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Sync higher that profile?

rederick
Dabbler
Posts: 14
Registered: 02-06-2014

Sync higher that profile?

Hello,

My VDSL sync has been over 60meg for a while, yet my BT profile is stuck at 57.

 

My stats are:

Line attenuation (dB):  	21.4		0.0
Signal attenuation (dB):	Not monitored		
Connection speed (kbps):	64142		9397
SNR margin (dB):        	3.1		6.2
Power (dBm):            	12.9		6.3
Interleave depth:       	8		1
INP:                    	51.00		0
G.INP:                  	Enabled		Not enabled

and the BT wholesale advanced test shows my profile is 58.71 Mbps

The Plusnet control panel says:

Estimated line speed:
There's no speed estimate currently held on your account.
Current line speed:
59.4 Mb

Is there anything that can be kicked? I'm getting speed tests (speedtest.net, fast.com, and thinkbroadband) around 55 Mbps.

 

Many thanks

 

 

 

6 REPLIES
Community Veteran
Posts: 4,937
Thanks: 355
Fixes: 16
Registered: 10-06-2010

Re: Sync higher that profile?

FTTC IP Profiles are usually about 96.8% of the line rate.

However, for "Retransmission High" profiles, the IP Profiles are about 91% of the sync speed, which corresponds to the 58.71 reported as the IP Profile by the BT speedtester.

So it looks like BT IP Profile is correct, and the Plusnet Current Line Speed ought to be slightly lower to match the BT IP Profile.

rederick
Dabbler
Posts: 14
Registered: 02-06-2014

Re: Sync higher that profile?

I've never heard of "retransmission high" profiles - what would one of those be?

In 11hours 50mins since I force rebooted modem, I've had these error stats:

RSCorr/RS (%):              0.0250        0.0049
RSUnCorr/RS (%):            0.0000        0.0000
ES/hour:                    0.18        10.0

I think the BTw IP Profile is too low for the sync, so you're saying this "retransmission high" profile is deliberately preventing the traditional method from working, and keeping the BTw IP Profile low - which means PlusNet never see the change.

Why would BTw limit this when Openreach have gone to the effort of introducing supported SNRM under 6db?

 

Community Veteran
Posts: 4,937
Thanks: 355
Fixes: 16
Registered: 10-06-2010

Re: Sync higher that profile?

There have always been two different levels of retransmission that the DLM can apply to a line.

Yes there is a certain amount of irony in that by reducing the SNRM, to give more bandwidth, this inevitably increases the error rate, which in some cases causes the DLM to increase the level of retransmission, which reduces the bandwidth.

The error stats you posted do not show what the retransmission was doing, so they are not really relevant. Yes of course there will be very few ES, because the retransmission corrects the vast majority of errors.

Retransmission is not completely free, retransmitting data uses bandwidth, so the more data that needs to be retransmitted, the lower throughput you have. The "Retransmission High" profile seems to include a (higher) built-in allowance for the expected loss of throughput that will be caused by the expected amount of retransmission. The limit is due to the level of retransmission, it's not really BTWholesale setting a lower limit for no reason.

Perhaps Plusnet can post your GEA test results. I expect that they will show a lower speed than the "sync speed" reported by your modem, and the IP Profile will be 96.7% of that lower speed.

rederick
Dabbler
Posts: 14
Registered: 02-06-2014

Re: Sync higher that profile?

Thank you, that all makes sense. I hadn't twigged retransmission meant fixes.  Surprising that OR would bother with a 3db sync profile and then have a separate system to make things slower - counter intuitive.

 

Plusnet Help Team
Plusnet Help Team
Posts: 4,707
Thanks: 1,035
Fixes: 227
Registered: 21-04-2017

Re: Sync higher that profile?

Hi there,

 

I thought I'd just add a copy of the test results of your connection, if you're interested.

Test Outcome Pass
Test Outcome Code GTC_FTTC_SERVICE_0003
Description No problem found, OAM test is not currently supported on this line.
Main Fault Location OK
Sync Status In Sync
Downstream Speed 60.7 Mbps
Upstream Speed 9.4 Mbps
Appointment Required N
Fault Report Advised N
NTE Power Status PowerOn
Voice Line Test Result Voice fault suspected - contact Voice CP to progress copper issue
Bridge Tap Not Detected
Repetitive Electrical Impulse Noise Not Detected
Estimated Line Length In Metres 730.7
Upstream Rate Assessment Reasonable
Downstream Rate Assessment Very Good
Interference Pattern Regular Interference Observed Daily
Service Impact No Impact Observed
Interference Duration Longest Occurrence ; 00:00 to 23:45
Interference Location Customer Premise
Interference Observed In Days 14
Home Wiring Problem Not Detected
Downstream Policing Discard Rate 0.0
Customer Traffic Level Upstream and Downstream Traffic Detected
Technology VDSL
Current 15Min Bin Retrains 0
Last 15Min Bin Retrains 0
Profile Name 0.128M-80M Downstream 3dB, Retransmission High - 0.128M-20M Upstream, Error Protection Off

 

I have tested your line after the suspected voice fault that's flagged up, and I'm detecting a battery contact. I've reported that through to Openreach now to further investigate as per this ticket.

If this post resolved your issue please click the 'This fixed my problem' button
 Anoush Mortazavi
 Plusnet Help Team
rederick
Dabbler
Posts: 14
Registered: 02-06-2014

Re: Sync higher that profile?

Many thanks!!