ADSL overhead = how much % lost?

Uthur · 15-08-2008 6:46pm #1

i've been upgraded to 7.6 Mbit/s by BT
i was on 3 MBit/s before

in theory how fast could my downloads
be now?

i was seemingly losing 16.8% of the
theoretical max before due to protocol
overhead etc. this seems to be now 18.4%
since the upgrade.

how much % should you lose with adsl anyway,
or how fast does 7.6 Mbit/s actually go in the
real world

PogMoThoin · 15-08-2008 7:56pm

Here, download this, choose Ireland, HeaNet, tell us what speed your getting after few mins. This will fill your bandwidth. No point doing it now at this hour of the evening, do it after 12 or in the morning.

FYI, I live 200-300m from exchange and I'm getting 6.4-6.5mbit on speedtests or ~750kbps from this server, but not at this hour of the evening.

Uthur · 15-08-2008 10:13pm

i can download from heanet and other fast sites
at 775 KB/s - is this as much as can be expected
from 7.6 Mbit/s ?

PogMoThoin · 15-08-2008 10:57pm

Yes, multiply by 8 to get bits (8 bits in a byte) = 6200 kbps

MrVestek · 16-08-2008 10:51am

Uthur wrote: »

i can download from heanet and other fast sites
at 775 KB/s - is this as much as can be expected
from 7.6 Mbit/s ?

Erh why are you complaining? You're getting slightly more than 7.6Mbps.

PogMoThoin · 16-08-2008 11:23am

Thisis what i get off-peak, I'm a stones throw from the exchange so this is the max you can expect

Uthur · 16-08-2008 2:19pm

PogMoThoin wrote: »

Thisis what i get off-peak, I'm a stones throw from the exchange so this is the max you can expect

i make this 833 KB /s - i'm not sure why it would be so much faster than
heanet

PogMoThoin · 16-08-2008 2:39pm

Because speedtest is not accurate, the ping times are way off also. Only accurate way of measuring download speed is to start a download and see what average speed your getting from a fast server, which is why I asked you do this.

MrVestek · 16-08-2008 4:25pm

PogMoThoin wrote: »

Because speedtest is not accurate, the ping times are way off also. Only accurate way of measuring download speed is to start a download and see what average speed your getting from a fast server, which is why I asked you do this.

Yup, most speed testers can be inaccurate as the servers might be overloaded themselves in the first place which impacts the results of the test.

Jonathan · 16-08-2008 11:51pm

The effective download speed is about 85% of total speed.

Uthur · 17-08-2008 10:28pm

jmccrohan wrote: »

The effective download speed is about 85% of total speed.

thanks jmc! as best i can determine, you are entirely correct

ADSL overhead = how much % lost?

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