Re: [v6ops] PD to hosts [was: DAD again [was: draft-ietf-v6ops-host-addr-availability discussion] ]

[Philip Homburg <[e-mail]>]

>> 1) How do packets reach the host. Is that documented somewhere?
>
>RFC3633 is largely silent on this, but when P is delegated to N, it is
>implied that the delegating router must somehow inject information
>into the routing system that will guide packets with destination
>address A to N.

I wonder where this should be documented. There seem to be some other
interesting interactions: a DHCPv6 server running on a host should not
hand out a PD to a host (because it doesn't work), but can hand it out to
a router. And can hand it out when there request comes through a relay agent.

A relay agent running on a router should install a routing table entry
if the PD request comes from a host.

There might be more interesting details.

>> 2) If a node M on the same ethernet link wants to communicate with addres=
>s
>>    A, it creates a destination cache entry for A picking a default router
>>    as next hop (because P is not onlink). Later, A can send the reply
>>    directly to M if M's address is onlink. That is likely to cause a
>>    neighbor cache entry for A at M, which will not be used because the
>>    destination cache entry is still in place.
>
>In this instance, the default router would return a Redirect to M to inform
>it that N is a better first hop for reaching address A. The Redirect would
>cause M to update its destination cache accordingly.

I wondered about redirect just after I hit sent. The neighbor discovery RFC
is very explict about the IsRouter flag in the neighbor cache.
In this case M has to set the IsRouter flag for A.

I wonder if A should then always set the Router flag in neighbor advertisements
as well. It looks like it has to, otherwise the neighbor cache will be
flushed.