It looks like the values displayed by the Graphs/collectd module for the interfaces are wrong or unusual. The totals transmitted or received values looks like multiplied by a factor ten.
Here are some screenshot to show this.
I first downloaded a "1 Gio" file = 1 gibioctet = 230 octets = 1,024 Mio = 1,073,741,824 bytes (see http://ovh.net/files/) and noted that the average download speed was around 45Mbps, which my usual VDSL speed.
Then I zoomed roughly on the time period during which the file downloaded :
Both graphs show the correct download speed but the totals in received or transmit values are wrong : they report +/- "9 G" (G what ?) when I actually downloaded +/- 1GB (giga byte)
Could it be that the graphs reports Gb (giga bits) instead of GB (giga bytes) ?? In that case it wouldn't really make sense since we are all counting bytes and not bits.
BTW the Bandwithd graphs look also wrong regarding the download speed unit :
The max receive speed recorded for my own computer is said to be 5,1Mbit/s, which is probably actually 5,1 Mbytes/s !
Can anybody confirm this ?
Thanks for your attention.