RE: [DNA] Re: LinkID v.s. Landmark Prefix

["Tero Kauppinen (JO/LMF)" <tero.kauppinen@ericsson.com>]

Hi Brett,

I'm having this endless LinkID v.s. Landmark battle in my head while trying to grasp what has been said and written. 

Anyway, I started think the following naïve example:

 R1 : advertising P1               R2 : adverstining P2
      thus {adv:P1, learned:P2}         thus {adv:P2, learned: P1}

 node H: knows P1, P2 and has chosen P1 as the landmark prefix

Let's assume that R1 stops advertising P1 and starts advertising a new prefix P3. The host doesn't receive RAs and is unaware of the change. The node moves to another AP and gets a "no" answer. The landmark approach indicates wrongly a link change, but CPL will show that there is actually no link change. If I have been able to follow the discussion, it has been said that the CPL decision should overwrite Landmark's decision in this case. 

I agree but I guess a lot of fuzz is because this is not clearly stated in the draft -- should it or is it still an open issue? This would practically mean that every time a "no" answer is received, the current list of all known prefixes on the link is checked in order to confirm that the RA doesn't contain a prefix which is already known to be on the link.

...or am I just once again completely lost? :)

Might also be that we should write down something about the case when a node changes the landmark prefix. If the node received a zero-lifetime advertisement for the current landmark prefix, it should pick another prefix. On the other hand, "5.2.3. The prefix MUST have a non-zero valid lifetime" is a way to say it.

--
Tero 

> -----Original Message-----
> From: owner-dna@ecselists.eng.monash.edu.au [mailto:owner-
> dna@ecselists.eng.monash.edu.au] On Behalf Of Greg Daley
> Sent: 28. heinäkuuta 2005 9:18
> To: Subba Reddy
> Cc: JinHyeock Choi; Erik Nordmark; Syam Madanapalli; Brett Pentland;
> greg.daley@eng.monash.edu.au; James Kempf; Dna
> Subject: Re: [DNA] Re: LinkID v.s. Landmark Prefix
> 
> Hi Subba,
> 
> ----- Original Message -----
> [cut]
> > >
> > > In this case, no change will be detected upon arrival to
> > > link M, and the previous prefix will remain configured.
> > >
> >
> > I am just giving one example, where H may not take wrong decision.
> [cut]
> 
> I understand that LinkID is quite robust against change.
> 
> The point I originally was making was that while it is robust,
> All of the schemes are flawed to some extent.
> 
> Some of the strategies described in LinkID (timers, etc)
> are applicable to all schemes, and would probably be adopted
> in any of the schemes now.
> 
> So the question is: Is the problem big enough that the
> advantage of advertising oldLinkID, gains significantly
> over the other schemes (when timeouts and prefix retraction
> advertisement are recommended)?
> 
> Are the other schemes good enough?
> 
> I don't expect there are clear answers which everyone agrees
> with, but it may be possible to discuss things until
> we agree about the comparison.
> 
> Greg