Re: Understanding IPv6-PD over PPPoE

[Marc Haber <mh+networkmanager-list zugschlus de>]

On Wed, Jun 16, 2021 at 12:44:29PM +0200, Bjørn Mork via networkmanager-list wrote:
> Steve Hill via networkmanager-list <networkmanager-list gnome org>
> writes:
>
> > That's a pain.  It basically makes it impossible for a single-NIC
> > machine to connect to an ISP that is only responding to IA_PD.  (Well, 
> > you can obviously set up a dummy NIC, which can be assigned a prefix,
> > but that's a kludge).
>
> Not at all.  Assigning a global address to lo (loopback) is perfectly
> fine.  No need to assign an address to a link unless you want to assign
> a prefix to it.  And you obviously don't want to do that for the link
> you received the IA_PD from, which is why it isn't allowed.

At least with 1&1 DSL in Germany (via Versatel), the Fritzbox itself
gets an IP address from an entirely different prefix than the prefix
that is eventually delegated for assignment to internal networks.

Unfortunately, it is pretty hard in Germany to get a dedicated VDSL
modem so that you can do the PPPoE yourself, so I can't comment about
the exchanges that go on on the wire.

> There is also the weird 3GPP solution, where you put a /64 hole in the
> IA_PD and assign that /64 prefix to the link.  Ref RFC 6603 and 3GPP TS
> 23.401.  Don't know if that's supported outside the mobile world.  It's
> butt ugly in any case.

I think that using more specifics is just fine. In the Hetzner
datacenter, you get a single /64 routed to your link local address, and
I frequently assign an /128 from this /64 to the external interface and
a /64 address to an internal bridge so that VMs can snarf their
addresses from that /64.

The really nice thing about IPv6 is that it is so darn flexible and
forgiving.

Greetings
Marc

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