[systemd-devel] networkd: IPv6 prefix delegation not updated when prefix changes

[Kevin P. Fleming]

Yes, I agree with you there.

On the other part I imagine there may be some way to trigger a service
to be run when a prefix on a link is being taken out of service.

On Mon, Apr 13, 2020 at 11:51 AM Tobias Brink <tobias.brink at gmail.com> wrote:
>
> "Kevin P. Fleming" <kevin at km6g.us> writes:
>
> > This is a bit tricky, since RAs and prefix delegation are not really
> > related. [...] What it can't do is trigger a new prefix delegation
> > request as a result, because they are not really related. [...]
> >
> > What you're experiencing here is a delegation which has expired
> > earlier than the DHCPv6 server claimed that it would expire, which is
> > really unfriendly.
>
> OK, so that part might not be fixable or needs some specific workaround
> for my situation. Nevertheless, as soon as networkd sends a Renew for
> the delegated prefix and it gets a NoBinding reponse, it should request a
> new delegated prefix, right? That didn't work for me either, see quoted parts
> below.
>
> > On Mon, Apr 13, 2020 at 11:18 AM Tobias Brink <tobias.brink at gmail.com> wrote:
> >>
> >> 4) Still a bit later, networkd wants to renew the 2001:1:0:1::/64 prefix
> >>    of br0 and sends a DHCPv6 Renew. The ISP-provided router responds
> >>    with "NoBindig", status message "prefix mismatch" (changing later to
> >>    "iapd not found"), which is of course correct. networkd, though, just
> >>    keeps retrying to renew that prefix without success.
> >>
> >> [...]
> >>
> >> At the very least, in step (4), I would have thought that after being
> >> unsuccessful in renewing the prefix, networkd would try to obtain a new
> >> one. RFC 8415 (Sec. 18.2.10.1) seems to agree as far as I understand:
> >> Upon a NoBinding response for any delegated prefix, the client should
> >> send a Request.
>
> Thanks,
>
> Tobias