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Question about line training

ericgripp
Grafter
Posts: 182
Registered: 26-04-2013

Question about line training

I know you've probably all seen this question a million times but im going ask it anyway
Long story short, installed on the 7th and so far so good. Its a world away from my old o2 LLU 20 meg connection being on fibre unlimited.
In my plusnet cp (https://portal.plus.net/my.html?action=data_transfer_speed) it says my line speed is 78Mb, and sure enough since install doing the odd speedtest here and there most testers consistently give me 69 to 73Mb which id say is acceptable.
Coming home from work tonight I did a quick check and tests are coming back around 40 - 50 Mb and whilst is still faster than my old connection, concernes me that the speed is fluctuated that much.
I appreciate that it will fluctuate with a new install but with my estimated speed to be 66 - 68Mb I thought it was great I managed 73Mb, but with this drop this evening will I even hit the 66Mb predicted ?
Never had any of this line training malarkey on LLU so would appreciate advice.
If it helps my exchange is SSPOR and im using the plusnet supplied router (which is my only gripe so far why cant I view my line stats unlike my old O2 LLU router ?)
Thanks
6 REPLIES
njay
Grafter
Posts: 184
Registered: 05-04-2013

Re: Question about line training

I find mine varies depending on time of day and its usually less about this time and just put it down to everyone's finished eating dinner and has hit the net Smiley
As long as your ip profile (run the bt wholesale speed test) isn't going down then I would not worry too much. Just give it another test tomorrow during the morning
ericgripp
Grafter
Posts: 182
Registered: 26-04-2013

Re: Question about line training

hi njay thanks for the reply
This is what I wasn't sure about, as on o2 LLU ADSL 2+ I didn't really see congestion or contention. Certainly there is no reported congestion issues at the exchange itself.
Also I have added the pro add on so does that not reduce the amount of contention/congestion ?
Or is it as you say more people are on so im noticing more crosstalk on the line ?
The BT Wholesale checker matches what plusnet have my linespeed set at which would suggest the ip profiles are correct.
So how badly does fibre suffer with speed loss if this isn't line training ?
Thanks again  Shocked
dannystokie
Grafter
Posts: 58
Registered: 02-04-2013

Re: Question about line training

There is no 10 day line training with FIbre, DLM is active all the time and comes into action if you disconnect a lot.
I've had Fibre since the 12th April and tend to get 73.5 Mb most of the time. Every now again it drops to 50 or 60 Mb, the other day it was at 68 Mb, this happens normally at peak times 7pm to 12 am (roughly)
it always goes back to normal and Fibre is new around here  so I take it as just normal teething troubles with new hardware at exchange or whatever.
Though, for the past week i have noticed no drop at all which is good news, this may be the same for you, just thought i'd try to reassure you Smiley.
njay
Grafter
Posts: 184
Registered: 05-04-2013

Re: Question about line training

I believe there are two factors at work.
One of them is DLM whch is active all the time and will alter my ip profile (sometimes aggressively) depending on line conditions. However unless your IP profile changes then this is not coming into effect.
The second is contention which on my exchange appears more likely as it certainly slows down a bit most nights. My ttb ping graph also increases. I now its not my use of the system as I streamed a 700mb film to my nexus 4 whilst out one morning last week and the tbb graph remained flat so n66u router wasn't struggling to service ping requests at the same time.
Seems a shame that there is contention already as my exchange hasn't been figured that long Sad
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: Question about line training

Hi there ericgripp, welcome to the forums by the way.
OK, let's start with DLM on FTTC.
As has been said, it's active all the time and there is no 10-day training period as such, but it can be especially aggressive in the first 2 days, it can be aggressive at other times as well, so as a general rule - do not turn off, reboot or disconnect the modem.
Should you ever have a real need to do that, the best method is to log into the Router, disconnect your PPP Internet session and then power down the Router. After about a minute power down the Modem and leave it off for at least an hour.
When you power up again wait for sync and all lights on the Modem to stabilise before powering up the Router. When the Router has booted, login and and click Connect to establish a PPP session.
The best way to check the the sync speed of your connection is to run the BTw Performance test (ignore the red preamble except make sure no other programs are using the Internet) and at the end of the first run, click the Further Diagnostics button, enter just your Phone number and Run the Further Diagnostics Test.  The results will show the DS IP profile for the Line (ignore the US profile). On FTTC the Profile x1.033 = sync speed.  If you ever want to post the results here, just do a Copy and Paste of the results and post (no need to grab an image).
Do not rely on the ping result from the first part of the BTw Speedtest, it can be very variable and dependant on Tester congestion. Use ping ntp.plus.net from a cmd prompt. Pingtest.net can be quite reliable as well. But remember all testers can get congested a peak times and you should not rely on a single result. The same applies to speedtesters. You can get momentary peaks/dips at anytime so if you get an "unusual" result, run several tests. To get a true picture of the capabilities of your connection, run tests at off-peak times and try several testers to find which ones give consistent results for you.
FTTC DLM has been reported to quite aggressively increase interleaving where it sees problems, but it will also reduce it over time if conditions improve.
FTTC has had a fairly rapid take up and there have been issues in many areas where there have been Exchange and BT backbone network problems at peak times.  A number of these have been overcome and new ones may crop up from time to time. In the area that is served by your exchange, the take-up is likely to be very high, so I wouldn't be too surprised to see peak-time slow downs. If however you see regular significant slowdowns you should complain about it.
One final point, the Current Line Speed at the member centre is initially set at the default value of 78Mbps for FTTC 80/20. This will update in due course to match the BT IP Profile, but if you want to ensure you get an accurate Profile from the BT Tester and ultimately the Current Line Speed, you need to login to the Router, drop the PPP session, wait about 30seconds and then click connect. This will initiate an update to the relevant servers. Doing that will also mean you generally hop to another Gateway at Plusnet, which is something you may want to try if there are instances of persistent problems with slow downs or increased ping, just to check if it's Gateway related. Use this to check which Gateway you are on
HTH.
ericgripp
Grafter
Posts: 182
Registered: 26-04-2013

Re: Question about line training

Quote from: Anotherone
Hi there ericgripp, welcome to the forums by the way.
.. cropped. ..
HTH.

Thanks !!! that's excellent info right there, many thanks Anotherone  Cheesy