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

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

> And given that we have two different styles to detect the link (an 
> explicit link identifier, compared to what I would characterize as 
> a 
> cookie or a landmark, where the host asks "does this landmark 
> still 
> exist" without an explicit linkid) we should express the need 
> based on 
> the property that a host should be able to determine whether it is 
> on 
> the same link or not from receiving a single message.
Yes. The advantage in using a 'Link Identifier' with a scope applicable to all the nodes in the network is that the host will be able to determine whether it is on the same link or not from receiving a single (RA) message. On the other hand, when such identifier is not available, the host can ask the question 'does this landmark still exist' everytime it has (good) reason to believe it may have changed link. 

Can we refer to the first scheme as 'link scoped identifier' and second as 'host scoped identifier' scheme? ;-)

The question to ask is, whether the cost of establishing the unique link identifier among all the nodes (routers) in the link is worth to avoid an extra 'does this landmark still exists' question and answer? 

Link scoped identifier scheme requires completely securing the link so that nobody can spoof a RA message or confuse the link identifier, while we (I am not sure about this) may not need complete security as long as a secure association between the host and the current AR is good in the host scoped identifier approach.

-Sathya