Re: [DNA] Confirming today's face-to-face meeting decisions

[Sathya Narayanan <sathya@research.panasonic.com>]

<snip> 
> > 2) Whether immediate change is detected in link-scoped 
> identifier is actually not clear - this is primarily because of 
> the non-dependency of the method on L2 trigger (and that is 
> arguably a good thing), so the average gain in the detection time 
> for link-scoped identifier approach MAY not be very high. Again, 
> we need some analysis.
> 
> I think this is a separate problem.  The point is in being able to 
> makea correct decision based on the reception of a single RA.  How 
> you get that RA is a separate problem.
Yes. It is a separate problem, but when we are talking (comparing) the quickness of link-change-detection we need to look at the complete picture. If the link-scoped approach has the property of link-change-detection when a unsolicited RA is received (which is a good thing about it), but how useful is it if you need the RS message to initiate it for rapid-detection is a valid point to consider in terms of the cost. If the link-scoped approach depends on a RS message, than host-scoped approach is (arguably) as good as the link-scoped approach with less out-of-band cost.


> > 3) I am not recommending timeout as the only change detection - 
> if you think about the mechanism proposed in RRD, when the 
> 'landmark still exists?' question is asked, if you receive a 'this 
> NEW landmark exists' answer thats an indication of link change. 
> Ofcourse, you need to authenticate this response - but in most 
> cases the router that responded is likely to be the router you are 
> going to use as default router and you need to authenticate it anyway.
> 
> I can't remember the details of RRD - are you saying that there is 
> a way
> for an RA with a prefix that you haven't seen before indicates a link
> change as oposed to a new router on the same link?
Yes - if we can design a mechnism that with a high probability can ensure that the confirmation of current landmark (from current AR) is likely to happen before any other router responds. Thats what I am trying to achieve with my MaxDelayForCurrRouter and MinDelayForOtherRouters variables. If these two variables are equal to zero, the probability is 1 - packet loss probability and the time window involved can be few milli-seconds (this needs to be confirmed using simulations, ofcourse).


Sathya