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

[Alexandre Petrescu <[e-mail]>]

Le 16/11/2015 18:53, Philip Homburg a écrit :
>>> 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.

I agree it shoul dbe 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.

Certainly yes.

In the past we tried a problem statement draft about how PD impacts 
routing at Relay.

> There might be more interesting details.

Which ones?

Alex

>
>>> 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.
>
>
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