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Can someone tell me if this makes sense?

buntings1
Newbie
Posts: 9
Registered: 06-05-2014

Can someone tell me if this makes sense?

Hi,
When we first upgraded to Fibre the download speed ( as measured using bt wholesale speed tester ) often reported in speeds in excess of the 40mbps that we signed up for. Unfortunately I forget what IP Profile we initially had.
I also notice from the Plusnet website:-
"When first activated, your line is 'fully rate adaptive'. This means there's no upper limit to your sync speed (within the capabilities of your broadband product)".
Which I presume means the sync speed will move up and down as it needs to but will never exceed the maximum speed I am contracted for ( ie 40mbps ).
2 or 3 months back we had a fault on the line and the speed dropped until it was fixed - but it something isnt quite the same since the line was fixed - the measured download speed is always lower than we used to get.
I should say I  really dont have any complaint with the speeds (especially given our rural location).....this evening the modem is showing an attainable rate of 54020kbit/s and a line speed of 39999kbit/s.  Since the line was fixed the linespeed is always 39999kbit/s - it never varies.
According to the BT speedchecker the "IP Profile for your line is - 37.05 Mbps"  and the acceptable range of speedsis 25.93 Mbps-37.05 Mbps . the download rate is usually around 35mbps
I have seen something on the web that implies the profile should be a maximum of around 38.7mbps - which is the profile  our neighbour (also on plusnet ) is getting - and the attainable line speed perhaps implies we should have?
I realise the speed is excellent and any slight boost wont do much so I am more curious to know if something is stuck that didnt used to be and shouldnt be - seems strange that the profile is unvarying and ever so slightly lower than next door given the attainable line speed reported by the modem.
Can anyone cast any light on the subject or tell me if these figures make sense?
Thanks
5 REPLIES
PeteSmith
Dabbler
Posts: 11
Registered: 29-12-2015

Re: Can someone tell me if this makes sense?

Hi.
You've got a 40Mb package (as you've said). This means the maximum speed you can sync at is 40M down, even if the line is capable of more.
I've got 80/20. My download is 70280 attainable, and upload is 26531. As I've got 80/20, the upload is capped at "20M", which is shown as 19999 in my modem.
Given you've got 39999, this is just a confirmation that you've got an attainable speed much higher than your capped speed, and it never drops below it.
HTH.
Pete.
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Andrue
Pro
Posts: 775
Thanks: 90
Fixes: 1
Registered: 12-01-2015

Re: Can someone tell me if this makes sense?

Quote from: buntings1
Which I presume means the sync speed will move up and down as it needs to but will never exceed the maximum speed I am contracted for ( ie 40mbps ).
Yes, although not perhaps quite as you've phrased it. It's not a dynamic process with hourly or daily fluctuations. The system is called 'Dynamic Line Management (or 'DLM' to its friends). This monitors the line and if it detects an excessive number of errors or disconnects in a short period of time it drops the speed to try and eliminate them. This usually happens in the early hours of the morning, at least as far as error counts are concerned.
So much, so dynamic.
However where it is less dynamic is in letting the speed go back up. There typically has to be several days and sometimes weeks of 'good behaviour' before DLM will start to relent. Depending on how severe the original intervention was it might give you back a large chunk of speed or a series of smaller chunks (I think that's right).
By now DLM should have well and truly backed off for you but it seems like your repaired line can no longer sustain the same speeds it did originally. This could be because the repair wasn't perfect but it could also be an unrelated problem known as crosstalk. This is where two or more telephone lines interfere with each other and it becomes more of a problem as more and more people on your cabinet sign up.
cedlor
Grafter
Posts: 687
Thanks: 2
Registered: 02-04-2015

Re: Can someone tell me if this makes sense?

Off Topic -  Didnt think DLM had any friends  Undecided
buntings1
Newbie
Posts: 9
Registered: 06-05-2014

Re: Can someone tell me if this makes sense?

Hi,
Thanks for the replies.
Re the line fault - actually the engineer diagnosed it as a faulty phone.... as such the actual line wasnt repaired so I guess shouldnt have degraded. unless crosstalk is an issue (gut feeling says there arent that many fibre customers here in what is quite a small village ). You are correct that the speed didnt return quickly and Plusnet needed to reset the profile (not sure how that works but couild it have been reset to a fixed value that would never creep up to full capacity of its own accord?)
So if I have understood correctly the line is capable of a much higher speed than I am contracted to receive but its capped to the an absolite speed of 39999 ( as per the modem stats )  - on top of that DLM is imposing an IP Profile to restrict the actual speed to something that exchange believes (rightly or wrongly!) the line can handle.
Im sure the speed initially wasnt capped at all - as I am sure the download speeds where often in excess of the magic  40 as measured by BT's own speedchecker.
Im not concerned enough to waste Plusnets time raising a formal request as there isnt a fault but I wonder if there are any helpful Plusnet people reading that might have a moment check things are working properly
As I said, more curiousity  rather than concern - being pragmatic any minor speed gain isnt going to make much difference on top of what is already a decent speed.
Gareth
Andrue
Pro
Posts: 775
Thanks: 90
Fixes: 1
Registered: 12-01-2015

Re: Can someone tell me if this makes sense?

Quote from: buntings1
So if I have understood correctly the line is capable of a much higher speed than I am contracted to receive but its capped to the an absolite speed of 39999 ( as per the modem stats )  - on top of that DLM is imposing an IP Profile to restrict the actual speed to something that exchange believes (rightly or wrongly!) the line can handle.
It does sound like it although it's worth pointing out that an attainable of 54Mb/s may turn out to be a bit lower if your modem is actually uncapped.
It does seem a bit odd that your IP profile is that much lower than your connection speed. When did you last reboot your modem? It's possible for the IP profile to lag behind the connection speed in some cases. If you haven't rebooted the modem in a while try turning it off for ten minutes then back on. That might cause the IP profile to be revised. Don't do this more than once or DLM will start to pay attention Wink
For what it's worth I think the IP profile is separate to DLM with FTTC. I'm not entirely sure but I think that DLM controls the connection speed then the IP profile is set by the network based on the connection speed. As noted above I think in some cases a connection can drop and remake so quickly that the profile doesn't get updated.
Unfortunately there's another wrinkle. PN have their own version of an IP profile. It's supposed to follow the actual profile but you met find that if your IP profile rises the PN one doesn't. We'll cross that bridge though when we reach the stream Smiley