Per request, the pointers to the current PI drafts are: http://www.ietf.org/internet-drafts/draft-hain-ipv6-pi-addr-07.txt http://www.ietf.org/internet-drafts/draft-hain-ipv6-pi-addr-use-07.txt As the USE draft discusses, the exchange points are likely to have a more prominent role than they do in the PA deployment model. For the obvious discussion about how this is impacted by natural impediments, there is an example for exception prefixes at: http://www.tndh.net/~tony/ietf/GrandCanyon.htm Depending on where these prefixes aggregate, there may or may not be any need for distributing these exception prefixes beyond one exchange point. In any case the only entities that need to know the detail are the ones directly involved in sorting it out. Tony