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Standard User RobertoS
(sensei) Sun 15-Jan-12 15:49:07
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Re: Advice please


[re: orly] [link to this post]
 
In reply to a post by orly:
Might want to update your page for BT...the FUP is not correct.
Done smile.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - IDNet Home Starter Fibre. Live BQM.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Standard User kasg
(committed) Sun 15-Jan-12 19:40:03
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Re: Advice please


[re: Bald_Eagle1] [link to this post]
 
In reply to a post by Bald_Eagle1:
It always states 37 Mb.

Notwithstanding your speed issues, clearly that is exactly what you want it to say, as at least it is not restricting your speed any further. The problem I have had is that mine dropped down to a much lower figure (14Mb I think) following a brief sync drop from the maximum and it stuck there, so I had to raise a ticket to get it put back to 37Mb, which is the highest value Plusnet use. I have read an explanation in the past of why it's 37Mb but it was a bit convoluted and I can't remember the details!

Kevin

plusnet Value Fibre
My Broadband Speed Test
Using OpenDNS
Standard User Bald_Eagle1
(member) Sun 15-Jan-12 20:54:26
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Re: Advice please


[re: kasg] [link to this post]
 
In reply to a post by kasg:
Notwithstanding your speed issues, clearly that is exactly what you want it to say, as at least it is not restricting your speed any further. The problem I have had is that mine dropped down to a much lower figure (14Mb I think) following a brief sync drop from the maximum and it stuck there, so I had to raise a ticket to get it put back to 37Mb, which is the highest value Plusnet use. I have read an explanation in the past of why it's 37Mb but it was a bit convoluted and I can't remember the details!


Except that BT's SIN 498 document regarding FTTC connections states:-

2.1.6 Downstream shaping
The CP is expected to shape the downstream traffic to match the actual VDSL2 line
rate in order to avoid excessive traffic loss.

AIUI, excessive traffic loss can cause transmission errors/retransmissions of data.
DLM sees these as a reason to apply Interleaving at varying levels to attempt to cope with corrected/retransmitted data, & in extreme cases of very high bursts of errors, can actually cause a re-sync at a lower speed, believing the connection is generally unstable.

At times I see lots of errors (Millions), & lots of re-syncs of my connection.

I never expected the full 40 Mb (possibly 800m - 1000m from the cabinet), but if Plusnet is attempting to transfer more data than my connection can actually handle, could the result be that my speeds are now even further restricted to sync below 30Mb?

I'm not 100% sure that Plusnet's profiling system is working as it should be, both for FTTC connections & the ADSL Profile query that originally started off this thread.

As the original poster has a MAAF (owned by Plusnet) account, I assume the same profiling systems are in use for both sets of customers.

FWIW, I have seen some Plusnet users mention very low Plusnet profiles, but were actually achieving higher speeds, & as soon as Plusnet's profile was manually increased, speeds have decreased (not sure though if that related to throughput only or sync speeds too).

My Plusnet profile has been 37Mb from day 1, although I may still have some outstanding physical D-side copper faults on my connection.


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Standard User kasg
(committed) Sun 15-Jan-12 21:44:44
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Re: Advice please


[re: Bald_Eagle1] [link to this post]
 
In reply to a post by Bald_Eagle1:
Except that BT's SIN 498 document regarding FTTC connections states:-

2.1.6 Downstream shaping
The CP is expected to shape the downstream traffic to match the actual VDSL2 line
rate in order to avoid excessive traffic loss.

AIUI, excessive traffic loss can cause transmission errors/retransmissions of data.
DLM sees these as a reason to apply Interleaving at varying levels to attempt to cope with corrected/retransmitted data, & in extreme cases of very high bursts of errors, can actually cause a re-sync at a lower speed, believing the connection is generally unstable.
At times I see lots of errors (Millions), & lots of re-syncs of my connection.

I never expected the full 40 Mb (possibly 800m - 1000m from the cabinet), but if Plusnet is attempting to transfer more data than my connection can actually handle, could the result be that my speeds are now even further restricted to sync below 30Mb?

That's interesting, I was not aware of that possibility.
In reply to a post by Bald_Eagle1:
As the original poster has a MAAF (owned by Plusnet) account, I assume the same profiling systems are in use for both sets of customers.

Yes, but MAAF customers can't get at it to see what it is set to.
In reply to a post by Bald_Eagle1:
FWIW, I have seen some Plusnet users mention very low Plusnet profiles, but were actually achieving higher speeds, & as soon as Plusnet's profile was manually increased, speeds have decreased (not sure though if that related to throughput only or sync speeds too).

That's never happened to me, I have always been limited by the Plusnet profile, which has occasionally been set too low and I have got it raised, which has increased speeds back to what they should be.

Kevin

plusnet Value Fibre
My Broadband Speed Test
Using OpenDNS
Standard User Bald_Eagle1
(member) Sun 15-Jan-12 22:20:09
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Re: Advice please


[re: kasg] [link to this post]
 
In reply to a post by kasg:
That's never happened to me, I have always been limited by the Plusnet profile, which has occasionally been set too low and I have got it raised, which has increased speeds back to what they should be.


Has that happened a few times for your connection?
Did it revert to your previous ADSL profile, or just some strange level?
Have you experienced physical D-side cable problems requiring engineer visits?

I have experienced terrible problems with my connection over the last few months, occasionally syncing at below 10Mb, & being stuck at that for quite a few days at a time, yet my Plusnet profile has never, ever budged from 37Mb.

e.g. this connection from 1st October (8c profile):-

Text
1
23
45
67
89
1011
1213
1415
1617
1819
2021
22
# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY statusStatus: Showtime
Retrain Reason: 2Max:    Upstream rate = 6797 Kbps, Downstream rate = 19204 Kbps
Path:   0, Upstream rate = 2000 Kbps, Downstream rate = 9816 Kbps 
Discovery Phase (Initial) Band PlanUS: (0,95) (696,1183) 
DS: (32,687) (1192,1627) Medley Phase (Final) Band Plan
US: (0,95) (696,1183) DS: (32,687) 
       VDSL Port Details       Upstream        DownstreamAttainable Net Data Rate:       6797 kbps         19204 kbps
Actual Aggregate Tx Power:        2.2 dBm           9.1 dBm============================================================================
  VDSL Band Status        U0      U1      U2      U3      D1      D2      D3  Line Attenuation(dB):  8.8     53.1     N/A     N/A    21.8    66.0     N/A   
Signal Attenuation(dB):  14.5    51.6     N/A     N/A    21.8     N/A     N/A           SNR Margin(dB):  14.8    14.8     N/A     N/A    17.4     N/A     N/A   
         TX Power(dBm): -9.4     1.8      N/A     N/A    9.1      N/A     N/A



Many engineer visits later, it has improved, but is still nowhere near what it was for the first month.
Standard User kasg
(committed) Sun 15-Jan-12 23:04:21
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Re: Advice please


[re: Bald_Eagle1] [link to this post]
 
In reply to a post by Bald_Eagle1:
In reply to a post by kasg:
That's never happened to me, I have always been limited by the Plusnet profile, which has occasionally been set too low and I have got it raised, which has increased speeds back to what they should be.


Has that happened a few times for your connection?


It's happened twice that I know of since I switched to FTTC.

In reply to a post by Bald_Eagle1:
Did it revert to your previous ADSL profile, or just some strange level?


No connection with previous ADSL profile, I think in both cases it was in response to a lower sync event, although I didn't know about one of them. In the one I knew about, it was consistent with the lower sync.

In reply to a post by Bald_Eagle1:
Have you experienced physical D-side cable problems requiring engineer visits?


Fortunately not. FYI I'm about 400m from the cabinet and have always had maximum sync, apart from those two brief events.

Kevin

plusnet Value Fibre
My Broadband Speed Test
Using OpenDNS
Standard User RobertoS
(sensei) Sun 15-Jan-12 23:42:41
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Re: Advice please


[re: Bald_Eagle1] [link to this post]
 
yet my Plusnet profile has never, ever budged from 37Mb
You do mean the Current line speed?

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - IDNet Home Starter Fibre. Live BQM.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Standard User Bald_Eagle1
(member) Mon 16-Jan-12 07:31:03
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Re: Advice please


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
yet my Plusnet profile has never, ever budged from 37Mb
You do mean the Current line speed?


Indeed I do mean Current line speed (as reported by Plusnet - in that area of their Portal).
However, for my connection, it has absolutely no relationship to actual sync speeds.

Actual line speeds are reported in Plusnet's Radius logs though.


37 Mb is Plusnet's maximum profile for the 40Mb service, meaning "unrestricted".
i.e. if a connection can achieve up to 40Mb sync speed, Plusnet will not restrict throughput at their end.

I think that is what BT's SIN 498 document was trying to say - that unless throughput is adjusted by the CP to actual line rates, it could cause a backlog due to traffic loss.

If my understanding is correct, DLM could see that as a problem connection & adjust sync rates, BRAS Rate (IP Profile), interleaving & possibly SNRM etc. accordingly.


Paul.

EDIT:

FWIW, The highest speed my connection has synced at since July is 29807k DS & 5971k US.

Attainable rates were 35224k DS & 5971k US.

At that time DS Interleaving depth was 473, & US Interleaving depth was 1.
Since I have been logging my stats, US Interleaving depth has ALWAYS been 1

On occasions, DS Interleaving depth has been over 1700
:-

http://i1255.photobucket.com/albums/hh629/Bald_Eagle...

Edited by Bald_Eagle1 (Mon 16-Jan-12 08:35:12)

Standard User RobertoS
(sensei) Mon 16-Jan-12 11:53:46
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Re: Advice please


[re: Bald_Eagle1] [link to this post]
 
What do PN say about that 37Mbps?

Tiny point of info that you may, (probably do), or may not know. Interleaving depth 1 is Fast Path.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - IDNet Home Starter Fibre. Live BQM.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Standard User Bald_Eagle1
(member) Mon 16-Jan-12 12:27:51
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Re: Advice please


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
What do PN say about that 37Mbps?


I have discussed it with them with a view to experimenting with a slightly lower value, say 32Mb to 35Mb.

However, they say it would only have a negative effect & reduce my speeds even further.
I'm not too sure about that as it has been acknowleded that there are a couple of slight discrepancies within Plusnet's profiling system, that I understand is currently being investigated.

e.g. Some users with a Plusnet reported "Current line speed" of 13 Mb or so, but syncing at 39999 k, with a BT IP profile of the usual 38xxx k, downloading at 37Mb or so.

When Plusnet manually increased those users' Plusnet proflies to their standard 37Mb, the users' throughput ended up a few Mb lower.

As those users already had very good (fast) connections, it probably had no effect on their sync speed & BT IP Profile.

Tiny point of info that you may, (probably do), or may not know. Interleaving depth 1 is Fast Path.


I am aware that an Interleaving depth of 1 is definitely Fast Path (Interleaving OFF).
However, a couple of users have reported an Interleaving depth of 19.
They believed that Interleaving was OFF (Fast Path) for their connections.

I presume that a depth of only 19 will have a very insignificant effect, & from what I recall of ADSL connections, the maximum Interleaving depth was either 64 or 256 (can't recall which at the moment).

I wonder if Fast Path (Interleaving OFF) is now actually banded for VDSL2 connections i.e. between 1 & "some other quite low value".

I believe another indicator as to whether Interleaving is ON or OFF is the presence (or not) of FEC errors, as Forward Error Correction is only ever implemented when Interleaving is ON.

Paul.
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