Overall picture

IPv6 PPP operational requirements are very different from those of IPv4.

Requirements:
try to clarify options we have
A major distinction:
static client: PC in home - static address assignment
roaming client: travelling note PC - dynamic address assignment
too hard to maintain static assignment, due to aggregation/cross ISP roaming

RADIUS attribute: 
for static clients, static address assignment
protocol used internally in ISP backend
Prefix assignment protocol (to be done):
for roaming clients, dynamic address assignment
a protocol to assign prefix dynamically, from an ISP to a customer

The work was just started, love to hear your comments