Re: [DNA] L2 link and L3 link

[Gregory Daley <Greg.Daley@eng.monash.edu.au>]

Hi Bernard, 

----- Original Message -----
From: Bernard Aboba <aboba@internaut.com>
Date: Friday, February 27, 2004 5:43 pm
Subject: Re: [DNA] L2 link and L3 link

> > 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 
> strangeactually.  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 
> thereforethat 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". 
> IP6CPprovides 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 
> reachablevia L2, but not demonstrate L3 reachability.

I guess what I meant by authoritative in this case 
may still need to be checked by neighbour discovery/routing
etc.

Greg