The splitting of national vs international traffic is an interesting point, and not very
common internationally i.e. the people that write the applications that provide traffic
calculations don't differentiate the two.
Arguably, it is possible to do this with BGP communities; assuming, of course, that both
Telecom and Telstra were willing to exchange national routing information at peering
points with other providers. Otherwise the split will not be very accurate.
From the perspective of software management, I do know
that boxes like the ERX pass traffic accounting information in the form of RADIUS interim
accounting records, and as such have absolutely no awareness of traffic paths. In order to
do a split, I'd guess that you'd have to come up with a way of reconciling NetFlow
data with radius records, and I'm pretty sure that'd be pretty hard to make