ipv6, stateful config and non-default prefixlen

[sthaug at nethelp.no]

> How does a router that is using dhclient to get delegated a address 
> prefix from an upstream router obtain its default route, since dhcpv6 
> can't provide a default route.
> And since it is a router it can't get its default route from router 
> advertisements from the upstream router?

It behaves both as a host and as a router:

- As a host it receives a default route from RA from its upstream
router - and it can also receive an address (IA_NA) or a prefix
(IA_PD) using DHCPv6.

- As a router it can send RA on its LAN segment(s), and it can also
act as a DHCPv6 server. In principle it could subdivide a prefix
obtained with DHCPv6 IA_PD (for instance a /56) into suitable /64
prefixes and announce these on separate LAN segments - thgough I
don't know of any boxes that do this automagically today.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no