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Current Line Speed/Sync Speed versus Router Speed

Adderman
Grafter
Posts: 36
Registered: ‎18-04-2008

Current Line Speed/Sync Speed versus Router Speed

Hello all.
I'm on PlusNet Broadband Your Way Option 1 (Monthly Contract) and use a Netgear DG834Gv5 router on ethernet  (no wireless at all).
Now please excuse me but I'm not a techie.
I have noticed lately some real slowing up of my broadband speeds from say 7.00pm on over the last few nights. Software updates and some websites have been really slow to load. So I took a look at my router stats for 20.35 hrs this evening 13/10/09 which showed the following:

ADSL Link          Downstream                                Upstream
Connection Speed 5440 kbps  **                          448 kbps
Line Attenuation  40.5 db                                         18.5 db
Noise Margin         10.5 db                                  21 db

(** I have normally been achieving just over 5600kbps but even then I don't know if that's good?)

Anyway, I took a look at the Plusnet Broadband Max links and they tell me this:

"Current line speed":
    4000
What does "Current line speed" mean?
The speed shown above is based on your sync speed. This is always a little higher than the speed at which data will actually be downloaded over your broadband connection. Find out more about sync speed.

6. Sync Speed (Line Rate)
Also known as Line Rate, the synchronisation (sync) speed is the speed at which your broadband modem or router communicates with the BT Exchange. This is always higher than the speed at which data will actually be downloaded over the connection. The sync rate is worked out by your phone line's characteristics, such as line length and quality. The shorter the line and the better the quality the faster the line will sync".

Eh?!  If "Current Line Speed" and "Sync Speed"  are (as Plusnet put it)  always higher than the data download speed how come it's my router which always shows the higher figure? This has shown like this everytime I look.
Am I misunderstanding things or is there an anomaly with my speeds? Am I getting the speed I should anyway?
Thanks very much
Adderman
8 REPLIES
Community Veteran
Posts: 6,319
Thanks: 86
Fixes: 3
Registered: ‎08-01-2008

Re: Current Line Speed/Sync Speed versus Router Speed

Hi,
the sync speed is the router's connection speed.  The line speed is automatically set a bit lower to prevent more data being fed to the router than it can handle (it stops the data 'bunching up' at the connection to your line if you like).
So the 'lne rate' that feeds your line is lower than your line speed (sync speed or router connection speed).
If you fancy some reading, try http://www.kitz.co.uk/adsl/IPprofile.htm this is very informative (and the rest of the site).
Anyway, the actual data rate will be less than the current line speed because that also includes 'overheads' as well as the data you want.
There are currently reports about slowing of speeds in the evening, see http://community.plus.net/forum/index.php/topic,79756.0.html
Hope that helps,
Alastair Walker.
Call me 'w23'
At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.
Opinions expressed in forum posts are those of the poster, others may have different views.
Adderman
Grafter
Posts: 36
Registered: ‎18-04-2008

Re: Current Line Speed/Sync Speed versus Router Speed

Thanks very much Alastair. Much appreciated.
So, in short, for the "bunching" reason you give, it is normal for my router's downstream connection speed - the 5440kbps given below - to be higher than Plusnet's stated "current line speed" - 4000. Would the difference normally be around the 1400 mark?
As it happens, tonight my router downstream connection speed shows 5632 and Plusnet's current line speed remains at 4000. My other router stats for tonight at 19.30hrs are:
ADSL Link                            Downstream  Upstream
Connection Speed           5632 kbps         448 kbps
Line Attenuation                   38.5 db          19.0 db
Noise Margin                          11.5 db         21 db
Any idea if these stats are in the "acceptable" range?
Thanks
Adderman
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: Current Line Speed/Sync Speed versus Router Speed

Hi Adderman,
Your profile is current 4500Kbps.
Sounds like it just had to catch up with an increase in synchronisation speed.
Grff
Grafter
Posts: 352
Thanks: 2
Registered: ‎02-08-2007

Re: Current Line Speed/Sync Speed versus Router Speed

Quote from: Adderman

I have noticed lately some real slowing up of my broadband speeds from say 7.00pm on over the last few nights. Software updates and some websites have been really slow to load.

A number of people have seen slow browsing to certain sites the last few nights.  Maybe it's just part of that.  I did read they were going to reset some equipment and try and get them to load balance better (at least that's how I read it).  It didn't have too much effect on my browsing yesterday, so maybe it'll be better tonight.
Carl
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: Current Line Speed/Sync Speed versus Router Speed

Yep - We tried balancing the network yesterday, which looks a little better but it's still not great.
We also reloaded a number of ellacoya switches as a number of them were reaching 100% CPU during busy times, which shouldn't be happening.  We're keeping an eye on things and not ignoring the issue.
Denzil
Grafter
Posts: 1,733
Registered: ‎31-07-2007

Re: Current Line Speed/Sync Speed versus Router Speed

Quote from: Adderman
Thanks very much Alastair. Much appreciated.
So, in short, for the "bunching" reason you give, it is normal for my router's downstream connection speed - the 5440kbps given below - to be higher than Plusnet's stated "current line speed" - 4000. Would the difference normally be around the 1400 mark?
As it happens, tonight my router downstream connection speed shows 5632 and Plusnet's current line speed remains at 4000. My other router stats for tonight at 19.30hrs are:
ADSL Link                             Downstream  Upstream
Connection Speed            5632 kbps         448 kbps
Line Attenuation                    38.5 db            19.0 db
Noise Margin                          11.5 db         21 db
Any idea if these stats are in the "acceptable" range?
Thanks
Adderman

Your stats are not too bad. The noise margin is a little high, which suggest you have a relatively noisy line, but 5632kbps is a decent speed. The "current line speed" shown in the Member Centre is the IP profile. The IP profile is always a round number somewhere below the sync rate. Have a look at Kitz's information in the link that walker23 posted. Sync rates usually vary a little over time. If your sync rate falls slightly below the threshold for your IP profile then the profile will drop to the next one down. Drops in profile happen very quickly. If the sync rate goes back up it can take a few days for the profile to go back up, which is why you will sometimes see a bigger difference.
Community Veteran
Posts: 6,319
Thanks: 86
Fixes: 3
Registered: ‎08-01-2008

Re: Current Line Speed/Sync Speed versus Router Speed

Quote from: Jameseh
Yep - We tried balancing the network yesterday, which looks a little better but it's still not great.
We also reloaded a number of ellacoya switches as a number of them were reaching 100% CPU during busy times, which shouldn't be happening.  We're keeping an eye on things and not ignoring the issue.

Great to see honesty about problems, lesser ISPs would just sweep these issues under the carpet.  I actually find this very reassuring that we still have an ISP with staff that really care. Smiley
Call me 'w23'
At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.
Opinions expressed in forum posts are those of the poster, others may have different views.
Adderman
Grafter
Posts: 36
Registered: ‎18-04-2008

Re: Current Line Speed/Sync Speed versus Router Speed

Walker23, Jamesh, Griff & Denzil -  thanks to you all. Wink Sometimes trying to interpret computer info is like wading through treacle but it's very reassuring to know there are people like yourselves around: your time and knowledge are appreciated.
Adderman