WPD-6, WAA-8, and WAA-9 of draft-ietf-v6ops-ipv6-cpe-router-04

[Philip Homburg <pch-v6ops@u-1.phicoh.com>]

WPD-6:
    Absent of other routing information the IPv6 CE router MUST
    use Router Discovery as specified in [RFC4861] to discover a
    default router(s) and install default route(s) in its routing
    table with the discovered router's address as the next-hop.

RFC-4861 describes how routers process Router Advertisements (mainly to
check them for consistency). Only hosts maintain a list of default routers.

It seems strange to me that a BCP mandates behavior that doesn't seem to be
covered by any of the standard track RFCs. If using router advertisements
to provide low-end routers with a default route is a desirable model, then
maybe there should be an RFC for that.

It looks like that at least one ISP treats this draft BCP as gospel. So I 
wonder whether the draft should mandate the weak host model. I can't think
of anything negative that would happen if a CPE assigns in WAA-8 the address
not to a virtual interface but to its WAN interface and then implements the
strong model.