Bit Meter issues (all bandwidth mons?)

ive noticed when using BitMeter and other BWM's in past they always report MORE usage than I use... e.g. today I had 30Mb download usage - i set away utorrent and downloaded and I noticed the 30Mb difference was getting larger, until eventually it ended at

1.82Gb - uTorrent download
1.95Gb - BitMeter download

a difference of about 130Mb (100Mb more than before I started downloading)
I didnt browse ANY pages or run any software as I was purely testing it as I need a reliable one to test my dads connection before he choses an ISP that has usage limits

I know there are over heads on Bit-Torrent but not 100Mb worth? - this tracker data packets would not use 100Mb would they?

I may give TBB mon a whizz

thanks

Is the P2P upload included in one but not the other? If so then that would easily account for that data.

100mb discrepancy between usable data, and transmitted data in nearly 2gb of data wouldn't shock me.
That's about 3% overhead.

Given that a standard ethernet frame has around 2% overhead if it is maximum size, and higher if it is not, 3% isn't huge.

Also it is worth noting that we have only looked at one layer, the ethernet frame, not the IP packet etc, and an IP packet has around 1% to around 4% over head.

All this also assumes an MTU of 1500 that applies end to end, every packet manages to contain a payload sufficient to make it the size of the MTU, and zero packet loss.

As Ian72 has pointed out, it really depends upon what is being measured within these two figures. I reckon 3% overhead is acceptable.

I would calculate that overhead as between 6.7% and 7% rather than 3%.

It is 130MB discrepancy on 1.82GB (or 1.95GB if you calculated from the higher figure).

That seems like a relatively high overhead to me.

thanks - i tried ThinkBroadBand monitor and that gave a difference of 125Mb over a 703Mb file?? thats a bit high?? so ive stuck with Bit Meter - its reading my wifi adapter which that itself probably has massive overheads

In reply to a post by ian72:

I would calculate that overhead as between 6.7% and 7% rather than 3%.

It is 130MB discrepancy on 1.82GB (or 1.95GB if you calculated from the higher figure).

That seems like a relatively high overhead to me.

sorry this included 30Mb already downloaded so i should have put 1.85Gb
and no this was just the download figures only