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

[Tobias Brink]

"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