Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[phiellaep]

Hello! I used to have ntl cable, then virgin cable, but after moving house I've ended up joining the ADSL massive. It's not as bad as I thought - however I do have a question regarding speed...

I'm on Virgin's National L package, where they claim to give you a connection that is 'as fast as they can do', with a monthly download limit of 40 GB.

Prepare for noob question...

When I look at my modem stats, I see that I am connected to the exchange at 19490 Kbps downstream, with 13.6 dB attenuation and a 9 dB noise margin. This seems pretty good to me, and probably due to my close proximity to the exchange.

However, my actual download speed is absolutely stable at 13.7 Mbps, nowhere near the 19490 Kbps connection.

My question is, is this big difference between 'connection speed' and actual internet throughput normal on ADSL? Should I be getting something closer to 19 Mbps?

A few notes about obvious household problems:
1. The house wiring is good.
2. The modem/router is connected directly to the main phone socket, which is an openreach one with a ring wire filter.
3. The computer is connected directly to the modem via Cat5e cable.

Thanks,

Philip

[razpag]

There's a lot better educated than me in the 'router' stakes, that will give you sound advice, but I usually work on a premis of Throughput Speed (Surfing Speed) being roughly at 85% of Synch Speed. You may well be subject to 'Traffic Shaping' by your SP, if your Synch Speed is regularly around the 19Meg mark ??

[phiellaep]

Thanks - believe me even that tiny bit of info you gave me is more than the official virgin forums could ever offer! I had to get away!

[HPsauce]

+1 for Razpag at 85% (at best). 

It could also be your PC, how old and what OS?

[phiellaep]

We're not talking about a slow machine (I'm a gamer, or used to be). Also, when I previously had a solid 20 Mbps cable connection I had no issues (same PC, same network card).

[waltergmw]

Hi phiellaep,

If you look here

http://www.kitz.co.uk/adsl/max_speed_calc.php

you'll see you might get 22 Mbps with that attenuation. However VM is sometimes found wanting re contention issues. It seems most unlikely though that your throughput speed will remain absolutely constant throughout 24 hours. As RP says there may well be traffic management involved adjusting the speed of everyones' different types of data.

We also need to see as much as possible on your modem's stats including errors reported.

Have you checked your MTU settings ?

http://www.kitz.co.uk/adsl/MTU.htm

and subsequent pages

Have you tried different speed testers as well - they don't all give the same results ?

Kind regards,
Walter

[phiellaep]

Thanks. Yes, I feel I should be getting something faster with that attenuation... Perhaps not 22 Mbps but better than 13 Mbps anyway...

I have checked my MTU settings and used DrTCP to try different values, as recommended by this site, but it doesn't seem to affect my speed.

As for time of day and different speedtesters, the speed really is pretty constant. It might vary over the range 12.5 - 13.8 Mbps but in general it is almost always 13.7 Mbps using www.speedtest.net.

As for modem stats, I will get these tonight and paste them here. Not sure about errors though(?)

[roseway]

It looks to me as though you may be subject to some sort of traffic management or capping by Virgin, as the download speed is so consistent. Your router stats may give us some more clues, and you may be able to tweak your connection speed up a bit, but it may not increase your actual download speed.

(Sorry about all the 'may's in that )

[phiellaep]

Yes, I think you might be right. But that is really annoying because Virgin's 'catch phrase' is that they will give you as fast a connection as possible. Clearly, it is possible for my connection to be better, so that's a load of rubbish. Unfortunately their tech support is so painful that I wouldn't get anywhere in discussing this with them.

[phiellaep]

Stats, with slightly wonky text :


System Up Time: 25:47:52

Port   Status   TxPkts   RxPkts   Collisions           Tx B/s   Rx B/s   Up Time
WAN   PPPoA   5581704   8373532   0                   24222   26130   25:38:26
LAN   10M/100M   6534996   5590364   0                   26697   24157   25:47:30

ADSL Link                     Downstream   Upstream
Connection Speed     19553 Kbps   1023 Kbps
Line Attenuation             13.6 dB           5.0 dB
Noise Margin             8.9 dB           12.5 dB

[Mick]

As others have said there may be traffic shaping taking place.  Have you carried out any tests to confirm if this is so?

You could try someting like this: http://www.measurementlab.net/measurement-lab-tools#tool2

or use a manual method if you know what you're doing.