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Standard User NuttyMucker
(member) Thu 02-Aug-12 20:02:49
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EchoLife HG612 (3B)


[link to this post]
 
Hi,

Does anyone know what the retrain reason figure of 2 means?

Anytime I have looked in the modem it has alwys been set to 0.

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2


I have been having issues with my line regarding ping and disconnections but when the engineer was here his jdsu reported no faults so that was it frown

ISP being good about this but I'm sure that they are [censored] off with me ringing and updating the ticket system with BT speedtests and ping monitor graphs.

I appear to get a packet loss spike always between 0400 and 0600hrs generally at weekends which causes my ping to jump up 10ms each time. Last night there was another which reduced the ping (A first)by 10ms to average 40ms, 50ms min being the highest.

I did have the ports reset a few weeks ago which brought the ping down to 20ms and my speed was great but only lasted a couple of days. My ping then continued to jump up to 50ms in 10ms increments. The ping has never fallen until last night.

Any ideas welcome.

Standard User Zarjaz
(knowledge is power) Thu 02-Aug-12 20:35:44
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Re: EchoLife HG612 (3B)


[re: NuttyMucker] [link to this post]
 
Did the engineer check for errors ?

Standard User BatBoy
(legend) Thu 02-Aug-12 21:31:26
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Re: EchoLife HG612 (3B)


[re: NuttyMucker] [link to this post]
 
Negative margin

http://community.plus.net/forum/?topic=104948.msg894217


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Standard User NuttyMucker
(member) Thu 02-Aug-12 21:52:01
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Re: EchoLife HG612 (3B)


[re: Zarjaz] [link to this post]
 
Did the engineer check for errors ?


yes and stated the line was performing within the acceptable range

Standard User NuttyMucker
(member) Thu 02-Aug-12 21:56:35
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Re: EchoLife HG612 (3B)


[re: BatBoy] [link to this post]
 
Hi Batboy

Thanks for that. I had a read at the link but still not quite sure what this means other than not good. Can you put it in layman terms so that I can understand whats going on.

TIA

Standard User StephenTodd
(member) Thu 02-Aug-12 22:07:59
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Re: EchoLife HG612 (3B)


[re: NuttyMucker] [link to this post]
 
When a modem syncs, it tries to establish a particular signal to noise margin, typically 6db. That is the ratio of the 'useful' signal and noise being picked up on the line: the noise can come from all sorts of things like bad connections in the wire, street lights, crosstalk from another line, medium wave wireless, microwaves, ..., ....

As the noise increases the margin goes down. If it goes down to 0db there is just still enough signal for the modem and hardware in the cab to understand each other and make sense of what is going on, though there will start to be quite a few misunderstandings (errors). Below 0 (negative margin) and the noise is too great for the system to work. The only thing to do is to resync; this time at a slower sync rate trying to get less data through the line. Similar(ish) to if there is noise on a telephone conversation you have to talk a little slower to make yourself clear.

BatBoy, thanks for that link to the codes: I'm sure I'll want to know them some time.

--
Moved (with trepidation) to BT Infinity 2 for upload speed. Happy BE user for several years.

Edited by StephenTodd (Thu 02-Aug-12 22:11:01)

Standard User RobertoS
(sensei) Thu 02-Aug-12 22:14:59
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Re: EchoLife HG612 (3B)


[re: NuttyMucker] [link to this post]
 
Looking at this and your earlier thread about latency/pings, you seem to have quite a high noise variation. Not too surprising given the 1.3km from the cabinet.

Have a read of my Noise Margin explanation.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - Plusnet Value Fibre FTTC 80/20 trial.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
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Standard User NuttyMucker
(member) Thu 02-Aug-12 22:32:29
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Re: EchoLife HG612 (3B)


[re: StephenTodd] [link to this post]
 
Excellent,

Thanks to all for the replies I know have a better understanding regarding this.

Nutty

Standard User MHC
(legend) Thu 02-Aug-12 23:03:41
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Re: EchoLife HG612 (3B)


[re: StephenTodd] [link to this post]
 
In reply to a post by StephenTodd:
Below 0 (negative margin) and the noise is too great for the system to work.


Not necessarily. Some coding/modulation techniques can work with negative SNRs - ADSL2+ for example. And if the negative SNR is the average across the full spectrum there could well be large portion where the SNR is positive and thus allowing data trasfer to take place.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User StephenTodd
(member) Fri 03-Aug-12 08:51:59
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Re: EchoLife HG612 (3B)


[re: MHC] [link to this post]
 
@MHC: Thanks for the correction. I think I have learned more by posting wrong answers on forums and getting corrected than by any other means.

--
Moved (with trepidation) to BT Infinity 2 for upload speed. Happy BE user for several years.
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