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

[Ole Troan <ot@cisco.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.

that's why the upstream interface is specified as behaving as a host for some functions. see W-1.

> 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.

targeted for Informational, but anyway.
yes, that a 'router' does SLAAC or router discovery caused quite a bit of head ache. the proposed way around that is to define that a home-gateway behaves as a host for certain functions while still forwarding packets.

note that the mechanism in WPD-6 suggests Router Discovery as a last resort.

> 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.

that would violate rfc3633. which require that a delegated prefix isn't used on the link between the RR and the DR. routers are generally following the weak host model, any particular reason why you require the strong host model?

cheers,
Ole