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Standard User Ixel
(regular) Mon 06-Aug-12 09:06:43
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A massive drop in attainable rate over night, and ptm301


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Hi all,
I have two queries. Over night I received a massive drop in my attainable rate/noise margin which isn't natural (doesn't occur every night). I've had infinity for about two months and over time my attainable rate has dropped from nearly 100Mbps to now 70-73Mbps~. I understand 100 to 85 may have been crosstalk as it was gradually lowering, but to suddenly lose from around 85 to nearly 70 is quite a jump in my oppinion.

Also, unusually ptm1.301 is connected, what does this mean? Is BT spying on me?

Thanks in advance. Will post graph for 24 hour period if requested.

Edited by Ixel (Mon 06-Aug-12 09:06:58)

Standard User StephenTodd
(member) Mon 06-Aug-12 09:52:48
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Re: A massive drop in attainable rate over night, and ptm301


[re: Ixel] [link to this post]
 
Noise at night is pretty common. Medium and short wave radio is one reason, and street lights as well sometimes. It could be some equipment of a neighbour (or even of your own), electric motor with bad brushes, radio ham equipment, .... I don't know whether the drop you had is within fairly normal limits or not. You mention the loss in max attainable rate (100->85->73) and that there is an associated loss in SNR; as a matter of interest what is the loss in SNR?

--
Moved (with trepidation) to BT Infinity 2 for upload speed. Happy BE user for several years.
Standard User Ixel
(regular) Mon 06-Aug-12 10:15:06
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Re: A massive drop in attainable rate over night, and ptm301


[re: StephenTodd] [link to this post]
 
The loss of SNR suddenly from around 6dB to 0.7dB, and by suddenly I mean within a minute. Disconnecting and reconnecting the power to the modem allowed me to connect again, but with a significant reduction in speed and the odd ptm1.301 being connected (BT's spy network?).

I don't usually see this happen every night, infact this is the first time such a significant drop has occurred, and that I've noticed ptm1.301 connected (as it's usually not connected).

Any ideas?

EDIT: After checking the graphs again (as I had only just woken up when I initially checked them) the massive drop occurred at around 8:30am.

Edited by Ixel (Mon 06-Aug-12 10:18:14)


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Standard User StephenTodd
(member) Mon 06-Aug-12 10:32:56
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Re: A massive drop in attainable rate over night, and ptm301


[re: Ixel] [link to this post]
 
I think that a loss of 6db is high but not exceptional; but maybe someone with more knowledge can correct that. Depending on the source of the noise causing it, it seems normal that it would kick in suddenly when it happened. Also that you could then reconnect at a lower speed, but (presumably) corresponding higher SNR.

I used to have a source of noise when I was on ADSL2 that was never traced, and then went away. It was around 6db if I remember correctly (I don't know if the db noise levels are equivalent on ADSL2 and VDSL); in my case it was regularly from 8:00am to 9:00am.

I don't know what ptm1.301 is. I see it is connected for me as well. From http://ukinfinity.wordpress.com/tag/brctl/ and https://en.wikipedia.org/wiki/TR-069 it looks as if it might be the interface used for updating the HomeHub as and when necessary,

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

Edited by StephenTodd (Mon 06-Aug-12 10:39:22)

Standard User MHC
(legend) Mon 06-Aug-12 11:10:00
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Re: A massive drop in attainable rate over night, and ptm301


[re: Ixel] [link to this post]
 
A 6dB change is certainly not a normal event and is likely to be caused by a new noise source starting up - there are many things that could cause it including a generators being used for roadworks, a fridge compressor or central heating pump having a partial brush failure and more.

Just keep monitoring it.


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

M H C


taurus excreta cerebrum vincit
Standard User Ixel
(regular) Mon 06-Aug-12 11:29:18
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Re: A massive drop in attainable rate over night, and ptm301


[re: MHC] [link to this post]
 
I've just checked the roadworks website for my area, and it could be something BT are doing or have inadvertently done.

Dates: Tuesday 7 August 2012 Thursday 9 August 2012
Company: BT
Impact: Signing only

I'll check it out later and see if there's any sign of them doing anything today. I'll keep monitoring it and hope that it increases again.
Standard User BatBoy
(legend) Mon 06-Aug-12 11:41:13
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Re: A massive drop in attainable rate over night, and ptm301


[re: Ixel] [link to this post]
 
I disabled PTM 301 on mine.


_____________________________________________________________________________________________ this is not usenet __________________
Standard User simon194
(member) Mon 06-Aug-12 11:53:07
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Re: A massive drop in attainable rate over night, and ptm301


[re: StephenTodd] [link to this post]
 
In reply to a post by StephenTodd:
I don't know what ptm1.301 is. I see it is connected for me as well. From http://ukinfinity.wordpress.com/tag/brctl/ and https://en.wikipedia.org/wiki/TR-069 it looks as if it might be the interface used for updating the HomeHub as and when necessary,

From the latest updated version of SIN498 in the "CP provided modem" section (the up and coming self-install option):

"CPs or their EUs will be responsible for maintaining the firmware of their Modems and monitoring their connectivity and performance, typically via a TR-69 interface using CPE WAN Management Protocol (CWMP)."
Standard User Ixel
(regular) Mon 06-Aug-12 16:29:32
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Re: A massive drop in attainable rate over night, and ptm301


[re: simon194] [link to this post]
 
I see, interesting. Well I hope this is just a temporary noise issue and not long-term/permanent. I couldn't see anyone working at the cab, or any signs of work being done by BT near or at it. Losing speed isn't a great deal to me as 60Mbps is still plenty, but what I'm not happy with is my further increase in ping due to higher interleaving depth and delay. Delay was 8, with interleaving depth of 1549, after the issue I had this morning that delay is now at 11 with an interleaving depth of 1651 :x.
Standard User simon194
(member) Mon 06-Aug-12 19:27:02
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Re: A massive drop in attainable rate over night, and ptm301


[re: Ixel] [link to this post]
 
In reply to a post by Ixel:
I see, interesting. Well I hope this is just a temporary noise issue and not long-term/permanent. I couldn't see anyone working at the cab, or any signs of work being done by BT near or at it. Losing speed isn't a great deal to me as 60Mbps is still plenty, but what I'm not happy with is my further increase in ping due to higher interleaving depth and delay. Delay was 8, with interleaving depth of 1549, after the issue I had this morning that delay is now at 11 with an interleaving depth of 1651 :x.


I had a similar sort of noise incident but it only lasted a couple of days but it was enough to drop the max attainable download rate from 87Mbps to 38Mbps and switch to an interleaving depth to 2106. It took 3 weeks to get back to fastpath.
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