Re: [DNA] L2 link and L3 link

[Bernard Aboba <aboba@internaut.com>]

> As an aside, It's interesting that Bernard mentioned PPPoE.
>
> PPPoE is inherently an L2 mechanism but defined by IETF.
>
> Do L3 DNA procedures apply here?

Sure, but only once "association" has taken place.  This is not so strange
actually.  In 802.11, class 1 data frames may be sent in State 1, but the
link isn't really "up" until the Reassociation Response is received
(802.11) or the 4-way handshake completes (802.11i).

> It may be that there's no L3 router advertised on the 'Ethernet'
> link. So existing router discovery procedures don't necessarily
> apply.

They will apply when the PPPoE link comes up. But you are correct that a
host needs to be able to recognize when PPPoE is required, so as to know
that it is in the "unauthenticated", "unassociated" state and therefore
that the link is not really "up".

> Should we rely on PADI messages to determine reachability,
> and then provide (authoritative) link hints when IP6CP
> has gone to open state?
>
> (I Guess so).

I think reachability can only be determined once the link is "up". IP6CP
provides an indication of when that occurs.  But I don't think that an L2
message can be used to prove L3 reachability; an endpoint can be reachable
via L2, but not demonstrate L3 reachability.

> >
> > And what about Point of Attachment/ L2 link?
>
> I guess that a (L3) link  is composed of devices
> mutually discoverable through the same set of
> Attachment Points.
>
> We don't need to use the term L2 Link. if
> we can identify the wireless media,
> ethernet segments and etc, as Attachment Points.
>
> Greg
>
>
>