2.

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC
Standard User Lethe
(fountain of knowledge) Tue 19-Feb-13 11:54:54
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Re: Sync speed and IP Profile getting lower and lower


[re: XRaySpeX] [link to this post]
 
You got me intrigued, as when I do connect with ADSL, I only get about 890 upstream (done all this whilst working with ISP to find out what is going on).

According to here:

http://en.wikipedia.org/wiki/G.992.3

ADSL.G.DMT.bis is ADSL2

Nick
Standard User XRaySpeX
(eat-sleep-adslguide) Tue 19-Feb-13 12:17:21
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Re: Sync speed and IP Profile getting lower and lower


[re: Lethe] [link to this post]
 
You're right! I overlooked the 'bis'.

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC
Administrator MrSaffron
(staff) Tue 19-Feb-13 12:33:34
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Re: Sync speed and IP Profile getting lower and lower


[re: XRaySpeX] [link to this post]
 
Different devices can have very different performance in different modes.

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User Lethe
(fountain of knowledge) Wed 20-Feb-13 09:23:17
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Exactly as predicted


[re: Lethe] [link to this post]
 
Dropped and reconnected at 06:35 this morning - now:

Download speedachieved during the test was - 2.6 Mbps
For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
IP Profile for your line is - 2.71 Mbps

And this will happen again early tomorrow sometime (between 03:00 and 07:00ish), and my profile will go down again... and as I said to the tech guy over the phone, at this rate I will have to dig out my 33.6kB modem next week.

Is this indicative of a bad line? I just do not know what to try any more.

Nick
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