Ok no problem, it was only a suggestion (as per thread title). The only thing that needs to be computed for 20000+ tunnels in realtime is the rrdtool collection data. The graphs (and textual data of my suggestion) only need to be computed on website page reloads. I'd have thought that computing all the graphic images would use significantly more CPU resources than a simple extraction of a time window (from txt file rrd data) and then a subtraction of 2 values. One point I made was that some graphs are actually not very useful unless your traffic is tightly within a band as the Y axis does not appear to scale. I.e. it needs to scale low enough when it is only DNS traffic over IPv6 and go high enough when you start downloading over IPv6. So I can not see why hardware would be even be considered the most obvious solution, to me it is just a software task. But I understand if that is not possible also since I also make presumptions (which I am free to make whilst not fully aware of facts otherwise). Thanks for the suggestion of doing some monitoring my end, or even more simply I can use "ifconfig 6in4" and view the numbers to write down on some paper.